OSCL-LXR linux-6.0.1/​drivers/​firewire/​core-device.c	Source navigation Diff markup Identifier search General search
	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
 /*
  * Device probing and sysfs code.
  *
  * Copyright (C) 2005-2006  Kristian Hoegsberg <krh@bitplanet.net>
  */
 
 #include <linux/bug.h>
 #include <linux/ctype.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/firewire.h>
 #include <linux/firewire-constants.h>
 #include <linux/idr.h>
 #include <linux/jiffies.h>
 #include <linux/kobject.h>
 #include <linux/list.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/random.h>
 #include <linux/rwsem.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/workqueue.h>
 
 #include <linux/atomic.h>
 #include <asm/byteorder.h>
 
 #include "core.h"
 
 void fw_csr_iterator_init(struct fw_csr_iterator *ci, const u32 *p)
 {
     ci->p = p + 1;
     ci->end = ci->p + (p[0] >> 16);
 }
 EXPORT_SYMBOL(fw_csr_iterator_init);
 
 int fw_csr_iterator_next(struct fw_csr_iterator *ci, int *key, int *value)
 {
     *key = *ci->p >> 24;
     *value = *ci->p & 0xffffff;
 
     return ci->p++ < ci->end;
 }
 EXPORT_SYMBOL(fw_csr_iterator_next);
 
 static const u32 *search_leaf(const u32 *directory, int search_key)
 {
     struct fw_csr_iterator ci;
     int last_key = 0, key, value;
 
     fw_csr_iterator_init(&ci, directory);
     while (fw_csr_iterator_next(&ci, &key, &value)) {
         if (last_key == search_key &&
             key == (CSR_DESCRIPTOR | CSR_LEAF))
             return ci.p - 1 + value;
 
         last_key = key;
     }
 
     return NULL;
 }
 
 static int textual_leaf_to_string(const u32 *block, char *buf, size_t size)
 {
     unsigned int quadlets, i;
     char c;
 
     if (!size || !buf)
         return -EINVAL;
 
     quadlets = min(block[0] >> 16, 256U);
     if (quadlets < 2)
         return -ENODATA;
 
     if (block[1] != 0 || block[2] != 0)
         /* unknown language/character set */
         return -ENODATA;
 
     block += 3;
     quadlets -= 2;
     for (i = 0; i < quadlets * 4 && i < size - 1; i++) {
         c = block[i / 4] >> (24 - 8 * (i % 4));
         if (c == '\0')
             break;
         buf[i] = c;
     }
     buf[i] = '\0';
 
     return i;
 }
 
 /**
  * fw_csr_string() - reads a string from the configuration ROM
  * @directory:  e.g. root directory or unit directory
  * @key:    the key of the preceding directory entry
  * @buf:    where to put the string
  * @size:   size of @buf, in bytes
  *
  * The string is taken from a minimal ASCII text descriptor leaf after
  * the immediate entry with @key.  The string is zero-terminated.
  * An overlong string is silently truncated such that it and the
  * zero byte fit into @size.
  *
  * Returns strlen(buf) or a negative error code.
  */
 int fw_csr_string(const u32 *directory, int key, char *buf, size_t size)
 {
     const u32 *leaf = search_leaf(directory, key);
     if (!leaf)
         return -ENOENT;
 
     return textual_leaf_to_string(leaf, buf, size);
 }
 EXPORT_SYMBOL(fw_csr_string);
 
 static void get_ids(const u32 *directory, int *id)
 {
     struct fw_csr_iterator ci;
     int key, value;
 
     fw_csr_iterator_init(&ci, directory);
     while (fw_csr_iterator_next(&ci, &key, &value)) {
         switch (key) {
         case CSR_VENDOR:    id[0] = value; break;
         case CSR_MODEL:     id[1] = value; break;
         case CSR_SPECIFIER_ID:  id[2] = value; break;
         case CSR_VERSION:   id[3] = value; break;
         }
     }
 }
 
 static void get_modalias_ids(struct fw_unit *unit, int *id)
 {
     get_ids(&fw_parent_device(unit)->config_rom[5], id);
     get_ids(unit->directory, id);
 }
 
 static bool match_ids(const struct ieee1394_device_id *id_table, int *id)
 {
     int match = 0;
 
     if (id[0] == id_table->vendor_id)
         match |= IEEE1394_MATCH_VENDOR_ID;
     if (id[1] == id_table->model_id)
         match |= IEEE1394_MATCH_MODEL_ID;
     if (id[2] == id_table->specifier_id)
         match |= IEEE1394_MATCH_SPECIFIER_ID;
     if (id[3] == id_table->version)
         match |= IEEE1394_MATCH_VERSION;
 
     return (match & id_table->match_flags) == id_table->match_flags;
 }
 
 static const struct ieee1394_device_id *unit_match(struct device *dev,
                            struct device_driver *drv)
 {
     const struct ieee1394_device_id *id_table =
             container_of(drv, struct fw_driver, driver)->id_table;
     int id[] = {0, 0, 0, 0};
 
     get_modalias_ids(fw_unit(dev), id);
 
     for (; id_table->match_flags != 0; id_table++)
         if (match_ids(id_table, id))
             return id_table;
 
