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core.c
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core.c
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/*
* nvmem framework core.
*
* Copyright (C) 2015 Srinivas Kandagatla <[email protected]>
* Copyright (C) 2013 Maxime Ripard <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/device.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/nvmem-consumer.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/slab.h>
struct nvmem_device {
const char *name;
struct module *owner;
struct device dev;
int stride;
int word_size;
int ncells;
int id;
int users;
size_t size;
bool read_only;
int flags;
struct bin_attribute eeprom;
struct device *base_dev;
nvmem_reg_read_t reg_read;
nvmem_reg_write_t reg_write;
void *priv;
};
#define FLAG_COMPAT BIT(0)
struct nvmem_cell {
const char *name;
int offset;
int bytes;
int bit_offset;
int nbits;
struct nvmem_device *nvmem;
struct list_head node;
};
static DEFINE_MUTEX(nvmem_mutex);
static DEFINE_IDA(nvmem_ida);
static LIST_HEAD(nvmem_cells);
static DEFINE_MUTEX(nvmem_cells_mutex);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key eeprom_lock_key;
#endif
#define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
void *val, size_t bytes)
{
if (nvmem->reg_read)
return nvmem->reg_read(nvmem->priv, offset, val, bytes);
return -EINVAL;
}
static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
void *val, size_t bytes)
{
if (nvmem->reg_write)
return nvmem->reg_write(nvmem->priv, offset, val, bytes);
return -EINVAL;
}
static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t pos, size_t count)
{
struct device *dev;
struct nvmem_device *nvmem;
int rc;
if (attr->private)
dev = attr->private;
else
dev = container_of(kobj, struct device, kobj);
nvmem = to_nvmem_device(dev);
/* Stop the user from reading */
if (pos >= nvmem->size)
return 0;
if (count < nvmem->word_size)
return -EINVAL;
if (pos + count > nvmem->size)
count = nvmem->size - pos;
count = round_down(count, nvmem->word_size);
rc = nvmem_reg_read(nvmem, pos, buf, count);
if (rc)
return rc;
return count;
}
static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
struct bin_attribute *attr,
char *buf, loff_t pos, size_t count)
{
struct device *dev;
struct nvmem_device *nvmem;
int rc;
if (attr->private)
dev = attr->private;
else
dev = container_of(kobj, struct device, kobj);
nvmem = to_nvmem_device(dev);
/* Stop the user from writing */
if (pos >= nvmem->size)
return -EFBIG;
if (count < nvmem->word_size)
return -EINVAL;
if (pos + count > nvmem->size)
count = nvmem->size - pos;
count = round_down(count, nvmem->word_size);
rc = nvmem_reg_write(nvmem, pos, buf, count);
if (rc)
return rc;
return count;
}
/* default read/write permissions */
static struct bin_attribute bin_attr_rw_nvmem = {
.attr = {
.name = "nvmem",
.mode = S_IWUSR | S_IRUGO,
},
.read = bin_attr_nvmem_read,
.write = bin_attr_nvmem_write,
};
static struct bin_attribute *nvmem_bin_rw_attributes[] = {
&bin_attr_rw_nvmem,
NULL,
};
static const struct attribute_group nvmem_bin_rw_group = {
.bin_attrs = nvmem_bin_rw_attributes,
};
static const struct attribute_group *nvmem_rw_dev_groups[] = {
&nvmem_bin_rw_group,
NULL,
};
/* read only permission */
static struct bin_attribute bin_attr_ro_nvmem = {
.attr = {
.name = "nvmem",
.mode = S_IRUGO,
},
.read = bin_attr_nvmem_read,
};
static struct bin_attribute *nvmem_bin_ro_attributes[] = {
&bin_attr_ro_nvmem,
NULL,
};
static const struct attribute_group nvmem_bin_ro_group = {
.bin_attrs = nvmem_bin_ro_attributes,
};
static const struct attribute_group *nvmem_ro_dev_groups[] = {
&nvmem_bin_ro_group,
NULL,
};
/* default read/write permissions, root only */
static struct bin_attribute bin_attr_rw_root_nvmem = {
.attr = {
.name = "nvmem",
