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 list_for_each_entry(p, &nvmem_cells, node)
291 if (p && !strcmp(p->name, cell_id))
297 static void nvmem_cell_drop(struct nvmem_cell *cell)
299 mutex_lock(&nvmem_cells_mutex);
300 list_del(&cell->node);
301 mutex_unlock(&nvmem_cells_mutex);
305 static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
307 struct nvmem_cell *cell;
308 struct list_head *p, *n;
310 list_for_each_safe(p, n, &nvmem_cells) {
311 cell = list_entry(p, struct nvmem_cell, node);
312 if (cell->nvmem == nvmem)
313 nvmem_cell_drop(cell);
317 static void nvmem_cell_add(struct nvmem_cell *cell)
319 mutex_lock(&nvmem_cells_mutex);
320 list_add_tail(&cell->node, &nvmem_cells);
321 mutex_unlock(&nvmem_cells_mutex);
324 static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
325 const struct nvmem_cell_info *info,
326 struct nvmem_cell *cell)
329 cell->offset = info->offset;
330 cell->bytes = info->bytes;
331 cell->name = info->name;
333 cell->bit_offset = info->bit_offset;
334 cell->nbits = info->nbits;
337 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
340 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
342 "cell %s unaligned to nvmem stride %d\n",
343 cell->name, nvmem->stride);
350 static int nvmem_add_cells(struct nvmem_device *nvmem,
351 const struct nvmem_config *cfg)
353 struct nvmem_cell **cells;
354 const struct nvmem_cell_info *info = cfg->cells;
357 cells = kcalloc(cfg->ncells, sizeof(*cells), GFP_KERNEL);
361 for (i = 0; i < cfg->ncells; i++) {
362 cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
368 rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
374 nvmem_cell_add(cells[i]);
377 nvmem->ncells = cfg->ncells;
378 /* remove tmp array */
384 nvmem_cell_drop(cells[i]);
392 * nvmem_setup_compat() - Create an additional binary entry in
393 * drivers sys directory, to be backwards compatible with the older
394 * drivers/misc/eeprom drivers.
396 static int nvmem_setup_compat(struct nvmem_device *nvmem,
397 const struct nvmem_config *config)
401 if (!config->base_dev)
404 if (nvmem->read_only) {
405 if (config->root_only)
406 nvmem->eeprom = bin_attr_ro_root_nvmem;
408 nvmem->eeprom = bin_attr_ro_nvmem;
410 if (config->root_only)
411 nvmem->eeprom = bin_attr_rw_root_nvmem;
413 nvmem->eeprom = bin_attr_rw_nvmem;
415 nvmem->eeprom.attr.name = "eeprom";
416 nvmem->eeprom.size = nvmem->size;
417 #ifdef CONFIG_DEBUG_LOCK_ALLOC
418 nvmem->eeprom.attr.key = &eeprom_lock_key;
420 nvmem->eeprom.private = &nvmem->dev;
421 nvmem->base_dev = config->base_dev;
423 rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
426 "Failed to create eeprom binary file %d\n", rval);
430 nvmem->flags |= FLAG_COMPAT;
436 * nvmem_register() - Register a nvmem device for given nvmem_config.
437 * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
439 * @config: nvmem device configuration with which nvmem device is created.
441 * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
445 struct nvmem_device *nvmem_register(const struct nvmem_config *config)
447 struct nvmem_device *nvmem;
448 struct device_node *np;
452 return ERR_PTR(-EINVAL);
454 nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
456 return ERR_PTR(-ENOMEM);
458 rval = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
461 return ERR_PTR(rval);
465 nvmem->owner = config->owner;
466 nvmem->stride = config->stride;
467 nvmem->word_size = config->word_size;
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 np = config->dev->of_node;
476 nvmem->dev.of_node = np;
477 dev_set_name(&nvmem->dev, "%s%d",
478 config->name ? : "nvmem", config->id);
480 nvmem->read_only = of_property_read_bool(np, "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);
544 EXPORT_SYMBOL_GPL(nvmem_unregister);
546 static struct nvmem_device *__nvmem_device_get(struct device_node *np,
547 struct nvmem_cell **cellp,
550 struct nvmem_device *nvmem = NULL;
552 mutex_lock(&nvmem_mutex);
555 nvmem = of_nvmem_find(np);
557 mutex_unlock(&nvmem_mutex);
558 return ERR_PTR(-EPROBE_DEFER);
561 struct nvmem_cell *cell = nvmem_find_cell(cell_id);
569 mutex_unlock(&nvmem_mutex);
570 return ERR_PTR(-ENOENT);
575 mutex_unlock(&nvmem_mutex);
577 if (!try_module_get(nvmem->owner)) {
579 "could not increase module refcount for cell %s\n",
582 mutex_lock(&nvmem_mutex);
584 mutex_unlock(&nvmem_mutex);
586 return ERR_PTR(-EINVAL);
592 static void __nvmem_device_put(struct nvmem_device *nvmem)
594 module_put(nvmem->owner);
595 mutex_lock(&nvmem_mutex);
597 mutex_unlock(&nvmem_mutex);
600 static int nvmem_match(struct device *dev, void *data)
602 return !strcmp(dev_name(dev), data);
605 static struct nvmem_device *nvmem_find(const char *name)
609 d = bus_find_device(&nvmem_bus_type, NULL, (void *)name, nvmem_match);
612 return ERR_PTR(-ENOENT);
614 return to_nvmem_device(d);
617 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
619 * of_nvmem_device_get() - Get nvmem device from a given id
621 * @dev node: Device tree node that uses the nvmem device
622 * @id: nvmem name from nvmem-names property.
