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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-or-later
 // SPI init/core code
 //
 // Copyright (C) 2005 David Brownell
 // Copyright (C) 2008 Secret Lab Technologies Ltd.
 
 #include <linux/kernel.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/cache.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
 #include <linux/mutex.h>
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
 #include <linux/clk/clk-conf.h>
 #include <linux/slab.h>
 #include <linux/mod_devicetable.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/spi-mem.h>
 #include <linux/gpio/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/pm_domain.h>
 #include <linux/property.h>
 #include <linux/export.h>
 #include <linux/sched/rt.h>
 #include <uapi/linux/sched/types.h>
 #include <linux/delay.h>
 #include <linux/kthread.h>
 #include <linux/ioport.h>
 #include <linux/acpi.h>
 #include <linux/highmem.h>
 #include <linux/idr.h>
 #include <linux/platform_data/x86/apple.h>
 #include <linux/ptp_clock_kernel.h>
 #include <linux/percpu.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/spi.h>
 EXPORT_TRACEPOINT_SYMBOL(spi_transfer_start);
 EXPORT_TRACEPOINT_SYMBOL(spi_transfer_stop);
 
 #include "internals.h"
 
 static DEFINE_IDR(spi_master_idr);
 
 static void spidev_release(struct device *dev)
 {
     struct spi_device   *spi = to_spi_device(dev);
 
     spi_controller_put(spi->controller);
     kfree(spi->driver_override);
     free_percpu(spi->pcpu_statistics);
     kfree(spi);
 }
 
 static ssize_t
 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
 {
     const struct spi_device *spi = to_spi_device(dev);
     int len;
 
     len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
     if (len != -ENODEV)
         return len;
 
     return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
 }
 static DEVICE_ATTR_RO(modalias);
 
 static ssize_t driver_override_store(struct device *dev,
                      struct device_attribute *a,
                      const char *buf, size_t count)
 {
     struct spi_device *spi = to_spi_device(dev);
     int ret;
 
     ret = driver_set_override(dev, &spi->driver_override, buf, count);
     if (ret)
         return ret;
 
     return count;
 }
 
 static ssize_t driver_override_show(struct device *dev,
                     struct device_attribute *a, char *buf)
 {
     const struct spi_device *spi = to_spi_device(dev);
     ssize_t len;
 
     device_lock(dev);
     len = snprintf(buf, PAGE_SIZE, "%s\n", spi->driver_override ? : "");
     device_unlock(dev);
     return len;
 }
 static DEVICE_ATTR_RW(driver_override);
 
 static struct spi_statistics __percpu *spi_alloc_pcpu_stats(struct device *dev)
 {
     struct spi_statistics __percpu *pcpu_stats;
 
     if (dev)
         pcpu_stats = devm_alloc_percpu(dev, struct spi_statistics);
     else
         pcpu_stats = alloc_percpu_gfp(struct spi_statistics, GFP_KERNEL);
 
     if (pcpu_stats) {
         int cpu;
 
         for_each_possible_cpu(cpu) {
             struct spi_statistics *stat;
 
             stat = per_cpu_ptr(pcpu_stats, cpu);
             u64_stats_init(&stat->syncp);
         }
     }
     return pcpu_stats;
 }
 
 #define spi_pcpu_stats_totalize(ret, in, field)             \
 do {                                    \
     int i;                              \
     ret = 0;                            \
     for_each_possible_cpu(i) {                  \
         const struct spi_statistics *pcpu_stats;        \
         u64 inc;                        \
         unsigned int start;                 \
         pcpu_stats = per_cpu_ptr(in, i);            \
         do {                            \
             start = u64_stats_fetch_begin_irq(      \
                     &pcpu_stats->syncp);        \
             inc = u64_stats_read(&pcpu_stats->field);   \
         } while (u64_stats_fetch_retry_irq(         \
                     &pcpu_stats->syncp, start));    \
         ret += inc;                     \
     }                               \
 } while (0)
 
 #define SPI_STATISTICS_ATTRS(field, file)               \
 static ssize_t spi_controller_##field##_show(struct device *dev,    \
                          struct device_attribute *attr, \
                          char *buf)         \
 {                                   \
     struct spi_controller *ctlr = container_of(dev,         \
                      struct spi_controller, dev);   \
     return spi_statistics_##field##_show(ctlr->pcpu_statistics, buf); \
 }                                   \
 static struct device_attribute dev_attr_spi_controller_##field = {  \
     .attr = { .name = file, .mode = 0444 },             \
     .show = spi_controller_##field##_show,              \
 };                                  \
 static ssize_t spi_device_##field##_show(struct device *dev,        \
                      struct device_attribute *attr, \
                     char *buf)          \
 {                                   \
     struct spi_device *spi = to_spi_device(dev);            \
     return spi_statistics_##field##_show(spi->pcpu_statistics, buf); \
 }                                   \
 static struct device_attribute dev_attr_spi_device_##field = {      \
     .attr = { .name = file, .mode = 0444 },             \
     .show = spi_device_##field##_show,              \
 }
 
 #define SPI_STATISTICS_SHOW_NAME(name, file, field)         \
 static ssize_t spi_statistics_##name##_show(struct spi_statistics __percpu *stat, \
                         char *buf)          \
 {                                   \
     ssize_t len;                            \
     u64 val;                            \
     spi_pcpu_stats_totalize(val, stat, field);          \
     len = sysfs_emit(buf, "%llu\n", val);               \
     return len;                         \
 }                                   \
 SPI_STATISTICS_ATTRS(name, file)
 
 #define SPI_STATISTICS_SHOW(field)                  \
     SPI_STATISTICS_SHOW_NAME(field, __stringify(field),     \
                  field)
 
 SPI_STATISTICS_SHOW(messages);
 SPI_STATISTICS_SHOW(transfers);
 SPI_STATISTICS_SHOW(errors);
 SPI_STATISTICS_SHOW(timedout);
 
 SPI_STATISTICS_SHOW(spi_sync);
 SPI_STATISTICS_SHOW(spi_sync_immediate);
 SPI_STATISTICS_SHOW(spi_async);
 
 SPI_STATISTICS_SHOW(bytes);
 SPI_STATISTICS_SHOW(bytes_rx);
 SPI_STATISTICS_SHOW(bytes_tx);
 
 #define SPI_STATISTICS_TRANSFER_BYTES_HISTO(index, number)      \
     SPI_STATISTICS_SHOW_NAME(transfer_bytes_histo##index,       \
                  "transfer_bytes_histo_" number,    \
                  transfer_bytes_histo[index])
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(0,  "0-1");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(1,  "2-3");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(2,  "4-7");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(3,  "8-15");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(4,  "16-31");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(5,  "32-63");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(6,  "64-127");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(7,  "128-255");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(8,  "256-511");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(9,  "512-1023");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(10, "1024-2047");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(11, "2048-4095");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(12, "4096-8191");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(13, "8192-16383");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(14, "16384-32767");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(15, "32768-65535");
 SPI_STATISTICS_TRANSFER_BYTES_HISTO(16, "65536+");
 
 SPI_STATISTICS_SHOW(transfers_split_maxsize);
 
 static struct attribute *spi_dev_attrs[] = {
     &dev_attr_modalias.attr,
     &dev_attr_driver_override.attr,
     NULL,
 };
 
 static const struct attribute_group spi_dev_group = {
     .attrs  = spi_dev_attrs,
 };
 
 static struct attribute *spi_device_statistics_attrs[] = {
     &dev_attr_spi_device_messages.attr,
     &dev_attr_spi_device_transfers.attr,
     &dev_attr_spi_device_errors.attr,
     &dev_attr_spi_device_timedout.attr,
     &dev_attr_spi_device_spi_sync.attr,
     &dev_attr_spi_device_spi_sync_immediate.attr,
     &dev_attr_spi_device_spi_async.attr,
     &dev_attr_spi_device_bytes.attr,
     &dev_attr_spi_device_bytes_rx.attr,
     &dev_attr_spi_device_bytes_tx.attr,
     &dev_attr_spi_device_transfer_bytes_histo0.attr,
     &dev_attr_spi_device_transfer_bytes_histo1.attr,
     &dev_attr_spi_device_transfer_bytes_histo2.attr,
     &dev_attr_spi_device_transfer_bytes_histo3.attr,
     &dev_attr_spi_device_transfer_bytes_histo4.attr,
     &dev_attr_spi_device_transfer_bytes_histo5.attr,
     &dev_attr_spi_device_transfer_bytes_histo6.attr,
     &dev_attr_spi_device_transfer_bytes_histo7.attr,
     &dev_attr_spi_device_transfer_bytes_histo8.attr,
     &dev_attr_spi_device_transfer_bytes_histo9.attr,
     &dev_attr_spi_device_transfer_bytes_histo10.attr,
     &dev_attr_spi_device_transfer_bytes_histo11.attr,
     &dev_attr_spi_device_transfer_bytes_histo12.attr,
     &dev_attr_spi_device_transfer_bytes_histo13.attr,
     &dev_attr_spi_device_transfer_bytes_histo14.attr,
     &dev_attr_spi_device_transfer_bytes_histo15.attr,
     &dev_attr_spi_device_transfer_bytes_histo16.attr,
     &dev_attr_spi_device_transfers_split_maxsize.attr,
     NULL,
 };
 
 static const struct attribute_group spi_device_statistics_group = {
     .name  = "statistics",
     .attrs  = spi_device_statistics_attrs,
 };
 
 static const struct attribute_group *spi_dev_groups[] = {
     &spi_dev_group,
     &spi_device_statistics_group,
     NULL,
 };
 
 static struct attribute *spi_controller_statistics_attrs[] = {
     &dev_attr_spi_controller_messages.attr,
     &dev_attr_spi_controller_transfers.attr,
     &dev_attr_spi_controller_errors.attr,
     &dev_attr_spi_controller_timedout.attr,
     &dev_attr_spi_controller_spi_sync.attr,
     &dev_attr_spi_controller_spi_sync_immediate.attr,
     &dev_attr_spi_controller_spi_async.attr,
     &dev_attr_spi_controller_bytes.attr,
     &dev_attr_spi_controller_bytes_rx.attr,
     &dev_attr_spi_controller_bytes_tx.attr,
     &dev_attr_spi_controller_transfer_bytes_histo0.attr,
     &dev_attr_spi_controller_transfer_bytes_histo1.attr,
     &dev_attr_spi_controller_transfer_bytes_histo2.attr,
     &dev_attr_spi_controller_transfer_bytes_histo3.attr,
     &dev_attr_spi_controller_transfer_bytes_histo4.attr,
     &dev_attr_spi_controller_transfer_bytes_histo5.attr,
     &dev_attr_spi_controller_transfer_bytes_histo6.attr,
     &dev_attr_spi_controller_transfer_bytes_histo7.attr,
     &dev_attr_spi_controller_transfer_bytes_histo8.attr,
     &dev_attr_spi_controller_transfer_bytes_histo9.attr,
     &dev_attr_spi_controller_transfer_bytes_histo10.attr,
     &dev_attr_spi_controller_transfer_bytes_histo11.attr,
     &dev_attr_spi_controller_transfer_bytes_histo12.attr,
     &dev_attr_spi_controller_transfer_bytes_histo13.attr,
     &dev_attr_spi_controller_transfer_bytes_histo14.attr,
     &dev_attr_spi_controller_transfer_bytes_histo15.attr,
     &dev_attr_spi_controller_transfer_bytes_histo16.attr,
     &dev_attr_spi_controller_transfers_split_maxsize.attr,
     NULL,
 };
 
 static const struct attribute_group spi_controller_statistics_group = {
     .name  = "statistics",
     .attrs  = spi_controller_statistics_attrs,
 };
 
 static const struct attribute_group *spi_master_groups[] = {
     &spi_controller_statistics_group,
     NULL,
 };
 
 static void spi_statistics_add_transfer_stats(struct spi_statistics __percpu *pcpu_stats,
                           struct spi_transfer *xfer,
                           struct spi_controller *ctlr)
 {
     int l2len = min(fls(xfer->len), SPI_STATISTICS_HISTO_SIZE) - 1;
     struct spi_statistics *stats;
 
     if (l2len < 0)
         l2len = 0;
 
     get_cpu();
     stats = this_cpu_ptr(pcpu_stats);
     u64_stats_update_begin(&stats->syncp);
 
     u64_stats_inc(&stats->transfers);
     u64_stats_inc(&stats->transfer_bytes_histo[l2len]);
 
     u64_stats_add(&stats->bytes, xfer->len);
     if ((xfer->tx_buf) &&
         (xfer->tx_buf != ctlr->dummy_tx))
         u64_stats_add(&stats->bytes_tx, xfer->len);
     if ((xfer->rx_buf) &&
         (xfer->rx_buf != ctlr->dummy_rx))
         u64_stats_add(&stats->bytes_rx, xfer->len);
 
     u64_stats_update_end(&stats->syncp);
     put_cpu();
 }
 
 /*
  * modalias support makes "modprobe $MODALIAS" new-style hotplug work,
  * and the sysfs version makes coldplug work too.
  */
 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id, const char *name)
 {
     while (id->name[0]) {
         if (!strcmp(name, id->name))
             return id;
         id++;
     }
     return NULL;
 }
 
 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
 {
     const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
 
     return spi_match_id(sdrv->id_table, sdev->modalias);
 }
 EXPORT_SYMBOL_GPL(spi_get_device_id);
 
 static int spi_match_device(struct device *dev, struct device_driver *drv)
 {
     const struct spi_device *spi = to_spi_device(dev);
     const struct spi_driver *sdrv = to_spi_driver(drv);
 
     /* Check override first, and if set, only use the named driver */
     if (spi->driver_override)
         return strcmp(spi->driver_override, drv->name) == 0;
 
     /* Attempt an OF style match */
     if (of_driver_match_device(dev, drv))
         return 1;
 
     /* Then try ACPI */
     if (acpi_driver_match_device(dev, drv))
         return 1;
 
     if (sdrv->id_table)
         return !!spi_match_id(sdrv->id_table, spi->modalias);
 
     return strcmp(spi->modalias, drv->name) == 0;
 }
 
 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
     const struct spi_device     *spi = to_spi_device(dev);
     int rc;
 
     rc = acpi_device_uevent_modalias(dev, env);
     if (rc != -ENODEV)
         return rc;
 
     return add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
 }
 
 static int spi_probe(struct device *dev)
 {
     const struct spi_driver     *sdrv = to_spi_driver(dev->driver);
     struct spi_device       *spi = to_spi_device(dev);
     int ret;
 
     ret = of_clk_set_defaults(dev->of_node, false);
     if (ret)
         return ret;
 
     if (dev->of_node) {
         spi->irq = of_irq_get(dev->of_node, 0);
         if (spi->irq == -EPROBE_DEFER)
             return -EPROBE_DEFER;
         if (spi->irq < 0)
             spi->irq = 0;
     }
 
     ret = dev_pm_domain_attach(dev, true);
     if (ret)
         return ret;
 
     if (sdrv->probe) {
         ret = sdrv->probe(spi);
         if (ret)
             dev_pm_domain_detach(dev, true);
     }
 
     return ret;
 }
 
 static void spi_remove(struct device *dev)
 {
     const struct spi_driver     *sdrv = to_spi_driver(dev->driver);
 
     if (sdrv->remove)
         sdrv->remove(to_spi_device(dev));
 
     dev_pm_domain_detach(dev, true);
 }
 
 static void spi_shutdown(struct device *dev)
 {
     if (dev->driver) {
         const struct spi_driver *sdrv = to_spi_driver(dev->driver);
 
         if (sdrv->shutdown)
             sdrv->shutdown(to_spi_device(dev));
     }
 }
 
 struct bus_type spi_bus_type = {
     .name       = "spi",
     .dev_groups = spi_dev_groups,
     .match      = spi_match_device,
     .uevent     = spi_uevent,
     .probe      = spi_probe,
     .remove     = spi_remove,
     .shutdown   = spi_shutdown,
 };
 EXPORT_SYMBOL_GPL(spi_bus_type);
 
 /**
  * __spi_register_driver - register a SPI driver
  * @owner: owner module of the driver to register
  * @sdrv: the driver to register
  * Context: can sleep
  *
  * Return: zero on success, else a negative error code.
  */
 int __spi_register_driver(struct module *owner, struct spi_driver *sdrv)
 {
     sdrv->driver.owner = owner;
     sdrv->driver.bus = &spi_bus_type;
 
     /*
      * For Really Good Reasons we use spi: modaliases not of:
      * modaliases for DT so module autoloading won't work if we
      * don't have a spi_device_id as well as a compatible string.
      */
     if (sdrv->driver.of_match_table) {
         const struct of_device_id *of_id;
 
         for (of_id = sdrv->driver.of_match_table; of_id->compatible[0];
              of_id++) {
             const char *of_name;
 
             /* Strip off any vendor prefix */
             of_name = strnchr(of_id->compatible,
                       sizeof(of_id->compatible), ',');
             if (of_name)
                 of_name++;
             else
                 of_name = of_id->compatible;
 
             if (sdrv->id_table) {
                 const struct spi_device_id *spi_id;
 
                 spi_id = spi_match_id(sdrv->id_table, of_name);
                 if (spi_id)
                     continue;
             } else {
                 if (strcmp(sdrv->driver.name, of_name) == 0)
                     continue;
             }
 
             pr_warn("SPI driver %s has no spi_device_id for %s\n",
                 sdrv->driver.name, of_id->compatible);
         }
     }
 
     return driver_register(&sdrv->driver);
 }
 EXPORT_SYMBOL_GPL(__spi_register_driver);
 