     return NULL;
 }
 
 static bool is_fw_unit(struct device *dev);
 
 static int fw_unit_match(struct device *dev, struct device_driver *drv)
 {
     /* We only allow binding to fw_units. */
     return is_fw_unit(dev) && unit_match(dev, drv) != NULL;
 }
 
 static int fw_unit_probe(struct device *dev)
 {
     struct fw_driver *driver =
             container_of(dev->driver, struct fw_driver, driver);
 
     return driver->probe(fw_unit(dev), unit_match(dev, dev->driver));
 }
 
 static void fw_unit_remove(struct device *dev)
 {
     struct fw_driver *driver =
             container_of(dev->driver, struct fw_driver, driver);
 
     driver->remove(fw_unit(dev));
 }
 
 static int get_modalias(struct fw_unit *unit, char *buffer, size_t buffer_size)
 {
     int id[] = {0, 0, 0, 0};
 
     get_modalias_ids(unit, id);
 
     return snprintf(buffer, buffer_size,
             "ieee1394:ven%08Xmo%08Xsp%08Xver%08X",
             id[0], id[1], id[2], id[3]);
 }
 
 static int fw_unit_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
     struct fw_unit *unit = fw_unit(dev);
     char modalias[64];
 
     get_modalias(unit, modalias, sizeof(modalias));
 
     if (add_uevent_var(env, "MODALIAS=%s", modalias))
         return -ENOMEM;
 
     return 0;
 }
 
 struct bus_type fw_bus_type = {
     .name = "firewire",
     .match = fw_unit_match,
     .probe = fw_unit_probe,
     .remove = fw_unit_remove,
 };
 EXPORT_SYMBOL(fw_bus_type);
 
 int fw_device_enable_phys_dma(struct fw_device *device)
 {
     int generation = device->generation;
 
     /* device->node_id, accessed below, must not be older than generation */
     smp_rmb();
 
     return device->card->driver->enable_phys_dma(device->card,
                              device->node_id,
                              generation);
 }
 EXPORT_SYMBOL(fw_device_enable_phys_dma);
 
 struct config_rom_attribute {
     struct device_attribute attr;
     u32 key;
 };
 
 static ssize_t show_immediate(struct device *dev,
                   struct device_attribute *dattr, char *buf)
 {
     struct config_rom_attribute *attr =
         container_of(dattr, struct config_rom_attribute, attr);
     struct fw_csr_iterator ci;
     const u32 *dir;
     int key, value, ret = -ENOENT;
 
     down_read(&fw_device_rwsem);
 
     if (is_fw_unit(dev))
         dir = fw_unit(dev)->directory;
     else
         dir = fw_device(dev)->config_rom + 5;
 
     fw_csr_iterator_init(&ci, dir);
     while (fw_csr_iterator_next(&ci, &key, &value))
         if (attr->key == key) {
             ret = snprintf(buf, buf ? PAGE_SIZE : 0,
                        "0x%06x\n", value);
             break;
         }
 
     up_read(&fw_device_rwsem);
 
     return ret;
 }
 
 #define IMMEDIATE_ATTR(name, key)               \
     { __ATTR(name, S_IRUGO, show_immediate, NULL), key }
 
 static ssize_t show_text_leaf(struct device *dev,
                   struct device_attribute *dattr, char *buf)
 {
     struct config_rom_attribute *attr =
         container_of(dattr, struct config_rom_attribute, attr);
     const u32 *dir;
     size_t bufsize;
     char dummy_buf[2];
     int ret;
 
     down_read(&fw_device_rwsem);
 
     if (is_fw_unit(dev))
         dir = fw_unit(dev)->directory;
     else
         dir = fw_device(dev)->config_rom + 5;
 
     if (buf) {
         bufsize = PAGE_SIZE - 1;
     } else {
         buf = dummy_buf;
         bufsize = 1;
     }
 
     ret = fw_csr_string(dir, attr->key, buf, bufsize);
 
     if (ret >= 0) {
         /* Strip trailing whitespace and add newline. */
         while (ret > 0 && isspace(buf[ret - 1]))
             ret--;
         strcpy(buf + ret, "\n");
         ret++;
     }
 
     up_read(&fw_device_rwsem);
 
     return ret;
 }
 
 #define TEXT_LEAF_ATTR(name, key)               \
     { __ATTR(name, S_IRUGO, show_text_leaf, NULL), key }
 
 static struct config_rom_attribute config_rom_attributes[] = {
     IMMEDIATE_ATTR(vendor, CSR_VENDOR),
     IMMEDIATE_ATTR(hardware_version, CSR_HARDWARE_VERSION),
     IMMEDIATE_ATTR(specifier_id, CSR_SPECIFIER_ID),
     IMMEDIATE_ATTR(version, CSR_VERSION),
     IMMEDIATE_ATTR(model, CSR_MODEL),
     TEXT_LEAF_ATTR(vendor_name, CSR_VENDOR),
     TEXT_LEAF_ATTR(model_name, CSR_MODEL),
     TEXT_LEAF_ATTR(hardware_version_name, CSR_HARDWARE_VERSION),
 };
 