.mode = S_IWUSR | S_IRUSR,
},
.read = bin_attr_nvmem_read,
.write = bin_attr_nvmem_write,
};
static struct bin_attribute *nvmem_bin_rw_root_attributes[] = {
&bin_attr_rw_root_nvmem,
NULL,
};
static const struct attribute_group nvmem_bin_rw_root_group = {
.bin_attrs = nvmem_bin_rw_root_attributes,
};
static const struct attribute_group *nvmem_rw_root_dev_groups[] = {
&nvmem_bin_rw_root_group,
NULL,
};
/* read only permission, root only */
static struct bin_attribute bin_attr_ro_root_nvmem = {
.attr = {
.name = "nvmem",
.mode = S_IRUSR,
},
.read = bin_attr_nvmem_read,
};
static struct bin_attribute *nvmem_bin_ro_root_attributes[] = {
&bin_attr_ro_root_nvmem,
NULL,
};
static const struct attribute_group nvmem_bin_ro_root_group = {
.bin_attrs = nvmem_bin_ro_root_attributes,
};
static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
&nvmem_bin_ro_root_group,
NULL,
};
static void nvmem_release(struct device *dev)
{
struct nvmem_device *nvmem = to_nvmem_device(dev);
ida_simple_remove(&nvmem_ida, nvmem->id);
kfree(nvmem);
}
static const struct device_type nvmem_provider_type = {
.release = nvmem_release,
};
static struct bus_type nvmem_bus_type = {
.name = "nvmem",
};
static int of_nvmem_match(struct device *dev, void *nvmem_np)
{
return dev->of_node == nvmem_np;
}
static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
{
struct device *d;
if (!nvmem_np)
return NULL;
d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match);
if (!d)
return NULL;
return to_nvmem_device(d);
}
static struct nvmem_cell *nvmem_find_cell(const char *cell_id)
{
struct nvmem_cell *p;
mutex_lock(&nvmem_cells_mutex);
list_for_each_entry(p, &nvmem_cells, node)
if (!strcmp(p->name, cell_id)) {
mutex_unlock(&nvmem_cells_mutex);
return p;
}
mutex_unlock(&nvmem_cells_mutex);
return NULL;
}
static void nvmem_cell_drop(struct nvmem_cell *cell)
{
mutex_lock(&nvmem_cells_mutex);
list_del(&cell->node);
mutex_unlock(&nvmem_cells_mutex);
kfree(cell);
}
static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
{
struct nvmem_cell *cell;
struct list_head *p, *n;
list_for_each_safe(p, n, &nvmem_cells) {
cell = list_entry(p, struct nvmem_cell, node);
if (cell->nvmem == nvmem)
nvmem_cell_drop(cell);
}
}
static void nvmem_cell_add(struct nvmem_cell *cell)
{
mutex_lock(&nvmem_cells_mutex);
list_add_tail(&cell->node, &nvmem_cells);
mutex_unlock(&nvmem_cells_mutex);
}
static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
const struct nvmem_cell_info *info,
struct nvmem_cell *cell)
{
cell->nvmem = nvmem;
cell->offset = info->offset;
cell->bytes = info->bytes;
cell->name = info->name;
cell->bit_offset = info->bit_offset;
cell->nbits = info->nbits;
if (cell->nbits)
cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
BITS_PER_BYTE);
if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
dev_err(&nvmem->dev,
"cell %s unaligned to nvmem stride %d\n",
cell->name, nvmem->stride);
return -EINVAL;
}
return 0;
}
static int nvmem_add_cells(struct nvmem_device *nvmem,
const struct nvmem_config *cfg)
{
struct nvmem_cell **cells;
const struct nvmem_cell_info *info = cfg->cells;
int i, rval;
cells = kcalloc(cfg->ncells, sizeof(*cells), GFP_KERNEL);
if (!cells)
return -ENOMEM;
for (i = 0; i < cfg->ncells; i++) {
cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
if (!cells[i]) {
rval = -ENOMEM;
goto err;
}
rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
if (rval) {
kfree(cells[i]);
goto err;
}
nvmem_cell_add(cells[i]);
}
nvmem->ncells = cfg->ncells;
/* remove tmp array */
kfree(cells);
return 0;
err:
while (i--)
nvmem_cell_drop(cells[i]);
kfree(cells);
return rval;
}
/*
* nvmem_setup_compat() - Create an additional binary entry in
* drivers sys directory, to be backwards compatible with the older
* drivers/misc/eeprom drivers.
