core.c 27.2 KB
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/*
 * nvmem framework core.
 *
 * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
 * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
 *
 * 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;
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	int			flags;
	struct bin_attribute	eeprom;
	struct device		*base_dev;
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	nvmem_reg_read_t	reg_read;
	nvmem_reg_write_t	reg_write;
	void *priv;
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};

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#define FLAG_COMPAT		BIT(0)

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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);

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#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key eeprom_lock_key;
#endif

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#define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
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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;
}
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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)
{
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	struct device *dev;
	struct nvmem_device *nvmem;
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	int rc;

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	if (attr->private)
		dev = attr->private;
	else
		dev = container_of(kobj, struct device, kobj);
	nvmem = to_nvmem_device(dev);

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	/* Stop the user from reading */
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	if (pos >= nvmem->size)
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		return 0;

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	if (count < nvmem->word_size)
		return -EINVAL;

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	if (pos + count > nvmem->size)
		count = nvmem->size - pos;

	count = round_down(count, nvmem->word_size);

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	rc = nvmem_reg_read(nvmem, pos, buf, count);
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	if (rc)
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		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)
{
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	struct device *dev;
	struct nvmem_device *nvmem;
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	int rc;

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	if (attr->private)
		dev = attr->private;
	else
		dev = container_of(kobj, struct device, kobj);
	nvmem = to_nvmem_device(dev);

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	/* Stop the user from writing */
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	if (pos >= nvmem->size)
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		return 0;

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	if (count < nvmem->word_size)
		return -EINVAL;

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	if (pos + count > nvmem->size)
		count = nvmem->size - pos;

	count = round_down(count, nvmem->word_size);

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	rc = nvmem_reg_write(nvmem, pos, buf, count);
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	if (rc)
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		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,
};

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/* 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,
};

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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;

	list_for_each_entry(p, &nvmem_cells, node)
		if (p && !strcmp(p->name, cell_id))
			return p;

	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]);
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		if (rval) {
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			kfree(cells[i]);
			goto err;
		}

		nvmem_cell_add(cells[i]);
	}

	nvmem->ncells = cfg->ncells;
	/* remove tmp array */
	kfree(cells);

	return 0;
err:
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	while (i--)
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		nvmem_cell_drop(cells[i]);

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	kfree(cells);

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	return rval;
}

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/*
 * 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;
}

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/**
 * 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;
	struct device_node *np;
	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;
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	nvmem->stride = config->stride;
	nvmem->word_size = config->word_size;
	nvmem->size = config->size;
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	nvmem->dev.type = &nvmem_provider_type;
	nvmem->dev.bus = &nvmem_bus_type;
	nvmem->dev.parent = config->dev;
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	nvmem->priv = config->priv;
	nvmem->reg_read = config->reg_read;
	nvmem->reg_write = config->reg_write;
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	np = config->dev->of_node;
	nvmem->dev.of_node = np;
	dev_set_name(&nvmem->dev, "%s%d",
		     config->name ? : "nvmem", config->id);

	nvmem->read_only = of_property_read_bool(np, "read-only") |
			   config->read_only;

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	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;
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	device_initialize(&nvmem->dev);

	dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);

	rval = device_add(&nvmem->dev);
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	if (rval)
		goto out;

	if (config->compat) {
		rval = nvmem_setup_compat(nvmem, config);
		if (rval)
			goto out;
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	}

	if (config->cells)
		nvmem_add_cells(nvmem, config);

	return nvmem;
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out:
	ida_simple_remove(&nvmem_ida, nvmem->id);
	kfree(nvmem);
	return ERR_PTR(rval);
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}
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)
{
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	mutex_lock(&nvmem_mutex);
	if (nvmem->users) {
		mutex_unlock(&nvmem_mutex);
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		return -EBUSY;
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	}
	mutex_unlock(&nvmem_mutex);
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	if (nvmem->flags & FLAG_COMPAT)
		device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);

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	nvmem_device_remove_all_cells(nvmem);
	device_del(&nvmem->dev);

	return 0;
}
EXPORT_SYMBOL_GPL(nvmem_unregister);

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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);
}

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static int nvmem_match(struct device *dev, void *data)
{
	return !strcmp(dev_name(dev), data);
}

static struct nvmem_device *nvmem_find(const char *name)
{
	struct device *d;

	d = bus_find_device(&nvmem_bus_type, NULL, (void *)name, nvmem_match);

	if (!d)
		return NULL;

	return to_nvmem_device(d);
}

#if IS_ENABLED(CONFIG_NVMEM) && IS_ENABLED(CONFIG_OF)
/**
 * of_nvmem_device_get() - Get nvmem device from a given id
 *
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 * @np: Device tree node that uses the nvmem device.
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 * @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
 *
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 * @dev: Device that uses the nvmem device.
 * @dev_name: name of the requested nvmem device.
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 *
 * 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
 *
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 * @dev: Device that uses the nvmem device.
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 * @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
 *
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 * @dev: Device that requests the nvmem device.
 * @id: name id for the requested nvmem device.
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 *
 * 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);