 static void init_fw_attribute_group(struct device *dev,
                     struct device_attribute *attrs,
                     struct fw_attribute_group *group)
 {
     struct device_attribute *attr;
     int i, j;
 
     for (j = 0; attrs[j].attr.name != NULL; j++)
         group->attrs[j] = &attrs[j].attr;
 
     for (i = 0; i < ARRAY_SIZE(config_rom_attributes); i++) {
         attr = &config_rom_attributes[i].attr;
         if (attr->show(dev, attr, NULL) < 0)
             continue;
         group->attrs[j++] = &attr->attr;
     }
 
     group->attrs[j] = NULL;
     group->groups[0] = &group->group;
     group->groups[1] = NULL;
     group->group.attrs = group->attrs;
     dev->groups = (const struct attribute_group **) group->groups;
 }
 
 static ssize_t modalias_show(struct device *dev,
                  struct device_attribute *attr, char *buf)
 {
     struct fw_unit *unit = fw_unit(dev);
     int length;
 
     length = get_modalias(unit, buf, PAGE_SIZE);
     strcpy(buf + length, "\n");
 
     return length + 1;
 }
 
 static ssize_t rom_index_show(struct device *dev,
                   struct device_attribute *attr, char *buf)
 {
     struct fw_device *device = fw_device(dev->parent);
     struct fw_unit *unit = fw_unit(dev);
 
     return sysfs_emit(buf, "%td\n", unit->directory - device->config_rom);
 }
 
 static struct device_attribute fw_unit_attributes[] = {
     __ATTR_RO(modalias),
     __ATTR_RO(rom_index),
     __ATTR_NULL,
 };
 
 static ssize_t config_rom_show(struct device *dev,
                    struct device_attribute *attr, char *buf)
 {
     struct fw_device *device = fw_device(dev);
     size_t length;
 
     down_read(&fw_device_rwsem);
     length = device->config_rom_length * 4;
     memcpy(buf, device->config_rom, length);
     up_read(&fw_device_rwsem);
 
     return length;
 }
 
 static ssize_t guid_show(struct device *dev,
              struct device_attribute *attr, char *buf)
 {
     struct fw_device *device = fw_device(dev);
     int ret;
 
     down_read(&fw_device_rwsem);
     ret = sysfs_emit(buf, "0x%08x%08x\n", device->config_rom[3], device->config_rom[4]);
     up_read(&fw_device_rwsem);
 
     return ret;
 }
 
 static ssize_t is_local_show(struct device *dev,
                  struct device_attribute *attr, char *buf)
 {
     struct fw_device *device = fw_device(dev);
 
     return sprintf(buf, "%u\n", device->is_local);
 }
 
 static int units_sprintf(char *buf, const u32 *directory)
 {
     struct fw_csr_iterator ci;
     int key, value;
     int specifier_id = 0;
     int version = 0;
 
     fw_csr_iterator_init(&ci, directory);
     while (fw_csr_iterator_next(&ci, &key, &value)) {
         switch (key) {
         case CSR_SPECIFIER_ID:
             specifier_id = value;
             break;
         case CSR_VERSION:
             version = value;
             break;
         }
     }
 
     return sprintf(buf, "0x%06x:0x%06x ", specifier_id, version);
 }
 
 static ssize_t units_show(struct device *dev,
               struct device_attribute *attr, char *buf)
 {
     struct fw_device *device = fw_device(dev);
     struct fw_csr_iterator ci;
     int key, value, i = 0;
 
     down_read(&fw_device_rwsem);
     fw_csr_iterator_init(&ci, &device->config_rom[5]);
     while (fw_csr_iterator_next(&ci, &key, &value)) {
         if (key != (CSR_UNIT | CSR_DIRECTORY))
             continue;
         i += units_sprintf(&buf[i], ci.p + value - 1);
         if (i >= PAGE_SIZE - (8 + 1 + 8 + 1))
             break;
     }
     up_read(&fw_device_rwsem);
 
     if (i)
         buf[i - 1] = '\n';
 
     return i;
 }
 
 static struct device_attribute fw_device_attributes[] = {
     __ATTR_RO(config_rom),
     __ATTR_RO(guid),
     __ATTR_RO(is_local),
     __ATTR_RO(units),
     __ATTR_NULL,
 };
 
 static int read_rom(struct fw_device *device,
             int generation, int index, u32 *data)
 {
     u64 offset = (CSR_REGISTER_BASE | CSR_CONFIG_ROM) + index * 4;
     int i, rcode;
 