*/
static int nvmem_setup_compat(struct nvmem_device *nvmem,
const struct nvmem_config *config)
{
int rval;
if (!config->base_dev)
return -EINVAL;
if (nvmem->read_only)
nvmem->eeprom = bin_attr_ro_root_nvmem;
else
nvmem->eeprom = bin_attr_rw_root_nvmem;
nvmem->eeprom.attr.name = "eeprom";
nvmem->eeprom.size = nvmem->size;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
nvmem->eeprom.attr.key = &eeprom_lock_key;
#endif
nvmem->eeprom.private = &nvmem->dev;
nvmem->base_dev = config->base_dev;
rval = device_create_bin_file(nvmem->base_dev, &nvmem->eeprom);
if (rval) {
dev_err(&nvmem->dev,
"Failed to create eeprom binary file %d\n", rval);
return rval;
}
nvmem->flags |= FLAG_COMPAT;
return 0;
}
/**
* nvmem_register() - Register a nvmem device for given nvmem_config.
* Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
*
* @config: nvmem device configuration with which nvmem device is created.
*
* Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
* on success.
*/
struct nvmem_device *nvmem_register(const struct nvmem_config *config)
{
struct nvmem_device *nvmem;
int rval;
if (!config->dev)
return ERR_PTR(-EINVAL);
nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
if (!nvmem)
return ERR_PTR(-ENOMEM);
rval = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
if (rval < 0) {
kfree(nvmem);
return ERR_PTR(rval);
}
nvmem->id = rval;
nvmem->owner = config->owner;
if (!nvmem->owner && config->dev->driver)
nvmem->owner = config->dev->driver->owner;
nvmem->stride = config->stride ?: 1;
nvmem->word_size = config->word_size ?: 1;
nvmem->size = config->size;
nvmem->dev.type = &nvmem_provider_type;
nvmem->dev.bus = &nvmem_bus_type;
nvmem->dev.parent = config->dev;
nvmem->priv = config->priv;
nvmem->reg_read = config->reg_read;
nvmem->reg_write = config->reg_write;
nvmem->dev.of_node = config->dev->of_node;
dev_set_name(&nvmem->dev, "%s%d",
config->name ? : "nvmem",
config->name ? config->id : nvmem->id);
nvmem->read_only = device_property_present(config->dev, "read-only") |
config->read_only;
if (config->root_only)
nvmem->dev.groups = nvmem->read_only ?
nvmem_ro_root_dev_groups :
nvmem_rw_root_dev_groups;
else
nvmem->dev.groups = nvmem->read_only ?
nvmem_ro_dev_groups :
nvmem_rw_dev_groups;
device_initialize(&nvmem->dev);
dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
rval = device_add(&nvmem->dev);
if (rval)
goto err_put_device;
if (config->compat) {
rval = nvmem_setup_compat(nvmem, config);
if (rval)
goto err_device_del;
}
if (config->cells)
nvmem_add_cells(nvmem, config);
return nvmem;
err_device_del:
device_del(&nvmem->dev);
err_put_device:
put_device(&nvmem->dev);
return ERR_PTR(rval);
}
EXPORT_SYMBOL_GPL(nvmem_register);
/**
* nvmem_unregister() - Unregister previously registered nvmem device
*
* @nvmem: Pointer to previously registered nvmem device.
