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0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * nvmem framework core.
0004  *
0005  * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
0006  * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
0007  */
0008 
0009 #include <linux/device.h>
0010 #include <linux/export.h>
0011 #include <linux/fs.h>
0012 #include <linux/idr.h>
0013 #include <linux/init.h>
0014 #include <linux/kref.h>
0015 #include <linux/module.h>
0016 #include <linux/nvmem-consumer.h>
0017 #include <linux/nvmem-provider.h>
0018 #include <linux/gpio/consumer.h>
0019 #include <linux/of.h>
0020 #include <linux/slab.h>
0021 
0022 struct nvmem_device {
0023     struct module       *owner;
0024     struct device       dev;
0025     int         stride;
0026     int         word_size;
0027     int         id;
0028     struct kref     refcnt;
0029     size_t          size;
0030     bool            read_only;
0031     bool            root_only;
0032     int         flags;
0033     enum nvmem_type     type;
0034     struct bin_attribute    eeprom;
0035     struct device       *base_dev;
0036     struct list_head    cells;
0037     const struct nvmem_keepout *keepout;
0038     unsigned int        nkeepout;
0039     nvmem_reg_read_t    reg_read;
0040     nvmem_reg_write_t   reg_write;
0041     nvmem_cell_post_process_t cell_post_process;
0042     struct gpio_desc    *wp_gpio;
0043     void *priv;
0044 };
0045 
0046 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
0047 
0048 #define FLAG_COMPAT     BIT(0)
0049 struct nvmem_cell_entry {
0050     const char      *name;
0051     int         offset;
0052     int         bytes;
0053     int         bit_offset;
0054     int         nbits;
0055     struct device_node  *np;
0056     struct nvmem_device *nvmem;
0057     struct list_head    node;
0058 };
0059 
0060 struct nvmem_cell {
0061     struct nvmem_cell_entry *entry;
0062     const char      *id;
0063 };
0064 
0065 static DEFINE_MUTEX(nvmem_mutex);
0066 static DEFINE_IDA(nvmem_ida);
0067 
0068 static DEFINE_MUTEX(nvmem_cell_mutex);
0069 static LIST_HEAD(nvmem_cell_tables);
0070 
0071 static DEFINE_MUTEX(nvmem_lookup_mutex);
0072 static LIST_HEAD(nvmem_lookup_list);
0073 
0074 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
0075 
0076 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
0077                 void *val, size_t bytes)
0078 {
0079     if (nvmem->reg_read)
0080         return nvmem->reg_read(nvmem->priv, offset, val, bytes);
0081 
0082     return -EINVAL;
0083 }
0084 
0085 static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
0086                  void *val, size_t bytes)
0087 {
0088     int ret;
0089 
0090     if (nvmem->reg_write) {
0091         gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
0092         ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);
0093         gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
0094         return ret;
0095     }
0096 
0097     return -EINVAL;
0098 }
0099 
0100 static int nvmem_access_with_keepouts(struct nvmem_device *nvmem,
0101                       unsigned int offset, void *val,
0102                       size_t bytes, int write)
0103 {
0104 
0105     unsigned int end = offset + bytes;
0106     unsigned int kend, ksize;
0107     const struct nvmem_keepout *keepout = nvmem->keepout;
0108     const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
0109     int rc;
0110 
0111     /*
0112      * Skip all keepouts before the range being accessed.
0113      * Keepouts are sorted.
0114      */
0115     while ((keepout < keepoutend) && (keepout->end <= offset))
0116         keepout++;
0117 
0118     while ((offset < end) && (keepout < keepoutend)) {
0119         /* Access the valid portion before the keepout. */
0120         if (offset < keepout->start) {
0121             kend = min(end, keepout->start);
0122             ksize = kend - offset;
0123             if (write)
0124                 rc = __nvmem_reg_write(nvmem, offset, val, ksize);
0125             else
0126                 rc = __nvmem_reg_read(nvmem, offset, val, ksize);
0127 
0128             if (rc)
0129                 return rc;
0130 
0131             offset += ksize;
0132             val += ksize;
0133         }
0134 
0135         /*
0136          * Now we're aligned to the start of this keepout zone. Go
0137          * through it.
0138          */
0139         kend = min(end, keepout->end);
0140         ksize = kend - offset;
0141         if (!write)
0142             memset(val, keepout->value, ksize);
0143 
0144         val += ksize;
0145         offset += ksize;
0146         keepout++;
0147     }
0148 
0149     /*
0150      * If we ran out of keepouts but there's still stuff to do, send it
0151      * down directly
0152      */
0153     if (offset < end) {
0154         ksize = end - offset;
0155         if (write)
0156             return __nvmem_reg_write(nvmem, offset, val, ksize);
0157         else
0158             return __nvmem_reg_read(nvmem, offset, val, ksize);
0159     }
0160 
0161     return 0;
0162 }
0163 
0164 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
0165               void *val, size_t bytes)
0166 {
0167     if (!nvmem->nkeepout)
0168         return __nvmem_reg_read(nvmem, offset, val, bytes);
0169 
0170     return nvmem_access_with_keepouts(nvmem, offset, val, bytes, false);
0171 }
0172 
0173 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
0174                void *val, size_t bytes)
0175 {
0176     if (!nvmem->nkeepout)
0177         return __nvmem_reg_write(nvmem, offset, val, bytes);
0178 
0179     return nvmem_access_with_keepouts(nvmem, offset, val, bytes, true);
0180 }
0181 
0182 #ifdef CONFIG_NVMEM_SYSFS
0183 static const char * const nvmem_type_str[] = {
0184     [NVMEM_TYPE_UNKNOWN] = "Unknown",
0185     [NVMEM_TYPE_EEPROM] = "EEPROM",
0186     [NVMEM_TYPE_OTP] = "OTP",
0187     [NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
0188     [NVMEM_TYPE_FRAM] = "FRAM",
0189 };
0190 
0191 #ifdef CONFIG_DEBUG_LOCK_ALLOC
0192 static struct lock_class_key eeprom_lock_key;
0193 #endif
0194 
0195 static ssize_t type_show(struct device *dev,
0196              struct device_attribute *attr, char *buf)
0197 {
0198     struct nvmem_device *nvmem = to_nvmem_device(dev);
0199 
0200     return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
0201 }
0202 
0203 static DEVICE_ATTR_RO(type);
0204 
0205 static struct attribute *nvmem_attrs[] = {
0206     &dev_attr_type.attr,
0207     NULL,
0208 };
0209 
0210 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
0211                    struct bin_attribute *attr, char *buf,
0212                    loff_t pos, size_t count)
0213 {
0214     struct device *dev;
0215     struct nvmem_device *nvmem;
0216     int rc;
0217 
0218     if (attr->private)
0219         dev = attr->private;
0220     else
0221         dev = kobj_to_dev(kobj);
0222     nvmem = to_nvmem_device(dev);
0223 
0224     /* Stop the user from reading */
0225     if (pos >= nvmem->size)
0226         return 0;
0227 
0228     if (!IS_ALIGNED(pos, nvmem->stride))
0229         return -EINVAL;
0230 
0231     if (count < nvmem->word_size)
0232         return -EINVAL;
0233 
0234     if (pos + count > nvmem->size)
0235         count = nvmem->size - pos;
0236 
0237     count = round_down(count, nvmem->word_size);
0238 
0239     if (!nvmem->reg_read)
0240         return -EPERM;
0241 
0242     rc = nvmem_reg_read(nvmem, pos, buf, count);
0243 
0244     if (rc)
0245         return rc;
0246 
0247     return count;