     /* device->node_id, accessed below, must not be older than generation */
     smp_rmb();
 
     for (i = 10; i < 100; i += 10) {
         rcode = fw_run_transaction(device->card,
                 TCODE_READ_QUADLET_REQUEST, device->node_id,
                 generation, device->max_speed, offset, data, 4);
         if (rcode != RCODE_BUSY)
             break;
         msleep(i);
     }
     be32_to_cpus(data);
 
     return rcode;
 }
 
 #define MAX_CONFIG_ROM_SIZE 256
 
 /*
  * Read the bus info block, perform a speed probe, and read all of the rest of
  * the config ROM.  We do all this with a cached bus generation.  If the bus
  * generation changes under us, read_config_rom will fail and get retried.
  * It's better to start all over in this case because the node from which we
  * are reading the ROM may have changed the ROM during the reset.
  * Returns either a result code or a negative error code.
  */
 static int read_config_rom(struct fw_device *device, int generation)
 {
     struct fw_card *card = device->card;
     const u32 *old_rom, *new_rom;
     u32 *rom, *stack;
     u32 sp, key;
     int i, end, length, ret;
 
     rom = kmalloc(sizeof(*rom) * MAX_CONFIG_ROM_SIZE +
               sizeof(*stack) * MAX_CONFIG_ROM_SIZE, GFP_KERNEL);
     if (rom == NULL)
         return -ENOMEM;
 
     stack = &rom[MAX_CONFIG_ROM_SIZE];
     memset(rom, 0, sizeof(*rom) * MAX_CONFIG_ROM_SIZE);
 
     device->max_speed = SCODE_100;
 
     /* First read the bus info block. */
     for (i = 0; i < 5; i++) {
         ret = read_rom(device, generation, i, &rom[i]);
         if (ret != RCODE_COMPLETE)
             goto out;
         /*
          * As per IEEE1212 7.2, during initialization, devices can
          * reply with a 0 for the first quadlet of the config
          * rom to indicate that they are booting (for example,
          * if the firmware is on the disk of a external
          * harddisk).  In that case we just fail, and the
          * retry mechanism will try again later.
          */
         if (i == 0 && rom[i] == 0) {
             ret = RCODE_BUSY;
             goto out;
         }
     }
 
     device->max_speed = device->node->max_speed;
 
     /*
      * Determine the speed of
      *   - devices with link speed less than PHY speed,
      *   - devices with 1394b PHY (unless only connected to 1394a PHYs),
      *   - all devices if there are 1394b repeaters.
      * Note, we cannot use the bus info block's link_spd as starting point
      * because some buggy firmwares set it lower than necessary and because
      * 1394-1995 nodes do not have the field.
      */
     if ((rom[2] & 0x7) < device->max_speed ||
         device->max_speed == SCODE_BETA ||
         card->beta_repeaters_present) {
         u32 dummy;
 
         /* for S1600 and S3200 */
         if (device->max_speed == SCODE_BETA)
             device->max_speed = card->link_speed;
 
         while (device->max_speed > SCODE_100) {
             if (read_rom(device, generation, 0, &dummy) ==
                 RCODE_COMPLETE)
                 break;
             device->max_speed--;
         }
     }
 
     /*
      * Now parse the config rom.  The config rom is a recursive
      * directory structure so we parse it using a stack of
      * references to the blocks that make up the structure.  We
      * push a reference to the root directory on the stack to
      * start things off.
      */
     length = i;
     sp = 0;
     stack[sp++] = 0xc0000005;
     while (sp > 0) {
         /*
          * Pop the next block reference of the stack.  The
          * lower 24 bits is the offset into the config rom,
          * the upper 8 bits are the type of the reference the
          * block.
          */
         key = stack[--sp];
         i = key & 0xffffff;
         if (WARN_ON(i >= MAX_CONFIG_ROM_SIZE)) {
             ret = -ENXIO;
             goto out;
         }
 
         /* Read header quadlet for the block to get the length. */
         ret = read_rom(device, generation, i, &rom[i]);
         if (ret != RCODE_COMPLETE)
             goto out;
         end = i + (rom[i] >> 16) + 1;
         if (end > MAX_CONFIG_ROM_SIZE) {
             /*
              * This block extends outside the config ROM which is
              * a firmware bug.  Ignore this whole block, i.e.
              * simply set a fake block length of 0.
              */
             fw_err(card, "skipped invalid ROM block %x at %llx\n",
                    rom[i],
                    i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
             rom[i] = 0;
             end = i;
         }
         i++;
 
         /*
          * Now read in the block.  If this is a directory
          * block, check the entries as we read them to see if
          * it references another block, and push it in that case.
          */
         for (; i < end; i++) {
             ret = read_rom(device, generation, i, &rom[i]);
             if (ret != RCODE_COMPLETE)
                 goto out;
 
             if ((key >> 30) != 3 || (rom[i] >> 30) < 2)
                 continue;
             /*
              * Offset points outside the ROM.  May be a firmware
              * bug or an Extended ROM entry (IEEE 1212-2001 clause
              * 7.7.18).  Simply overwrite this pointer here by a
              * fake immediate entry so that later iterators over
              * the ROM don't have to check offsets all the time.
              */
             if (i + (rom[i] & 0xffffff) >= MAX_CONFIG_ROM_SIZE) {
                 fw_err(card,
                        "skipped unsupported ROM entry %x at %llx\n",
                        rom[i],
                        i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
                 rom[i] = 0;
                 continue;
             }
             stack[sp++] = i + rom[i];
         }
         if (length < i)
             length = i;
     }
 
     old_rom = device->config_rom;
     new_rom = kmemdup(rom, length * 4, GFP_KERNEL);
     if (new_rom == NULL) {
         ret = -ENOMEM;
         goto out;
     }
 