 /*-------------------------------------------------------------------------*/
 
 /*
  * SPI devices should normally not be created by SPI device drivers; that
  * would make them board-specific.  Similarly with SPI controller drivers.
  * Device registration normally goes into like arch/.../mach.../board-YYY.c
  * with other readonly (flashable) information about mainboard devices.
  */
 
 struct boardinfo {
     struct list_head    list;
     struct spi_board_info   board_info;
 };
 
 static LIST_HEAD(board_list);
 static LIST_HEAD(spi_controller_list);
 
 /*
  * Used to protect add/del operation for board_info list and
  * spi_controller list, and their matching process also used
  * to protect object of type struct idr.
  */
 static DEFINE_MUTEX(board_lock);
 
 /**
  * spi_alloc_device - Allocate a new SPI device
  * @ctlr: Controller to which device is connected
  * Context: can sleep
  *
  * Allows a driver to allocate and initialize a spi_device without
  * registering it immediately.  This allows a driver to directly
  * fill the spi_device with device parameters before calling
  * spi_add_device() on it.
  *
  * Caller is responsible to call spi_add_device() on the returned
  * spi_device structure to add it to the SPI controller.  If the caller
  * needs to discard the spi_device without adding it, then it should
  * call spi_dev_put() on it.
  *
  * Return: a pointer to the new device, or NULL.
  */
 struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
 {
     struct spi_device   *spi;
 
     if (!spi_controller_get(ctlr))
         return NULL;
 
     spi = kzalloc(sizeof(*spi), GFP_KERNEL);
     if (!spi) {
         spi_controller_put(ctlr);
         return NULL;
     }
 
     spi->pcpu_statistics = spi_alloc_pcpu_stats(NULL);
     if (!spi->pcpu_statistics) {
         kfree(spi);
         spi_controller_put(ctlr);
         return NULL;
     }
 
     spi->master = spi->controller = ctlr;
     spi->dev.parent = &ctlr->dev;
     spi->dev.bus = &spi_bus_type;
     spi->dev.release = spidev_release;
     spi->mode = ctlr->buswidth_override_bits;
 
     device_initialize(&spi->dev);
     return spi;
 }
 EXPORT_SYMBOL_GPL(spi_alloc_device);
 
 static void spi_dev_set_name(struct spi_device *spi)
 {
     struct acpi_device *adev = ACPI_COMPANION(&spi->dev);
 
     if (adev) {
         dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
         return;
     }
 
     dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->controller->dev),
              spi->chip_select);
 }
 
 static int spi_dev_check(struct device *dev, void *data)
 {
     struct spi_device *spi = to_spi_device(dev);
     struct spi_device *new_spi = data;
 
     if (spi->controller == new_spi->controller &&
         spi->chip_select == new_spi->chip_select)
         return -EBUSY;
     return 0;
 }
 
 static void spi_cleanup(struct spi_device *spi)
 {
     if (spi->controller->cleanup)
         spi->controller->cleanup(spi);
 }
 
 static int __spi_add_device(struct spi_device *spi)
 {
     struct spi_controller *ctlr = spi->controller;
     struct device *dev = ctlr->dev.parent;
     int status;
 
     /*
      * We need to make sure there's no other device with this
      * chipselect **BEFORE** we call setup(), else we'll trash
      * its configuration.
      */
     status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
     if (status) {
         dev_err(dev, "chipselect %d already in use\n",
                 spi->chip_select);
         return status;
     }
 
     /* Controller may unregister concurrently */
     if (IS_ENABLED(CONFIG_SPI_DYNAMIC) &&
         !device_is_registered(&ctlr->dev)) {
         return -ENODEV;
     }
 
     if (ctlr->cs_gpiods)
         spi->cs_gpiod = ctlr->cs_gpiods[spi->chip_select];
 
     /*
      * Drivers may modify this initial i/o setup, but will
      * normally rely on the device being setup.  Devices
      * using SPI_CS_HIGH can't coexist well otherwise...
      */
     status = spi_setup(spi);
     if (status < 0) {
         dev_err(dev, "can't setup %s, status %d\n",
                 dev_name(&spi->dev), status);
         return status;
     }
 
     /* Device may be bound to an active driver when this returns */
     status = device_add(&spi->dev);
     if (status < 0) {
         dev_err(dev, "can't add %s, status %d\n",
                 dev_name(&spi->dev), status);
         spi_cleanup(spi);
     } else {
         dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
     }
 
     return status;
 }
 
 /**
  * spi_add_device - Add spi_device allocated with spi_alloc_device
  * @spi: spi_device to register
  *
  * Companion function to spi_alloc_device.  Devices allocated with
  * spi_alloc_device can be added onto the spi bus with this function.
  *
  * Return: 0 on success; negative errno on failure
  */
 int spi_add_device(struct spi_device *spi)
 {
     struct spi_controller *ctlr = spi->controller;
     struct device *dev = ctlr->dev.parent;
     int status;
 
     /* Chipselects are numbered 0..max; validate. */
     if (spi->chip_select >= ctlr->num_chipselect) {
         dev_err(dev, "cs%d >= max %d\n", spi->chip_select,
             ctlr->num_chipselect);
         return -EINVAL;
     }
 
     /* Set the bus ID string */
     spi_dev_set_name(spi);
 
     mutex_lock(&ctlr->add_lock);
     status = __spi_add_device(spi);
     mutex_unlock(&ctlr->add_lock);
     return status;
 }
 EXPORT_SYMBOL_GPL(spi_add_device);
 
 static int spi_add_device_locked(struct spi_device *spi)
 {
     struct spi_controller *ctlr = spi->controller;
     struct device *dev = ctlr->dev.parent;
 
     /* Chipselects are numbered 0..max; validate. */
     if (spi->chip_select >= ctlr->num_chipselect) {
         dev_err(dev, "cs%d >= max %d\n", spi->chip_select,
             ctlr->num_chipselect);
         return -EINVAL;
     }
 
     /* Set the bus ID string */
     spi_dev_set_name(spi);
 
     WARN_ON(!mutex_is_locked(&ctlr->add_lock));
     return __spi_add_device(spi);
 }
 
 /**
  * spi_new_device - instantiate one new SPI device
  * @ctlr: Controller to which device is connected
  * @chip: Describes the SPI device
  * Context: can sleep
  *
  * On typical mainboards, this is purely internal; and it's not needed
  * after board init creates the hard-wired devices.  Some development
  * platforms may not be able to use spi_register_board_info though, and
  * this is exported so that for example a USB or parport based adapter
  * driver could add devices (which it would learn about out-of-band).
  *
  * Return: the new device, or NULL.
  */
 struct spi_device *spi_new_device(struct spi_controller *ctlr,
                   struct spi_board_info *chip)
 {
     struct spi_device   *proxy;
     int         status;
 
     /*
      * NOTE:  caller did any chip->bus_num checks necessary.
      *
      * Also, unless we change the return value convention to use
      * error-or-pointer (not NULL-or-pointer), troubleshootability
      * suggests syslogged diagnostics are best here (ugh).
      */
 
     proxy = spi_alloc_device(ctlr);
     if (!proxy)
         return NULL;
 
     WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
 
     proxy->chip_select = chip->chip_select;
     proxy->max_speed_hz = chip->max_speed_hz;
     proxy->mode = chip->mode;
     proxy->irq = chip->irq;
     strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
     proxy->dev.platform_data = (void *) chip->platform_data;
     proxy->controller_data = chip->controller_data;
     proxy->controller_state = NULL;
 
     if (chip->swnode) {
         status = device_add_software_node(&proxy->dev, chip->swnode);
         if (status) {
             dev_err(&ctlr->dev, "failed to add software node to '%s': %d\n",
                 chip->modalias, status);
             goto err_dev_put;
         }
     }
 
     status = spi_add_device(proxy);
     if (status < 0)
         goto err_dev_put;
 
     return proxy;
 
 err_dev_put:
     device_remove_software_node(&proxy->dev);
     spi_dev_put(proxy);
     return NULL;
 }
 EXPORT_SYMBOL_GPL(spi_new_device);
 
 /**
  * spi_unregister_device - unregister a single SPI device
  * @spi: spi_device to unregister
  *
  * Start making the passed SPI device vanish. Normally this would be handled
  * by spi_unregister_controller().
  */
 void spi_unregister_device(struct spi_device *spi)
 {
     if (!spi)
         return;
 
     if (spi->dev.of_node) {
         of_node_clear_flag(spi->dev.of_node, OF_POPULATED);
         of_node_put(spi->dev.of_node);
     }
     if (ACPI_COMPANION(&spi->dev))
         acpi_device_clear_enumerated(ACPI_COMPANION(&spi->dev));
     device_remove_software_node(&spi->dev);
     device_del(&spi->dev);
     spi_cleanup(spi);
     put_device(&spi->dev);
 }
 EXPORT_SYMBOL_GPL(spi_unregister_device);
 
 static void spi_match_controller_to_boardinfo(struct spi_controller *ctlr,
                           struct spi_board_info *bi)
 {
     struct spi_device *dev;
 
     if (ctlr->bus_num != bi->bus_num)
         return;
 
     dev = spi_new_device(ctlr, bi);
     if (!dev)
         dev_err(ctlr->dev.parent, "can't create new device for %s\n",
             bi->modalias);
 }
 
 /**
  * spi_register_board_info - register SPI devices for a given board
  * @info: array of chip descriptors
  * @n: how many descriptors are provided
  * Context: can sleep
  *
  * Board-specific early init code calls this (probably during arch_initcall)
  * with segments of the SPI device table.  Any device nodes are created later,
  * after the relevant parent SPI controller (bus_num) is defined.  We keep
  * this table of devices forever, so that reloading a controller driver will
  * not make Linux forget about these hard-wired devices.
  *
  * Other code can also call this, e.g. a particular add-on board might provide
  * SPI devices through its expansion connector, so code initializing that board
  * would naturally declare its SPI devices.
  *
  * The board info passed can safely be __initdata ... but be careful of
  * any embedded pointers (platform_data, etc), they're copied as-is.
  *
  * Return: zero on success, else a negative error code.
  */
 int spi_register_board_info(struct spi_board_info const *info, unsigned n)
 {
     struct boardinfo *bi;
     int i;
 
     if (!n)
         return 0;
 
     bi = kcalloc(n, sizeof(*bi), GFP_KERNEL);
     if (!bi)
         return -ENOMEM;
 
     for (i = 0; i < n; i++, bi++, info++) {
         struct spi_controller *ctlr;
 
         memcpy(&bi->board_info, info, sizeof(*info));
 
         mutex_lock(&board_lock);
         list_add_tail(&bi->list, &board_list);
         list_for_each_entry(ctlr, &spi_controller_list, list)
             spi_match_controller_to_boardinfo(ctlr,
                               &bi->board_info);
         mutex_unlock(&board_lock);
     }
 
     return 0;
 }
 
 /*-------------------------------------------------------------------------*/
 
 /* Core methods for SPI resource management */
 
 /**
  * spi_res_alloc - allocate a spi resource that is life-cycle managed
  *                 during the processing of a spi_message while using
  *                 spi_transfer_one
  * @spi:     the spi device for which we allocate memory
  * @release: the release code to execute for this resource
  * @size:    size to alloc and return
  * @gfp:     GFP allocation flags
  *
  * Return: the pointer to the allocated data
  *
  * This may get enhanced in the future to allocate from a memory pool
  * of the @spi_device or @spi_controller to avoid repeated allocations.
  */
 static void *spi_res_alloc(struct spi_device *spi, spi_res_release_t release,
                size_t size, gfp_t gfp)
 {
     struct spi_res *sres;
 
     sres = kzalloc(sizeof(*sres) + size, gfp);
     if (!sres)
         return NULL;
 
     INIT_LIST_HEAD(&sres->entry);
     sres->release = release;
 
     return sres->data;
 }
 
 /**
  * spi_res_free - free an spi resource
  * @res: pointer to the custom data of a resource
  */
 static void spi_res_free(void *res)
 {
     struct spi_res *sres = container_of(res, struct spi_res, data);
 
     if (!res)
         return;
 
     WARN_ON(!list_empty(&sres->entry));
     kfree(sres);
 }
 
 /**
  * spi_res_add - add a spi_res to the spi_message
  * @message: the spi message
  * @res:     the spi_resource
  */
 static void spi_res_add(struct spi_message *message, void *res)
 {
     struct spi_res *sres = container_of(res, struct spi_res, data);
 
     WARN_ON(!list_empty(&sres->entry));
     list_add_tail(&sres->entry, &message->resources);
 }
 
 /**
  * spi_res_release - release all spi resources for this message
  * @ctlr:  the @spi_controller
  * @message: the @spi_message
  */
 static void spi_res_release(struct spi_controller *ctlr, struct spi_message *message)
 {
     struct spi_res *res, *tmp;
 
     list_for_each_entry_safe_reverse(res, tmp, &message->resources, entry) {
         if (res->release)
             res->release(ctlr, message, res->data);
 
         list_del(&res->entry);
 
         kfree(res);
     }
 }
 
 /*-------------------------------------------------------------------------*/
 
 static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 {
     bool activate = enable;
 
     /*
      * Avoid calling into the driver (or doing delays) if the chip select
      * isn't actually changing from the last time this was called.
      */
     if (!force && ((enable && spi->controller->last_cs == spi->chip_select) ||
                 (!enable && spi->controller->last_cs != spi->chip_select)) &&
         (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH)))
         return;
 
     trace_spi_set_cs(spi, activate);
 
     spi->controller->last_cs = enable ? spi->chip_select : -1;
     spi->controller->last_cs_mode_high = spi->mode & SPI_CS_HIGH;
 
     if ((spi->cs_gpiod || !spi->controller->set_cs_timing) && !activate) {
         spi_delay_exec(&spi->cs_hold, NULL);
     }
 
     if (spi->mode & SPI_CS_HIGH)
         enable = !enable;
 
     if (spi->cs_gpiod) {
         if (!(spi->mode & SPI_NO_CS)) {
             /*
              * Historically ACPI has no means of the GPIO polarity and
              * thus the SPISerialBus() resource defines it on the per-chip
              * basis. In order to avoid a chain of negations, the GPIO
              * polarity is considered being Active High. Even for the cases
              * when _DSD() is involved (in the updated versions of ACPI)
              * the GPIO CS polarity must be defined Active High to avoid
              * ambiguity. That's why we use enable, that takes SPI_CS_HIGH
              * into account.
              */
             if (has_acpi_companion(&spi->dev))
                 gpiod_set_value_cansleep(spi->cs_gpiod, !enable);
             else
                 /* Polarity handled by GPIO library */
                 gpiod_set_value_cansleep(spi->cs_gpiod, activate);
         }
         /* Some SPI masters need both GPIO CS & slave_select */
         if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
             spi->controller->set_cs)
             spi->controller->set_cs(spi, !enable);
     } else if (spi->controller->set_cs) {
         spi->controller->set_cs(spi, !enable);
     }
 
     if (spi->cs_gpiod || !spi->controller->set_cs_timing) {
         if (activate)
             spi_delay_exec(&spi->cs_setup, NULL);
         else
             spi_delay_exec(&spi->cs_inactive, NULL);
     }
 }
 
 #ifdef CONFIG_HAS_DMA
 int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
         struct sg_table *sgt, void *buf, size_t len,
         enum dma_data_direction dir)
 {
     const bool vmalloced_buf = is_vmalloc_addr(buf);
     unsigned int max_seg_size = dma_get_max_seg_size(dev);
 #ifdef CONFIG_HIGHMEM
     const bool kmap_buf = ((unsigned long)buf >= PKMAP_BASE &&
                 (unsigned long)buf < (PKMAP_BASE +
                     (LAST_PKMAP * PAGE_SIZE)));
 #else
     const bool kmap_buf = false;
 #endif
     int desc_len;
     int sgs;
     struct page *vm_page;
     struct scatterlist *sg;
     void *sg_buf;
     size_t min;
     int i, ret;
 
     if (vmalloced_buf || kmap_buf) {
         desc_len = min_t(unsigned long, max_seg_size, PAGE_SIZE);
         sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
     } else if (virt_addr_valid(buf)) {
         desc_len = min_t(size_t, max_seg_size, ctlr->max_dma_len);
         sgs = DIV_ROUND_UP(len, desc_len);
     } else {
         return -EINVAL;
     }
 
     ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
     if (ret != 0)
         return ret;
 
     sg = &sgt->sgl[0];
     for (i = 0; i < sgs; i++) {
 
         if (vmalloced_buf || kmap_buf) {
             /*
              * Next scatterlist entry size is the minimum between
              * the desc_len and the remaining buffer length that
              * fits in a page.
              */
             min = min_t(size_t, desc_len,
                     min_t(size_t, len,
                       PAGE_SIZE - offset_in_page(buf)));
             if (vmalloced_buf)
                 vm_page = vmalloc_to_page(buf);
             else
                 vm_page = kmap_to_page(buf);
             if (!vm_page) {
                 sg_free_table(sgt);
                 return -ENOMEM;
             }
             sg_set_page(sg, vm_page,
                     min, offset_in_page(buf));
         } else {
             min = min_t(size_t, len, desc_len);
             sg_buf = buf;
             sg_set_buf(sg, sg_buf, min);
         }
 
         buf += min;
         len -= min;
         sg = sg_next(sg);
     }
 
     ret = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
     if (!ret)
         ret = -ENOMEM;
     if (ret < 0) {
         sg_free_table(sgt);
         return ret;
     }
 
     sgt->nents = ret;
 
     return 0;
 }
 
 void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
            struct sg_table *sgt, enum dma_data_direction dir)
 {
     if (sgt->orig_nents) {
         dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
         sg_free_table(sgt);
     }
 }
 
 static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
 {
     struct device *tx_dev, *rx_dev;
     struct spi_transfer *xfer;
     int ret;
 
     if (!ctlr->can_dma)
         return 0;
 
     if (ctlr->dma_tx)
         tx_dev = ctlr->dma_tx->device->dev;
     else if (ctlr->dma_map_dev)
         tx_dev = ctlr->dma_map_dev;
     else
         tx_dev = ctlr->dev.parent;
 
     if (ctlr->dma_rx)
         rx_dev = ctlr->dma_rx->device->dev;
     else if (ctlr->dma_map_dev)
         rx_dev = ctlr->dma_map_dev;
     else
         rx_dev = ctlr->dev.parent;
 
     list_for_each_entry(xfer, &msg->transfers, transfer_list) {
         if (!ctlr->can_dma(ctlr, msg->spi, xfer))
             continue;
 
         if (xfer->tx_buf != NULL) {
             ret = spi_map_buf(ctlr, tx_dev, &xfer->tx_sg,
                       (void *)xfer->tx_buf, xfer->len,
                       DMA_TO_DEVICE);
             if (ret != 0)
                 return ret;
         }
 
         if (xfer->rx_buf != NULL) {
             ret = spi_map_buf(ctlr, rx_dev, &xfer->rx_sg,
                       xfer->rx_buf, xfer->len,
                       DMA_FROM_DEVICE);
             if (ret != 0) {
                 spi_unmap_buf(ctlr, tx_dev, &xfer->tx_sg,
                           DMA_TO_DEVICE);
                 return ret;
             }
         }
     }
 
     ctlr->cur_msg_mapped = true;
 
     return 0;
 }
 
 static int __spi_unmap_msg(struct spi_controller *ctlr, struct spi_message *msg)
 {
     struct spi_transfer *xfer;
     struct device *tx_dev, *rx_dev;
 
     if (!ctlr->cur_msg_mapped || !ctlr->can_dma)
         return 0;
 
     if (ctlr->dma_tx)
         tx_dev = ctlr->dma_tx->device->dev;
     else if (ctlr->dma_map_dev)
         tx_dev = ctlr->dma_map_dev;
     else
         tx_dev = ctlr->dev.parent;
 
     if (ctlr->dma_rx)
         rx_dev = ctlr->dma_rx->device->dev;
     else if (ctlr->dma_map_dev)
         rx_dev = ctlr->dma_map_dev;
     else
         rx_dev = ctlr->dev.parent;
 
     list_for_each_entry(xfer, &msg->transfers, transfer_list) {
         if (!ctlr->can_dma(ctlr, msg->spi, xfer))
             continue;
 
         spi_unmap_buf(ctlr, rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE);
         spi_unmap_buf(ctlr, tx_dev, &xfer->tx_sg, DMA_TO_DEVICE);
     }
 
     ctlr->cur_msg_mapped = false;
 
     return 0;
 }
 #else /* !CONFIG_HAS_DMA */
 static inline int __spi_map_msg(struct spi_controller *ctlr,
                 struct spi_message *msg)
 {
     return 0;
 }
 
 static inline int __spi_unmap_msg(struct spi_controller *ctlr,
                   struct spi_message *msg)
 {
     return 0;
 }
 #endif /* !CONFIG_HAS_DMA */
 
 static inline int spi_unmap_msg(struct spi_controller *ctlr,
                 struct spi_message *msg)
 {
     struct spi_transfer *xfer;
 
     list_for_each_entry(xfer, &msg->transfers, transfer_list) {
         /*
          * Restore the original value of tx_buf or rx_buf if they are
          * NULL.
          */
         if (xfer->tx_buf == ctlr->dummy_tx)
             xfer->tx_buf = NULL;
         if (xfer->rx_buf == ctlr->dummy_rx)
             xfer->rx_buf = NULL;
     }
 
     return __spi_unmap_msg(ctlr, msg);
 }
 
 static int spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
 {
     struct spi_transfer *xfer;
     void *tmp;
     unsigned int max_tx, max_rx;
 
     if ((ctlr->flags & (SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX))
         && !(msg->spi->mode & SPI_3WIRE)) {
         max_tx = 0;
         max_rx = 0;
 
         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
             if ((ctlr->flags & SPI_CONTROLLER_MUST_TX) &&
                 !xfer->tx_buf)
                 max_tx = max(xfer->len, max_tx);
             if ((ctlr->flags & SPI_CONTROLLER_MUST_RX) &&
                 !xfer->rx_buf)
                 max_rx = max(xfer->len, max_rx);
         }
 
         if (max_tx) {
             tmp = krealloc(ctlr->dummy_tx, max_tx,
                        GFP_KERNEL | GFP_DMA | __GFP_ZERO);
             if (!tmp)
                 return -ENOMEM;
             ctlr->dummy_tx = tmp;
         }
 
         if (max_rx) {
             tmp = krealloc(ctlr->dummy_rx, max_rx,
                        GFP_KERNEL | GFP_DMA);
             if (!tmp)
                 return -ENOMEM;
             ctlr->dummy_rx = tmp;
         }
 
         if (max_tx || max_rx) {
             list_for_each_entry(xfer, &msg->transfers,
                         transfer_list) {
                 if (!xfer->len)
                     continue;
                 if (!xfer->tx_buf)
                     xfer->tx_buf = ctlr->dummy_tx;
                 if (!xfer->rx_buf)
                     xfer->rx_buf = ctlr->dummy_rx;
             }
         }
     }
 
     return __spi_map_msg(ctlr, msg);
 }
 
 static int spi_transfer_wait(struct spi_controller *ctlr,
                  struct spi_message *msg,
                  struct spi_transfer *xfer)
 {
     struct spi_statistics __percpu *statm = ctlr->pcpu_statistics;
     struct spi_statistics __percpu *stats = msg->spi->pcpu_statistics;
     u32 speed_hz = xfer->speed_hz;
     unsigned long long ms;
 
     if (spi_controller_is_slave(ctlr)) {
         if (wait_for_completion_interruptible(&ctlr->xfer_completion)) {
             dev_dbg(&msg->spi->dev, "SPI transfer interrupted\n");
             return -EINTR;
         }
     } else {
         if (!speed_hz)
             speed_hz = 100000;
 
         /*
          * For each byte we wait for 8 cycles of the SPI clock.
          * Since speed is defined in Hz and we want milliseconds,
          * use respective multiplier, but before the division,
          * otherwise we may get 0 for short transfers.
          */
         ms = 8LL * MSEC_PER_SEC * xfer->len;
         do_div(ms, speed_hz);
 
         /*
          * Increase it twice and add 200 ms tolerance, use
          * predefined maximum in case of overflow.
          */
         ms += ms + 200;
         if (ms > UINT_MAX)
             ms = UINT_MAX;
 
         ms = wait_for_completion_timeout(&ctlr->xfer_completion,
                          msecs_to_jiffies(ms));
 
         if (ms == 0) {
             SPI_STATISTICS_INCREMENT_FIELD(statm, timedout);
             SPI_STATISTICS_INCREMENT_FIELD(stats, timedout);
             dev_err(&msg->spi->dev,
                 "SPI transfer timed out\n");
             return -ETIMEDOUT;
         }
     }
 
     return 0;
 }
 
 static void _spi_transfer_delay_ns(u32 ns)
 {
     if (!ns)
         return;
     if (ns <= NSEC_PER_USEC) {
         ndelay(ns);
     } else {
         u32 us = DIV_ROUND_UP(ns, NSEC_PER_USEC);
 
         if (us <= 10)
             udelay(us);
         else
             usleep_range(us, us + DIV_ROUND_UP(us, 10));
     }
 }
 
 int spi_delay_to_ns(struct spi_delay *_delay, struct spi_transfer *xfer)
 {
     u32 delay = _delay->value;
     u32 unit = _delay->unit;
     u32 hz;
 
     if (!delay)
         return 0;
 
     switch (unit) {
     case SPI_DELAY_UNIT_USECS:
         delay *= NSEC_PER_USEC;
         break;
     case SPI_DELAY_UNIT_NSECS:
         /* Nothing to do here */
         break;
     case SPI_DELAY_UNIT_SCK:
         /* Clock cycles need to be obtained from spi_transfer */
         if (!xfer)
             return -EINVAL;
         /*
          * If there is unknown effective speed, approximate it
          * by underestimating with half of the requested hz.
          */
         hz = xfer->effective_speed_hz ?: xfer->speed_hz / 2;
         if (!hz)
             return -EINVAL;
 
         /* Convert delay to nanoseconds */
         delay *= DIV_ROUND_UP(NSEC_PER_SEC, hz);
         break;
     default:
         return -EINVAL;
     }
 
     return delay;
 }
 EXPORT_SYMBOL_GPL(spi_delay_to_ns);
 
 int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer)
 {
     int delay;
 
     might_sleep();
 
     if (!_delay)
         return -EINVAL;
 
     delay = spi_delay_to_ns(_delay, xfer);
     if (delay < 0)
         return delay;
 
     _spi_transfer_delay_ns(delay);
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(spi_delay_exec);
 
 static void _spi_transfer_cs_change_delay(struct spi_message *msg,
                       struct spi_transfer *xfer)
 {
     u32 default_delay_ns = 10 * NSEC_PER_USEC;
     u32 delay = xfer->cs_change_delay.value;
     u32 unit = xfer->cs_change_delay.unit;
     int ret;
 
     /* Return early on "fast" mode - for everything but USECS */
     if (!delay) {
         if (unit == SPI_DELAY_UNIT_USECS)
             _spi_transfer_delay_ns(default_delay_ns);
         return;
     }
 
     ret = spi_delay_exec(&xfer->cs_change_delay, xfer);
     if (ret) {
         dev_err_once(&msg->spi->dev,
                  "Use of unsupported delay unit %i, using default of %luus\n",
                  unit, default_delay_ns / NSEC_PER_USEC);
         _spi_transfer_delay_ns(default_delay_ns);
     }
 }
 
 /*
  * spi_transfer_one_message - Default implementation of transfer_one_message()
  *
  * This is a standard implementation of transfer_one_message() for
  * drivers which implement a transfer_one() operation.  It provides
  * standard handling of delays and chip select management.
  */
 static int spi_transfer_one_message(struct spi_controller *ctlr,
                     struct spi_message *msg)
 {
     struct spi_transfer *xfer;
     bool keep_cs = false;
     int ret = 0;
     struct spi_statistics __percpu *statm = ctlr->pcpu_statistics;
     struct spi_statistics __percpu *stats = msg->spi->pcpu_statistics;
 
     spi_set_cs(msg->spi, true, false);
 
     SPI_STATISTICS_INCREMENT_FIELD(statm, messages);
     SPI_STATISTICS_INCREMENT_FIELD(stats, messages);
 
     list_for_each_entry(xfer, &msg->transfers, transfer_list) {
         trace_spi_transfer_start(msg, xfer);
 
         spi_statistics_add_transfer_stats(statm, xfer, ctlr);
         spi_statistics_add_transfer_stats(stats, xfer, ctlr);
 
         if (!ctlr->ptp_sts_supported) {
             xfer->ptp_sts_word_pre = 0;
             ptp_read_system_prets(xfer->ptp_sts);
         }
 
         if ((xfer->tx_buf || xfer->rx_buf) && xfer->len) {
             reinit_completion(&ctlr->xfer_completion);
 
 fallback_pio:
             ret = ctlr->transfer_one(ctlr, msg->spi, xfer);
             if (ret < 0) {
                 if (ctlr->cur_msg_mapped &&
                    (xfer->error & SPI_TRANS_FAIL_NO_START)) {
                     __spi_unmap_msg(ctlr, msg);
                     ctlr->fallback = true;
                     xfer->error &= ~SPI_TRANS_FAIL_NO_START;
                     goto fallback_pio;
                 }
 
                 SPI_STATISTICS_INCREMENT_FIELD(statm,
                                    errors);
                 SPI_STATISTICS_INCREMENT_FIELD(stats,
                                    errors);
                 dev_err(&msg->spi->dev,
                     "SPI transfer failed: %d\n", ret);
                 goto out;
             }
 
             if (ret > 0) {
                 ret = spi_transfer_wait(ctlr, msg, xfer);
                 if (ret < 0)
                     msg->status = ret;
             }
         } else {
             if (xfer->len)
                 dev_err(&msg->spi->dev,
                     "Bufferless transfer has length %u\n",
                     xfer->len);
         }
 
         if (!ctlr->ptp_sts_supported) {
             ptp_read_system_postts(xfer->ptp_sts);
             xfer->ptp_sts_word_post = xfer->len;
         }
 
         trace_spi_transfer_stop(msg, xfer);
 
         if (msg->status != -EINPROGRESS)
             goto out;
 
         spi_transfer_delay_exec(xfer);
 
         if (xfer->cs_change) {
             if (list_is_last(&xfer->transfer_list,
                      &msg->transfers)) {
                 keep_cs = true;
             } else {
                 spi_set_cs(msg->spi, false, false);
                 _spi_transfer_cs_change_delay(msg, xfer);
                 spi_set_cs(msg->spi, true, false);
             }
         }
 
         msg->actual_length += xfer->len;
     }
 
 out:
     if (ret != 0 || !keep_cs)
         spi_set_cs(msg->spi, false, false);
 
     if (msg->status == -EINPROGRESS)
         msg->status = ret;
 
     if (msg->status && ctlr->handle_err)
         ctlr->handle_err(ctlr, msg);
 
     spi_finalize_current_message(ctlr);
 
     return ret;
 }
 
 /**
  * spi_finalize_current_transfer - report completion of a transfer
  * @ctlr: the controller reporting completion
  *
  * Called by SPI drivers using the core transfer_one_message()
  * implementation to notify it that the current interrupt driven
  * transfer has finished and the next one may be scheduled.
  */
 void spi_finalize_current_transfer(struct spi_controller *ctlr)
 {
     complete(&ctlr->xfer_completion);
 }
 EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
 
 static void spi_idle_runtime_pm(struct spi_controller *ctlr)
 {
     if (ctlr->auto_runtime_pm) {
         pm_runtime_mark_last_busy(ctlr->dev.parent);
         pm_runtime_put_autosuspend(ctlr->dev.parent);
     }
 }
 
 static int __spi_pump_transfer_message(struct spi_controller *ctlr,
         struct spi_message *msg, bool was_busy)
 {
     struct spi_transfer *xfer;
     int ret;
 
     if (!was_busy && ctlr->auto_runtime_pm) {
         ret = pm_runtime_get_sync(ctlr->dev.parent);
         if (ret < 0) {
             pm_runtime_put_noidle(ctlr->dev.parent);
             dev_err(&ctlr->dev, "Failed to power device: %d\n",
                 ret);
             return ret;
         }
     }
 
     if (!was_busy)
         trace_spi_controller_busy(ctlr);
 
     if (!was_busy && ctlr->prepare_transfer_hardware) {
         ret = ctlr->prepare_transfer_hardware(ctlr);
         if (ret) {
             dev_err(&ctlr->dev,
                 "failed to prepare transfer hardware: %d\n",
                 ret);
 
             if (ctlr->auto_runtime_pm)
                 pm_runtime_put(ctlr->dev.parent);
 
             msg->status = ret;
             spi_finalize_current_message(ctlr);
 
             return ret;
         }
     }
 
     trace_spi_message_start(msg);
 
     if (ctlr->prepare_message) {
         ret = ctlr->prepare_message(ctlr, msg);
         if (ret) {
             dev_err(&ctlr->dev, "failed to prepare message: %d\n",
                 ret);
             msg->status = ret;
             spi_finalize_current_message(ctlr);
             return ret;
         }
         msg->prepared = true;
     }
 
     ret = spi_map_msg(ctlr, msg);
     if (ret) {
         msg->status = ret;
         spi_finalize_current_message(ctlr);
         return ret;
     }
 
     if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
             xfer->ptp_sts_word_pre = 0;
             ptp_read_system_prets(xfer->ptp_sts);
         }
     }
 
     /*
      * Drivers implementation of transfer_one_message() must arrange for
      * spi_finalize_current_message() to get called. Most drivers will do
      * this in the calling context, but some don't. For those cases, a
      * completion is used to guarantee that this function does not return
      * until spi_finalize_current_message() is done accessing
      * ctlr->cur_msg.
      * Use of the following two flags enable to opportunistically skip the
      * use of the completion since its use involves expensive spin locks.
      * In case of a race with the context that calls
      * spi_finalize_current_message() the completion will always be used,
      * due to strict ordering of these flags using barriers.
      */
     WRITE_ONCE(ctlr->cur_msg_incomplete, true);
     WRITE_ONCE(ctlr->cur_msg_need_completion, false);
     reinit_completion(&ctlr->cur_msg_completion);
     smp_wmb(); /* Make these available to spi_finalize_current_message() */
 
     ret = ctlr->transfer_one_message(ctlr, msg);
     if (ret) {
         dev_err(&ctlr->dev,
             "failed to transfer one message from queue\n");
         return ret;
     }
 