0248 }
0249 
0250 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
0251                     struct bin_attribute *attr, char *buf,
0252                     loff_t pos, size_t count)
0253 {
0254     struct device *dev;
0255     struct nvmem_device *nvmem;
0256     int rc;
0257 
0258     if (attr->private)
0259         dev = attr->private;
0260     else
0261         dev = kobj_to_dev(kobj);
0262     nvmem = to_nvmem_device(dev);
0263 
0264     /* Stop the user from writing */
0265     if (pos >= nvmem->size)
0266         return -EFBIG;
0267 
0268     if (!IS_ALIGNED(pos, nvmem->stride))
0269         return -EINVAL;
0270 
0271     if (count < nvmem->word_size)
0272         return -EINVAL;
0273 
0274     if (pos + count > nvmem->size)
0275         count = nvmem->size - pos;
0276 
0277     count = round_down(count, nvmem->word_size);
0278 
0279     if (!nvmem->reg_write)
0280         return -EPERM;
0281 
0282     rc = nvmem_reg_write(nvmem, pos, buf, count);
0283 
0284     if (rc)
0285         return rc;
0286 
0287     return count;
0288 }
0289 
0290 static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
0291 {
0292     umode_t mode = 0400;
0293 
0294     if (!nvmem->root_only)
0295         mode |= 0044;
0296 
0297     if (!nvmem->read_only)
0298         mode |= 0200;
0299 
0300     if (!nvmem->reg_write)
0301         mode &= ~0200;
0302 
0303     if (!nvmem->reg_read)
0304         mode &= ~0444;
0305 
0306     return mode;
0307 }
0308 
0309 static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
0310                      struct bin_attribute *attr, int i)
0311 {
0312     struct device *dev = kobj_to_dev(kobj);
0313     struct nvmem_device *nvmem = to_nvmem_device(dev);
0314 
0315     attr->size = nvmem->size;
0316 
0317     return nvmem_bin_attr_get_umode(nvmem);
0318 }
0319 
0320 /* default read/write permissions */
0321 static struct bin_attribute bin_attr_rw_nvmem = {
0322     .attr   = {
0323         .name   = "nvmem",
0324         .mode   = 0644,
0325     },
0326     .read   = bin_attr_nvmem_read,
0327     .write  = bin_attr_nvmem_write,
0328 };
0329 
0330 static struct bin_attribute *nvmem_bin_attributes[] = {
0331     &bin_attr_rw_nvmem,
0332     NULL,
0333 };
0334 
0335 static const struct attribute_group nvmem_bin_group = {
0336     .bin_attrs  = nvmem_bin_attributes,
0337     .attrs      = nvmem_attrs,
0338     .is_bin_visible = nvmem_bin_attr_is_visible,
0339 };
0340 
0341 static const struct attribute_group *nvmem_dev_groups[] = {
0342     &nvmem_bin_group,
0343     NULL,
0344 };
0345 
0346 static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
0347     .attr   = {
0348         .name   = "eeprom",
0349     },
0350     .read   = bin_attr_nvmem_read,
0351     .write  = bin_attr_nvmem_write,
0352 };
0353 
0354 /*
0355  * nvmem_setup_compat() - Create an additional binary entry in
0356  * drivers sys directory, to be backwards compatible with the older
0357  * drivers/misc/eeprom drivers.
0358  */
0359 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
0360                     const struct nvmem_config *config)
0361 {
0362     int rval;
0363 
0364     if (!config->compat)
0365         return 0;
0366 
0367     if (!config->base_dev)
0368         return -EINVAL;
0369 
0370     if (config->type == NVMEM_TYPE_FRAM)
0371         bin_attr_nvmem_eeprom_compat.attr.name = "fram";
0372 
0373     nvmem->eeprom = bin_attr_nvmem_eeprom_compat;
0374     nvmem->eeprom.attr.mode = nvmem_bin_attr_get_umode(nvmem);
0375     nvmem->eeprom.size = nvmem->size;
0376 #ifdef CONFIG_DEBUG_LOCK_ALLOC
0377     nvmem->eeprom.attr.key = &eeprom_lock_key;
0378 #endif
0379     nvmem->eeprom.private = &nvmem->dev;
0380     nvmem->base_dev = config->base_dev;
0381 
0382     rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
0383     if (rval) {
0384         dev_err(&nvmem->dev,
0385             "Failed to create eeprom binary file %d\n", rval);
0386         return rval;
0387     }
0388 
0389     nvmem->flags |= FLAG_COMPAT;
0390 
0391     return 0;
0392 }
0393 
0394 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
0395                   const struct nvmem_config *config)
0396 {
0397     if (config->compat)
0398         device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
0399 }
0400 
0401 #else /* CONFIG_NVMEM_SYSFS */
0402 
0403 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
0404                     const struct nvmem_config *config)
0405 {
0406     return -ENOSYS;
0407 }
0408 static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
0409                       const struct nvmem_config *config)
0410 {
0411 }
0412 
0413 #endif /* CONFIG_NVMEM_SYSFS */
0414 
0415 static void nvmem_release(struct device *dev)
0416 {
0417     struct nvmem_device *nvmem = to_nvmem_device(dev);
0418 
0419     ida_free(&nvmem_ida, nvmem->id);
0420     gpiod_put(nvmem->wp_gpio);
0421     kfree(nvmem);
0422 }
0423 
0424 static const struct device_type nvmem_provider_type = {
0425     .release    = nvmem_release,
0426 };
0427 
0428 static struct bus_type nvmem_bus_type = {
0429     .name       = "nvmem",
0430 };
0431 
0432 static void nvmem_cell_entry_drop(struct nvmem_cell_entry *cell)
0433 {
0434     blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
0435     mutex_lock(&nvmem_mutex);
0436     list_del(&cell->node);
0437     mutex_unlock(&nvmem_mutex);
0438     of_node_put(cell->np);
0439     kfree_const(cell->name);
0440     kfree(cell);
0441 }
0442 
0443 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
0444 {
0445     struct nvmem_cell_entry *cell, *p;
0446 
0447     list_for_each_entry_safe(cell, p, &nvmem->cells, node)
0448         nvmem_cell_entry_drop(cell);
0449 }
0450 
0451 static void nvmem_cell_entry_add(struct nvmem_cell_entry *cell)
0452 {
0453     mutex_lock(&nvmem_mutex);
0454     list_add_tail(&cell->node, &cell->nvmem->cells);
0455     mutex_unlock(&nvmem_mutex);
0456     blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
0457 }
0458 
0459 static int nvmem_cell_info_to_nvmem_cell_entry_nodup(struct nvmem_device *nvmem,
0460                              const struct nvmem_cell_info *info,
0461                              struct nvmem_cell_entry *cell)
0462 {
0463     cell->nvmem = nvmem;
0464     cell->offset = info->offset;
0465     cell->bytes = info->bytes;
0466     cell->name = info->name;
0467 
0468     cell->bit_offset = info->bit_offset;
0469     cell->nbits = info->nbits;
0470     cell->np = info->np;
0471 
0472     if (cell->nbits)
0473         cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
0474                        BITS_PER_BYTE);
0475 
0476     if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
0477         dev_err(&nvmem->dev,
0478             "cell %s unaligned to nvmem stride %d\n",
0479             cell->name ?: "<unknown>", nvmem->stride);
0480         return -EINVAL;
0481     }
0482 
0483     return 0;
0484 }
0485 
0486 static int nvmem_cell_info_to_nvmem_cell_entry(struct nvmem_device *nvmem,
0487                            const struct nvmem_cell_info *info,
0488                            struct nvmem_cell_entry *cell)
0489 {
0490     int err;
0491 
0492     err = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, cell);
0493     if (err)
0494         return err;
0495 
0496     cell->name = kstrdup_const(info->name, GFP_KERNEL);
0497     if (!cell->name)
0498         return -ENOMEM;
0499 
0500     return 0;
0501 }
0502 
0503 /**
0504  * nvmem_add_cells() - Add cell information to an nvmem device
0505  *
0506  * @nvmem: nvmem device to add cells to.