     down_write(&fw_device_rwsem);
     device->config_rom = new_rom;
     device->config_rom_length = length;
     up_write(&fw_device_rwsem);
 
     kfree(old_rom);
     ret = RCODE_COMPLETE;
     device->max_rec = rom[2] >> 12 & 0xf;
     device->cmc = rom[2] >> 30 & 1;
     device->irmc    = rom[2] >> 31 & 1;
  out:
     kfree(rom);
 
     return ret;
 }
 
 static void fw_unit_release(struct device *dev)
 {
     struct fw_unit *unit = fw_unit(dev);
 
     fw_device_put(fw_parent_device(unit));
     kfree(unit);
 }
 
 static struct device_type fw_unit_type = {
     .uevent     = fw_unit_uevent,
     .release    = fw_unit_release,
 };
 
 static bool is_fw_unit(struct device *dev)
 {
     return dev->type == &fw_unit_type;
 }
 
 static void create_units(struct fw_device *device)
 {
     struct fw_csr_iterator ci;
     struct fw_unit *unit;
     int key, value, i;
 
     i = 0;
     fw_csr_iterator_init(&ci, &device->config_rom[5]);
     while (fw_csr_iterator_next(&ci, &key, &value)) {
         if (key != (CSR_UNIT | CSR_DIRECTORY))
             continue;
 
         /*
          * Get the address of the unit directory and try to
          * match the drivers id_tables against it.
          */
         unit = kzalloc(sizeof(*unit), GFP_KERNEL);
         if (unit == NULL)
             continue;
 
         unit->directory = ci.p + value - 1;
         unit->device.bus = &fw_bus_type;
         unit->device.type = &fw_unit_type;
         unit->device.parent = &device->device;
         dev_set_name(&unit->device, "%s.%d", dev_name(&device->device), i++);
 
         BUILD_BUG_ON(ARRAY_SIZE(unit->attribute_group.attrs) <
                 ARRAY_SIZE(fw_unit_attributes) +
                 ARRAY_SIZE(config_rom_attributes));
         init_fw_attribute_group(&unit->device,
                     fw_unit_attributes,
                     &unit->attribute_group);
 
         if (device_register(&unit->device) < 0)
             goto skip_unit;
 
         fw_device_get(device);
         continue;
 
     skip_unit:
         kfree(unit);
     }
 }
 
 static int shutdown_unit(struct device *device, void *data)
 {
     device_unregister(device);
 
     return 0;
 }
 
 /*
  * fw_device_rwsem acts as dual purpose mutex:
  *   - serializes accesses to fw_device_idr,
  *   - serializes accesses to fw_device.config_rom/.config_rom_length and
  *     fw_unit.directory, unless those accesses happen at safe occasions
  */
 DECLARE_RWSEM(fw_device_rwsem);
 
 DEFINE_IDR(fw_device_idr);
 int fw_cdev_major;
 
 struct fw_device *fw_device_get_by_devt(dev_t devt)
 {
     struct fw_device *device;
 
     down_read(&fw_device_rwsem);
     device = idr_find(&fw_device_idr, MINOR(devt));
     if (device)
         fw_device_get(device);
     up_read(&fw_device_rwsem);
 
     return device;
 }
 
 struct workqueue_struct *fw_workqueue;
 EXPORT_SYMBOL(fw_workqueue);
 
 static void fw_schedule_device_work(struct fw_device *device,
                     unsigned long delay)
 {
     queue_delayed_work(fw_workqueue, &device->work, delay);
 }
 
 /*
  * These defines control the retry behavior for reading the config
  * rom.  It shouldn't be necessary to tweak these; if the device
  * doesn't respond to a config rom read within 10 seconds, it's not
  * going to respond at all.  As for the initial delay, a lot of
  * devices will be able to respond within half a second after bus
  * reset.  On the other hand, it's not really worth being more
  * aggressive than that, since it scales pretty well; if 10 devices
  * are plugged in, they're all getting read within one second.
  */
 
 #define MAX_RETRIES 10
 #define RETRY_DELAY (3 * HZ)
 #define INITIAL_DELAY   (HZ / 2)
 #define SHUTDOWN_DELAY  (2 * HZ)
 
 static void fw_device_shutdown(struct work_struct *work)
 {
     struct fw_device *device =
         container_of(work, struct fw_device, work.work);
     int minor = MINOR(device->device.devt);
 
     if (time_before64(get_jiffies_64(),
               device->card->reset_jiffies + SHUTDOWN_DELAY)
         && !list_empty(&device->card->link)) {
         fw_schedule_device_work(device, SHUTDOWN_DELAY);
         return;
     }
 
     if (atomic_cmpxchg(&device->state,
                FW_DEVICE_GONE,
                FW_DEVICE_SHUTDOWN) != FW_DEVICE_GONE)
         return;
 
     fw_device_cdev_remove(device);
     device_for_each_child(&device->device, NULL, shutdown_unit);
     device_unregister(&device->device);
 
     down_write(&fw_device_rwsem);
     idr_remove(&fw_device_idr, minor);
     up_write(&fw_device_rwsem);
 
     fw_device_put(device);
 }
 
 static void fw_device_release(struct device *dev)
 {
     struct fw_device *device = fw_device(dev);
     struct fw_card *card = device->card;
     unsigned long flags;
 