624 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
627 struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
630 struct device_node *nvmem_np;
633 index = of_property_match_string(np, "nvmem-names", id);
635 nvmem_np = of_parse_phandle(np, "nvmem", index);
637 return ERR_PTR(-EINVAL);
639 return __nvmem_device_get(nvmem_np, NULL, NULL);
641 EXPORT_SYMBOL_GPL(of_nvmem_device_get);
645 * nvmem_device_get() - Get nvmem device from a given id
647 * @dev : Device that uses the nvmem device
648 * @id: nvmem name from nvmem-names property.
650 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
653 struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
655 if (dev->of_node) { /* try dt first */
656 struct nvmem_device *nvmem;
658 nvmem = of_nvmem_device_get(dev->of_node, dev_name);
660 if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
665 return nvmem_find(dev_name);
667 EXPORT_SYMBOL_GPL(nvmem_device_get);
669 static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
671 struct nvmem_device **nvmem = res;
673 if (WARN_ON(!nvmem || !*nvmem))
676 return *nvmem == data;
679 static void devm_nvmem_device_release(struct device *dev, void *res)
681 nvmem_device_put(*(struct nvmem_device **)res);
685 * devm_nvmem_device_put() - put alredy got nvmem device
687 * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
688 * that needs to be released.
690 void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
694 ret = devres_release(dev, devm_nvmem_device_release,
695 devm_nvmem_device_match, nvmem);
699 EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
702 * nvmem_device_put() - put alredy got nvmem device
704 * @nvmem: pointer to nvmem device that needs to be released.
706 void nvmem_device_put(struct nvmem_device *nvmem)
708 __nvmem_device_put(nvmem);
710 EXPORT_SYMBOL_GPL(nvmem_device_put);
713 * devm_nvmem_device_get() - Get nvmem cell of device form a given id
715 * @dev node: Device tree node that uses the nvmem cell
716 * @id: nvmem name in nvmems property.
718 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
719 * on success. The nvmem_cell will be freed by the automatically once the
722 struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
724 struct nvmem_device **ptr, *nvmem;
726 ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
728 return ERR_PTR(-ENOMEM);
730 nvmem = nvmem_device_get(dev, id);
731 if (!IS_ERR(nvmem)) {
733 devres_add(dev, ptr);
740 EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
742 static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
744 struct nvmem_cell *cell = NULL;
745 struct nvmem_device *nvmem;
747 nvmem = __nvmem_device_get(NULL, &cell, cell_id);
749 return ERR_CAST(nvmem);
754 #if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
756 * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
758 * @dev node: Device tree node that uses the nvmem cell
759 * @id: nvmem cell name from nvmem-cell-names property.
761 * Return: Will be an ERR_PTR() on error or a valid pointer
762 * to a struct nvmem_cell. The nvmem_cell will be freed by the
765 struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
768 struct device_node *cell_np, *nvmem_np;
769 struct nvmem_cell *cell;
770 struct nvmem_device *nvmem;
772 int rval, len, index;
774 index = of_property_match_string(np, "nvmem-cell-names", name);
776 cell_np = of_parse_phandle(np, "nvmem-cells", index);
778 return ERR_PTR(-EINVAL);
780 nvmem_np = of_get_next_parent(cell_np);
782 return ERR_PTR(-EINVAL);
784 nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
786 return ERR_CAST(nvmem);
788 addr = of_get_property(cell_np, "reg", &len);
789 if (!addr || (len < 2 * sizeof(u32))) {
790 dev_err(&nvmem->dev, "nvmem: invalid reg on %s\n",
796 cell = kzalloc(sizeof(*cell), GFP_KERNEL);
803 cell->offset = be32_to_cpup(addr++);
804 cell->bytes = be32_to_cpup(addr);
805 cell->name = cell_np->name;
807 addr = of_get_property(cell_np, "bits", &len);
808 if (addr && len == (2 * sizeof(u32))) {
809 cell->bit_offset = be32_to_cpup(addr++);
810 cell->nbits = be32_to_cpup(addr);
814 cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
817 if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
819 "cell %s unaligned to nvmem stride %d\n",
820 cell->name, nvmem->stride);
825 nvmem_cell_add(cell);
833 __nvmem_device_put(nvmem);
835 return ERR_PTR(rval);
837 EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
841 * nvmem_cell_get() - Get nvmem cell of device form a given cell name
843 * @dev node: Device tree node that uses the nvmem cell
844 * @id: nvmem cell name to get.