0507  * @info: nvmem cell info to add to the device
0508  * @ncells: number of cells in info
0509  *
0510  * Return: 0 or negative error code on failure.
0511  */
0512 static int nvmem_add_cells(struct nvmem_device *nvmem,
0513             const struct nvmem_cell_info *info,
0514             int ncells)
0515 {
0516     struct nvmem_cell_entry **cells;
0517     int i, rval;
0518 
0519     cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
0520     if (!cells)
0521         return -ENOMEM;
0522 
0523     for (i = 0; i < ncells; i++) {
0524         cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
0525         if (!cells[i]) {
0526             rval = -ENOMEM;
0527             goto err;
0528         }
0529 
0530         rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, &info[i], cells[i]);
0531         if (rval) {
0532             kfree(cells[i]);
0533             goto err;
0534         }
0535 
0536         nvmem_cell_entry_add(cells[i]);
0537     }
0538 
0539     /* remove tmp array */
0540     kfree(cells);
0541 
0542     return 0;
0543 err:
0544     while (i--)
0545         nvmem_cell_entry_drop(cells[i]);
0546 
0547     kfree(cells);
0548 
0549     return rval;
0550 }
0551 
0552 /**
0553  * nvmem_register_notifier() - Register a notifier block for nvmem events.
0554  *
0555  * @nb: notifier block to be called on nvmem events.
0556  *
0557  * Return: 0 on success, negative error number on failure.
0558  */
0559 int nvmem_register_notifier(struct notifier_block *nb)
0560 {
0561     return blocking_notifier_chain_register(&nvmem_notifier, nb);
0562 }
0563 EXPORT_SYMBOL_GPL(nvmem_register_notifier);
0564 
0565 /**
0566  * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
0567  *
0568  * @nb: notifier block to be unregistered.
0569  *
0570  * Return: 0 on success, negative error number on failure.
0571  */
0572 int nvmem_unregister_notifier(struct notifier_block *nb)
0573 {
0574     return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
0575 }
0576 EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);
0577 
0578 static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
0579 {
0580     const struct nvmem_cell_info *info;
0581     struct nvmem_cell_table *table;
0582     struct nvmem_cell_entry *cell;
0583     int rval = 0, i;
0584 
0585     mutex_lock(&nvmem_cell_mutex);
0586     list_for_each_entry(table, &nvmem_cell_tables, node) {
0587         if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
0588             for (i = 0; i < table->ncells; i++) {
0589                 info = &table->cells[i];
0590 
0591                 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
0592                 if (!cell) {
0593                     rval = -ENOMEM;
0594                     goto out;
0595                 }
0596 
0597                 rval = nvmem_cell_info_to_nvmem_cell_entry(nvmem, info, cell);
0598                 if (rval) {
0599                     kfree(cell);
0600                     goto out;
0601                 }
0602 
0603                 nvmem_cell_entry_add(cell);
0604             }
0605         }
0606     }
0607 
0608 out:
0609     mutex_unlock(&nvmem_cell_mutex);
0610     return rval;
0611 }
0612 
0613 static struct nvmem_cell_entry *
0614 nvmem_find_cell_entry_by_name(struct nvmem_device *nvmem, const char *cell_id)
0615 {
0616     struct nvmem_cell_entry *iter, *cell = NULL;
0617 
0618     mutex_lock(&nvmem_mutex);
0619     list_for_each_entry(iter, &nvmem->cells, node) {
0620         if (strcmp(cell_id, iter->name) == 0) {
0621             cell = iter;
0622             break;
0623         }
0624     }
0625     mutex_unlock(&nvmem_mutex);
0626 
0627     return cell;
0628 }
0629 
0630 static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
0631 {
0632     unsigned int cur = 0;
0633     const struct nvmem_keepout *keepout = nvmem->keepout;
0634     const struct nvmem_keepout *keepoutend = keepout + nvmem->nkeepout;
0635 
0636     while (keepout < keepoutend) {
0637         /* Ensure keepouts are sorted and don't overlap. */
0638         if (keepout->start < cur) {
0639             dev_err(&nvmem->dev,
0640                 "Keepout regions aren't sorted or overlap.\n");
0641 
0642             return -ERANGE;
0643         }
0644 
0645         if (keepout->end < keepout->start) {
0646             dev_err(&nvmem->dev,
0647                 "Invalid keepout region.\n");
0648 
0649             return -EINVAL;
0650         }
0651 
0652         /*
0653          * Validate keepouts (and holes between) don't violate
0654          * word_size constraints.
0655          */
0656         if ((keepout->end - keepout->start < nvmem->word_size) ||
0657             ((keepout->start != cur) &&
0658              (keepout->start - cur < nvmem->word_size))) {
0659 
0660             dev_err(&nvmem->dev,
0661                 "Keepout regions violate word_size constraints.\n");
0662 
0663             return -ERANGE;
0664         }
0665 
0666         /* Validate keepouts don't violate stride (alignment). */
0667         if (!IS_ALIGNED(keepout->start, nvmem->stride) ||
0668             !IS_ALIGNED(keepout->end, nvmem->stride)) {
0669 
0670             dev_err(&nvmem->dev,
0671                 "Keepout regions violate stride.\n");
0672 
0673             return -EINVAL;
0674         }
0675 
0676         cur = keepout->end;
0677         keepout++;
0678     }
0679 
0680     return 0;
0681 }
0682 
0683 static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
0684 {
0685     struct device_node *parent, *child;
0686     struct device *dev = &nvmem->dev;
0687     struct nvmem_cell_entry *cell;
0688     const __be32 *addr;
0689     int len;
0690 
0691     parent = dev->of_node;
0692 
0693     for_each_child_of_node(parent, child) {
0694         addr = of_get_property(child, "reg", &len);
0695         if (!addr)
0696             continue;
0697         if (len < 2 * sizeof(u32)) {
0698             dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
0699             of_node_put(child);
0700             return -EINVAL;
0701         }
0702 
0703         cell = kzalloc(sizeof(*cell), GFP_KERNEL);
0704         if (!cell) {
0705             of_node_put(child);
0706             return -ENOMEM;
0707         }
0708 
0709         cell->nvmem = nvmem;
0710         cell->offset = be32_to_cpup(addr++);
0711         cell->bytes = be32_to_cpup(addr);
0712         cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);
0713 
0714         addr = of_get_property(child, "bits", &len);
0715         if (addr && len == (2 * sizeof(u32))) {
0716             cell->bit_offset = be32_to_cpup(addr++);
0717             cell->nbits = be32_to_cpup(addr);
0718         }
0719 
0720         if (cell->nbits)
0721             cell->bytes = DIV_ROUND_UP(
0722                     cell->nbits + cell->bit_offset,
0723                     BITS_PER_BYTE);
0724 
0725         if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
0726             dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
0727                 cell->name, nvmem->stride);
0728             /* Cells already added will be freed later. */
0729             kfree_const(cell->name);
0730             kfree(cell);
0731             of_node_put(child);
0732             return -EINVAL;
0733         }
0734 
0735         cell->np = of_node_get(child);
0736         nvmem_cell_entry_add(cell);
0737     }
0738 
0739     return 0;
0740 }
0741 
0742 /**
0743  * nvmem_register() - Register a nvmem device for given nvmem_config.
0744  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
0745  *
0746  * @config: nvmem device configuration with which nvmem device is created.
0747  *
0748  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
0749  * on success.
