2 * nvmem framework core.
4 * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
5 * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 and
9 * only version 2 as published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
17 #include <linux/device.h>
18 #include <linux/export.h>
20 #include <linux/idr.h>
21 #include <linux/init.h>
22 #include <linux/module.h>
23 #include <linux/nvmem-consumer.h>
24 #include <linux/nvmem-provider.h>
26 #include <linux/slab.h>
40 struct bin_attribute eeprom;
41 struct device *base_dev;
42 nvmem_reg_read_t reg_read;
43 nvmem_reg_write_t reg_write;
47 #define FLAG_COMPAT BIT(0)
55 struct nvmem_device *nvmem;
56 struct list_head node;
59 static DEFINE_MUTEX(nvmem_mutex);
60 static DEFINE_IDA(nvmem_ida);
62 static LIST_HEAD(nvmem_cells);
63 static DEFINE_MUTEX(nvmem_cells_mutex);
65 #ifdef CONFIG_DEBUG_LOCK_ALLOC
66 static struct lock_class_key eeprom_lock_key;
69 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
70 static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
71 void *val, size_t bytes)
74 return nvmem->reg_read(nvmem->priv, offset, val, bytes);
79 static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
80 void *val, size_t bytes)
83 return nvmem->reg_write(nvmem->priv, offset, val, bytes);
88 static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
89 struct bin_attribute *attr,
90 char *buf, loff_t pos, size_t count)
93 struct nvmem_device *nvmem;
99 dev = container_of(kobj, struct device, kobj);
100 nvmem = to_nvmem_device(dev);
102 /* Stop the user from reading */
103 if (pos >= nvmem->size)
106 if (count < nvmem->word_size)
109 if (pos + count > nvmem->size)
110 count = nvmem->size - pos;
112 count = round_down(count, nvmem->word_size);
114 rc = nvmem_reg_read(nvmem, pos, buf, count);
122 static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
123 struct bin_attribute *attr,
124 char *buf, loff_t pos, size_t count)
127 struct nvmem_device *nvmem;
133 dev = container_of(kobj, struct device, kobj);
134 nvmem = to_nvmem_device(dev);
136 /* Stop the user from writing */
137 if (pos >= nvmem->size)
140 if (count < nvmem->word_size)
143 if (pos + count > nvmem->size)
144 count = nvmem->size - pos;
146 count = round_down(count, nvmem->word_size);
148 rc = nvmem_reg_write(nvmem, pos, buf, count);
156 /* default read/write permissions */
157 static struct bin_attribute bin_attr_rw_nvmem = {
160 .mode = S_IWUSR | S_IRUGO,
162 .read = bin_attr_nvmem_read,
163 .write = bin_attr_nvmem_write,
166 static struct bin_attribute *nvmem_bin_rw_attributes[] = {
171 static const struct attribute_group nvmem_bin_rw_group = {
172 .bin_attrs = nvmem_bin_rw_attributes,
175 static const struct attribute_group *nvmem_rw_dev_groups[] = {
180 /* read only permission */
181 static struct bin_attribute bin_attr_ro_nvmem = {
186 .read = bin_attr_nvmem_read,
189 static struct bin_attribute *nvmem_bin_ro_attributes[] = {
194 static const struct attribute_group nvmem_bin_ro_group = {
195 .bin_attrs = nvmem_bin_ro_attributes,
198 static const struct attribute_group *nvmem_ro_dev_groups[] = {
203 /* default read/write permissions, root only */
204 static struct bin_attribute bin_attr_rw_root_nvmem = {
207 .mode = S_IWUSR | S_IRUSR,
209 .read = bin_attr_nvmem_read,
210 .write = bin_attr_nvmem_write,
213 static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
214 &bin_attr_rw_root_nvmem,
218 static const struct attribute_group nvmem_bin_rw_root_group = {
219 .bin_attrs = nvmem_bin_rw_root_attributes,
222 static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
223 &nvmem_bin_rw_root_group,
227 /* read only permission, root only */
228 static struct bin_attribute bin_attr_ro_root_nvmem = {
233 .read = bin_attr_nvmem_read,