     WRITE_ONCE(ctlr->cur_msg_need_completion, true);
     smp_mb(); /* See spi_finalize_current_message()... */
     if (READ_ONCE(ctlr->cur_msg_incomplete))
         wait_for_completion(&ctlr->cur_msg_completion);
 
     return 0;
 }
 
 /**
  * __spi_pump_messages - function which processes spi message queue
  * @ctlr: controller to process queue for
  * @in_kthread: true if we are in the context of the message pump thread
  *
  * This function checks if there is any spi message in the queue that
  * needs processing and if so call out to the driver to initialize hardware
  * and transfer each message.
  *
  * Note that it is called both from the kthread itself and also from
  * inside spi_sync(); the queue extraction handling at the top of the
  * function should deal with this safely.
  */
 static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
 {
     struct spi_message *msg;
     bool was_busy = false;
     unsigned long flags;
     int ret;
 
     /* Take the IO mutex */
     mutex_lock(&ctlr->io_mutex);
 
     /* Lock queue */
     spin_lock_irqsave(&ctlr->queue_lock, flags);
 
     /* Make sure we are not already running a message */
     if (ctlr->cur_msg)
         goto out_unlock;
 
     /* Check if the queue is idle */
     if (list_empty(&ctlr->queue) || !ctlr->running) {
         if (!ctlr->busy)
             goto out_unlock;
 
         /* Defer any non-atomic teardown to the thread */
         if (!in_kthread) {
             if (!ctlr->dummy_rx && !ctlr->dummy_tx &&
                 !ctlr->unprepare_transfer_hardware) {
                 spi_idle_runtime_pm(ctlr);
                 ctlr->busy = false;
                 ctlr->queue_empty = true;
                 trace_spi_controller_idle(ctlr);
             } else {
                 kthread_queue_work(ctlr->kworker,
                            &ctlr->pump_messages);
             }
             goto out_unlock;
         }
 
         ctlr->busy = false;
         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
 
         kfree(ctlr->dummy_rx);
         ctlr->dummy_rx = NULL;
         kfree(ctlr->dummy_tx);
         ctlr->dummy_tx = NULL;
         if (ctlr->unprepare_transfer_hardware &&
             ctlr->unprepare_transfer_hardware(ctlr))
             dev_err(&ctlr->dev,
                 "failed to unprepare transfer hardware\n");
         spi_idle_runtime_pm(ctlr);
         trace_spi_controller_idle(ctlr);
 
         spin_lock_irqsave(&ctlr->queue_lock, flags);
         ctlr->queue_empty = true;
         goto out_unlock;
     }
 
     /* Extract head of queue */
     msg = list_first_entry(&ctlr->queue, struct spi_message, queue);
     ctlr->cur_msg = msg;
 
     list_del_init(&msg->queue);
     if (ctlr->busy)
         was_busy = true;
     else
         ctlr->busy = true;
     spin_unlock_irqrestore(&ctlr->queue_lock, flags);
 
     ret = __spi_pump_transfer_message(ctlr, msg, was_busy);
     kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
 
     ctlr->cur_msg = NULL;
     ctlr->fallback = false;
 
     mutex_unlock(&ctlr->io_mutex);
 
     /* Prod the scheduler in case transfer_one() was busy waiting */
     if (!ret)
         cond_resched();
     return;
 
 out_unlock:
     spin_unlock_irqrestore(&ctlr->queue_lock, flags);
     mutex_unlock(&ctlr->io_mutex);
 }
 
 /**
  * spi_pump_messages - kthread work function which processes spi message queue
  * @work: pointer to kthread work struct contained in the controller struct
  */
 static void spi_pump_messages(struct kthread_work *work)
 {
     struct spi_controller *ctlr =
         container_of(work, struct spi_controller, pump_messages);
 
     __spi_pump_messages(ctlr, true);
 }
 
 /**
  * spi_take_timestamp_pre - helper to collect the beginning of the TX timestamp
  * @ctlr: Pointer to the spi_controller structure of the driver
  * @xfer: Pointer to the transfer being timestamped
  * @progress: How many words (not bytes) have been transferred so far
  * @irqs_off: If true, will disable IRQs and preemption for the duration of the
  *        transfer, for less jitter in time measurement. Only compatible
  *        with PIO drivers. If true, must follow up with
  *        spi_take_timestamp_post or otherwise system will crash.
  *        WARNING: for fully predictable results, the CPU frequency must
  *        also be under control (governor).
  *
  * This is a helper for drivers to collect the beginning of the TX timestamp
  * for the requested byte from the SPI transfer. The frequency with which this
  * function must be called (once per word, once for the whole transfer, once
  * per batch of words etc) is arbitrary as long as the @tx buffer offset is
  * greater than or equal to the requested byte at the time of the call. The
  * timestamp is only taken once, at the first such call. It is assumed that
  * the driver advances its @tx buffer pointer monotonically.
  */
 void spi_take_timestamp_pre(struct spi_controller *ctlr,
                 struct spi_transfer *xfer,
                 size_t progress, bool irqs_off)
 {
     if (!xfer->ptp_sts)
         return;
 
     if (xfer->timestamped)
         return;
 
     if (progress > xfer->ptp_sts_word_pre)
         return;
 
     /* Capture the resolution of the timestamp */
     xfer->ptp_sts_word_pre = progress;
 
     if (irqs_off) {
         local_irq_save(ctlr->irq_flags);
         preempt_disable();
     }
 
     ptp_read_system_prets(xfer->ptp_sts);
 }
 EXPORT_SYMBOL_GPL(spi_take_timestamp_pre);
 
 /**
  * spi_take_timestamp_post - helper to collect the end of the TX timestamp
  * @ctlr: Pointer to the spi_controller structure of the driver
  * @xfer: Pointer to the transfer being timestamped
  * @progress: How many words (not bytes) have been transferred so far
  * @irqs_off: If true, will re-enable IRQs and preemption for the local CPU.
  *
  * This is a helper for drivers to collect the end of the TX timestamp for
  * the requested byte from the SPI transfer. Can be called with an arbitrary
  * frequency: only the first call where @tx exceeds or is equal to the
  * requested word will be timestamped.
  */
 void spi_take_timestamp_post(struct spi_controller *ctlr,
                  struct spi_transfer *xfer,
                  size_t progress, bool irqs_off)
 {
     if (!xfer->ptp_sts)
         return;
 
     if (xfer->timestamped)
         return;
 
     if (progress < xfer->ptp_sts_word_post)
         return;
 
     ptp_read_system_postts(xfer->ptp_sts);
 
     if (irqs_off) {
         local_irq_restore(ctlr->irq_flags);
         preempt_enable();
     }
 
     /* Capture the resolution of the timestamp */
     xfer->ptp_sts_word_post = progress;
 
     xfer->timestamped = true;
 }
 EXPORT_SYMBOL_GPL(spi_take_timestamp_post);
 
 /**
  * spi_set_thread_rt - set the controller to pump at realtime priority
  * @ctlr: controller to boost priority of
  *
  * This can be called because the controller requested realtime priority
  * (by setting the ->rt value before calling spi_register_controller()) or
  * because a device on the bus said that its transfers needed realtime
  * priority.
  *
  * NOTE: at the moment if any device on a bus says it needs realtime then
  * the thread will be at realtime priority for all transfers on that
  * controller.  If this eventually becomes a problem we may see if we can
  * find a way to boost the priority only temporarily during relevant
  * transfers.
  */
 static void spi_set_thread_rt(struct spi_controller *ctlr)
 {
     dev_info(&ctlr->dev,
         "will run message pump with realtime priority\n");
     sched_set_fifo(ctlr->kworker->task);
 }
 
 static int spi_init_queue(struct spi_controller *ctlr)
 {
     ctlr->running = false;
     ctlr->busy = false;
     ctlr->queue_empty = true;
 
     ctlr->kworker = kthread_create_worker(0, dev_name(&ctlr->dev));
     if (IS_ERR(ctlr->kworker)) {
         dev_err(&ctlr->dev, "failed to create message pump kworker\n");
         return PTR_ERR(ctlr->kworker);
     }
 
     kthread_init_work(&ctlr->pump_messages, spi_pump_messages);
 
     /*
      * Controller config will indicate if this controller should run the
      * message pump with high (realtime) priority to reduce the transfer
      * latency on the bus by minimising the delay between a transfer
      * request and the scheduling of the message pump thread. Without this
      * setting the message pump thread will remain at default priority.
      */
     if (ctlr->rt)
         spi_set_thread_rt(ctlr);
 
     return 0;
 }
 
 /**
  * spi_get_next_queued_message() - called by driver to check for queued
  * messages
  * @ctlr: the controller to check for queued messages
  *
  * If there are more messages in the queue, the next message is returned from
  * this call.
  *
  * Return: the next message in the queue, else NULL if the queue is empty.
  */
 struct spi_message *spi_get_next_queued_message(struct spi_controller *ctlr)
 {
     struct spi_message *next;
     unsigned long flags;
 
     /* Get a pointer to the next message, if any */
     spin_lock_irqsave(&ctlr->queue_lock, flags);
     next = list_first_entry_or_null(&ctlr->queue, struct spi_message,
                     queue);
     spin_unlock_irqrestore(&ctlr->queue_lock, flags);
 
     return next;
 }
 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
 
 /**
  * spi_finalize_current_message() - the current message is complete
  * @ctlr: the controller to return the message to
  *
  * Called by the driver to notify the core that the message in the front of the
  * queue is complete and can be removed from the queue.
  */
 void spi_finalize_current_message(struct spi_controller *ctlr)
 {
     struct spi_transfer *xfer;
     struct spi_message *mesg;
     int ret;
 
     mesg = ctlr->cur_msg;
 
     if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
         list_for_each_entry(xfer, &mesg->transfers, transfer_list) {
             ptp_read_system_postts(xfer->ptp_sts);
             xfer->ptp_sts_word_post = xfer->len;
         }
     }
 
     if (unlikely(ctlr->ptp_sts_supported))
         list_for_each_entry(xfer, &mesg->transfers, transfer_list)
             WARN_ON_ONCE(xfer->ptp_sts && !xfer->timestamped);
 
     spi_unmap_msg(ctlr, mesg);
 
     /*
      * In the prepare_messages callback the SPI bus has the opportunity
      * to split a transfer to smaller chunks.
      *
      * Release the split transfers here since spi_map_msg() is done on
      * the split transfers.
      */
     spi_res_release(ctlr, mesg);
 
     if (mesg->prepared && ctlr->unprepare_message) {
         ret = ctlr->unprepare_message(ctlr, mesg);
         if (ret) {
             dev_err(&ctlr->dev, "failed to unprepare message: %d\n",
                 ret);
         }
     }
 
     mesg->prepared = false;
 
     WRITE_ONCE(ctlr->cur_msg_incomplete, false);
     smp_mb(); /* See __spi_pump_transfer_message()... */
     if (READ_ONCE(ctlr->cur_msg_need_completion))
         complete(&ctlr->cur_msg_completion);
 
     trace_spi_message_done(mesg);
 
     mesg->state = NULL;
     if (mesg->complete)
         mesg->complete(mesg->context);
 }
 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
 
 static int spi_start_queue(struct spi_controller *ctlr)
 {
     unsigned long flags;
 
     spin_lock_irqsave(&ctlr->queue_lock, flags);
 
     if (ctlr->running || ctlr->busy) {
         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
         return -EBUSY;
     }
 
     ctlr->running = true;
     ctlr->cur_msg = NULL;
     spin_unlock_irqrestore(&ctlr->queue_lock, flags);
 
     kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
 
     return 0;
 }
 
 static int spi_stop_queue(struct spi_controller *ctlr)
 {
     unsigned long flags;
     unsigned limit = 500;
     int ret = 0;
 
     spin_lock_irqsave(&ctlr->queue_lock, flags);
 
     /*
      * This is a bit lame, but is optimized for the common execution path.
      * A wait_queue on the ctlr->busy could be used, but then the common
      * execution path (pump_messages) would be required to call wake_up or
      * friends on every SPI message. Do this instead.
      */
     while ((!list_empty(&ctlr->queue) || ctlr->busy) && limit--) {
         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
         usleep_range(10000, 11000);
         spin_lock_irqsave(&ctlr->queue_lock, flags);
     }
 
     if (!list_empty(&ctlr->queue) || ctlr->busy)
         ret = -EBUSY;
     else
         ctlr->running = false;
 
     spin_unlock_irqrestore(&ctlr->queue_lock, flags);
 
     if (ret) {
         dev_warn(&ctlr->dev, "could not stop message queue\n");
         return ret;
     }
     return ret;
 }
 
 static int spi_destroy_queue(struct spi_controller *ctlr)
 {
     int ret;
 
     ret = spi_stop_queue(ctlr);
 
     /*
      * kthread_flush_worker will block until all work is done.
      * If the reason that stop_queue timed out is that the work will never
      * finish, then it does no good to call flush/stop thread, so
      * return anyway.
      */
     if (ret) {
         dev_err(&ctlr->dev, "problem destroying queue\n");
         return ret;
     }
 
     kthread_destroy_worker(ctlr->kworker);
 
     return 0;
 }
 
 static int __spi_queued_transfer(struct spi_device *spi,
                  struct spi_message *msg,
                  bool need_pump)
 {
     struct spi_controller *ctlr = spi->controller;
     unsigned long flags;
 
     spin_lock_irqsave(&ctlr->queue_lock, flags);
 
     if (!ctlr->running) {
         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
         return -ESHUTDOWN;
     }
     msg->actual_length = 0;
     msg->status = -EINPROGRESS;
 
     list_add_tail(&msg->queue, &ctlr->queue);
     ctlr->queue_empty = false;
     if (!ctlr->busy && need_pump)
         kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
 
     spin_unlock_irqrestore(&ctlr->queue_lock, flags);
     return 0;
 }
 
 /**
  * spi_queued_transfer - transfer function for queued transfers
  * @spi: spi device which is requesting transfer
  * @msg: spi message which is to handled is queued to driver queue
  *
  * Return: zero on success, else a negative error code.
  */
 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
 {
     return __spi_queued_transfer(spi, msg, true);
 }
 
 static int spi_controller_initialize_queue(struct spi_controller *ctlr)
 {
     int ret;
 
     ctlr->transfer = spi_queued_transfer;
     if (!ctlr->transfer_one_message)
         ctlr->transfer_one_message = spi_transfer_one_message;
 
     /* Initialize and start queue */
     ret = spi_init_queue(ctlr);
     if (ret) {
         dev_err(&ctlr->dev, "problem initializing queue\n");
         goto err_init_queue;
     }
     ctlr->queued = true;
     ret = spi_start_queue(ctlr);
     if (ret) {
         dev_err(&ctlr->dev, "problem starting queue\n");
         goto err_start_queue;
     }
 
     return 0;
 
 err_start_queue:
     spi_destroy_queue(ctlr);
 err_init_queue:
     return ret;
 }
 
 /**
  * spi_flush_queue - Send all pending messages in the queue from the callers'
  *           context
  * @ctlr: controller to process queue for
  *
  * This should be used when one wants to ensure all pending messages have been
  * sent before doing something. Is used by the spi-mem code to make sure SPI
  * memory operations do not preempt regular SPI transfers that have been queued
  * before the spi-mem operation.
  */
 void spi_flush_queue(struct spi_controller *ctlr)
 {
     if (ctlr->transfer == spi_queued_transfer)
         __spi_pump_messages(ctlr, false);
 }
 
 /*-------------------------------------------------------------------------*/
 
 #if defined(CONFIG_OF)
 static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
                struct device_node *nc)
 {
     u32 value;
     int rc;
 
     /* Mode (clock phase/polarity/etc.) */
     if (of_property_read_bool(nc, "spi-cpha"))
         spi->mode |= SPI_CPHA;
     if (of_property_read_bool(nc, "spi-cpol"))
         spi->mode |= SPI_CPOL;
     if (of_property_read_bool(nc, "spi-3wire"))
         spi->mode |= SPI_3WIRE;
     if (of_property_read_bool(nc, "spi-lsb-first"))
         spi->mode |= SPI_LSB_FIRST;
     if (of_property_read_bool(nc, "spi-cs-high"))
         spi->mode |= SPI_CS_HIGH;
 
     /* Device DUAL/QUAD mode */
     if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
         switch (value) {
         case 0:
             spi->mode |= SPI_NO_TX;
             break;
         case 1:
             break;
         case 2:
             spi->mode |= SPI_TX_DUAL;
             break;
         case 4:
             spi->mode |= SPI_TX_QUAD;
             break;
         case 8:
             spi->mode |= SPI_TX_OCTAL;
             break;
         default:
             dev_warn(&ctlr->dev,
                 "spi-tx-bus-width %d not supported\n",
                 value);
             break;
         }
     }
 
     if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
         switch (value) {
         case 0:
             spi->mode |= SPI_NO_RX;
             break;
         case 1:
             break;
         case 2:
             spi->mode |= SPI_RX_DUAL;
             break;
         case 4:
             spi->mode |= SPI_RX_QUAD;
             break;
         case 8:
             spi->mode |= SPI_RX_OCTAL;
             break;
         default:
             dev_warn(&ctlr->dev,
                 "spi-rx-bus-width %d not supported\n",
                 value);
             break;
         }
     }
 
     if (spi_controller_is_slave(ctlr)) {
         if (!of_node_name_eq(nc, "slave")) {
             dev_err(&ctlr->dev, "%pOF is not called 'slave'\n",
                 nc);
             return -EINVAL;
         }
         return 0;
     }
 
     /* Device address */
     rc = of_property_read_u32(nc, "reg", &value);
     if (rc) {
         dev_err(&ctlr->dev, "%pOF has no valid 'reg' property (%d)\n",
             nc, rc);
         return rc;
     }
     spi->chip_select = value;
 