     /*
      * Take the card lock so we don't set this to NULL while a
      * FW_NODE_UPDATED callback is being handled or while the
      * bus manager work looks at this node.
      */
     spin_lock_irqsave(&card->lock, flags);
     device->node->data = NULL;
     spin_unlock_irqrestore(&card->lock, flags);
 
     fw_node_put(device->node);
     kfree(device->config_rom);
     kfree(device);
     fw_card_put(card);
 }
 
 static struct device_type fw_device_type = {
     .release = fw_device_release,
 };
 
 static bool is_fw_device(struct device *dev)
 {
     return dev->type == &fw_device_type;
 }
 
 static int update_unit(struct device *dev, void *data)
 {
     struct fw_unit *unit = fw_unit(dev);
     struct fw_driver *driver = (struct fw_driver *)dev->driver;
 
     if (is_fw_unit(dev) && driver != NULL && driver->update != NULL) {
         device_lock(dev);
         driver->update(unit);
         device_unlock(dev);
     }
 
     return 0;
 }
 
 static void fw_device_update(struct work_struct *work)
 {
     struct fw_device *device =
         container_of(work, struct fw_device, work.work);
 
     fw_device_cdev_update(device);
     device_for_each_child(&device->device, NULL, update_unit);
 }
 
 /*
  * If a device was pending for deletion because its node went away but its
  * bus info block and root directory header matches that of a newly discovered
  * device, revive the existing fw_device.
  * The newly allocated fw_device becomes obsolete instead.
  */
 static int lookup_existing_device(struct device *dev, void *data)
 {
     struct fw_device *old = fw_device(dev);
     struct fw_device *new = data;
     struct fw_card *card = new->card;
     int match = 0;
 
     if (!is_fw_device(dev))
         return 0;
 
     down_read(&fw_device_rwsem); /* serialize config_rom access */
     spin_lock_irq(&card->lock);  /* serialize node access */
 
     if (memcmp(old->config_rom, new->config_rom, 6 * 4) == 0 &&
         atomic_cmpxchg(&old->state,
                FW_DEVICE_GONE,
                FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
         struct fw_node *current_node = new->node;
         struct fw_node *obsolete_node = old->node;
 
         new->node = obsolete_node;
         new->node->data = new;
         old->node = current_node;
         old->node->data = old;
 
         old->max_speed = new->max_speed;
         old->node_id = current_node->node_id;
         smp_wmb();  /* update node_id before generation */
         old->generation = card->generation;
         old->config_rom_retries = 0;
         fw_notice(card, "rediscovered device %s\n", dev_name(dev));
 
         old->workfn = fw_device_update;
         fw_schedule_device_work(old, 0);
 
         if (current_node == card->root_node)
             fw_schedule_bm_work(card, 0);
 
         match = 1;
     }
 
     spin_unlock_irq(&card->lock);
     up_read(&fw_device_rwsem);
 
     return match;
 }
 
 enum { BC_UNKNOWN = 0, BC_UNIMPLEMENTED, BC_IMPLEMENTED, };
 
 static void set_broadcast_channel(struct fw_device *device, int generation)
 {
     struct fw_card *card = device->card;
     __be32 data;
     int rcode;
 
     if (!card->broadcast_channel_allocated)
         return;
 
     /*
      * The Broadcast_Channel Valid bit is required by nodes which want to
      * transmit on this channel.  Such transmissions are practically
      * exclusive to IP over 1394 (RFC 2734).  IP capable nodes are required
      * to be IRM capable and have a max_rec of 8 or more.  We use this fact
      * to narrow down to which nodes we send Broadcast_Channel updates.
      */
     if (!device->irmc || device->max_rec < 8)
         return;
 
     /*
      * Some 1394-1995 nodes crash if this 1394a-2000 register is written.
      * Perform a read test first.
      */
     if (device->bc_implemented == BC_UNKNOWN) {
         rcode = fw_run_transaction(card, TCODE_READ_QUADLET_REQUEST,
                 device->node_id, generation, device->max_speed,
                 CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
                 &data, 4);
         switch (rcode) {
         case RCODE_COMPLETE:
             if (data & cpu_to_be32(1 << 31)) {
                 device->bc_implemented = BC_IMPLEMENTED;
                 break;
             }
             fallthrough;    /* to case address error */
         case RCODE_ADDRESS_ERROR:
             device->bc_implemented = BC_UNIMPLEMENTED;
         }
     }
 
     if (device->bc_implemented == BC_IMPLEMENTED) {
         data = cpu_to_be32(BROADCAST_CHANNEL_INITIAL |
                    BROADCAST_CHANNEL_VALID);
         fw_run_transaction(card, TCODE_WRITE_QUADLET_REQUEST,
                 device->node_id, generation, device->max_speed,
                 CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
                 &data, 4);
     }
 }
 
 int fw_device_set_broadcast_channel(struct device *dev, void *gen)
 {
     if (is_fw_device(dev))
         set_broadcast_channel(fw_device(dev), (long)gen);
 
     return 0;
 }
 
 static void fw_device_init(struct work_struct *work)
 {
     struct fw_device *device =
         container_of(work, struct fw_device, work.work);
     struct fw_card *card = device->card;
     struct device *revived_dev;
     int minor, ret;
 