236 static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
237 &bin_attr_ro_root_nvmem,
241 static const struct attribute_group nvmem_bin_ro_root_group = {
242 .bin_attrs = nvmem_bin_ro_root_attributes,
245 static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
246 &nvmem_bin_ro_root_group,
250 static void nvmem_release(struct device *dev)
252 struct nvmem_device *nvmem = to_nvmem_device(dev);
254 ida_simple_remove(&nvmem_ida, nvmem->id);
258 static const struct device_type nvmem_provider_type = {
259 .release = nvmem_release,
262 static struct bus_type nvmem_bus_type = {
266 static int of_nvmem_match(struct device *dev, void *nvmem_np)
268 return dev->of_node == nvmem_np;
271 static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
278 d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match);
283 return to_nvmem_device(d);
286 static struct nvmem_cell *nvmem_find_cell(const char *cell_id)
288 struct nvmem_cell *p;
290 mutex_lock(&nvmem_cells_mutex);
292 list_for_each_entry(p, &nvmem_cells, node)
293 if (!strcmp(p->name, cell_id)) {
294 mutex_unlock(&nvmem_cells_mutex);
298 mutex_unlock(&nvmem_cells_mutex);
303 static void nvmem_cell_drop(struct nvmem_cell *cell)
305 mutex_lock(&nvmem_cells_mutex);
306 list_del(&cell->node);
307 mutex_unlock(&nvmem_cells_mutex);
311 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
313 struct nvmem_cell *cell;
314 struct list_head *p, *n;
316 list_for_each_safe(p, n, &nvmem_cells) {
317 cell = list_entry(p, struct nvmem_cell, node);
318 if (cell->nvmem == nvmem)
319 nvmem_cell_drop(cell);
323 static void nvmem_cell_add(struct nvmem_cell *cell)
325 mutex_lock(&nvmem_cells_mutex);
326 list_add_tail(&cell->node, &nvmem_cells);
327 mutex_unlock(&nvmem_cells_mutex);
330 static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
331 const struct nvmem_cell_info *info,
332 struct nvmem_cell *cell)
335 cell->offset = info->offset;
336 cell->bytes = info->bytes;
337 cell->name = info->name;
339 cell->bit_offset = info->bit_offset;
340 cell->nbits = info->nbits;
343 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
346 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
348 "cell %s unaligned to nvmem stride %d\n",
349 cell->name, nvmem->stride);
356 static int nvmem_add_cells(struct nvmem_device *nvmem,
357 const struct nvmem_config *cfg)
359 struct nvmem_cell **cells;
360 const struct nvmem_cell_info *info = cfg->cells;
363 cells = kcalloc(cfg->ncells, sizeof(*cells), GFP_KERNEL);
367 for (i = 0; i < cfg->ncells; i++) {
368 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
374 rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
380 nvmem_cell_add(cells[i]);
383 nvmem->ncells = cfg->ncells;
384 /* remove tmp array */
390 nvmem_cell_drop(cells[i]);
398 * nvmem_setup_compat() - Create an additional binary entry in
399 * drivers sys directory, to be backwards compatible with the older
400 * drivers/misc/eeprom drivers.
402 static int nvmem_setup_compat(struct nvmem_device *nvmem,
403 const struct nvmem_config *config)
407 if (!config->base_dev)
410 if (nvmem->read_only)
411 nvmem->eeprom = bin_attr_ro_root_nvmem;
413 nvmem->eeprom = bin_attr_rw_root_nvmem;
414 nvmem->eeprom.attr.name = "eeprom";
415 nvmem->eeprom.size = nvmem->size;
416 #ifdef CONFIG_DEBUG_LOCK_ALLOC
417 nvmem->eeprom.attr.key = &eeprom_lock_key;
419 nvmem->eeprom.private = &nvmem->dev;
420 nvmem->base_dev = config->base_dev;
422 rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
425 "Failed to create eeprom binary file %d\n", rval);
429 nvmem->flags |= FLAG_COMPAT;
435 * nvmem_register() - Register a nvmem device for given nvmem_config.
436 * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
438 * @config: nvmem device configuration with which nvmem device is created.