     /* Device speed */
     if (!of_property_read_u32(nc, "spi-max-frequency", &value))
         spi->max_speed_hz = value;
 
     return 0;
 }
 
 static struct spi_device *
 of_register_spi_device(struct spi_controller *ctlr, struct device_node *nc)
 {
     struct spi_device *spi;
     int rc;
 
     /* Alloc an spi_device */
     spi = spi_alloc_device(ctlr);
     if (!spi) {
         dev_err(&ctlr->dev, "spi_device alloc error for %pOF\n", nc);
         rc = -ENOMEM;
         goto err_out;
     }
 
     /* Select device driver */
     rc = of_modalias_node(nc, spi->modalias,
                 sizeof(spi->modalias));
     if (rc < 0) {
         dev_err(&ctlr->dev, "cannot find modalias for %pOF\n", nc);
         goto err_out;
     }
 
     rc = of_spi_parse_dt(ctlr, spi, nc);
     if (rc)
         goto err_out;
 
     /* Store a pointer to the node in the device structure */
     of_node_get(nc);
     spi->dev.of_node = nc;
     spi->dev.fwnode = of_fwnode_handle(nc);
 
     /* Register the new device */
     rc = spi_add_device(spi);
     if (rc) {
         dev_err(&ctlr->dev, "spi_device register error %pOF\n", nc);
         goto err_of_node_put;
     }
 
     return spi;
 
 err_of_node_put:
     of_node_put(nc);
 err_out:
     spi_dev_put(spi);
     return ERR_PTR(rc);
 }
 
 /**
  * of_register_spi_devices() - Register child devices onto the SPI bus
  * @ctlr:   Pointer to spi_controller device
  *
  * Registers an spi_device for each child node of controller node which
  * represents a valid SPI slave.
  */
 static void of_register_spi_devices(struct spi_controller *ctlr)
 {
     struct spi_device *spi;
     struct device_node *nc;
 
     if (!ctlr->dev.of_node)
         return;
 
     for_each_available_child_of_node(ctlr->dev.of_node, nc) {
         if (of_node_test_and_set_flag(nc, OF_POPULATED))
             continue;
         spi = of_register_spi_device(ctlr, nc);
         if (IS_ERR(spi)) {
             dev_warn(&ctlr->dev,
                  "Failed to create SPI device for %pOF\n", nc);
             of_node_clear_flag(nc, OF_POPULATED);
         }
     }
 }
 #else
 static void of_register_spi_devices(struct spi_controller *ctlr) { }
 #endif
 
 /**
  * spi_new_ancillary_device() - Register ancillary SPI device
  * @spi:         Pointer to the main SPI device registering the ancillary device
  * @chip_select: Chip Select of the ancillary device
  *
  * Register an ancillary SPI device; for example some chips have a chip-select
  * for normal device usage and another one for setup/firmware upload.
  *
  * This may only be called from main SPI device's probe routine.
  *
  * Return: 0 on success; negative errno on failure
  */
 struct spi_device *spi_new_ancillary_device(struct spi_device *spi,
                          u8 chip_select)
 {
     struct spi_device *ancillary;
     int rc = 0;
 
     /* Alloc an spi_device */
     ancillary = spi_alloc_device(spi->controller);
     if (!ancillary) {
         rc = -ENOMEM;
         goto err_out;
     }
 
     strlcpy(ancillary->modalias, "dummy", sizeof(ancillary->modalias));
 
     /* Use provided chip-select for ancillary device */
     ancillary->chip_select = chip_select;
 
     /* Take over SPI mode/speed from SPI main device */
     ancillary->max_speed_hz = spi->max_speed_hz;
     ancillary->mode = spi->mode;
 
     /* Register the new device */
     rc = spi_add_device_locked(ancillary);
     if (rc) {
         dev_err(&spi->dev, "failed to register ancillary device\n");
         goto err_out;
     }
 
     return ancillary;
 
 err_out:
     spi_dev_put(ancillary);
     return ERR_PTR(rc);
 }
 EXPORT_SYMBOL_GPL(spi_new_ancillary_device);
 
 #ifdef CONFIG_ACPI
 struct acpi_spi_lookup {
     struct spi_controller   *ctlr;
     u32         max_speed_hz;
     u32         mode;
     int         irq;
     u8          bits_per_word;
     u8          chip_select;
     int         n;
     int         index;
 };
 
 static int acpi_spi_count(struct acpi_resource *ares, void *data)
 {
     struct acpi_resource_spi_serialbus *sb;
     int *count = data;
 
     if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
         return 1;
 
     sb = &ares->data.spi_serial_bus;
     if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_SPI)
         return 1;
 
     *count = *count + 1;
 
     return 1;
 }
 
 /**
  * acpi_spi_count_resources - Count the number of SpiSerialBus resources
  * @adev:   ACPI device
  *
  * Returns the number of SpiSerialBus resources in the ACPI-device's
  * resource-list; or a negative error code.
  */
 int acpi_spi_count_resources(struct acpi_device *adev)
 {
     LIST_HEAD(r);
     int count = 0;
     int ret;
 
     ret = acpi_dev_get_resources(adev, &r, acpi_spi_count, &count);
     if (ret < 0)
         return ret;
 
     acpi_dev_free_resource_list(&r);
 
     return count;
 }
 EXPORT_SYMBOL_GPL(acpi_spi_count_resources);
 
 static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
                         struct acpi_spi_lookup *lookup)
 {
     const union acpi_object *obj;
 
     if (!x86_apple_machine)
         return;
 
     if (!acpi_dev_get_property(dev, "spiSclkPeriod", ACPI_TYPE_BUFFER, &obj)
         && obj->buffer.length >= 4)
         lookup->max_speed_hz  = NSEC_PER_SEC / *(u32 *)obj->buffer.pointer;
 
     if (!acpi_dev_get_property(dev, "spiWordSize", ACPI_TYPE_BUFFER, &obj)
         && obj->buffer.length == 8)
         lookup->bits_per_word = *(u64 *)obj->buffer.pointer;
 
     if (!acpi_dev_get_property(dev, "spiBitOrder", ACPI_TYPE_BUFFER, &obj)
         && obj->buffer.length == 8 && !*(u64 *)obj->buffer.pointer)
         lookup->mode |= SPI_LSB_FIRST;
 
     if (!acpi_dev_get_property(dev, "spiSPO", ACPI_TYPE_BUFFER, &obj)
         && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
         lookup->mode |= SPI_CPOL;
 
     if (!acpi_dev_get_property(dev, "spiSPH", ACPI_TYPE_BUFFER, &obj)
         && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
         lookup->mode |= SPI_CPHA;
 }
 
 static struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev);
 
 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
 {
     struct acpi_spi_lookup *lookup = data;
     struct spi_controller *ctlr = lookup->ctlr;
 
     if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
         struct acpi_resource_spi_serialbus *sb;
         acpi_handle parent_handle;
         acpi_status status;
 
         sb = &ares->data.spi_serial_bus;
         if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
 
             if (lookup->index != -1 && lookup->n++ != lookup->index)
                 return 1;
 
             status = acpi_get_handle(NULL,
                          sb->resource_source.string_ptr,
                          &parent_handle);
 
             if (ACPI_FAILURE(status))
                 return -ENODEV;
 
             if (ctlr) {
                 if (ACPI_HANDLE(ctlr->dev.parent) != parent_handle)
                     return -ENODEV;
             } else {
                 struct acpi_device *adev;
 
                 adev = acpi_fetch_acpi_dev(parent_handle);
                 if (!adev)
                     return -ENODEV;
 
                 ctlr = acpi_spi_find_controller_by_adev(adev);
                 if (!ctlr)
                     return -EPROBE_DEFER;
 
                 lookup->ctlr = ctlr;
             }
 
             /*
              * ACPI DeviceSelection numbering is handled by the
              * host controller driver in Windows and can vary
              * from driver to driver. In Linux we always expect
              * 0 .. max - 1 so we need to ask the driver to
              * translate between the two schemes.
              */
             if (ctlr->fw_translate_cs) {
                 int cs = ctlr->fw_translate_cs(ctlr,
                         sb->device_selection);
                 if (cs < 0)
                     return cs;
                 lookup->chip_select = cs;
             } else {
                 lookup->chip_select = sb->device_selection;
             }
 
             lookup->max_speed_hz = sb->connection_speed;
             lookup->bits_per_word = sb->data_bit_length;
 
             if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
                 lookup->mode |= SPI_CPHA;
             if (sb->clock_polarity == ACPI_SPI_START_HIGH)
                 lookup->mode |= SPI_CPOL;
             if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
                 lookup->mode |= SPI_CS_HIGH;
         }
     } else if (lookup->irq < 0) {
         struct resource r;
 
         if (acpi_dev_resource_interrupt(ares, 0, &r))
             lookup->irq = r.start;
     }
 
     /* Always tell the ACPI core to skip this resource */
     return 1;
 }
 
 /**
  * acpi_spi_device_alloc - Allocate a spi device, and fill it in with ACPI information
  * @ctlr: controller to which the spi device belongs
  * @adev: ACPI Device for the spi device
  * @index: Index of the spi resource inside the ACPI Node
  *
  * This should be used to allocate a new spi device from and ACPI Node.
  * The caller is responsible for calling spi_add_device to register the spi device.
  *
  * If ctlr is set to NULL, the Controller for the spi device will be looked up
  * using the resource.
  * If index is set to -1, index is not used.
  * Note: If index is -1, ctlr must be set.
  *
  * Return: a pointer to the new device, or ERR_PTR on error.
  */
 struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
                      struct acpi_device *adev,
                      int index)
 {
     acpi_handle parent_handle = NULL;
     struct list_head resource_list;
     struct acpi_spi_lookup lookup = {};
     struct spi_device *spi;
     int ret;
 
     if (!ctlr && index == -1)
         return ERR_PTR(-EINVAL);
 
     lookup.ctlr     = ctlr;
     lookup.irq      = -1;
     lookup.index        = index;
     lookup.n        = 0;
 
     INIT_LIST_HEAD(&resource_list);
     ret = acpi_dev_get_resources(adev, &resource_list,
                      acpi_spi_add_resource, &lookup);
     acpi_dev_free_resource_list(&resource_list);
 
     if (ret < 0)
         /* Found SPI in _CRS but it points to another controller */
         return ERR_PTR(ret);
 
     if (!lookup.max_speed_hz &&
         ACPI_SUCCESS(acpi_get_parent(adev->handle, &parent_handle)) &&
         ACPI_HANDLE(lookup.ctlr->dev.parent) == parent_handle) {
         /* Apple does not use _CRS but nested devices for SPI slaves */
         acpi_spi_parse_apple_properties(adev, &lookup);
     }
 
     if (!lookup.max_speed_hz)
         return ERR_PTR(-ENODEV);
 
     spi = spi_alloc_device(lookup.ctlr);
     if (!spi) {
         dev_err(&lookup.ctlr->dev, "failed to allocate SPI device for %s\n",
             dev_name(&adev->dev));
         return ERR_PTR(-ENOMEM);
     }
 
     ACPI_COMPANION_SET(&spi->dev, adev);
     spi->max_speed_hz   = lookup.max_speed_hz;
     spi->mode       |= lookup.mode;
     spi->irq        = lookup.irq;
     spi->bits_per_word  = lookup.bits_per_word;
     spi->chip_select    = lookup.chip_select;
 
     return spi;
 }
 EXPORT_SYMBOL_GPL(acpi_spi_device_alloc);
 
 static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
                         struct acpi_device *adev)
 {
     struct spi_device *spi;
 
     if (acpi_bus_get_status(adev) || !adev->status.present ||
         acpi_device_enumerated(adev))
         return AE_OK;
 
     spi = acpi_spi_device_alloc(ctlr, adev, -1);
     if (IS_ERR(spi)) {
         if (PTR_ERR(spi) == -ENOMEM)
             return AE_NO_MEMORY;
         else
             return AE_OK;
     }
 
     acpi_set_modalias(adev, acpi_device_hid(adev), spi->modalias,
               sizeof(spi->modalias));
 
     if (spi->irq < 0)
         spi->irq = acpi_dev_gpio_irq_get(adev, 0);
 
     acpi_device_set_enumerated(adev);
 
     adev->power.flags.ignore_parent = true;
     if (spi_add_device(spi)) {
         adev->power.flags.ignore_parent = false;
         dev_err(&ctlr->dev, "failed to add SPI device %s from ACPI\n",
             dev_name(&adev->dev));
         spi_dev_put(spi);
     }
 
     return AE_OK;
 }
 
 static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
                        void *data, void **return_value)
 {
     struct acpi_device *adev = acpi_fetch_acpi_dev(handle);
     struct spi_controller *ctlr = data;
 
     if (!adev)
         return AE_OK;
 
     return acpi_register_spi_device(ctlr, adev);
 }
 
 #define SPI_ACPI_ENUMERATE_MAX_DEPTH        32
 
 static void acpi_register_spi_devices(struct spi_controller *ctlr)
 {
     acpi_status status;
     acpi_handle handle;
 
     handle = ACPI_HANDLE(ctlr->dev.parent);
     if (!handle)
         return;
 
     status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
                      SPI_ACPI_ENUMERATE_MAX_DEPTH,
                      acpi_spi_add_device, NULL, ctlr, NULL);
     if (ACPI_FAILURE(status))
         dev_warn(&ctlr->dev, "failed to enumerate SPI slaves\n");
 }
 #else
 static inline void acpi_register_spi_devices(struct spi_controller *ctlr) {}
 #endif /* CONFIG_ACPI */
 
 static void spi_controller_release(struct device *dev)
 {
     struct spi_controller *ctlr;
 
     ctlr = container_of(dev, struct spi_controller, dev);
     kfree(ctlr);
 }
 
 static struct class spi_master_class = {
     .name       = "spi_master",
     .owner      = THIS_MODULE,
     .dev_release    = spi_controller_release,
     .dev_groups = spi_master_groups,
 };
 
 #ifdef CONFIG_SPI_SLAVE
 /**
  * spi_slave_abort - abort the ongoing transfer request on an SPI slave
  *           controller
  * @spi: device used for the current transfer
  */
 int spi_slave_abort(struct spi_device *spi)
 {
     struct spi_controller *ctlr = spi->controller;
 
     if (spi_controller_is_slave(ctlr) && ctlr->slave_abort)
         return ctlr->slave_abort(ctlr);
 
     return -ENOTSUPP;
 }
 EXPORT_SYMBOL_GPL(spi_slave_abort);
 
 static ssize_t slave_show(struct device *dev, struct device_attribute *attr,
               char *buf)
 {
     struct spi_controller *ctlr = container_of(dev, struct spi_controller,
                            dev);
     struct device *child;
 
     child = device_find_any_child(&ctlr->dev);
     return sprintf(buf, "%s\n",
                child ? to_spi_device(child)->modalias : NULL);
 }
 
 static ssize_t slave_store(struct device *dev, struct device_attribute *attr,
                const char *buf, size_t count)
 {
     struct spi_controller *ctlr = container_of(dev, struct spi_controller,
                            dev);
     struct spi_device *spi;
     struct device *child;
     char name[32];
     int rc;
 
     rc = sscanf(buf, "%31s", name);
     if (rc != 1 || !name[0])
         return -EINVAL;
 
     child = device_find_any_child(&ctlr->dev);
     if (child) {
         /* Remove registered slave */
         device_unregister(child);
         put_device(child);
     }
 
     if (strcmp(name, "(null)")) {
         /* Register new slave */
         spi = spi_alloc_device(ctlr);
         if (!spi)
             return -ENOMEM;
 
         strlcpy(spi->modalias, name, sizeof(spi->modalias));
 
         rc = spi_add_device(spi);
         if (rc) {
             spi_dev_put(spi);
             return rc;
         }
     }
 
     return count;
 }
 
 static DEVICE_ATTR_RW(slave);
 
 static struct attribute *spi_slave_attrs[] = {
     &dev_attr_slave.attr,
     NULL,
 };
 
 static const struct attribute_group spi_slave_group = {
     .attrs = spi_slave_attrs,
 };
 
 static const struct attribute_group *spi_slave_groups[] = {
     &spi_controller_statistics_group,
     &spi_slave_group,
     NULL,
 };
 
 static struct class spi_slave_class = {
     .name       = "spi_slave",
     .owner      = THIS_MODULE,
     .dev_release    = spi_controller_release,
     .dev_groups = spi_slave_groups,
 };
 #else
 extern struct class spi_slave_class;    /* dummy */
 #endif
 