     /*
      * All failure paths here set node->data to NULL, so that we
      * don't try to do device_for_each_child() on a kfree()'d
      * device.
      */
 
     ret = read_config_rom(device, device->generation);
     if (ret != RCODE_COMPLETE) {
         if (device->config_rom_retries < MAX_RETRIES &&
             atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
             device->config_rom_retries++;
             fw_schedule_device_work(device, RETRY_DELAY);
         } else {
             if (device->node->link_on)
                 fw_notice(card, "giving up on node %x: reading config rom failed: %s\n",
                       device->node_id,
                       fw_rcode_string(ret));
             if (device->node == card->root_node)
                 fw_schedule_bm_work(card, 0);
             fw_device_release(&device->device);
         }
         return;
     }
 
     revived_dev = device_find_child(card->device,
                     device, lookup_existing_device);
     if (revived_dev) {
         put_device(revived_dev);
         fw_device_release(&device->device);
 
         return;
     }
 
     device_initialize(&device->device);
 
     fw_device_get(device);
     down_write(&fw_device_rwsem);
     minor = idr_alloc(&fw_device_idr, device, 0, 1 << MINORBITS,
             GFP_KERNEL);
     up_write(&fw_device_rwsem);
 
     if (minor < 0)
         goto error;
 
     device->device.bus = &fw_bus_type;
     device->device.type = &fw_device_type;
     device->device.parent = card->device;
     device->device.devt = MKDEV(fw_cdev_major, minor);
     dev_set_name(&device->device, "fw%d", minor);
 
     BUILD_BUG_ON(ARRAY_SIZE(device->attribute_group.attrs) <
             ARRAY_SIZE(fw_device_attributes) +
             ARRAY_SIZE(config_rom_attributes));
     init_fw_attribute_group(&device->device,
                 fw_device_attributes,
                 &device->attribute_group);
 
     if (device_add(&device->device)) {
         fw_err(card, "failed to add device\n");
         goto error_with_cdev;
     }
 
     create_units(device);
 
     /*
      * Transition the device to running state.  If it got pulled
      * out from under us while we did the initialization work, we
      * have to shut down the device again here.  Normally, though,
      * fw_node_event will be responsible for shutting it down when
      * necessary.  We have to use the atomic cmpxchg here to avoid
      * racing with the FW_NODE_DESTROYED case in
      * fw_node_event().
      */
     if (atomic_cmpxchg(&device->state,
                FW_DEVICE_INITIALIZING,
                FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
         device->workfn = fw_device_shutdown;
         fw_schedule_device_work(device, SHUTDOWN_DELAY);
     } else {
         fw_notice(card, "created device %s: GUID %08x%08x, S%d00\n",
               dev_name(&device->device),
               device->config_rom[3], device->config_rom[4],
               1 << device->max_speed);
         device->config_rom_retries = 0;
 
         set_broadcast_channel(device, device->generation);
 
         add_device_randomness(&device->config_rom[3], 8);
     }
 
     /*
      * Reschedule the IRM work if we just finished reading the
      * root node config rom.  If this races with a bus reset we
      * just end up running the IRM work a couple of extra times -
      * pretty harmless.
      */
     if (device->node == card->root_node)
         fw_schedule_bm_work(card, 0);
 
     return;
 
  error_with_cdev:
     down_write(&fw_device_rwsem);
     idr_remove(&fw_device_idr, minor);
     up_write(&fw_device_rwsem);
  error:
     fw_device_put(device);      /* fw_device_idr's reference */
 
     put_device(&device->device);    /* our reference */
 }
 
 /* Reread and compare bus info block and header of root directory */
 static int reread_config_rom(struct fw_device *device, int generation,
                  bool *changed)
 {
     u32 q;
     int i, rcode;
 
     for (i = 0; i < 6; i++) {
         rcode = read_rom(device, generation, i, &q);
         if (rcode != RCODE_COMPLETE)
             return rcode;
 
         if (i == 0 && q == 0)
             /* inaccessible (see read_config_rom); retry later */
             return RCODE_BUSY;
 
         if (q != device->config_rom[i]) {
             *changed = true;
             return RCODE_COMPLETE;
         }
     }
 
     *changed = false;
     return RCODE_COMPLETE;
 }
 
 static void fw_device_refresh(struct work_struct *work)
 {
     struct fw_device *device =
         container_of(work, struct fw_device, work.work);
     struct fw_card *card = device->card;
     int ret, node_id = device->node_id;
     bool changed;
 
     ret = reread_config_rom(device, device->generation, &changed);
     if (ret != RCODE_COMPLETE)
         goto failed_config_rom;
 
     if (!changed) {
         if (atomic_cmpxchg(&device->state,
                    FW_DEVICE_INITIALIZING,
                    FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
             goto gone;
 
         fw_device_update(work);
         device->config_rom_retries = 0;
         goto out;
     }
 