440 * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
444 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
446 struct nvmem_device *nvmem;
450 return ERR_PTR(-EINVAL);
452 nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
454 return ERR_PTR(-ENOMEM);
456 rval = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
459 return ERR_PTR(rval);
463 nvmem->owner = config->owner;
464 if (!nvmem->owner && config->dev->driver)
465 nvmem->owner = config->dev->driver->owner;
466 nvmem->stride = config->stride ?: 1;
467 nvmem->word_size = config->word_size ?: 1;
468 nvmem->size = config->size;
469 nvmem->dev.type = &nvmem_provider_type;
470 nvmem->dev.bus = &nvmem_bus_type;
471 nvmem->dev.parent = config->dev;
472 nvmem->priv = config->priv;
473 nvmem->reg_read = config->reg_read;
474 nvmem->reg_write = config->reg_write;
475 nvmem->dev.of_node = config->dev->of_node;
476 dev_set_name(&nvmem->dev, "%s%d",
477 config->name ? : "nvmem",
478 config->name ? config->id : nvmem->id);
480 nvmem->read_only = device_property_present(config->dev, "read-only") |
483 if (config->root_only)
484 nvmem->dev.groups = nvmem->read_only ?
485 nvmem_ro_root_dev_groups :
486 nvmem_rw_root_dev_groups;
488 nvmem->dev.groups = nvmem->read_only ?
489 nvmem_ro_dev_groups :
492 device_initialize(&nvmem->dev);
494 dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
496 rval = device_add(&nvmem->dev);
500 if (config->compat) {
501 rval = nvmem_setup_compat(nvmem, config);
507 nvmem_add_cells(nvmem, config);
512 device_del(&nvmem->dev);
514 put_device(&nvmem->dev);
516 return ERR_PTR(rval);
518 EXPORT_SYMBOL_GPL(nvmem_register);
521 * nvmem_unregister() - Unregister previously registered nvmem device
523 * @nvmem: Pointer to previously registered nvmem device.
525 * Return: Will be an negative on error or a zero on success.
527 int nvmem_unregister(struct nvmem_device *nvmem)
529 mutex_lock(&nvmem_mutex);
531 mutex_unlock(&nvmem_mutex);
534 mutex_unlock(&nvmem_mutex);
536 if (nvmem->flags & FLAG_COMPAT)
537 device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
539 nvmem_device_remove_all_cells(nvmem);
540 device_del(&nvmem->dev);
541 put_device(&nvmem->dev);
545 EXPORT_SYMBOL_GPL(nvmem_unregister);
547 static struct nvmem_device *__nvmem_device_get(struct device_node *np,
548 struct nvmem_cell **cellp,
551 struct nvmem_device *nvmem = NULL;
553 mutex_lock(&nvmem_mutex);
556 nvmem = of_nvmem_find(np);
558 mutex_unlock(&nvmem_mutex);
559 return ERR_PTR(-EPROBE_DEFER);
562 struct nvmem_cell *cell = nvmem_find_cell(cell_id);
570 mutex_unlock(&nvmem_mutex);
571 return ERR_PTR(-ENOENT);
576 mutex_unlock(&nvmem_mutex);
578 if (!try_module_get(nvmem->owner)) {
580 "could not increase module refcount for cell %s\n",
583 mutex_lock(&nvmem_mutex);
585 mutex_unlock(&nvmem_mutex);
587 return ERR_PTR(-EINVAL);
593 static void __nvmem_device_put(struct nvmem_device *nvmem)
595 module_put(nvmem->owner);
596 mutex_lock(&nvmem_mutex);
598 mutex_unlock(&nvmem_mutex);
601 static struct nvmem_device *nvmem_find(const char *name)
605 d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);
610 return to_nvmem_device(d);
613 #if IS_ENABLED(CONFIG_OF)
615 * of_nvmem_device_get() - Get nvmem device from a given id
617 * @np: Device tree node that uses the nvmem device.
618 * @id: nvmem name from nvmem-names property.
620 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
623 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
626 struct device_node *nvmem_np;
629 index = of_property_match_string(np, "nvmem-names", id);
631 nvmem_np = of_parse_phandle(np, "nvmem", index);
633 return ERR_PTR(-EINVAL);
635 return __nvmem_device_get(nvmem_np, NULL, NULL);
637 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
641 * nvmem_device_get() - Get nvmem device from a given id
643 * @dev: Device that uses the nvmem device.