 /**
  * __spi_alloc_controller - allocate an SPI master or slave controller
  * @dev: the controller, possibly using the platform_bus
  * @size: how much zeroed driver-private data to allocate; the pointer to this
  *  memory is in the driver_data field of the returned device, accessible
  *  with spi_controller_get_devdata(); the memory is cacheline aligned;
  *  drivers granting DMA access to portions of their private data need to
  *  round up @size using ALIGN(size, dma_get_cache_alignment()).
  * @slave: flag indicating whether to allocate an SPI master (false) or SPI
  *  slave (true) controller
  * Context: can sleep
  *
  * This call is used only by SPI controller drivers, which are the
  * only ones directly touching chip registers.  It's how they allocate
  * an spi_controller structure, prior to calling spi_register_controller().
  *
  * This must be called from context that can sleep.
  *
  * The caller is responsible for assigning the bus number and initializing the
  * controller's methods before calling spi_register_controller(); and (after
  * errors adding the device) calling spi_controller_put() to prevent a memory
  * leak.
  *
  * Return: the SPI controller structure on success, else NULL.
  */
 struct spi_controller *__spi_alloc_controller(struct device *dev,
                           unsigned int size, bool slave)
 {
     struct spi_controller   *ctlr;
     size_t ctlr_size = ALIGN(sizeof(*ctlr), dma_get_cache_alignment());
 
     if (!dev)
         return NULL;
 
     ctlr = kzalloc(size + ctlr_size, GFP_KERNEL);
     if (!ctlr)
         return NULL;
 
     device_initialize(&ctlr->dev);
     INIT_LIST_HEAD(&ctlr->queue);
     spin_lock_init(&ctlr->queue_lock);
     spin_lock_init(&ctlr->bus_lock_spinlock);
     mutex_init(&ctlr->bus_lock_mutex);
     mutex_init(&ctlr->io_mutex);
     mutex_init(&ctlr->add_lock);
     ctlr->bus_num = -1;
     ctlr->num_chipselect = 1;
     ctlr->slave = slave;
     if (IS_ENABLED(CONFIG_SPI_SLAVE) && slave)
         ctlr->dev.class = &spi_slave_class;
     else
         ctlr->dev.class = &spi_master_class;
     ctlr->dev.parent = dev;
     pm_suspend_ignore_children(&ctlr->dev, true);
     spi_controller_set_devdata(ctlr, (void *)ctlr + ctlr_size);
 
     return ctlr;
 }
 EXPORT_SYMBOL_GPL(__spi_alloc_controller);
 
 static void devm_spi_release_controller(struct device *dev, void *ctlr)
 {
     spi_controller_put(*(struct spi_controller **)ctlr);
 }
 
 /**
  * __devm_spi_alloc_controller - resource-managed __spi_alloc_controller()
  * @dev: physical device of SPI controller
  * @size: how much zeroed driver-private data to allocate
  * @slave: whether to allocate an SPI master (false) or SPI slave (true)
  * Context: can sleep
  *
  * Allocate an SPI controller and automatically release a reference on it
  * when @dev is unbound from its driver.  Drivers are thus relieved from
  * having to call spi_controller_put().
  *
  * The arguments to this function are identical to __spi_alloc_controller().
  *
  * Return: the SPI controller structure on success, else NULL.
  */
 struct spi_controller *__devm_spi_alloc_controller(struct device *dev,
                            unsigned int size,
                            bool slave)
 {
     struct spi_controller **ptr, *ctlr;
 
     ptr = devres_alloc(devm_spi_release_controller, sizeof(*ptr),
                GFP_KERNEL);
     if (!ptr)
         return NULL;
 
     ctlr = __spi_alloc_controller(dev, size, slave);
     if (ctlr) {
         ctlr->devm_allocated = true;
         *ptr = ctlr;
         devres_add(dev, ptr);
     } else {
         devres_free(ptr);
     }
 
     return ctlr;
 }
 EXPORT_SYMBOL_GPL(__devm_spi_alloc_controller);
 
 /**
  * spi_get_gpio_descs() - grab chip select GPIOs for the master
  * @ctlr: The SPI master to grab GPIO descriptors for
  */
 static int spi_get_gpio_descs(struct spi_controller *ctlr)
 {
     int nb, i;
     struct gpio_desc **cs;
     struct device *dev = &ctlr->dev;
     unsigned long native_cs_mask = 0;
     unsigned int num_cs_gpios = 0;
 
     nb = gpiod_count(dev, "cs");
     if (nb < 0) {
         /* No GPIOs at all is fine, else return the error */
         if (nb == -ENOENT)
             return 0;
         return nb;
     }
 
     ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);
 
     cs = devm_kcalloc(dev, ctlr->num_chipselect, sizeof(*cs),
               GFP_KERNEL);
     if (!cs)
         return -ENOMEM;
     ctlr->cs_gpiods = cs;
 
     for (i = 0; i < nb; i++) {
         /*
          * Most chipselects are active low, the inverted
          * semantics are handled by special quirks in gpiolib,
          * so initializing them GPIOD_OUT_LOW here means
          * "unasserted", in most cases this will drive the physical
          * line high.
          */
         cs[i] = devm_gpiod_get_index_optional(dev, "cs", i,
                               GPIOD_OUT_LOW);
         if (IS_ERR(cs[i]))
             return PTR_ERR(cs[i]);
 
         if (cs[i]) {
             /*
              * If we find a CS GPIO, name it after the device and
              * chip select line.
              */
             char *gpioname;
 
             gpioname = devm_kasprintf(dev, GFP_KERNEL, "%s CS%d",
                           dev_name(dev), i);
             if (!gpioname)
                 return -ENOMEM;
             gpiod_set_consumer_name(cs[i], gpioname);
             num_cs_gpios++;
             continue;
         }
 
         if (ctlr->max_native_cs && i >= ctlr->max_native_cs) {
             dev_err(dev, "Invalid native chip select %d\n", i);
             return -EINVAL;
         }
         native_cs_mask |= BIT(i);
     }
 
     ctlr->unused_native_cs = ffs(~native_cs_mask) - 1;
 
     if ((ctlr->flags & SPI_MASTER_GPIO_SS) && num_cs_gpios &&
         ctlr->max_native_cs && ctlr->unused_native_cs >= ctlr->max_native_cs) {
         dev_err(dev, "No unused native chip select available\n");
         return -EINVAL;
     }
 
     return 0;
 }
 
 static int spi_controller_check_ops(struct spi_controller *ctlr)
 {
     /*
      * The controller may implement only the high-level SPI-memory like
      * operations if it does not support regular SPI transfers, and this is
      * valid use case.
      * If ->mem_ops is NULL, we request that at least one of the
      * ->transfer_xxx() method be implemented.
      */
     if (ctlr->mem_ops) {
         if (!ctlr->mem_ops->exec_op)
             return -EINVAL;
     } else if (!ctlr->transfer && !ctlr->transfer_one &&
            !ctlr->transfer_one_message) {
         return -EINVAL;
     }
 
     return 0;
 }
 
 /**
  * spi_register_controller - register SPI master or slave controller
  * @ctlr: initialized master, originally from spi_alloc_master() or
  *  spi_alloc_slave()
  * Context: can sleep
  *
  * SPI controllers connect to their drivers using some non-SPI bus,
  * such as the platform bus.  The final stage of probe() in that code
  * includes calling spi_register_controller() to hook up to this SPI bus glue.
  *
  * SPI controllers use board specific (often SOC specific) bus numbers,
  * and board-specific addressing for SPI devices combines those numbers
  * with chip select numbers.  Since SPI does not directly support dynamic
  * device identification, boards need configuration tables telling which
  * chip is at which address.
  *
  * This must be called from context that can sleep.  It returns zero on
  * success, else a negative error code (dropping the controller's refcount).
  * After a successful return, the caller is responsible for calling
  * spi_unregister_controller().
  *
  * Return: zero on success, else a negative error code.
  */
 int spi_register_controller(struct spi_controller *ctlr)
 {
     struct device       *dev = ctlr->dev.parent;
     struct boardinfo    *bi;
     int         status;
     int         id, first_dynamic;
 
     if (!dev)
         return -ENODEV;
 
     /*
      * Make sure all necessary hooks are implemented before registering
      * the SPI controller.
      */
     status = spi_controller_check_ops(ctlr);
     if (status)
         return status;
 
     if (ctlr->bus_num >= 0) {
         /* Devices with a fixed bus num must check-in with the num */
         mutex_lock(&board_lock);
         id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
             ctlr->bus_num + 1, GFP_KERNEL);
         mutex_unlock(&board_lock);
         if (WARN(id < 0, "couldn't get idr"))
             return id == -ENOSPC ? -EBUSY : id;
         ctlr->bus_num = id;
     } else if (ctlr->dev.of_node) {
         /* Allocate dynamic bus number using Linux idr */
         id = of_alias_get_id(ctlr->dev.of_node, "spi");
         if (id >= 0) {
             ctlr->bus_num = id;
             mutex_lock(&board_lock);
             id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
                        ctlr->bus_num + 1, GFP_KERNEL);
             mutex_unlock(&board_lock);
             if (WARN(id < 0, "couldn't get idr"))
                 return id == -ENOSPC ? -EBUSY : id;
         }
     }
     if (ctlr->bus_num < 0) {
         first_dynamic = of_alias_get_highest_id("spi");
         if (first_dynamic < 0)
             first_dynamic = 0;
         else
             first_dynamic++;
 
         mutex_lock(&board_lock);
         id = idr_alloc(&spi_master_idr, ctlr, first_dynamic,
                    0, GFP_KERNEL);
         mutex_unlock(&board_lock);
         if (WARN(id < 0, "couldn't get idr"))
             return id;
         ctlr->bus_num = id;
     }
     ctlr->bus_lock_flag = 0;
     init_completion(&ctlr->xfer_completion);
     init_completion(&ctlr->cur_msg_completion);
     if (!ctlr->max_dma_len)
         ctlr->max_dma_len = INT_MAX;
 
     /*
      * Register the device, then userspace will see it.
      * Registration fails if the bus ID is in use.
      */
     dev_set_name(&ctlr->dev, "spi%u", ctlr->bus_num);
 
     if (!spi_controller_is_slave(ctlr) && ctlr->use_gpio_descriptors) {
         status = spi_get_gpio_descs(ctlr);
         if (status)
             goto free_bus_id;
         /*
          * A controller using GPIO descriptors always
          * supports SPI_CS_HIGH if need be.
          */
         ctlr->mode_bits |= SPI_CS_HIGH;
     }
 
     /*
      * Even if it's just one always-selected device, there must
      * be at least one chipselect.
      */
     if (!ctlr->num_chipselect) {
         status = -EINVAL;
         goto free_bus_id;
     }
 
     /* Setting last_cs to -1 means no chip selected */
     ctlr->last_cs = -1;
 
     status = device_add(&ctlr->dev);
     if (status < 0)
         goto free_bus_id;
     dev_dbg(dev, "registered %s %s\n",
             spi_controller_is_slave(ctlr) ? "slave" : "master",
             dev_name(&ctlr->dev));
 
     /*
      * If we're using a queued driver, start the queue. Note that we don't
      * need the queueing logic if the driver is only supporting high-level
      * memory operations.
      */
     if (ctlr->transfer) {
         dev_info(dev, "controller is unqueued, this is deprecated\n");
     } else if (ctlr->transfer_one || ctlr->transfer_one_message) {
         status = spi_controller_initialize_queue(ctlr);
         if (status) {
             device_del(&ctlr->dev);
             goto free_bus_id;
         }
     }
     /* Add statistics */
     ctlr->pcpu_statistics = spi_alloc_pcpu_stats(dev);
     if (!ctlr->pcpu_statistics) {
         dev_err(dev, "Error allocating per-cpu statistics\n");
         status = -ENOMEM;
         goto destroy_queue;
     }
 
     mutex_lock(&board_lock);
     list_add_tail(&ctlr->list, &spi_controller_list);
     list_for_each_entry(bi, &board_list, list)
         spi_match_controller_to_boardinfo(ctlr, &bi->board_info);
     mutex_unlock(&board_lock);
 
     /* Register devices from the device tree and ACPI */
     of_register_spi_devices(ctlr);
     acpi_register_spi_devices(ctlr);
     return status;
 
 destroy_queue:
     spi_destroy_queue(ctlr);
 free_bus_id:
     mutex_lock(&board_lock);
     idr_remove(&spi_master_idr, ctlr->bus_num);
     mutex_unlock(&board_lock);
     return status;
 }
 EXPORT_SYMBOL_GPL(spi_register_controller);
 
 static void devm_spi_unregister(struct device *dev, void *res)
 {
     spi_unregister_controller(*(struct spi_controller **)res);
 }
 
 /**
  * devm_spi_register_controller - register managed SPI master or slave
  *  controller
  * @dev:    device managing SPI controller
  * @ctlr: initialized controller, originally from spi_alloc_master() or
  *  spi_alloc_slave()
  * Context: can sleep
  *
  * Register a SPI device as with spi_register_controller() which will
  * automatically be unregistered and freed.
  *
  * Return: zero on success, else a negative error code.
  */
 int devm_spi_register_controller(struct device *dev,
                  struct spi_controller *ctlr)
 {
     struct spi_controller **ptr;
     int ret;
 
     ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
     if (!ptr)
         return -ENOMEM;
 
     ret = spi_register_controller(ctlr);
     if (!ret) {
         *ptr = ctlr;
         devres_add(dev, ptr);
     } else {
         devres_free(ptr);
     }
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(devm_spi_register_controller);
 
 static int __unregister(struct device *dev, void *null)
 {
     spi_unregister_device(to_spi_device(dev));
     return 0;
 }
 
 /**
  * spi_unregister_controller - unregister SPI master or slave controller
  * @ctlr: the controller being unregistered
  * Context: can sleep
  *
  * This call is used only by SPI controller drivers, which are the
  * only ones directly touching chip registers.
  *
  * This must be called from context that can sleep.
  *
  * Note that this function also drops a reference to the controller.
  */
 void spi_unregister_controller(struct spi_controller *ctlr)
 {
     struct spi_controller *found;
     int id = ctlr->bus_num;
 
     /* Prevent addition of new devices, unregister existing ones */
     if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
         mutex_lock(&ctlr->add_lock);
 
     device_for_each_child(&ctlr->dev, NULL, __unregister);
 
     /* First make sure that this controller was ever added */
     mutex_lock(&board_lock);
     found = idr_find(&spi_master_idr, id);
     mutex_unlock(&board_lock);
     if (ctlr->queued) {
         if (spi_destroy_queue(ctlr))
             dev_err(&ctlr->dev, "queue remove failed\n");
     }
     mutex_lock(&board_lock);
     list_del(&ctlr->list);
     mutex_unlock(&board_lock);
 
     device_del(&ctlr->dev);
 
     /* Free bus id */
     mutex_lock(&board_lock);
     if (found == ctlr)
         idr_remove(&spi_master_idr, id);
     mutex_unlock(&board_lock);
 
     if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
         mutex_unlock(&ctlr->add_lock);
 
     /* Release the last reference on the controller if its driver
      * has not yet been converted to devm_spi_alloc_master/slave().
      */
     if (!ctlr->devm_allocated)
         put_device(&ctlr->dev);
 }
 EXPORT_SYMBOL_GPL(spi_unregister_controller);
 
 int spi_controller_suspend(struct spi_controller *ctlr)
 {
     int ret;
 
     /* Basically no-ops for non-queued controllers */
     if (!ctlr->queued)
         return 0;
 
     ret = spi_stop_queue(ctlr);
     if (ret)
         dev_err(&ctlr->dev, "queue stop failed\n");
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(spi_controller_suspend);
 
 int spi_controller_resume(struct spi_controller *ctlr)
 {
     int ret;
 
     if (!ctlr->queued)
         return 0;
 
     ret = spi_start_queue(ctlr);
     if (ret)
         dev_err(&ctlr->dev, "queue restart failed\n");
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(spi_controller_resume);
 
 /*-------------------------------------------------------------------------*/
 
 /* Core methods for spi_message alterations */
 
 static void __spi_replace_transfers_release(struct spi_controller *ctlr,
                         struct spi_message *msg,
                         void *res)
 {
     struct spi_replaced_transfers *rxfer = res;
     size_t i;
 
     /* Call extra callback if requested */
     if (rxfer->release)
         rxfer->release(ctlr, msg, res);
 
     /* Insert replaced transfers back into the message */
     list_splice(&rxfer->replaced_transfers, rxfer->replaced_after);
 
     /* Remove the formerly inserted entries */
     for (i = 0; i < rxfer->inserted; i++)
         list_del(&rxfer->inserted_transfers[i].transfer_list);
 }
 
 /**
  * spi_replace_transfers - replace transfers with several transfers
  *                         and register change with spi_message.resources
  * @msg:           the spi_message we work upon
  * @xfer_first:    the first spi_transfer we want to replace
  * @remove:        number of transfers to remove
  * @insert:        the number of transfers we want to insert instead
  * @release:       extra release code necessary in some circumstances
  * @extradatasize: extra data to allocate (with alignment guarantees
  *                 of struct @spi_transfer)
  * @gfp:           gfp flags
  *
  * Returns: pointer to @spi_replaced_transfers,
  *          PTR_ERR(...) in case of errors.
  */
 static struct spi_replaced_transfers *spi_replace_transfers(
     struct spi_message *msg,
     struct spi_transfer *xfer_first,
     size_t remove,
     size_t insert,
     spi_replaced_release_t release,
     size_t extradatasize,
     gfp_t gfp)
 {
     struct spi_replaced_transfers *rxfer;
     struct spi_transfer *xfer;
     size_t i;
 
     /* Allocate the structure using spi_res */
     rxfer = spi_res_alloc(msg->spi, __spi_replace_transfers_release,
                   struct_size(rxfer, inserted_transfers, insert)
                   + extradatasize,
                   gfp);
     if (!rxfer)
         return ERR_PTR(-ENOMEM);
 
     /* The release code to invoke before running the generic release */
     rxfer->release = release;
 
     /* Assign extradata */
     if (extradatasize)
         rxfer->extradata =
             &rxfer->inserted_transfers[insert];
 
     /* Init the replaced_transfers list */
     INIT_LIST_HEAD(&rxfer->replaced_transfers);
 
     /*
      * Assign the list_entry after which we should reinsert
      * the @replaced_transfers - it may be spi_message.messages!
      */
     rxfer->replaced_after = xfer_first->transfer_list.prev;
 