     /*
      * Something changed.  We keep things simple and don't investigate
      * further.  We just destroy all previous units and create new ones.
      */
     device_for_each_child(&device->device, NULL, shutdown_unit);
 
     ret = read_config_rom(device, device->generation);
     if (ret != RCODE_COMPLETE)
         goto failed_config_rom;
 
     fw_device_cdev_update(device);
     create_units(device);
 
     /* Userspace may want to re-read attributes. */
     kobject_uevent(&device->device.kobj, KOBJ_CHANGE);
 
     if (atomic_cmpxchg(&device->state,
                FW_DEVICE_INITIALIZING,
                FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
         goto gone;
 
     fw_notice(card, "refreshed device %s\n", dev_name(&device->device));
     device->config_rom_retries = 0;
     goto out;
 
  failed_config_rom:
     if (device->config_rom_retries < MAX_RETRIES &&
         atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
         device->config_rom_retries++;
         fw_schedule_device_work(device, RETRY_DELAY);
         return;
     }
 
     fw_notice(card, "giving up on refresh of device %s: %s\n",
           dev_name(&device->device), fw_rcode_string(ret));
  gone:
     atomic_set(&device->state, FW_DEVICE_GONE);
     device->workfn = fw_device_shutdown;
     fw_schedule_device_work(device, SHUTDOWN_DELAY);
  out:
     if (node_id == card->root_node->node_id)
         fw_schedule_bm_work(card, 0);
 }
 
 static void fw_device_workfn(struct work_struct *work)
 {
     struct fw_device *device = container_of(to_delayed_work(work),
                         struct fw_device, work);
     device->workfn(work);
 }
 
 void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 {
     struct fw_device *device;
 
     switch (event) {
     case FW_NODE_CREATED:
         /*
          * Attempt to scan the node, regardless whether its self ID has
          * the L (link active) flag set or not.  Some broken devices
          * send L=0 but have an up-and-running link; others send L=1
          * without actually having a link.
          */
  create:
         device = kzalloc(sizeof(*device), GFP_ATOMIC);
         if (device == NULL)
             break;
 
         /*
          * Do minimal initialization of the device here, the
          * rest will happen in fw_device_init().
          *
          * Attention:  A lot of things, even fw_device_get(),
          * cannot be done before fw_device_init() finished!
          * You can basically just check device->state and
          * schedule work until then, but only while holding
          * card->lock.
          */
         atomic_set(&device->state, FW_DEVICE_INITIALIZING);
         device->card = fw_card_get(card);
         device->node = fw_node_get(node);
         device->node_id = node->node_id;
         device->generation = card->generation;
         device->is_local = node == card->local_node;
         mutex_init(&device->client_list_mutex);
         INIT_LIST_HEAD(&device->client_list);
 
         /*
          * Set the node data to point back to this device so
          * FW_NODE_UPDATED callbacks can update the node_id
          * and generation for the device.
          */
         node->data = device;
 
         /*
          * Many devices are slow to respond after bus resets,
          * especially if they are bus powered and go through
          * power-up after getting plugged in.  We schedule the
          * first config rom scan half a second after bus reset.
          */
         device->workfn = fw_device_init;
         INIT_DELAYED_WORK(&device->work, fw_device_workfn);
         fw_schedule_device_work(device, INITIAL_DELAY);
         break;
 
     case FW_NODE_INITIATED_RESET:
     case FW_NODE_LINK_ON:
         device = node->data;
         if (device == NULL)
             goto create;
 
         device->node_id = node->node_id;
         smp_wmb();  /* update node_id before generation */
         device->generation = card->generation;
         if (atomic_cmpxchg(&device->state,
                 FW_DEVICE_RUNNING,
                 FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) {
             device->workfn = fw_device_refresh;
             fw_schedule_device_work(device,
                 device->is_local ? 0 : INITIAL_DELAY);
         }
         break;
 
     case FW_NODE_UPDATED:
         device = node->data;
         if (device == NULL)
             break;
 
         device->node_id = node->node_id;
         smp_wmb();  /* update node_id before generation */
         device->generation = card->generation;
         if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
             device->workfn = fw_device_update;
             fw_schedule_device_work(device, 0);
         }
         break;
 
     case FW_NODE_DESTROYED:
     case FW_NODE_LINK_OFF:
         if (!node->data)
             break;
 
         /*
          * Destroy the device associated with the node.  There
          * are two cases here: either the device is fully
          * initialized (FW_DEVICE_RUNNING) or we're in the
          * process of reading its config rom
          * (FW_DEVICE_INITIALIZING).  If it is fully
          * initialized we can reuse device->work to schedule a
          * full fw_device_shutdown().  If not, there's work
          * scheduled to read it's config rom, and we just put
          * the device in shutdown state to have that code fail
          * to create the device.
          */
         device = node->data;
         if (atomic_xchg(&device->state,
                 FW_DEVICE_GONE) == FW_DEVICE_RUNNING) {
             device->workfn = fw_device_shutdown;
             fw_schedule_device_work(device,
                 list_empty(&card->link) ? 0 : SHUTDOWN_DELAY);
         }
         break;
     }
 }

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