0750  */
0751 
0752 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
0753 {
0754     struct nvmem_device *nvmem;
0755     int rval;
0756 
0757     if (!config->dev)
0758         return ERR_PTR(-EINVAL);
0759 
0760     if (!config->reg_read && !config->reg_write)
0761         return ERR_PTR(-EINVAL);
0762 
0763     nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
0764     if (!nvmem)
0765         return ERR_PTR(-ENOMEM);
0766 
0767     rval  = ida_alloc(&nvmem_ida, GFP_KERNEL);
0768     if (rval < 0) {
0769         kfree(nvmem);
0770         return ERR_PTR(rval);
0771     }
0772 
0773     if (config->wp_gpio)
0774         nvmem->wp_gpio = config->wp_gpio;
0775     else if (!config->ignore_wp)
0776         nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
0777                             GPIOD_OUT_HIGH);
0778     if (IS_ERR(nvmem->wp_gpio)) {
0779         ida_free(&nvmem_ida, nvmem->id);
0780         rval = PTR_ERR(nvmem->wp_gpio);
0781         kfree(nvmem);
0782         return ERR_PTR(rval);
0783     }
0784 
0785     kref_init(&nvmem->refcnt);
0786     INIT_LIST_HEAD(&nvmem->cells);
0787 
0788     nvmem->id = rval;
0789     nvmem->owner = config->owner;
0790     if (!nvmem->owner && config->dev->driver)
0791         nvmem->owner = config->dev->driver->owner;
0792     nvmem->stride = config->stride ?: 1;
0793     nvmem->word_size = config->word_size ?: 1;
0794     nvmem->size = config->size;
0795     nvmem->dev.type = &nvmem_provider_type;
0796     nvmem->dev.bus = &nvmem_bus_type;
0797     nvmem->dev.parent = config->dev;
0798     nvmem->root_only = config->root_only;
0799     nvmem->priv = config->priv;
0800     nvmem->type = config->type;
0801     nvmem->reg_read = config->reg_read;
0802     nvmem->reg_write = config->reg_write;
0803     nvmem->cell_post_process = config->cell_post_process;
0804     nvmem->keepout = config->keepout;
0805     nvmem->nkeepout = config->nkeepout;
0806     if (config->of_node)
0807         nvmem->dev.of_node = config->of_node;
0808     else if (!config->no_of_node)
0809         nvmem->dev.of_node = config->dev->of_node;
0810 
0811     switch (config->id) {
0812     case NVMEM_DEVID_NONE:
0813         dev_set_name(&nvmem->dev, "%s", config->name);
0814         break;
0815     case NVMEM_DEVID_AUTO:
0816         dev_set_name(&nvmem->dev, "%s%d", config->name, nvmem->id);
0817         break;
0818     default:
0819         dev_set_name(&nvmem->dev, "%s%d",
0820                  config->name ? : "nvmem",
0821                  config->name ? config->id : nvmem->id);
0822         break;
0823     }
0824 
0825     nvmem->read_only = device_property_present(config->dev, "read-only") ||
0826                config->read_only || !nvmem->reg_write;
0827 
0828 #ifdef CONFIG_NVMEM_SYSFS
0829     nvmem->dev.groups = nvmem_dev_groups;
0830 #endif
0831 
0832     if (nvmem->nkeepout) {
0833         rval = nvmem_validate_keepouts(nvmem);
0834         if (rval) {
0835             ida_free(&nvmem_ida, nvmem->id);
0836             kfree(nvmem);
0837             return ERR_PTR(rval);
0838         }
0839     }
0840 
0841     dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
0842 
0843     rval = device_register(&nvmem->dev);
0844     if (rval)
0845         goto err_put_device;
0846 
0847     if (config->compat) {
0848         rval = nvmem_sysfs_setup_compat(nvmem, config);
0849         if (rval)
0850             goto err_device_del;
0851     }
0852 
0853     if (config->cells) {
0854         rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
0855         if (rval)
0856             goto err_teardown_compat;
0857     }
0858 
0859     rval = nvmem_add_cells_from_table(nvmem);
0860     if (rval)
0861         goto err_remove_cells;
0862 
0863     rval = nvmem_add_cells_from_of(nvmem);
0864     if (rval)
0865         goto err_remove_cells;
0866 
0867     blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
0868 
0869     return nvmem;
0870 
0871 err_remove_cells:
0872     nvmem_device_remove_all_cells(nvmem);
0873 err_teardown_compat:
0874     if (config->compat)
0875         nvmem_sysfs_remove_compat(nvmem, config);
0876 err_device_del:
0877     device_del(&nvmem->dev);
0878 err_put_device:
0879     put_device(&nvmem->dev);
0880 
0881     return ERR_PTR(rval);
0882 }
0883 EXPORT_SYMBOL_GPL(nvmem_register);
0884 
0885 static void nvmem_device_release(struct kref *kref)
0886 {
0887     struct nvmem_device *nvmem;
0888 
0889     nvmem = container_of(kref, struct nvmem_device, refcnt);
0890 
0891     blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);
0892 
0893     if (nvmem->flags & FLAG_COMPAT)
0894         device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
0895 
0896     nvmem_device_remove_all_cells(nvmem);
0897     device_unregister(&nvmem->dev);
0898 }
0899 
0900 /**
0901  * nvmem_unregister() - Unregister previously registered nvmem device
0902  *
0903  * @nvmem: Pointer to previously registered nvmem device.
0904  */
0905 void nvmem_unregister(struct nvmem_device *nvmem)
0906 {
0907     if (nvmem)
0908         kref_put(&nvmem->refcnt, nvmem_device_release);
0909 }
0910 EXPORT_SYMBOL_GPL(nvmem_unregister);
0911 
0912 static void devm_nvmem_unregister(void *nvmem)
0913 {
0914     nvmem_unregister(nvmem);
0915 }
0916 
0917 /**
0918  * devm_nvmem_register() - Register a managed nvmem device for given
0919  * nvmem_config.
0920  * Also creates a binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
0921  *
0922  * @dev: Device that uses the nvmem device.
0923  * @config: nvmem device configuration with which nvmem device is created.
0924  *
0925  * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
0926  * on success.
0927  */
0928 struct nvmem_device *devm_nvmem_register(struct device *dev,
0929                      const struct nvmem_config *config)
0930 {
0931     struct nvmem_device *nvmem;
0932     int ret;
0933 
0934     nvmem = nvmem_register(config);
0935     if (IS_ERR(nvmem))
0936         return nvmem;
0937 
0938     ret = devm_add_action_or_reset(dev, devm_nvmem_unregister, nvmem);
0939     if (ret)
0940         return ERR_PTR(ret);
0941 
0942     return nvmem;
0943 }
0944 EXPORT_SYMBOL_GPL(devm_nvmem_register);
0945 
0946 static struct nvmem_device *__nvmem_device_get(void *data,
0947             int (*match)(struct device *dev, const void *data))
0948 {
0949     struct nvmem_device *nvmem = NULL;
0950     struct device *dev;
0951 
0952     mutex_lock(&nvmem_mutex);
0953     dev = bus_find_device(&nvmem_bus_type, NULL, data, match);
0954     if (dev)
0955         nvmem = to_nvmem_device(dev);
0956     mutex_unlock(&nvmem_mutex);
0957     if (!nvmem)
0958         return ERR_PTR(-EPROBE_DEFER);
0959 
0960     if (!try_module_get(nvmem->owner)) {
0961         dev_err(&nvmem->dev,
0962             "could not increase module refcount for cell %s\n",
0963             nvmem_dev_name(nvmem));
0964 
0965         put_device(&nvmem->dev);
0966         return ERR_PTR(-EINVAL);
0967     }
0968 
0969     kref_get(&nvmem->refcnt);
0970 
0971     return nvmem;
0972 }
0973 
0974 static void __nvmem_device_put(struct nvmem_device *nvmem)
0975 {
0976     put_device(&nvmem->dev);
0977     module_put(nvmem->owner);
0978     kref_put(&nvmem->refcnt, nvmem_device_release);
0979 }
0980 
0981 #if IS_ENABLED(CONFIG_OF)
0982 /**
0983  * of_nvmem_device_get() - Get nvmem device from a given id
0984  *
0985  * @np: Device tree node that uses the nvmem device.