644 * @dev_name: name of the requested nvmem device.
646 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
649 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
651 if (dev->of_node) { /* try dt first */
652 struct nvmem_device *nvmem;
654 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
656 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
661 return nvmem_find(dev_name);
663 EXPORT_SYMBOL_GPL(nvmem_device_get);
665 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
667 struct nvmem_device **nvmem = res;
669 if (WARN_ON(!nvmem || !*nvmem))
672 return *nvmem == data;
675 static void devm_nvmem_device_release(struct device *dev, void *res)
677 nvmem_device_put(*(struct nvmem_device **)res);
681 * devm_nvmem_device_put() - put alredy got nvmem device
683 * @dev: Device that uses the nvmem device.
684 * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
685 * that needs to be released.
687 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
691 ret = devres_release(dev, devm_nvmem_device_release,
692 devm_nvmem_device_match, nvmem);
696 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
699 * nvmem_device_put() - put alredy got nvmem device
701 * @nvmem: pointer to nvmem device that needs to be released.
703 void nvmem_device_put(struct nvmem_device *nvmem)
705 __nvmem_device_put(nvmem);
707 EXPORT_SYMBOL_GPL(nvmem_device_put);
710 * devm_nvmem_device_get() - Get nvmem cell of device form a given id
712 * @dev: Device that requests the nvmem device.
713 * @id: name id for the requested nvmem device.
715 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
716 * on success. The nvmem_cell will be freed by the automatically once the
719 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
721 struct nvmem_device **ptr, *nvmem;
723 ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
725 return ERR_PTR(-ENOMEM);
727 nvmem = nvmem_device_get(dev, id);
728 if (!IS_ERR(nvmem)) {
730 devres_add(dev, ptr);
737 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
739 static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
741 struct nvmem_cell *cell = NULL;
742 struct nvmem_device *nvmem;
744 nvmem = __nvmem_device_get(NULL, &cell, cell_id);
746 return ERR_CAST(nvmem);
751 #if IS_ENABLED(CONFIG_OF)
753 * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
755 * @np: Device tree node that uses the nvmem cell.
756 * @name: nvmem cell name from nvmem-cell-names property, or NULL
757 * for the cell at index 0 (the lone cell with no accompanying
758 * nvmem-cell-names property).
760 * Return: Will be an ERR_PTR() on error or a valid pointer
761 * to a struct nvmem_cell. The nvmem_cell will be freed by the
764 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
767 struct device_node *cell_np, *nvmem_np;
768 struct nvmem_cell *cell;
769 struct nvmem_device *nvmem;
774 /* if cell name exists, find index to the name */
776 index = of_property_match_string(np, "nvmem-cell-names", name);
778 cell_np = of_parse_phandle(np, "nvmem-cells", index);
780 return ERR_PTR(-EINVAL);
782 nvmem_np = of_get_next_parent(cell_np);
784 return ERR_PTR(-EINVAL);
786 nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
787 of_node_put(nvmem_np);
789 return ERR_CAST(nvmem);
791 addr = of_get_property(cell_np, "reg", &len);
792 if (!addr || (len < 2 * sizeof(u32))) {
793 dev_err(&nvmem->dev, "nvmem: invalid reg on %pOF\n",
799 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
806 cell->offset = be32_to_cpup(addr++);
807 cell->bytes = be32_to_cpup(addr);
808 cell->name = cell_np->name;
810 addr = of_get_property(cell_np, "bits", &len);
811 if (addr && len == (2 * sizeof(u32))) {
812 cell->bit_offset = be32_to_cpup(addr++);
813 cell->nbits = be32_to_cpup(addr);
817 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
820 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
822 "cell %s unaligned to nvmem stride %d\n",
823 cell->name, nvmem->stride);
828 nvmem_cell_add(cell);
836 __nvmem_device_put(nvmem);
838 return ERR_PTR(rval);
840 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
844 * nvmem_cell_get() - Get nvmem cell of device form a given cell name
846 * @dev: Device that requests the nvmem cell.
847 * @cell_id: nvmem cell name to get.