     /* Remove the requested number of transfers */
     for (i = 0; i < remove; i++) {
         /*
          * If the entry after replaced_after it is msg->transfers
          * then we have been requested to remove more transfers
          * than are in the list.
          */
         if (rxfer->replaced_after->next == &msg->transfers) {
             dev_err(&msg->spi->dev,
                 "requested to remove more spi_transfers than are available\n");
             /* Insert replaced transfers back into the message */
             list_splice(&rxfer->replaced_transfers,
                     rxfer->replaced_after);
 
             /* Free the spi_replace_transfer structure... */
             spi_res_free(rxfer);
 
             /* ...and return with an error */
             return ERR_PTR(-EINVAL);
         }
 
         /*
          * Remove the entry after replaced_after from list of
          * transfers and add it to list of replaced_transfers.
          */
         list_move_tail(rxfer->replaced_after->next,
                    &rxfer->replaced_transfers);
     }
 
     /*
      * Create copy of the given xfer with identical settings
      * based on the first transfer to get removed.
      */
     for (i = 0; i < insert; i++) {
         /* We need to run in reverse order */
         xfer = &rxfer->inserted_transfers[insert - 1 - i];
 
         /* Copy all spi_transfer data */
         memcpy(xfer, xfer_first, sizeof(*xfer));
 
         /* Add to list */
         list_add(&xfer->transfer_list, rxfer->replaced_after);
 
         /* Clear cs_change and delay for all but the last */
         if (i) {
             xfer->cs_change = false;
             xfer->delay.value = 0;
         }
     }
 
     /* Set up inserted... */
     rxfer->inserted = insert;
 
     /* ...and register it with spi_res/spi_message */
     spi_res_add(msg, rxfer);
 
     return rxfer;
 }
 
 static int __spi_split_transfer_maxsize(struct spi_controller *ctlr,
                     struct spi_message *msg,
                     struct spi_transfer **xferp,
                     size_t maxsize,
                     gfp_t gfp)
 {
     struct spi_transfer *xfer = *xferp, *xfers;
     struct spi_replaced_transfers *srt;
     size_t offset;
     size_t count, i;
 
     /* Calculate how many we have to replace */
     count = DIV_ROUND_UP(xfer->len, maxsize);
 
     /* Create replacement */
     srt = spi_replace_transfers(msg, xfer, 1, count, NULL, 0, gfp);
     if (IS_ERR(srt))
         return PTR_ERR(srt);
     xfers = srt->inserted_transfers;
 
     /*
      * Now handle each of those newly inserted spi_transfers.
      * Note that the replacements spi_transfers all are preset
      * to the same values as *xferp, so tx_buf, rx_buf and len
      * are all identical (as well as most others)
      * so we just have to fix up len and the pointers.
      *
      * This also includes support for the depreciated
      * spi_message.is_dma_mapped interface.
      */
 
     /*
      * The first transfer just needs the length modified, so we
      * run it outside the loop.
      */
     xfers[0].len = min_t(size_t, maxsize, xfer[0].len);
 
     /* All the others need rx_buf/tx_buf also set */
     for (i = 1, offset = maxsize; i < count; offset += maxsize, i++) {
         /* Update rx_buf, tx_buf and dma */
         if (xfers[i].rx_buf)
             xfers[i].rx_buf += offset;
         if (xfers[i].rx_dma)
             xfers[i].rx_dma += offset;
         if (xfers[i].tx_buf)
             xfers[i].tx_buf += offset;
         if (xfers[i].tx_dma)
             xfers[i].tx_dma += offset;
 
         /* Update length */
         xfers[i].len = min(maxsize, xfers[i].len - offset);
     }
 
     /*
      * We set up xferp to the last entry we have inserted,
      * so that we skip those already split transfers.
      */
     *xferp = &xfers[count - 1];
 
     /* Increment statistics counters */
     SPI_STATISTICS_INCREMENT_FIELD(ctlr->pcpu_statistics,
                        transfers_split_maxsize);
     SPI_STATISTICS_INCREMENT_FIELD(msg->spi->pcpu_statistics,
                        transfers_split_maxsize);
 
     return 0;
 }
 
 /**
  * spi_split_transfers_maxsize - split spi transfers into multiple transfers
  *                               when an individual transfer exceeds a
  *                               certain size
  * @ctlr:    the @spi_controller for this transfer
  * @msg:   the @spi_message to transform
  * @maxsize:  the maximum when to apply this
  * @gfp: GFP allocation flags
  *
  * Return: status of transformation
  */
 int spi_split_transfers_maxsize(struct spi_controller *ctlr,
                 struct spi_message *msg,
                 size_t maxsize,
                 gfp_t gfp)
 {
     struct spi_transfer *xfer;
     int ret;
 
     /*
      * Iterate over the transfer_list,
      * but note that xfer is advanced to the last transfer inserted
      * to avoid checking sizes again unnecessarily (also xfer does
      * potentially belong to a different list by the time the
      * replacement has happened).
      */
     list_for_each_entry(xfer, &msg->transfers, transfer_list) {
         if (xfer->len > maxsize) {
             ret = __spi_split_transfer_maxsize(ctlr, msg, &xfer,
                                maxsize, gfp);
             if (ret)
                 return ret;
         }
     }
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize);
 
 /*-------------------------------------------------------------------------*/
 
 /* Core methods for SPI controller protocol drivers.  Some of the
  * other core methods are currently defined as inline functions.
  */
 
 static int __spi_validate_bits_per_word(struct spi_controller *ctlr,
                     u8 bits_per_word)
 {
     if (ctlr->bits_per_word_mask) {
         /* Only 32 bits fit in the mask */
         if (bits_per_word > 32)
             return -EINVAL;
         if (!(ctlr->bits_per_word_mask & SPI_BPW_MASK(bits_per_word)))
             return -EINVAL;
     }
 
     return 0;
 }
 
 /**
  * spi_setup - setup SPI mode and clock rate
  * @spi: the device whose settings are being modified
  * Context: can sleep, and no requests are queued to the device
  *
  * SPI protocol drivers may need to update the transfer mode if the
  * device doesn't work with its default.  They may likewise need
  * to update clock rates or word sizes from initial values.  This function
  * changes those settings, and must be called from a context that can sleep.
  * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
  * effect the next time the device is selected and data is transferred to
  * or from it.  When this function returns, the spi device is deselected.
  *
  * Note that this call will fail if the protocol driver specifies an option
  * that the underlying controller or its driver does not support.  For
  * example, not all hardware supports wire transfers using nine bit words,
  * LSB-first wire encoding, or active-high chipselects.
  *
  * Return: zero on success, else a negative error code.
  */
 int spi_setup(struct spi_device *spi)
 {
     unsigned    bad_bits, ugly_bits;
     int     status = 0;
 
     /*
      * Check mode to prevent that any two of DUAL, QUAD and NO_MOSI/MISO
      * are set at the same time.
      */
     if ((hweight_long(spi->mode &
         (SPI_TX_DUAL | SPI_TX_QUAD | SPI_NO_TX)) > 1) ||
         (hweight_long(spi->mode &
         (SPI_RX_DUAL | SPI_RX_QUAD | SPI_NO_RX)) > 1)) {
         dev_err(&spi->dev,
         "setup: can not select any two of dual, quad and no-rx/tx at the same time\n");
         return -EINVAL;
     }
     /* If it is SPI_3WIRE mode, DUAL and QUAD should be forbidden */
     if ((spi->mode & SPI_3WIRE) && (spi->mode &
         (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
          SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL)))
         return -EINVAL;
     /*
      * Help drivers fail *cleanly* when they need options
      * that aren't supported with their current controller.
      * SPI_CS_WORD has a fallback software implementation,
      * so it is ignored here.
      */
     bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD |
                  SPI_NO_TX | SPI_NO_RX);
     ugly_bits = bad_bits &
             (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
              SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL);
     if (ugly_bits) {
         dev_warn(&spi->dev,
              "setup: ignoring unsupported mode bits %x\n",
              ugly_bits);
         spi->mode &= ~ugly_bits;
         bad_bits &= ~ugly_bits;
     }
     if (bad_bits) {
         dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
             bad_bits);
         return -EINVAL;
     }
 
     if (!spi->bits_per_word) {
         spi->bits_per_word = 8;
     } else {
         /*
          * Some controllers may not support the default 8 bits-per-word
          * so only perform the check when this is explicitly provided.
          */
         status = __spi_validate_bits_per_word(spi->controller,
                               spi->bits_per_word);
         if (status)
             return status;
     }
 
     if (spi->controller->max_speed_hz &&
         (!spi->max_speed_hz ||
          spi->max_speed_hz > spi->controller->max_speed_hz))
         spi->max_speed_hz = spi->controller->max_speed_hz;
 
     mutex_lock(&spi->controller->io_mutex);
 
     if (spi->controller->setup) {
         status = spi->controller->setup(spi);
         if (status) {
             mutex_unlock(&spi->controller->io_mutex);
             dev_err(&spi->controller->dev, "Failed to setup device: %d\n",
                 status);
             return status;
         }
     }
 
     if (spi->controller->auto_runtime_pm && spi->controller->set_cs) {
         status = pm_runtime_resume_and_get(spi->controller->dev.parent);
         if (status < 0) {
             mutex_unlock(&spi->controller->io_mutex);
             dev_err(&spi->controller->dev, "Failed to power device: %d\n",
                 status);
             return status;
         }
 
         /*
          * We do not want to return positive value from pm_runtime_get,
          * there are many instances of devices calling spi_setup() and
          * checking for a non-zero return value instead of a negative
          * return value.
          */
         status = 0;
 
         spi_set_cs(spi, false, true);
         pm_runtime_mark_last_busy(spi->controller->dev.parent);
         pm_runtime_put_autosuspend(spi->controller->dev.parent);
     } else {
         spi_set_cs(spi, false, true);
     }
 
     mutex_unlock(&spi->controller->io_mutex);
 
     if (spi->rt && !spi->controller->rt) {
         spi->controller->rt = true;
         spi_set_thread_rt(spi->controller);
     }
 
     trace_spi_setup(spi, status);
 
     dev_dbg(&spi->dev, "setup mode %lu, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
             spi->mode & SPI_MODE_X_MASK,
             (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
             (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
             (spi->mode & SPI_3WIRE) ? "3wire, " : "",
             (spi->mode & SPI_LOOP) ? "loopback, " : "",
             spi->bits_per_word, spi->max_speed_hz,
             status);
 
     return status;
 }
 EXPORT_SYMBOL_GPL(spi_setup);
 
 static int _spi_xfer_word_delay_update(struct spi_transfer *xfer,
                        struct spi_device *spi)
 {
     int delay1, delay2;
 
     delay1 = spi_delay_to_ns(&xfer->word_delay, xfer);
     if (delay1 < 0)
         return delay1;
 
     delay2 = spi_delay_to_ns(&spi->word_delay, xfer);
     if (delay2 < 0)
         return delay2;
 
     if (delay1 < delay2)
         memcpy(&xfer->word_delay, &spi->word_delay,
                sizeof(xfer->word_delay));
 
     return 0;
 }
 
 static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 {
     struct spi_controller *ctlr = spi->controller;
     struct spi_transfer *xfer;
     int w_size;
 
     if (list_empty(&message->transfers))
         return -EINVAL;
 
     /*
      * If an SPI controller does not support toggling the CS line on each
      * transfer (indicated by the SPI_CS_WORD flag) or we are using a GPIO
      * for the CS line, we can emulate the CS-per-word hardware function by
      * splitting transfers into one-word transfers and ensuring that
      * cs_change is set for each transfer.
      */
     if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
                       spi->cs_gpiod)) {
         size_t maxsize;
         int ret;
 
         maxsize = (spi->bits_per_word + 7) / 8;
 
         /* spi_split_transfers_maxsize() requires message->spi */
         message->spi = spi;
 
         ret = spi_split_transfers_maxsize(ctlr, message, maxsize,
                           GFP_KERNEL);
         if (ret)
             return ret;
 
         list_for_each_entry(xfer, &message->transfers, transfer_list) {
             /* Don't change cs_change on the last entry in the list */
             if (list_is_last(&xfer->transfer_list, &message->transfers))
                 break;
             xfer->cs_change = 1;
         }
     }
 
     /*
      * Half-duplex links include original MicroWire, and ones with
      * only one data pin like SPI_3WIRE (switches direction) or where
      * either MOSI or MISO is missing.  They can also be caused by
      * software limitations.
      */
     if ((ctlr->flags & SPI_CONTROLLER_HALF_DUPLEX) ||
         (spi->mode & SPI_3WIRE)) {
         unsigned flags = ctlr->flags;
 
         list_for_each_entry(xfer, &message->transfers, transfer_list) {
             if (xfer->rx_buf && xfer->tx_buf)
                 return -EINVAL;
             if ((flags & SPI_CONTROLLER_NO_TX) && xfer->tx_buf)
                 return -EINVAL;
             if ((flags & SPI_CONTROLLER_NO_RX) && xfer->rx_buf)
                 return -EINVAL;
         }
     }
 
     /*
      * Set transfer bits_per_word and max speed as spi device default if
      * it is not set for this transfer.
      * Set transfer tx_nbits and rx_nbits as single transfer default
      * (SPI_NBITS_SINGLE) if it is not set for this transfer.
      * Ensure transfer word_delay is at least as long as that required by
      * device itself.
      */
     message->frame_length = 0;
     list_for_each_entry(xfer, &message->transfers, transfer_list) {
         xfer->effective_speed_hz = 0;
         message->frame_length += xfer->len;
         if (!xfer->bits_per_word)
             xfer->bits_per_word = spi->bits_per_word;
 
         if (!xfer->speed_hz)
             xfer->speed_hz = spi->max_speed_hz;
 
         if (ctlr->max_speed_hz && xfer->speed_hz > ctlr->max_speed_hz)
             xfer->speed_hz = ctlr->max_speed_hz;
 
         if (__spi_validate_bits_per_word(ctlr, xfer->bits_per_word))
             return -EINVAL;
 
         /*
          * SPI transfer length should be multiple of SPI word size
          * where SPI word size should be power-of-two multiple.
          */
         if (xfer->bits_per_word <= 8)
             w_size = 1;
         else if (xfer->bits_per_word <= 16)
             w_size = 2;
         else
             w_size = 4;
 
         /* No partial transfers accepted */
         if (xfer->len % w_size)
             return -EINVAL;
 
         if (xfer->speed_hz && ctlr->min_speed_hz &&
             xfer->speed_hz < ctlr->min_speed_hz)
             return -EINVAL;
 
         if (xfer->tx_buf && !xfer->tx_nbits)
             xfer->tx_nbits = SPI_NBITS_SINGLE;
         if (xfer->rx_buf && !xfer->rx_nbits)
             xfer->rx_nbits = SPI_NBITS_SINGLE;
         /*
          * Check transfer tx/rx_nbits:
          * 1. check the value matches one of single, dual and quad
          * 2. check tx/rx_nbits match the mode in spi_device
          */
         if (xfer->tx_buf) {
             if (spi->mode & SPI_NO_TX)
                 return -EINVAL;
             if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
                 xfer->tx_nbits != SPI_NBITS_DUAL &&
                 xfer->tx_nbits != SPI_NBITS_QUAD)
                 return -EINVAL;
             if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
                 !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
                 return -EINVAL;
             if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
                 !(spi->mode & SPI_TX_QUAD))
                 return -EINVAL;
         }
         /* Check transfer rx_nbits */
         if (xfer->rx_buf) {
             if (spi->mode & SPI_NO_RX)
                 return -EINVAL;
             if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
                 xfer->rx_nbits != SPI_NBITS_DUAL &&
                 xfer->rx_nbits != SPI_NBITS_QUAD)
                 return -EINVAL;
             if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
                 !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
                 return -EINVAL;
             if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
                 !(spi->mode & SPI_RX_QUAD))
                 return -EINVAL;
         }
 
         if (_spi_xfer_word_delay_update(xfer, spi))
             return -EINVAL;
     }
 
     message->status = -EINPROGRESS;
 
     return 0;
 }
 
 static int __spi_async(struct spi_device *spi, struct spi_message *message)
 {
     struct spi_controller *ctlr = spi->controller;
     struct spi_transfer *xfer;
 
     /*
      * Some controllers do not support doing regular SPI transfers. Return
      * ENOTSUPP when this is the case.
      */
     if (!ctlr->transfer)
         return -ENOTSUPP;
 
     message->spi = spi;
 