0986  * @id: nvmem name from nvmem-names property.
0987  *
0988  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
0989  * on success.
0990  */
0991 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
0992 {
0993 
0994     struct device_node *nvmem_np;
0995     struct nvmem_device *nvmem;
0996     int index = 0;
0997 
0998     if (id)
0999         index = of_property_match_string(np, "nvmem-names", id);
1000 
1001     nvmem_np = of_parse_phandle(np, "nvmem", index);
1002     if (!nvmem_np)
1003         return ERR_PTR(-ENOENT);
1004 
1005     nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1006     of_node_put(nvmem_np);
1007     return nvmem;
1008 }
1009 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
1010 #endif
1011 
1012 /**
1013  * nvmem_device_get() - Get nvmem device from a given id
1014  *
1015  * @dev: Device that uses the nvmem device.
1016  * @dev_name: name of the requested nvmem device.
1017  *
1018  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1019  * on success.
1020  */
1021 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
1022 {
1023     if (dev->of_node) { /* try dt first */
1024         struct nvmem_device *nvmem;
1025 
1026         nvmem = of_nvmem_device_get(dev->of_node, dev_name);
1027 
1028         if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
1029             return nvmem;
1030 
1031     }
1032 
1033     return __nvmem_device_get((void *)dev_name, device_match_name);
1034 }
1035 EXPORT_SYMBOL_GPL(nvmem_device_get);
1036 
1037 /**
1038  * nvmem_device_find() - Find nvmem device with matching function
1039  *
1040  * @data: Data to pass to match function
1041  * @match: Callback function to check device
1042  *
1043  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
1044  * on success.
1045  */
1046 struct nvmem_device *nvmem_device_find(void *data,
1047             int (*match)(struct device *dev, const void *data))
1048 {
1049     return __nvmem_device_get(data, match);
1050 }
1051 EXPORT_SYMBOL_GPL(nvmem_device_find);
1052 
1053 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
1054 {
1055     struct nvmem_device **nvmem = res;
1056 
1057     if (WARN_ON(!nvmem || !*nvmem))
1058         return 0;
1059 
1060     return *nvmem == data;
1061 }
1062 
1063 static void devm_nvmem_device_release(struct device *dev, void *res)
1064 {
1065     nvmem_device_put(*(struct nvmem_device **)res);
1066 }
1067 
1068 /**
1069  * devm_nvmem_device_put() - put alredy got nvmem device
1070  *
1071  * @dev: Device that uses the nvmem device.
1072  * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
1073  * that needs to be released.
1074  */
1075 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
1076 {
1077     int ret;
1078 
1079     ret = devres_release(dev, devm_nvmem_device_release,
1080                  devm_nvmem_device_match, nvmem);
1081 
1082     WARN_ON(ret);
1083 }
1084 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
1085 
1086 /**
1087  * nvmem_device_put() - put alredy got nvmem device
1088  *
1089  * @nvmem: pointer to nvmem device that needs to be released.
1090  */
1091 void nvmem_device_put(struct nvmem_device *nvmem)
1092 {
1093     __nvmem_device_put(nvmem);
1094 }
1095 EXPORT_SYMBOL_GPL(nvmem_device_put);
1096 
1097 /**
1098  * devm_nvmem_device_get() - Get nvmem cell of device form a given id
1099  *
1100  * @dev: Device that requests the nvmem device.
1101  * @id: name id for the requested nvmem device.
1102  *
1103  * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
1104  * on success.  The nvmem_cell will be freed by the automatically once the
1105  * device is freed.
1106  */
1107 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
1108 {
1109     struct nvmem_device **ptr, *nvmem;
1110 
1111     ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
1112     if (!ptr)
1113         return ERR_PTR(-ENOMEM);
1114 
1115     nvmem = nvmem_device_get(dev, id);
1116     if (!IS_ERR(nvmem)) {
1117         *ptr = nvmem;
1118         devres_add(dev, ptr);
1119     } else {
1120         devres_free(ptr);
1121     }
1122 
1123     return nvmem;
1124 }
1125 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
1126 
1127 static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry, const char *id)
1128 {
1129     struct nvmem_cell *cell;
1130     const char *name = NULL;
1131 
1132     cell = kzalloc(sizeof(*cell), GFP_KERNEL);
1133     if (!cell)
1134         return ERR_PTR(-ENOMEM);
1135 
1136     if (id) {
1137         name = kstrdup_const(id, GFP_KERNEL);
1138         if (!name) {
1139             kfree(cell);
1140             return ERR_PTR(-ENOMEM);
1141         }
1142     }
1143 
1144     cell->id = name;
1145     cell->entry = entry;
1146 
1147     return cell;
1148 }
1149 
1150 static struct nvmem_cell *
1151 nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
1152 {
1153     struct nvmem_cell_entry *cell_entry;
1154     struct nvmem_cell *cell = ERR_PTR(-ENOENT);
1155     struct nvmem_cell_lookup *lookup;
1156     struct nvmem_device *nvmem;
1157     const char *dev_id;
1158 
1159     if (!dev)
1160         return ERR_PTR(-EINVAL);
1161 
1162     dev_id = dev_name(dev);
1163 
1164     mutex_lock(&nvmem_lookup_mutex);
1165 
1166     list_for_each_entry(lookup, &nvmem_lookup_list, node) {
1167         if ((strcmp(lookup->dev_id, dev_id) == 0) &&
1168             (strcmp(lookup->con_id, con_id) == 0)) {
1169             /* This is the right entry. */
1170             nvmem = __nvmem_device_get((void *)lookup->nvmem_name,
1171                            device_match_name);
1172             if (IS_ERR(nvmem)) {
1173                 /* Provider may not be registered yet. */
1174                 cell = ERR_CAST(nvmem);
1175                 break;
1176             }
1177 
1178             cell_entry = nvmem_find_cell_entry_by_name(nvmem,
1179                                    lookup->cell_name);
1180             if (!cell_entry) {
1181                 __nvmem_device_put(nvmem);
1182                 cell = ERR_PTR(-ENOENT);
1183             } else {
1184                 cell = nvmem_create_cell(cell_entry, con_id);
1185                 if (IS_ERR(cell))
1186                     __nvmem_device_put(nvmem);
1187             }
1188             break;
1189         }
1190     }
1191 
1192     mutex_unlock(&nvmem_lookup_mutex);
1193     return cell;
1194 }
1195 
1196 #if IS_ENABLED(CONFIG_OF)
1197 static struct nvmem_cell_entry *
1198 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
1199 {
1200     struct nvmem_cell_entry *iter, *cell = NULL;
1201 
1202     mutex_lock(&nvmem_mutex);
1203     list_for_each_entry(iter, &nvmem->cells, node) {
1204         if (np == iter->np) {
1205             cell = iter;
1206             break;
1207         }
1208     }
1209     mutex_unlock(&nvmem_mutex);
1210 
1211     return cell;
1212 }
1213 
1214 /**
1215  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
1216  *
1217  * @np: Device tree node that uses the nvmem cell.
1218  * @id: nvmem cell name from nvmem-cell-names property, or NULL
1219  *      for the cell at index 0 (the lone cell with no accompanying
1220  *      nvmem-cell-names property).