849 * Return: Will be an ERR_PTR() on error or a valid pointer
850 * to a struct nvmem_cell. The nvmem_cell will be freed by the
853 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *cell_id)
855 struct nvmem_cell *cell;
857 if (dev->of_node) { /* try dt first */
858 cell = of_nvmem_cell_get(dev->of_node, cell_id);
859 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
863 return nvmem_cell_get_from_list(cell_id);
865 EXPORT_SYMBOL_GPL(nvmem_cell_get);
867 static void devm_nvmem_cell_release(struct device *dev, void *res)
869 nvmem_cell_put(*(struct nvmem_cell **)res);
873 * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
875 * @dev: Device that requests the nvmem cell.
876 * @id: nvmem cell name id to get.
878 * Return: Will be an ERR_PTR() on error or a valid pointer
879 * to a struct nvmem_cell. The nvmem_cell will be freed by the
880 * automatically once the device is freed.
882 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
884 struct nvmem_cell **ptr, *cell;
886 ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
888 return ERR_PTR(-ENOMEM);
890 cell = nvmem_cell_get(dev, id);
893 devres_add(dev, ptr);
900 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
902 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
904 struct nvmem_cell **c = res;
906 if (WARN_ON(!c || !*c))
913 * devm_nvmem_cell_put() - Release previously allocated nvmem cell
914 * from devm_nvmem_cell_get.
916 * @dev: Device that requests the nvmem cell.
917 * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
919 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
923 ret = devres_release(dev, devm_nvmem_cell_release,
924 devm_nvmem_cell_match, cell);
928 EXPORT_SYMBOL(devm_nvmem_cell_put);
931 * nvmem_cell_put() - Release previously allocated nvmem cell.
933 * @cell: Previously allocated nvmem cell by nvmem_cell_get().
935 void nvmem_cell_put(struct nvmem_cell *cell)
937 struct nvmem_device *nvmem = cell->nvmem;
939 __nvmem_device_put(nvmem);
940 nvmem_cell_drop(cell);
942 EXPORT_SYMBOL_GPL(nvmem_cell_put);
944 static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
947 int i, bit_offset = cell->bit_offset;
954 /* setup rest of the bytes if any */
955 for (i = 1; i < cell->bytes; i++) {
956 /* Get bits from next byte and shift them towards msb */
957 *p |= *b << (BITS_PER_BYTE - bit_offset);
963 /* result fits in less bytes */
964 if (cell->bytes != DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE))
967 /* clear msb bits if any leftover in the last byte */
968 *p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
971 static int __nvmem_cell_read(struct nvmem_device *nvmem,
972 struct nvmem_cell *cell,
973 void *buf, size_t *len)
977 rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
982 /* shift bits in-place */
983 if (cell->bit_offset || cell->nbits)
984 nvmem_shift_read_buffer_in_place(cell, buf);
993 * nvmem_cell_read() - Read a given nvmem cell
995 * @cell: nvmem cell to be read.
996 * @len: pointer to length of cell which will be populated on successful read;
999 * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
1000 * buffer should be freed by the consumer with a kfree().
1002 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1004 struct nvmem_device *nvmem = cell->nvmem;
1009 return ERR_PTR(-EINVAL);
1011 buf = kzalloc(cell->bytes, GFP_KERNEL);
1013 return ERR_PTR(-ENOMEM);
1015 rc = __nvmem_cell_read(nvmem, cell, buf, len);
1023 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1025 static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1028 struct nvmem_device *nvmem = cell->nvmem;
1029 int i, rc, nbits, bit_offset = cell->bit_offset;
1030 u8 v, *p, *buf, *b, pbyte, pbits;
1032 nbits = cell->nbits;
1033 buf = kzalloc(cell->bytes, GFP_KERNEL);
1035 return ERR_PTR(-ENOMEM);
1037 memcpy(buf, _buf, len);
1044 /* setup the first byte with lsb bits from nvmem */
1045 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1046 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1048 /* setup rest of the byte if any */
1049 for (i = 1; i < cell->bytes; i++) {
1050 /* Get last byte bits and shift them towards lsb */
1051 pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1059 /* if it's not end on byte boundary */
1060 if ((nbits + bit_offset) % BITS_PER_BYTE) {
1061 /* setup the last byte with msb bits from nvmem */
1062 rc = nvmem_reg_read(nvmem,
1063 cell->offset + cell->bytes - 1, &v, 1);
1064 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1072 * nvmem_cell_write() - Write to a given nvmem cell
1074 * @cell: nvmem cell to be written.