*
* Return: Will be an negative on error or a zero on success.
*/
int nvmem_unregister(struct nvmem_device *nvmem)
{
mutex_lock(&nvmem_mutex);
if (nvmem->users) {
mutex_unlock(&nvmem_mutex);
return -EBUSY;
}
mutex_unlock(&nvmem_mutex);
if (nvmem->flags & FLAG_COMPAT)
device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
nvmem_device_remove_all_cells(nvmem);
device_del(&nvmem->dev);
put_device(&nvmem->dev);
return 0;
}
EXPORT_SYMBOL_GPL(nvmem_unregister);
static struct nvmem_device *__nvmem_device_get(struct device_node *np,
struct nvmem_cell **cellp,
const char *cell_id)
{
struct nvmem_device *nvmem = NULL;
mutex_lock(&nvmem_mutex);
if (np) {
nvmem = of_nvmem_find(np);
if (!nvmem) {
mutex_unlock(&nvmem_mutex);
return ERR_PTR(-EPROBE_DEFER);
}
} else {
struct nvmem_cell *cell = nvmem_find_cell(cell_id);
if (cell) {
nvmem = cell->nvmem;
*cellp = cell;
}
if (!nvmem) {
mutex_unlock(&nvmem_mutex);
return ERR_PTR(-ENOENT);
}
}
nvmem->users++;
mutex_unlock(&nvmem_mutex);
if (!try_module_get(nvmem->owner)) {
dev_err(&nvmem->dev,
"could not increase module refcount for cell %s\n",
nvmem->name);
mutex_lock(&nvmem_mutex);
nvmem->users--;
mutex_unlock(&nvmem_mutex);
return ERR_PTR(-EINVAL);
}
return nvmem;
}
static void __nvmem_device_put(struct nvmem_device *nvmem)
{
module_put(nvmem->owner);
mutex_lock(&nvmem_mutex);
nvmem->users--;
mutex_unlock(&nvmem_mutex);
}
static struct nvmem_device *nvmem_find(const char *name)
{
struct device *d;
d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);
if (!d)
return NULL;
return to_nvmem_device(d);
}
#if IS_ENABLED(CONFIG_OF)
/**
* of_nvmem_device_get() - Get nvmem device from a given id
*
* @np: Device tree node that uses the nvmem device.
* @id: nvmem name from nvmem-names property.
*
* Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
* on success.
*/
struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
{
struct device_node *nvmem_np;
int index;
index = of_property_match_string(np, "nvmem-names", id);
nvmem_np = of_parse_phandle(np, "nvmem", index);
if (!nvmem_np)
return ERR_PTR(-EINVAL);
return __nvmem_device_get(nvmem_np, NULL, NULL);
}
EXPORT_SYMBOL_GPL(of_nvmem_device_get);
#endif
/**
* nvmem_device_get() - Get nvmem device from a given id
*
* @dev: Device that uses the nvmem device.
* @dev_name: name of the requested nvmem device.
*
* Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
* on success.
*/
struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
{
if (dev->of_node) { /* try dt first */
struct nvmem_device *nvmem;
nvmem = of_nvmem_device_get(dev->of_node, dev_name);
if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
return nvmem;
}
return nvmem_find(dev_name);
}
EXPORT_SYMBOL_GPL(nvmem_device_get);
static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
{
struct nvmem_device **nvmem = res;
if (WARN_ON(!nvmem || !*nvmem))
return 0;
return *nvmem == data;
}
static void devm_nvmem_device_release(struct device *dev, void *res)
{
nvmem_device_put(*(struct nvmem_device **)res);
}
/**
* devm_nvmem_device_put() - put alredy got nvmem device
*
* @dev: Device that uses the nvmem device.
* @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
* that needs to be released.