1221  *
1222  * Return: Will be an ERR_PTR() on error or a valid pointer
1223  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1224  * nvmem_cell_put().
1225  */
1226 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
1227 {
1228     struct device_node *cell_np, *nvmem_np;
1229     struct nvmem_device *nvmem;
1230     struct nvmem_cell_entry *cell_entry;
1231     struct nvmem_cell *cell;
1232     int index = 0;
1233 
1234     /* if cell name exists, find index to the name */
1235     if (id)
1236         index = of_property_match_string(np, "nvmem-cell-names", id);
1237 
1238     cell_np = of_parse_phandle(np, "nvmem-cells", index);
1239     if (!cell_np)
1240         return ERR_PTR(-ENOENT);
1241 
1242     nvmem_np = of_get_next_parent(cell_np);
1243     if (!nvmem_np)
1244         return ERR_PTR(-EINVAL);
1245 
1246     nvmem = __nvmem_device_get(nvmem_np, device_match_of_node);
1247     of_node_put(nvmem_np);
1248     if (IS_ERR(nvmem))
1249         return ERR_CAST(nvmem);
1250 
1251     cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
1252     if (!cell_entry) {
1253         __nvmem_device_put(nvmem);
1254         return ERR_PTR(-ENOENT);
1255     }
1256 
1257     cell = nvmem_create_cell(cell_entry, id);
1258     if (IS_ERR(cell))
1259         __nvmem_device_put(nvmem);
1260 
1261     return cell;
1262 }
1263 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
1264 #endif
1265 
1266 /**
1267  * nvmem_cell_get() - Get nvmem cell of device form a given cell name
1268  *
1269  * @dev: Device that requests the nvmem cell.
1270  * @id: nvmem cell name to get (this corresponds with the name from the
1271  *      nvmem-cell-names property for DT systems and with the con_id from
1272  *      the lookup entry for non-DT systems).
1273  *
1274  * Return: Will be an ERR_PTR() on error or a valid pointer
1275  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1276  * nvmem_cell_put().
1277  */
1278 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
1279 {
1280     struct nvmem_cell *cell;
1281 
1282     if (dev->of_node) { /* try dt first */
1283         cell = of_nvmem_cell_get(dev->of_node, id);
1284         if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
1285             return cell;
1286     }
1287 
1288     /* NULL cell id only allowed for device tree; invalid otherwise */
1289     if (!id)
1290         return ERR_PTR(-EINVAL);
1291 
1292     return nvmem_cell_get_from_lookup(dev, id);
1293 }
1294 EXPORT_SYMBOL_GPL(nvmem_cell_get);
1295 
1296 static void devm_nvmem_cell_release(struct device *dev, void *res)
1297 {
1298     nvmem_cell_put(*(struct nvmem_cell **)res);
1299 }
1300 
1301 /**
1302  * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
1303  *
1304  * @dev: Device that requests the nvmem cell.
1305  * @id: nvmem cell name id to get.
1306  *
1307  * Return: Will be an ERR_PTR() on error or a valid pointer
1308  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
1309  * automatically once the device is freed.
1310  */
1311 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
1312 {
1313     struct nvmem_cell **ptr, *cell;
1314 
1315     ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
1316     if (!ptr)
1317         return ERR_PTR(-ENOMEM);
1318 
1319     cell = nvmem_cell_get(dev, id);
1320     if (!IS_ERR(cell)) {
1321         *ptr = cell;
1322         devres_add(dev, ptr);
1323     } else {
1324         devres_free(ptr);
1325     }
1326 
1327     return cell;
1328 }
1329 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
1330 
1331 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
1332 {
1333     struct nvmem_cell **c = res;
1334 
1335     if (WARN_ON(!c || !*c))
1336         return 0;
1337 
1338     return *c == data;
1339 }
1340 
1341 /**
1342  * devm_nvmem_cell_put() - Release previously allocated nvmem cell
1343  * from devm_nvmem_cell_get.
1344  *
1345  * @dev: Device that requests the nvmem cell.
1346  * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
1347  */
1348 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
1349 {
1350     int ret;
1351 
1352     ret = devres_release(dev, devm_nvmem_cell_release,
1353                 devm_nvmem_cell_match, cell);
1354 
1355     WARN_ON(ret);
1356 }
1357 EXPORT_SYMBOL(devm_nvmem_cell_put);
1358 
1359 /**
1360  * nvmem_cell_put() - Release previously allocated nvmem cell.
1361  *
1362  * @cell: Previously allocated nvmem cell by nvmem_cell_get().
1363  */
1364 void nvmem_cell_put(struct nvmem_cell *cell)
1365 {
1366     struct nvmem_device *nvmem = cell->entry->nvmem;
1367 
1368     if (cell->id)
1369         kfree_const(cell->id);
1370 
1371     kfree(cell);
1372     __nvmem_device_put(nvmem);
1373 }
1374 EXPORT_SYMBOL_GPL(nvmem_cell_put);
1375 
1376 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell_entry *cell, void *buf)
1377 {
1378     u8 *p, *b;
1379     int i, extra, bit_offset = cell->bit_offset;
1380 
1381     p = b = buf;
1382     if (bit_offset) {
1383         /* First shift */
1384         *b++ >>= bit_offset;
1385 
1386         /* setup rest of the bytes if any */
1387         for (i = 1; i < cell->bytes; i++) {
1388             /* Get bits from next byte and shift them towards msb */
1389             *p |= *b << (BITS_PER_BYTE - bit_offset);
1390 
1391             p = b;
1392             *b++ >>= bit_offset;
1393         }
1394     } else {
1395         /* point to the msb */
1396         p += cell->bytes - 1;
1397     }
1398 
1399     /* result fits in less bytes */
1400     extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
1401     while (--extra >= 0)
1402         *p-- = 0;
1403 
1404     /* clear msb bits if any leftover in the last byte */
1405     if (cell->nbits % BITS_PER_BYTE)
1406         *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
1407 }
1408 
1409 static int __nvmem_cell_read(struct nvmem_device *nvmem,
1410               struct nvmem_cell_entry *cell,
1411               void *buf, size_t *len, const char *id)
1412 {
1413     int rc;
1414 
1415     rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
1416 
1417     if (rc)
1418         return rc;
1419 
1420     /* shift bits in-place */
1421     if (cell->bit_offset || cell->nbits)
1422         nvmem_shift_read_buffer_in_place(cell, buf);
1423 
1424     if (nvmem->cell_post_process) {
1425         rc = nvmem->cell_post_process(nvmem->priv, id,
1426                           cell->offset, buf, cell->bytes);
1427         if (rc)
1428             return rc;
1429     }
1430 
1431     if (len)
1432         *len = cell->bytes;
1433 
1434     return 0;
1435 }
1436 
1437 /**
1438  * nvmem_cell_read() - Read a given nvmem cell
1439  *
1440  * @cell: nvmem cell to be read.
1441  * @len: pointer to length of cell which will be populated on successful read;
1442  *   can be NULL.
1443  *
1444  * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1445  * buffer should be freed by the consumer with a kfree().