     SPI_STATISTICS_INCREMENT_FIELD(ctlr->pcpu_statistics, spi_async);
     SPI_STATISTICS_INCREMENT_FIELD(spi->pcpu_statistics, spi_async);
 
     trace_spi_message_submit(message);
 
     if (!ctlr->ptp_sts_supported) {
         list_for_each_entry(xfer, &message->transfers, transfer_list) {
             xfer->ptp_sts_word_pre = 0;
             ptp_read_system_prets(xfer->ptp_sts);
         }
     }
 
     return ctlr->transfer(spi, message);
 }
 
 /**
  * spi_async - asynchronous SPI transfer
  * @spi: device with which data will be exchanged
  * @message: describes the data transfers, including completion callback
  * Context: any (irqs may be blocked, etc)
  *
  * This call may be used in_irq and other contexts which can't sleep,
  * as well as from task contexts which can sleep.
  *
  * The completion callback is invoked in a context which can't sleep.
  * Before that invocation, the value of message->status is undefined.
  * When the callback is issued, message->status holds either zero (to
  * indicate complete success) or a negative error code.  After that
  * callback returns, the driver which issued the transfer request may
  * deallocate the associated memory; it's no longer in use by any SPI
  * core or controller driver code.
  *
  * Note that although all messages to a spi_device are handled in
  * FIFO order, messages may go to different devices in other orders.
  * Some device might be higher priority, or have various "hard" access
  * time requirements, for example.
  *
  * On detection of any fault during the transfer, processing of
  * the entire message is aborted, and the device is deselected.
  * Until returning from the associated message completion callback,
  * no other spi_message queued to that device will be processed.
  * (This rule applies equally to all the synchronous transfer calls,
  * which are wrappers around this core asynchronous primitive.)
  *
  * Return: zero on success, else a negative error code.
  */
 int spi_async(struct spi_device *spi, struct spi_message *message)
 {
     struct spi_controller *ctlr = spi->controller;
     int ret;
     unsigned long flags;
 
     ret = __spi_validate(spi, message);
     if (ret != 0)
         return ret;
 
     spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
 
     if (ctlr->bus_lock_flag)
         ret = -EBUSY;
     else
         ret = __spi_async(spi, message);
 
     spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(spi_async);
 
 /**
  * spi_async_locked - version of spi_async with exclusive bus usage
  * @spi: device with which data will be exchanged
  * @message: describes the data transfers, including completion callback
  * Context: any (irqs may be blocked, etc)
  *
  * This call may be used in_irq and other contexts which can't sleep,
  * as well as from task contexts which can sleep.
  *
  * The completion callback is invoked in a context which can't sleep.
  * Before that invocation, the value of message->status is undefined.
  * When the callback is issued, message->status holds either zero (to
  * indicate complete success) or a negative error code.  After that
  * callback returns, the driver which issued the transfer request may
  * deallocate the associated memory; it's no longer in use by any SPI
  * core or controller driver code.
  *
  * Note that although all messages to a spi_device are handled in
  * FIFO order, messages may go to different devices in other orders.
  * Some device might be higher priority, or have various "hard" access
  * time requirements, for example.
  *
  * On detection of any fault during the transfer, processing of
  * the entire message is aborted, and the device is deselected.
  * Until returning from the associated message completion callback,
  * no other spi_message queued to that device will be processed.
  * (This rule applies equally to all the synchronous transfer calls,
  * which are wrappers around this core asynchronous primitive.)
  *
  * Return: zero on success, else a negative error code.
  */
 static int spi_async_locked(struct spi_device *spi, struct spi_message *message)
 {
     struct spi_controller *ctlr = spi->controller;
     int ret;
     unsigned long flags;
 
     ret = __spi_validate(spi, message);
     if (ret != 0)
         return ret;
 
     spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
 
     ret = __spi_async(spi, message);
 
     spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
 
     return ret;
 
 }
 
 static void __spi_transfer_message_noqueue(struct spi_controller *ctlr, struct spi_message *msg)
 {
     bool was_busy;
     int ret;
 
     mutex_lock(&ctlr->io_mutex);
 
     was_busy = ctlr->busy;
 
     ctlr->cur_msg = msg;
     ret = __spi_pump_transfer_message(ctlr, msg, was_busy);
     if (ret)
         goto out;
 
     ctlr->cur_msg = NULL;
     ctlr->fallback = false;
 
     if (!was_busy) {
         kfree(ctlr->dummy_rx);
         ctlr->dummy_rx = NULL;
         kfree(ctlr->dummy_tx);
         ctlr->dummy_tx = NULL;
         if (ctlr->unprepare_transfer_hardware &&
             ctlr->unprepare_transfer_hardware(ctlr))
             dev_err(&ctlr->dev,
                 "failed to unprepare transfer hardware\n");
         spi_idle_runtime_pm(ctlr);
     }
 
 out:
     mutex_unlock(&ctlr->io_mutex);
 }
 
 /*-------------------------------------------------------------------------*/
 
 /*
  * Utility methods for SPI protocol drivers, layered on
  * top of the core.  Some other utility methods are defined as
  * inline functions.
  */
 
 static void spi_complete(void *arg)
 {
     complete(arg);
 }
 
 static int __spi_sync(struct spi_device *spi, struct spi_message *message)
 {
     DECLARE_COMPLETION_ONSTACK(done);
     int status;
     struct spi_controller *ctlr = spi->controller;
 
     status = __spi_validate(spi, message);
     if (status != 0)
         return status;
 
     message->spi = spi;
 
     SPI_STATISTICS_INCREMENT_FIELD(ctlr->pcpu_statistics, spi_sync);
     SPI_STATISTICS_INCREMENT_FIELD(spi->pcpu_statistics, spi_sync);
 
     /*
      * Checking queue_empty here only guarantees async/sync message
      * ordering when coming from the same context. It does not need to
      * guard against reentrancy from a different context. The io_mutex
      * will catch those cases.
      */
     if (READ_ONCE(ctlr->queue_empty) && !ctlr->must_async) {
         message->actual_length = 0;
         message->status = -EINPROGRESS;
 
         trace_spi_message_submit(message);
 
         SPI_STATISTICS_INCREMENT_FIELD(ctlr->pcpu_statistics, spi_sync_immediate);
         SPI_STATISTICS_INCREMENT_FIELD(spi->pcpu_statistics, spi_sync_immediate);
 
         __spi_transfer_message_noqueue(ctlr, message);
 
         return message->status;
     }
 
     /*
      * There are messages in the async queue that could have originated
      * from the same context, so we need to preserve ordering.
      * Therefor we send the message to the async queue and wait until they
      * are completed.
      */
     message->complete = spi_complete;
     message->context = &done;
     status = spi_async_locked(spi, message);
     if (status == 0) {
         wait_for_completion(&done);
         status = message->status;
     }
     message->context = NULL;
 
     return status;
 }
 
 /**
  * spi_sync - blocking/synchronous SPI data transfers
  * @spi: device with which data will be exchanged
  * @message: describes the data transfers
  * Context: can sleep
  *
  * This call may only be used from a context that may sleep.  The sleep
  * is non-interruptible, and has no timeout.  Low-overhead controller
  * drivers may DMA directly into and out of the message buffers.
  *
  * Note that the SPI device's chip select is active during the message,
  * and then is normally disabled between messages.  Drivers for some
  * frequently-used devices may want to minimize costs of selecting a chip,
  * by leaving it selected in anticipation that the next message will go
  * to the same chip.  (That may increase power usage.)
  *
  * Also, the caller is guaranteeing that the memory associated with the
  * message will not be freed before this call returns.
  *
  * Return: zero on success, else a negative error code.
  */
 int spi_sync(struct spi_device *spi, struct spi_message *message)
 {
     int ret;
 
     mutex_lock(&spi->controller->bus_lock_mutex);
     ret = __spi_sync(spi, message);
     mutex_unlock(&spi->controller->bus_lock_mutex);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(spi_sync);
 
 /**
  * spi_sync_locked - version of spi_sync with exclusive bus usage
  * @spi: device with which data will be exchanged
  * @message: describes the data transfers
  * Context: can sleep
  *
  * This call may only be used from a context that may sleep.  The sleep
  * is non-interruptible, and has no timeout.  Low-overhead controller
  * drivers may DMA directly into and out of the message buffers.
  *
  * This call should be used by drivers that require exclusive access to the
  * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
  * be released by a spi_bus_unlock call when the exclusive access is over.
  *
  * Return: zero on success, else a negative error code.
  */
 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
 {
     return __spi_sync(spi, message);
 }
 EXPORT_SYMBOL_GPL(spi_sync_locked);
 
 /**
  * spi_bus_lock - obtain a lock for exclusive SPI bus usage
  * @ctlr: SPI bus master that should be locked for exclusive bus access
  * Context: can sleep
  *
  * This call may only be used from a context that may sleep.  The sleep
  * is non-interruptible, and has no timeout.
  *
  * This call should be used by drivers that require exclusive access to the
  * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
  * exclusive access is over. Data transfer must be done by spi_sync_locked
  * and spi_async_locked calls when the SPI bus lock is held.
  *
  * Return: always zero.
  */
 int spi_bus_lock(struct spi_controller *ctlr)
 {
     unsigned long flags;
 
     mutex_lock(&ctlr->bus_lock_mutex);
 
     spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
     ctlr->bus_lock_flag = 1;
     spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
 
     /* Mutex remains locked until spi_bus_unlock() is called */
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(spi_bus_lock);
 
 /**
  * spi_bus_unlock - release the lock for exclusive SPI bus usage
  * @ctlr: SPI bus master that was locked for exclusive bus access
  * Context: can sleep
  *
  * This call may only be used from a context that may sleep.  The sleep
  * is non-interruptible, and has no timeout.
  *
  * This call releases an SPI bus lock previously obtained by an spi_bus_lock
  * call.
  *
  * Return: always zero.
  */
 int spi_bus_unlock(struct spi_controller *ctlr)
 {
     ctlr->bus_lock_flag = 0;
 
     mutex_unlock(&ctlr->bus_lock_mutex);
 
     return 0;
 }
 EXPORT_SYMBOL_GPL(spi_bus_unlock);
 
 /* Portable code must never pass more than 32 bytes */
 #define SPI_BUFSIZ  max(32, SMP_CACHE_BYTES)
 
 static u8   *buf;
 
 /**
  * spi_write_then_read - SPI synchronous write followed by read
  * @spi: device with which data will be exchanged
  * @txbuf: data to be written (need not be dma-safe)
  * @n_tx: size of txbuf, in bytes
  * @rxbuf: buffer into which data will be read (need not be dma-safe)
  * @n_rx: size of rxbuf, in bytes
  * Context: can sleep
  *
  * This performs a half duplex MicroWire style transaction with the
  * device, sending txbuf and then reading rxbuf.  The return value
  * is zero for success, else a negative errno status code.
  * This call may only be used from a context that may sleep.
  *
  * Parameters to this routine are always copied using a small buffer.
  * Performance-sensitive or bulk transfer code should instead use
  * spi_{async,sync}() calls with dma-safe buffers.
  *
  * Return: zero on success, else a negative error code.
  */
 int spi_write_then_read(struct spi_device *spi,
         const void *txbuf, unsigned n_tx,
         void *rxbuf, unsigned n_rx)
 {
     static DEFINE_MUTEX(lock);
 
     int         status;
     struct spi_message  message;
     struct spi_transfer x[2];
     u8          *local_buf;
 
     /*
      * Use preallocated DMA-safe buffer if we can. We can't avoid
      * copying here, (as a pure convenience thing), but we can
      * keep heap costs out of the hot path unless someone else is
      * using the pre-allocated buffer or the transfer is too large.
      */
     if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
         local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
                     GFP_KERNEL | GFP_DMA);
         if (!local_buf)
             return -ENOMEM;
     } else {
         local_buf = buf;
     }
 
     spi_message_init(&message);
     memset(x, 0, sizeof(x));
     if (n_tx) {
         x[0].len = n_tx;
         spi_message_add_tail(&x[0], &message);
     }
     if (n_rx) {
         x[1].len = n_rx;
         spi_message_add_tail(&x[1], &message);
     }
 
     memcpy(local_buf, txbuf, n_tx);
     x[0].tx_buf = local_buf;
     x[1].rx_buf = local_buf + n_tx;
 
     /* Do the i/o */
     status = spi_sync(spi, &message);
     if (status == 0)
         memcpy(rxbuf, x[1].rx_buf, n_rx);
 
     if (x[0].tx_buf == buf)
         mutex_unlock(&lock);
     else
         kfree(local_buf);
 
     return status;
 }
 EXPORT_SYMBOL_GPL(spi_write_then_read);
 
 /*-------------------------------------------------------------------------*/
 
 #if IS_ENABLED(CONFIG_OF_DYNAMIC)
 /* Must call put_device() when done with returned spi_device device */
 static struct spi_device *of_find_spi_device_by_node(struct device_node *node)
 {
     struct device *dev = bus_find_device_by_of_node(&spi_bus_type, node);
 
     return dev ? to_spi_device(dev) : NULL;
 }
 
 /* The spi controllers are not using spi_bus, so we find it with another way */
 static struct spi_controller *of_find_spi_controller_by_node(struct device_node *node)
 {
     struct device *dev;
 
     dev = class_find_device_by_of_node(&spi_master_class, node);
     if (!dev && IS_ENABLED(CONFIG_SPI_SLAVE))
         dev = class_find_device_by_of_node(&spi_slave_class, node);
     if (!dev)
         return NULL;
 
     /* Reference got in class_find_device */
     return container_of(dev, struct spi_controller, dev);
 }
 
 static int of_spi_notify(struct notifier_block *nb, unsigned long action,
              void *arg)
 {
     struct of_reconfig_data *rd = arg;
     struct spi_controller *ctlr;
     struct spi_device *spi;
 
     switch (of_reconfig_get_state_change(action, arg)) {
     case OF_RECONFIG_CHANGE_ADD:
         ctlr = of_find_spi_controller_by_node(rd->dn->parent);
         if (ctlr == NULL)
             return NOTIFY_OK;   /* Not for us */
 
         if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) {
             put_device(&ctlr->dev);
             return NOTIFY_OK;
         }
 
         spi = of_register_spi_device(ctlr, rd->dn);
         put_device(&ctlr->dev);
 
         if (IS_ERR(spi)) {
             pr_err("%s: failed to create for '%pOF'\n",
                     __func__, rd->dn);
             of_node_clear_flag(rd->dn, OF_POPULATED);
             return notifier_from_errno(PTR_ERR(spi));
         }
         break;
 
     case OF_RECONFIG_CHANGE_REMOVE:
         /* Already depopulated? */
         if (!of_node_check_flag(rd->dn, OF_POPULATED))
             return NOTIFY_OK;
 
         /* Find our device by node */
         spi = of_find_spi_device_by_node(rd->dn);
         if (spi == NULL)
             return NOTIFY_OK;   /* No? not meant for us */
 
         /* Unregister takes one ref away */
         spi_unregister_device(spi);
 
         /* And put the reference of the find */
         put_device(&spi->dev);
         break;
     }
 
     return NOTIFY_OK;
 }
 
 static struct notifier_block spi_of_notifier = {
     .notifier_call = of_spi_notify,
 };
 #else /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
 extern struct notifier_block spi_of_notifier;
 #endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
 
 #if IS_ENABLED(CONFIG_ACPI)
 static int spi_acpi_controller_match(struct device *dev, const void *data)
 {
     return ACPI_COMPANION(dev->parent) == data;
 }
 
 static struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev)
 {
     struct device *dev;
 
     dev = class_find_device(&spi_master_class, NULL, adev,
                 spi_acpi_controller_match);
     if (!dev && IS_ENABLED(CONFIG_SPI_SLAVE))
         dev = class_find_device(&spi_slave_class, NULL, adev,
                     spi_acpi_controller_match);
     if (!dev)
         return NULL;
 
     return container_of(dev, struct spi_controller, dev);
 }
 
 static struct spi_device *acpi_spi_find_device_by_adev(struct acpi_device *adev)
 {
     struct device *dev;
 
     dev = bus_find_device_by_acpi_dev(&spi_bus_type, adev);
     return to_spi_device(dev);
 }
 
 static int acpi_spi_notify(struct notifier_block *nb, unsigned long value,
                void *arg)
 {
     struct acpi_device *adev = arg;
     struct spi_controller *ctlr;
     struct spi_device *spi;
 
     switch (value) {
     case ACPI_RECONFIG_DEVICE_ADD:
         ctlr = acpi_spi_find_controller_by_adev(adev->parent);
         if (!ctlr)
             break;
 
         acpi_register_spi_device(ctlr, adev);
         put_device(&ctlr->dev);
         break;
     case ACPI_RECONFIG_DEVICE_REMOVE:
         if (!acpi_device_enumerated(adev))
             break;
 
         spi = acpi_spi_find_device_by_adev(adev);
         if (!spi)
             break;
 
         spi_unregister_device(spi);
         put_device(&spi->dev);
         break;
     }
 
     return NOTIFY_OK;
 }
 
 static struct notifier_block spi_acpi_notifier = {
     .notifier_call = acpi_spi_notify,
 };
 #else
 extern struct notifier_block spi_acpi_notifier;
 #endif
 
 static int __init spi_init(void)
 {
     int status;
 
     buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
     if (!buf) {
         status = -ENOMEM;
         goto err0;
     }
 
     status = bus_register(&spi_bus_type);
     if (status < 0)
         goto err1;
 
     status = class_register(&spi_master_class);
     if (status < 0)
         goto err2;
 
     if (IS_ENABLED(CONFIG_SPI_SLAVE)) {
         status = class_register(&spi_slave_class);
         if (status < 0)
             goto err3;
     }
 
     if (IS_ENABLED(CONFIG_OF_DYNAMIC))
         WARN_ON(of_reconfig_notifier_register(&spi_of_notifier));
     if (IS_ENABLED(CONFIG_ACPI))
         WARN_ON(acpi_reconfig_notifier_register(&spi_acpi_notifier));
 
     return 0;
 
 err3:
     class_unregister(&spi_master_class);
 err2:
     bus_unregister(&spi_bus_type);
 err1:
     kfree(buf);
     buf = NULL;
 err0:
     return status;
 }
 
 /*
  * A board_info is normally registered in arch_initcall(),
  * but even essential drivers wait till later.
  *
  * REVISIT only boardinfo really needs static linking. The rest (device and
  * driver registration) _could_ be dynamically linked (modular) ... Costs
  * include needing to have boardinfo data structures be much more public.
  */
 postcore_initcall(spi_init);