*/
void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
{
int ret;
ret = devres_release(dev, devm_nvmem_device_release,
devm_nvmem_device_match, nvmem);
WARN_ON(ret);
}
EXPORT_SYMBOL_GPL(devm_nvmem_device_put);
/**
* nvmem_device_put() - put alredy got nvmem device
*
* @nvmem: pointer to nvmem device that needs to be released.
*/
void nvmem_device_put(struct nvmem_device *nvmem)
{
__nvmem_device_put(nvmem);
}
EXPORT_SYMBOL_GPL(nvmem_device_put);
/**
* devm_nvmem_device_get() - Get nvmem cell of device form a given id
*
* @dev: Device that requests the nvmem device.
* @id: name id for the requested nvmem device.
*
* Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
* on success. The nvmem_cell will be freed by the automatically once the
* device is freed.
*/
struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
{
struct nvmem_device **ptr, *nvmem;
ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
if (!ptr)
return ERR_PTR(-ENOMEM);
nvmem = nvmem_device_get(dev, id);
if (!IS_ERR(nvmem)) {
*ptr = nvmem;
devres_add(dev, ptr);
} else {
devres_free(ptr);
}
return nvmem;
}
EXPORT_SYMBOL_GPL(devm_nvmem_device_get);
static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
{
struct nvmem_cell *cell = NULL;
struct nvmem_device *nvmem;
nvmem = __nvmem_device_get(NULL, &cell, cell_id);
if (IS_ERR(nvmem))
return ERR_CAST(nvmem);
return cell;
}
#if IS_ENABLED(CONFIG_OF)
/**
* of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
*
* @np: Device tree node that uses the nvmem cell.
* @name: nvmem cell name from nvmem-cell-names property, or NULL
* for the cell at index 0 (the lone cell with no accompanying
* nvmem-cell-names property).
*
* Return: Will be an ERR_PTR() on error or a valid pointer
* to a struct nvmem_cell. The nvmem_cell will be freed by the
* nvmem_cell_put().
*/
struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
const char *name)
{
struct device_node *cell_np, *nvmem_np;
struct nvmem_cell *cell;
struct nvmem_device *nvmem;
const __be32 *addr;
int rval, len;
int index = 0;
/* if cell name exists, find index to the name */
if (name)
index = of_property_match_string(np, "nvmem-cell-names", name);
cell_np = of_parse_phandle(np, "nvmem-cells", index);
if (!cell_np)
return ERR_PTR(-EINVAL);
nvmem_np = of_get_next_parent(cell_np);
if (!nvmem_np)
return ERR_PTR(-EINVAL);
nvmem = __nvmem_device_get(nvmem_np, NULL, NULL);
of_node_put(nvmem_np);
if (IS_ERR(nvmem))
return ERR_CAST(nvmem);
addr = of_get_property(cell_np, "reg", &len);
if (!addr || (len < 2 * sizeof(u32))) {
dev_err(&nvmem->dev, "nvmem: invalid reg on %pOF\n",
cell_np);
rval = -EINVAL;
goto err_mem;
}
cell = kzalloc(sizeof(*cell), GFP_KERNEL);
if (!cell) {
rval = -ENOMEM;
goto err_mem;
}
cell->nvmem = nvmem;
cell->offset = be32_to_cpup(addr++);
cell->bytes = be32_to_cpup(addr);
cell->name = cell_np->name;
addr = of_get_property(cell_np, "bits", &len);
if (addr && len == (2 * sizeof(u32))) {
cell->bit_offset = be32_to_cpup(addr++);
cell->nbits = be32_to_cpup(addr);
}
if (cell->nbits)
cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
BITS_PER_BYTE);
if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
dev_err(&nvmem->dev,
"cell %s unaligned to nvmem stride %d\n",
cell->name, nvmem->stride);
rval = -EINVAL;
goto err_sanity;
}
nvmem_cell_add(cell);
return cell;
err_sanity:
kfree(cell);
err_mem:
__nvmem_device_put(nvmem);
return ERR_PTR(rval);
}
EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
#endif
/**
* nvmem_cell_get() - Get nvmem cell of device form a given cell name
*
* @dev: Device that requests the nvmem cell.