1446  */
1447 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1448 {
1449     struct nvmem_device *nvmem = cell->entry->nvmem;
1450     u8 *buf;
1451     int rc;
1452 
1453     if (!nvmem)
1454         return ERR_PTR(-EINVAL);
1455 
1456     buf = kzalloc(cell->entry->bytes, GFP_KERNEL);
1457     if (!buf)
1458         return ERR_PTR(-ENOMEM);
1459 
1460     rc = __nvmem_cell_read(nvmem, cell->entry, buf, len, cell->id);
1461     if (rc) {
1462         kfree(buf);
1463         return ERR_PTR(rc);
1464     }
1465 
1466     return buf;
1467 }
1468 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1469 
1470 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell_entry *cell,
1471                          u8 *_buf, int len)
1472 {
1473     struct nvmem_device *nvmem = cell->nvmem;
1474     int i, rc, nbits, bit_offset = cell->bit_offset;
1475     u8 v, *p, *buf, *b, pbyte, pbits;
1476 
1477     nbits = cell->nbits;
1478     buf = kzalloc(cell->bytes, GFP_KERNEL);
1479     if (!buf)
1480         return ERR_PTR(-ENOMEM);
1481 
1482     memcpy(buf, _buf, len);
1483     p = b = buf;
1484 
1485     if (bit_offset) {
1486         pbyte = *b;
1487         *b <<= bit_offset;
1488 
1489         /* setup the first byte with lsb bits from nvmem */
1490         rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1491         if (rc)
1492             goto err;
1493         *b++ |= GENMASK(bit_offset - 1, 0) & v;
1494 
1495         /* setup rest of the byte if any */
1496         for (i = 1; i < cell->bytes; i++) {
1497             /* Get last byte bits and shift them towards lsb */
1498             pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1499             pbyte = *b;
1500             p = b;
1501             *b <<= bit_offset;
1502             *b++ |= pbits;
1503         }
1504     }
1505 
1506     /* if it's not end on byte boundary */
1507     if ((nbits + bit_offset) % BITS_PER_BYTE) {
1508         /* setup the last byte with msb bits from nvmem */
1509         rc = nvmem_reg_read(nvmem,
1510                     cell->offset + cell->bytes - 1, &v, 1);
1511         if (rc)
1512             goto err;
1513         *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1514 
1515     }
1516 
1517     return buf;
1518 err:
1519     kfree(buf);
1520     return ERR_PTR(rc);
1521 }
1522 
1523 static int __nvmem_cell_entry_write(struct nvmem_cell_entry *cell, void *buf, size_t len)
1524 {
1525     struct nvmem_device *nvmem = cell->nvmem;
1526     int rc;
1527 
1528     if (!nvmem || nvmem->read_only ||
1529         (cell->bit_offset == 0 && len != cell->bytes))
1530         return -EINVAL;
1531 
1532     if (cell->bit_offset || cell->nbits) {
1533         buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1534         if (IS_ERR(buf))
1535             return PTR_ERR(buf);
1536     }
1537 
1538     rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1539 
1540     /* free the tmp buffer */
1541     if (cell->bit_offset || cell->nbits)
1542         kfree(buf);
1543 
1544     if (rc)
1545         return rc;
1546 
1547     return len;
1548 }
1549 
1550 /**
1551  * nvmem_cell_write() - Write to a given nvmem cell
1552  *
1553  * @cell: nvmem cell to be written.
1554  * @buf: Buffer to be written.
1555  * @len: length of buffer to be written to nvmem cell.
1556  *
1557  * Return: length of bytes written or negative on failure.
1558  */
1559 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1560 {
1561     return __nvmem_cell_entry_write(cell->entry, buf, len);
1562 }
1563 
1564 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1565 
1566 static int nvmem_cell_read_common(struct device *dev, const char *cell_id,
1567                   void *val, size_t count)
1568 {
1569     struct nvmem_cell *cell;
1570     void *buf;
1571     size_t len;
1572 
1573     cell = nvmem_cell_get(dev, cell_id);
1574     if (IS_ERR(cell))
1575         return PTR_ERR(cell);
1576 
1577     buf = nvmem_cell_read(cell, &len);
1578     if (IS_ERR(buf)) {
1579         nvmem_cell_put(cell);
1580         return PTR_ERR(buf);
1581     }
1582     if (len != count) {
1583         kfree(buf);
1584         nvmem_cell_put(cell);
1585         return -EINVAL;
1586     }
1587     memcpy(val, buf, count);
1588     kfree(buf);
1589     nvmem_cell_put(cell);
1590 
1591     return 0;
1592 }
1593 
1594 /**
1595  * nvmem_cell_read_u8() - Read a cell value as a u8
1596  *
1597  * @dev: Device that requests the nvmem cell.
1598  * @cell_id: Name of nvmem cell to read.
1599  * @val: pointer to output value.
1600  *
1601  * Return: 0 on success or negative errno.
1602  */
1603 int nvmem_cell_read_u8(struct device *dev, const char *cell_id, u8 *val)
1604 {
1605     return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1606 }
1607 EXPORT_SYMBOL_GPL(nvmem_cell_read_u8);
1608 
1609 /**
1610  * nvmem_cell_read_u16() - Read a cell value as a u16
1611  *
1612  * @dev: Device that requests the nvmem cell.
1613  * @cell_id: Name of nvmem cell to read.
1614  * @val: pointer to output value.
1615  *
1616  * Return: 0 on success or negative errno.
1617  */
1618 int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
1619 {
1620     return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1621 }
1622 EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);
1623 
1624 /**
1625  * nvmem_cell_read_u32() - Read a cell value as a u32
1626  *
1627  * @dev: Device that requests the nvmem cell.
1628  * @cell_id: Name of nvmem cell to read.
1629  * @val: pointer to output value.
1630  *
1631  * Return: 0 on success or negative errno.
1632  */
1633 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1634 {
1635     return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1636 }
1637 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1638 
1639 /**
1640  * nvmem_cell_read_u64() - Read a cell value as a u64
1641  *
1642  * @dev: Device that requests the nvmem cell.
1643  * @cell_id: Name of nvmem cell to read.
1644  * @val: pointer to output value.
1645  *
1646  * Return: 0 on success or negative errno.
1647  */
1648 int nvmem_cell_read_u64(struct device *dev, const char *cell_id, u64 *val)
1649 {
1650     return nvmem_cell_read_common(dev, cell_id, val, sizeof(*val));
1651 }
1652 EXPORT_SYMBOL_GPL(nvmem_cell_read_u64);
1653 
1654 static const void *nvmem_cell_read_variable_common(struct device *dev,
1655                            const char *cell_id,
1656                            size_t max_len, size_t *len)
1657 {
1658     struct nvmem_cell *cell;
1659     int nbits;
1660     void *buf;
1661 
1662     cell = nvmem_cell_get(dev, cell_id);
1663     if (IS_ERR(cell))
1664         return cell;
1665 
1666     nbits = cell->entry->nbits;
1667     buf = nvmem_cell_read(cell, len);
1668     nvmem_cell_put(cell);
1669     if (IS_ERR(buf))
1670         return buf;
1671 
1672     /*
1673      * If nbits is set then nvmem_cell_read() can significantly exaggerate
1674      * the length of the real data. Throw away the extra junk.
1675      */
1676     if (nbits)
1677         *len = DIV_ROUND_UP(nbits, 8);
1678 
1679     if (*len > max_len) {
1680         kfree(buf);
1681         return ERR_PTR(-ERANGE);
1682     }
1683 
1684     return buf;
1685 }
1686 
1687 /**
1688  * nvmem_cell_read_variable_le_u32() - Read up to 32-bits of data as a little endian number.
1689  *
1690  * @dev: Device that requests the nvmem cell.
1691  * @cell_id: Name of nvmem cell to read.
1692  * @val: pointer to output value.
1693  *
1694  * Return: 0 on success or negative errno.
1695  */
1696 int nvmem_cell_read_variable_le_u32(struct device *dev, const char *cell_id,
1697                     u32 *val)
1698 {
1699     size_t len;
1700     const u8 *buf;
1701     int i;
1702 
1703     buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1704     if (IS_ERR(buf))
1705         return PTR_ERR(buf);
1706 
1707     /* Copy w/ implicit endian conversion */
1708     *val = 0;
1709     for (i = 0; i < len; i++)
1710         *val |= buf[i] << (8 * i);
1711 
1712     kfree(buf);
1713 
1714     return 0;
1715 }
1716 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u32);
1717 
1718 /**
1719  * nvmem_cell_read_variable_le_u64() - Read up to 64-bits of data as a little endian number.