846 * Return: Will be an ERR_PTR() on error or a valid pointer
847 * to a struct nvmem_cell. The nvmem_cell will be freed by the
850 struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *cell_id)
852 struct nvmem_cell *cell;
854 if (dev->of_node) { /* try dt first */
855 cell = of_nvmem_cell_get(dev->of_node, cell_id);
856 if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
860 return nvmem_cell_get_from_list(cell_id);
862 EXPORT_SYMBOL_GPL(nvmem_cell_get);
864 static void devm_nvmem_cell_release(struct device *dev, void *res)
866 nvmem_cell_put(*(struct nvmem_cell **)res);
870 * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
872 * @dev node: Device tree node that uses the nvmem cell
873 * @id: nvmem id in nvmem-names property.
875 * Return: Will be an ERR_PTR() on error or a valid pointer
876 * to a struct nvmem_cell. The nvmem_cell will be freed by the
877 * automatically once the device is freed.
879 struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
881 struct nvmem_cell **ptr, *cell;
883 ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
885 return ERR_PTR(-ENOMEM);
887 cell = nvmem_cell_get(dev, id);
890 devres_add(dev, ptr);
897 EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
899 static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
901 struct nvmem_cell **c = res;
903 if (WARN_ON(!c || !*c))
910 * devm_nvmem_cell_put() - Release previously allocated nvmem cell
911 * from devm_nvmem_cell_get.
913 * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get()
915 void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
919 ret = devres_release(dev, devm_nvmem_cell_release,
920 devm_nvmem_cell_match, cell);
924 EXPORT_SYMBOL(devm_nvmem_cell_put);
927 * nvmem_cell_put() - Release previously allocated nvmem cell.
929 * @cell: Previously allocated nvmem cell by nvmem_cell_get()
931 void nvmem_cell_put(struct nvmem_cell *cell)
933 struct nvmem_device *nvmem = cell->nvmem;
935 __nvmem_device_put(nvmem);
936 nvmem_cell_drop(cell);
938 EXPORT_SYMBOL_GPL(nvmem_cell_put);
940 static inline void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell,
944 int i, extra, bit_offset = cell->bit_offset;
951 /* setup rest of the bytes if any */
952 for (i = 1; i < cell->bytes; i++) {
953 /* Get bits from next byte and shift them towards msb */
954 *p |= *b << (BITS_PER_BYTE - bit_offset);
960 /* point to the msb */
961 p += cell->bytes - 1;
964 /* result fits in less bytes */
965 extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
969 /* clear msb bits if any leftover in the last byte */
970 if (cell->nbits % BITS_PER_BYTE)
971 *p &= GENMASK((cell->nbits % BITS_PER_BYTE) - 1, 0);
974 static int __nvmem_cell_read(struct nvmem_device *nvmem,
975 struct nvmem_cell *cell,
976 void *buf, size_t *len)
980 rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
985 /* shift bits in-place */
986 if (cell->bit_offset || cell->nbits)
987 nvmem_shift_read_buffer_in_place(cell, buf);
995 * nvmem_cell_read() - Read a given nvmem cell
997 * @cell: nvmem cell to be read.
998 * @len: pointer to length of cell which will be populated on successful read.
1000 * Return: ERR_PTR() on error or a valid pointer to a char * buffer on success.
1001 * The buffer should be freed by the consumer with a kfree().