* @cell_id: nvmem cell name to get.
*
* Return: Will be an ERR_PTR() on error or a valid pointer
* to a struct nvmem_cell. The nvmem_cell will be freed by the
* nvmem_cell_put().
*/
struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *cell_id)
{
struct nvmem_cell *cell;
if (dev->of_node) { /* try dt first */
cell = of_nvmem_cell_get(dev->of_node, cell_id);
if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
return cell;
}
return nvmem_cell_get_from_list(cell_id);
}
EXPORT_SYMBOL_GPL(nvmem_cell_get);
static void devm_nvmem_cell_release(struct device *dev, void *res)
{
nvmem_cell_put(*(struct nvmem_cell **)res);
}
/**
* devm_nvmem_cell_get() - Get nvmem cell of device form a given id
*
* @dev: Device that requests the nvmem cell.
* @id: nvmem cell name id to get.
*
* Return: Will be an ERR_PTR() on error or a valid pointer
* to a struct nvmem_cell. The nvmem_cell will be freed by the
* automatically once the device is freed.
*/
struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
{
struct nvmem_cell **ptr, *cell;
ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
if (!ptr)
return ERR_PTR(-ENOMEM);
cell = nvmem_cell_get(dev, id);
if (!IS_ERR(cell)) {
*ptr = cell;
devres_add(dev, ptr);
} else {
devres_free(ptr);
}
return cell;
}
EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);
static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
{
struct nvmem_cell **c = res;
if (WARN_ON(!c || !*c))
return 0;
return *c == data;
}
/**
* devm_nvmem_cell_put() - Release previously allocated nvmem cell
* from devm_nvmem_cell_get.
*
* @dev: Device that requests the nvmem cell.
* @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
*/
void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
{
int ret;
ret = devres_release(dev, devm_nvmem_cell_release,
devm_nvmem_cell_match, cell);
WARN_ON(ret);
}
EXPORT_SYMBOL(devm_nvmem_cell_put);
/**
* nvmem_cell_put() - Release previously allocated nvmem cell.
*
* @cell: Previously allocated nvmem cell by nvmem_cell_get().
*/
void nvmem_cell_put(struct nvmem_cell *cell)
{
struct nvmem_device *nvmem = cell->nvmem;
__nvmem_device_put(nvmem);
nvmem_cell_drop(cell);
}
EXPORT_SYMBOL_GPL(nvmem_cell_put);
static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
{
u8 *p, *b;
int i, bit_offset = cell->bit_offset;
p = b = buf;
if (bit_offset) {
/* First shift */
*b++ >>= bit_offset;
/* setup rest of the bytes if any */
for (i = 1; i < cell->bytes; i++) {
/* Get bits from next byte and shift them towards msb */
*p |= *b << (BITS_PER_BYTE - bit_offset);
p = b;
*b++ >>= bit_offset;
}
/* result fits in less bytes */
if (cell->bytes != DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE))
*p-- = 0;
}
/* clear msb bits if any leftover in the last byte */
*p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
}
static int __nvmem_cell_read(struct nvmem_device *nvmem,
struct nvmem_cell *cell,
void *buf, size_t *len)
{
int rc;
rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
if (rc)
return rc;
/* shift bits in-place */
if (cell->bit_offset || cell->nbits)
nvmem_shift_read_buffer_in_place(cell, buf);
if (len)
*len = cell->bytes;
return 0;
}
/**
* nvmem_cell_read() - Read a given nvmem cell
*
* @cell: nvmem cell to be read.
* @len: pointer to length of cell which will be populated on successful read;
* can be NULL.
*
* Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
* buffer should be freed by the consumer with a kfree().