1075 * @buf: Buffer to be written.
1076 * @len: length of buffer to be written to nvmem cell.
1078 * Return: length of bytes written or negative on failure.
1080 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1082 struct nvmem_device *nvmem = cell->nvmem;
1085 if (!nvmem || nvmem->read_only ||
1086 (cell->bit_offset == 0 && len != cell->bytes))
1089 if (cell->bit_offset || cell->nbits) {
1090 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1092 return PTR_ERR(buf);
1095 rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1097 /* free the tmp buffer */
1098 if (cell->bit_offset || cell->nbits)
1106 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1109 * nvmem_cell_read_u32() - Read a cell value as an u32
1111 * @dev: Device that requests the nvmem cell.
1112 * @cell_id: Name of nvmem cell to read.
1113 * @val: pointer to output value.
1115 * Return: 0 on success or negative errno.
1117 int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
1119 struct nvmem_cell *cell;
1123 cell = nvmem_cell_get(dev, cell_id);
1125 return PTR_ERR(cell);
1127 buf = nvmem_cell_read(cell, &len);
1129 nvmem_cell_put(cell);
1130 return PTR_ERR(buf);
1132 if (len != sizeof(*val)) {
1134 nvmem_cell_put(cell);
1137 memcpy(val, buf, sizeof(*val));
1140 nvmem_cell_put(cell);
1143 EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);
1146 * nvmem_device_cell_read() - Read a given nvmem device and cell
1148 * @nvmem: nvmem device to read from.
1149 * @info: nvmem cell info to be read.
1150 * @buf: buffer pointer which will be populated on successful read.
1152 * Return: length of successful bytes read on success and negative
1153 * error code on error.
1155 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1156 struct nvmem_cell_info *info, void *buf)
1158 struct nvmem_cell cell;
1165 rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1169 rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1175 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1178 * nvmem_device_cell_write() - Write cell to a given nvmem device
1180 * @nvmem: nvmem device to be written to.
1181 * @info: nvmem cell info to be written.
1182 * @buf: buffer to be written to cell.
1184 * Return: length of bytes written or negative error code on failure.
1186 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1187 struct nvmem_cell_info *info, void *buf)
1189 struct nvmem_cell cell;
1195 rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1199 return nvmem_cell_write(&cell, buf, cell.bytes);
1201 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1204 * nvmem_device_read() - Read from a given nvmem device
1206 * @nvmem: nvmem device to read from.
1207 * @offset: offset in nvmem device.
1208 * @bytes: number of bytes to read.
1209 * @buf: buffer pointer which will be populated on successful read.
1211 * Return: length of successful bytes read on success and negative
1212 * error code on error.
1214 int nvmem_device_read(struct nvmem_device *nvmem,
1215 unsigned int offset,
1216 size_t bytes, void *buf)
1223 rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1230 EXPORT_SYMBOL_GPL(nvmem_device_read);
1233 * nvmem_device_write() - Write cell to a given nvmem device
1235 * @nvmem: nvmem device to be written to.
1236 * @offset: offset in nvmem device.
1237 * @bytes: number of bytes to write.
1238 * @buf: buffer to be written.
1240 * Return: length of bytes written or negative error code on failure.
1242 int nvmem_device_write(struct nvmem_device *nvmem,
1243 unsigned int offset,
1244 size_t bytes, void *buf)
1251 rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1259 EXPORT_SYMBOL_GPL(nvmem_device_write);
1261 static int __init nvmem_init(void)
1263 return bus_register(&nvmem_bus_type);
1266 static void __exit nvmem_exit(void)
1268 bus_unregister(&nvmem_bus_type);
1271 subsys_initcall(nvmem_init);
1272 module_exit(nvmem_exit);
1274 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1275 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1276 MODULE_DESCRIPTION("nvmem Driver Core");
1277 MODULE_LICENSE("GPL v2");