1003 void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
1005 struct nvmem_device *nvmem = cell->nvmem;
1010 return ERR_PTR(-EINVAL);
1012 buf = kzalloc(cell->bytes, GFP_KERNEL);
1014 return ERR_PTR(-ENOMEM);
1016 rc = __nvmem_cell_read(nvmem, cell, buf, len);
1024 EXPORT_SYMBOL_GPL(nvmem_cell_read);
1026 static inline void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
1029 struct nvmem_device *nvmem = cell->nvmem;
1030 int i, rc, nbits, bit_offset = cell->bit_offset;
1031 u8 v, *p, *buf, *b, pbyte, pbits;
1033 nbits = cell->nbits;
1034 buf = kzalloc(cell->bytes, GFP_KERNEL);
1036 return ERR_PTR(-ENOMEM);
1038 memcpy(buf, _buf, len);
1045 /* setup the first byte with lsb bits from nvmem */
1046 rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1049 *b++ |= GENMASK(bit_offset - 1, 0) & v;
1051 /* setup rest of the byte if any */
1052 for (i = 1; i < cell->bytes; i++) {
1053 /* Get last byte bits and shift them towards lsb */
1054 pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
1062 /* if it's not end on byte boundary */
1063 if ((nbits + bit_offset) % BITS_PER_BYTE) {
1064 /* setup the last byte with msb bits from nvmem */
1065 rc = nvmem_reg_read(nvmem,
1066 cell->offset + cell->bytes - 1, &v, 1);
1069 *p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;
1080 * nvmem_cell_write() - Write to a given nvmem cell
1082 * @cell: nvmem cell to be written.
1083 * @buf: Buffer to be written.
1084 * @len: length of buffer to be written to nvmem cell.
1086 * Return: length of bytes written or negative on failure.
1088 int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
1090 struct nvmem_device *nvmem = cell->nvmem;
1093 if (!nvmem || nvmem->read_only ||
1094 (cell->bit_offset == 0 && len != cell->bytes))
1097 if (cell->bit_offset || cell->nbits) {
1098 buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
1100 return PTR_ERR(buf);
1103 rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1105 /* free the tmp buffer */
1106 if (cell->bit_offset || cell->nbits)
1114 EXPORT_SYMBOL_GPL(nvmem_cell_write);
1117 * nvmem_device_cell_read() - Read a given nvmem device and cell
1119 * @nvmem: nvmem device to read from.
1120 * @info: nvmem cell info to be read.
1121 * @buf: buffer pointer which will be populated on successful read.
1123 * Return: length of successful bytes read on success and negative
1124 * error code on error.
1126 ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
1127 struct nvmem_cell_info *info, void *buf)
1129 struct nvmem_cell cell;
1136 rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1140 rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1146 EXPORT_SYMBOL_GPL(nvmem_device_cell_read);
1149 * nvmem_device_cell_write() - Write cell to a given nvmem device
1151 * @nvmem: nvmem device to be written to.
1152 * @info: nvmem cell info to be written
1153 * @buf: buffer to be written to cell.
1155 * Return: length of bytes written or negative error code on failure.
1157 int nvmem_device_cell_write(struct nvmem_device *nvmem,
1158 struct nvmem_cell_info *info, void *buf)
1160 struct nvmem_cell cell;
1166 rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1170 return nvmem_cell_write(&cell, buf, cell.bytes);
1172 EXPORT_SYMBOL_GPL(nvmem_device_cell_write);
1175 * nvmem_device_read() - Read from a given nvmem device
1177 * @nvmem: nvmem device to read from.
1178 * @offset: offset in nvmem device.
1179 * @bytes: number of bytes to read.
1180 * @buf: buffer pointer which will be populated on successful read.
1182 * Return: length of successful bytes read on success and negative
1183 * error code on error.
1185 int nvmem_device_read(struct nvmem_device *nvmem,
1186 unsigned int offset,
1187 size_t bytes, void *buf)
1194 rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1201 EXPORT_SYMBOL_GPL(nvmem_device_read);
1204 * nvmem_device_write() - Write cell to a given nvmem device
1206 * @nvmem: nvmem device to be written to.
1207 * @offset: offset in nvmem device.
1208 * @bytes: number of bytes to write.
1209 * @buf: buffer to be written.
1211 * Return: length of bytes written or negative error code on failure.
1213 int nvmem_device_write(struct nvmem_device *nvmem,
1214 unsigned int offset,
1215 size_t bytes, void *buf)
1222 rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1230 EXPORT_SYMBOL_GPL(nvmem_device_write);
1232 static int __init nvmem_init(void)
1234 return bus_register(&nvmem_bus_type);
1237 static void __exit nvmem_exit(void)
1239 bus_unregister(&nvmem_bus_type);
1242 subsys_initcall(nvmem_init);
1243 module_exit(nvmem_exit);
1245 MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
1246 MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
1247 MODULE_DESCRIPTION("nvmem Driver Core");
1248 MODULE_LICENSE("GPL v2");