1720  *
1721  * @dev: Device that requests the nvmem cell.
1722  * @cell_id: Name of nvmem cell to read.
1723  * @val: pointer to output value.
1724  *
1725  * Return: 0 on success or negative errno.
1726  */
1727 int nvmem_cell_read_variable_le_u64(struct device *dev, const char *cell_id,
1728                     u64 *val)
1729 {
1730     size_t len;
1731     const u8 *buf;
1732     int i;
1733 
1734     buf = nvmem_cell_read_variable_common(dev, cell_id, sizeof(*val), &len);
1735     if (IS_ERR(buf))
1736         return PTR_ERR(buf);
1737 
1738     /* Copy w/ implicit endian conversion */
1739     *val = 0;
1740     for (i = 0; i < len; i++)
1741         *val |= (uint64_t)buf[i] << (8 * i);
1742 
1743     kfree(buf);
1744 
1745     return 0;
1746 }
1747 EXPORT_SYMBOL_GPL(nvmem_cell_read_variable_le_u64);
1748 
1749 /**
1750  * nvmem_device_cell_read() - Read a given nvmem device and cell
1751  *
1752  * @nvmem: nvmem device to read from.
1753  * @info: nvmem cell info to be read.
1754  * @buf: buffer pointer which will be populated on successful read.
1755  *
1756  * Return: length of successful bytes read on success and negative
1757  * error code on error.
1758  */
1759 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1760                struct nvmem_cell_info *info, void *buf)
1761 {
1762     struct nvmem_cell_entry cell;
1763     int rc;
1764     ssize_t len;
1765 
1766     if (!nvmem)
1767         return -EINVAL;
1768 
1769     rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1770     if (rc)
1771         return rc;
1772 
1773     rc = __nvmem_cell_read(nvmem, &cell, buf, &len, NULL);
1774     if (rc)
1775         return rc;
1776 
1777     return len;
1778 }
1779 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1780 
1781 /**
1782  * nvmem_device_cell_write() - Write cell to a given nvmem device
1783  *
1784  * @nvmem: nvmem device to be written to.
1785  * @info: nvmem cell info to be written.
1786  * @buf: buffer to be written to cell.
1787  *
1788  * Return: length of bytes written or negative error code on failure.
1789  */
1790 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1791                 struct nvmem_cell_info *info, void *buf)
1792 {
1793     struct nvmem_cell_entry cell;
1794     int rc;
1795 
1796     if (!nvmem)
1797         return -EINVAL;
1798 
1799     rc = nvmem_cell_info_to_nvmem_cell_entry_nodup(nvmem, info, &cell);
1800     if (rc)
1801         return rc;
1802 
1803     return __nvmem_cell_entry_write(&cell, buf, cell.bytes);
1804 }
1805 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1806 
1807 /**
1808  * nvmem_device_read() - Read from a given nvmem device
1809  *
1810  * @nvmem: nvmem device to read from.
1811  * @offset: offset in nvmem device.
1812  * @bytes: number of bytes to read.
1813  * @buf: buffer pointer which will be populated on successful read.
1814  *
1815  * Return: length of successful bytes read on success and negative
1816  * error code on error.
1817  */
1818 int nvmem_device_read(struct nvmem_device *nvmem,
1819               unsigned int offset,
1820               size_t bytes, void *buf)
1821 {
1822     int rc;
1823 
1824     if (!nvmem)
1825         return -EINVAL;
1826 
1827     rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1828 
1829     if (rc)
1830         return rc;
1831 
1832     return bytes;
1833 }
1834 EXPORT_SYMBOL_GPL(nvmem_device_read);
1835 
1836 /**
1837  * nvmem_device_write() - Write cell to a given nvmem device
1838  *
1839  * @nvmem: nvmem device to be written to.
1840  * @offset: offset in nvmem device.
1841  * @bytes: number of bytes to write.
1842  * @buf: buffer to be written.
1843  *
1844  * Return: length of bytes written or negative error code on failure.
1845  */
1846 int nvmem_device_write(struct nvmem_device *nvmem,
1847                unsigned int offset,
1848                size_t bytes, void *buf)
1849 {
1850     int rc;
1851 
1852     if (!nvmem)
1853         return -EINVAL;
1854 
1855     rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1856 
1857     if (rc)
1858         return rc;
1859 
1860 
1861     return bytes;
1862 }
1863 EXPORT_SYMBOL_GPL(nvmem_device_write);
1864 
1865 /**
1866  * nvmem_add_cell_table() - register a table of cell info entries
1867  *
1868  * @table: table of cell info entries
1869  */
1870 void nvmem_add_cell_table(struct nvmem_cell_table *table)
1871 {
1872     mutex_lock(&nvmem_cell_mutex);
1873     list_add_tail(&table->node, &nvmem_cell_tables);
1874     mutex_unlock(&nvmem_cell_mutex);
1875 }
1876 EXPORT_SYMBOL_GPL(nvmem_add_cell_table);
1877 
1878 /**
1879  * nvmem_del_cell_table() - remove a previously registered cell info table
1880  *
1881  * @table: table of cell info entries
1882  */
1883 void nvmem_del_cell_table(struct nvmem_cell_table *table)
1884 {
1885     mutex_lock(&nvmem_cell_mutex);
1886     list_del(&table->node);
1887     mutex_unlock(&nvmem_cell_mutex);
1888 }
1889 EXPORT_SYMBOL_GPL(nvmem_del_cell_table);
1890 
1891 /**
1892  * nvmem_add_cell_lookups() - register a list of cell lookup entries
1893  *
1894  * @entries: array of cell lookup entries
1895  * @nentries: number of cell lookup entries in the array
1896  */
1897 void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1898 {
1899     int i;
1900 
1901     mutex_lock(&nvmem_lookup_mutex);
1902     for (i = 0; i < nentries; i++)
1903         list_add_tail(&entries[i].node, &nvmem_lookup_list);
1904     mutex_unlock(&nvmem_lookup_mutex);
1905 }
1906 EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);
1907 
1908 /**
1909  * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
1910  *                            entries
1911  *
1912  * @entries: array of cell lookup entries
1913  * @nentries: number of cell lookup entries in the array
1914  */
1915 void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
1916 {
1917     int i;
1918 
1919     mutex_lock(&nvmem_lookup_mutex);
1920     for (i = 0; i < nentries; i++)
1921         list_del(&entries[i].node);
1922     mutex_unlock(&nvmem_lookup_mutex);
1923 }
1924 EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);
1925 
1926 /**
1927  * nvmem_dev_name() - Get the name of a given nvmem device.
1928  *
1929  * @nvmem: nvmem device.
1930  *
1931  * Return: name of the nvmem device.
1932  */
1933 const char *nvmem_dev_name(struct nvmem_device *nvmem)
1934 {
1935     return dev_name(&nvmem->dev);
1936 }
1937 EXPORT_SYMBOL_GPL(nvmem_dev_name);
1938 
1939 static int __init nvmem_init(void)
1940 {
1941     return bus_register(&nvmem_bus_type);
1942 }
1943 
1944 static void __exit nvmem_exit(void)
1945 {
1946     bus_unregister(&nvmem_bus_type);
1947 }
1948 
1949 subsys_initcall(nvmem_init);
1950 module_exit(nvmem_exit);
1951 
1952 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1953 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1954 MODULE_DESCRIPTION("nvmem Driver Core");
1955 MODULE_LICENSE("GPL v2");
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