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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_NVMEM) && IS_ENABLED(CONFIG_OF)
/**
 * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
 *
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 * @np: Device tree node that uses the nvmem cell.
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 * @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).
753 754 755 756 757 758 759 760 761 762 763 764
 *
 * 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;
765 766
	int rval, len;
	int index = 0;
767

768 769 770
	/* if cell name exists, find index to the name */
	if (name)
		index = of_property_match_string(np, "nvmem-cell-names", name);
771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838

	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);
	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 %s\n",
			cell_np->full_name);
		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
 *
839 840
 * @dev: Device that requests the nvmem cell.
 * @cell_id: nvmem cell name to get.
841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867
 *
 * 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
 *
868 869
 * @dev: Device that requests the nvmem cell.
 * @id: nvmem cell name id to get.
870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908
 *
 * 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.
 *
909 910
 * @dev: Device that requests the nvmem cell.
 * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
911 912 913 914 915 916 917 918 919 920 921 922 923 924 925
 */
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.
 *
926
 * @cell: Previously allocated nvmem cell by nvmem_cell_get().
927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970
 */
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 inline 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;

971
	rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);
972

973
	if (rc)
974 975 976
		return rc;

	/* shift bits in-place */
977
	if (cell->bit_offset || cell->nbits)
978 979
		nvmem_shift_read_buffer_in_place(cell, buf);

980 981
	if (len)
		*len = cell->bytes;
982 983 984 985 986 987 988 989

	return 0;
}

/**
 * nvmem_cell_read() - Read a given nvmem cell
 *
 * @cell: nvmem cell to be read.
990 991
 * @len: pointer to length of cell which will be populated on successful read;
 *	 can be NULL.
992
 *
993 994
 * 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().
995 996 997 998 999 1000 1001
 */
void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
{
	struct nvmem_device *nvmem = cell->nvmem;
	u8 *buf;
	int rc;

1002
	if (!nvmem)
1003 1004 1005 1006 1007 1008 1009
		return ERR_PTR(-EINVAL);

	buf = kzalloc(cell->bytes, GFP_KERNEL);
	if (!buf)
		return ERR_PTR(-ENOMEM);

	rc = __nvmem_cell_read(nvmem, cell, buf, len);
1010
	if (rc) {
1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038
		kfree(buf);
		return ERR_PTR(rc);
	}

	return buf;
}
EXPORT_SYMBOL_GPL(nvmem_cell_read);

static inline void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
						    u8 *_buf, int len)
{
	struct nvmem_device *nvmem = cell->nvmem;
	int i, rc, nbits, bit_offset = cell->bit_offset;
	u8 v, *p, *buf, *b, pbyte, pbits;

	nbits = cell->nbits;
	buf = kzalloc(cell->bytes, GFP_KERNEL);
	if (!buf)
		return ERR_PTR(-ENOMEM);

	memcpy(buf, _buf, len);
	p = b = buf;

	if (bit_offset) {
		pbyte = *b;
		*b <<= bit_offset;

		/* setup the first byte with lsb bits from nvmem */
1039
		rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055
		*b++ |= GENMASK(bit_offset - 1, 0) & v;

		/* setup rest of the byte if any */
		for (i = 1; i < cell->bytes; i++) {
			/* Get last byte bits and shift them towards lsb */
			pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
			pbyte = *b;
			p = b;
			*b <<= bit_offset;
			*b++ |= pbits;
		}
	}

	/* if it's not end on byte boundary */
	if ((nbits + bit_offset) % BITS_PER_BYTE) {
		/* setup the last byte with msb bits from nvmem */
1056
		rc = nvmem_reg_read(nvmem,
1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078
				    cell->offset + cell->bytes - 1, &v, 1);
		*p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;

	}

	return buf;
}

/**
 * nvmem_cell_write() - Write to a given nvmem cell
 *
 * @cell: nvmem cell to be written.
 * @buf: Buffer to be written.
 * @len: length of buffer to be written to nvmem cell.
 *
 * Return: length of bytes written or negative on failure.
 */
int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
{
	struct nvmem_device *nvmem = cell->nvmem;
	int rc;

1079
	if (!nvmem || nvmem->read_only ||
1080 1081 1082 1083 1084 1085 1086 1087 1088
	    (cell->bit_offset == 0 && len != cell->bytes))
		return -EINVAL;

	if (cell->bit_offset || cell->nbits) {
		buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
		if (IS_ERR(buf))
			return PTR_ERR(buf);
	}

1089
	rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);
1090 1091

	/* free the tmp buffer */
1092
	if (cell->bit_offset || cell->nbits)
1093 1094
		kfree(buf);

1095
	if (rc)
1096 1097 1098 1099 1100 1101
		return rc;

	return len;
}
EXPORT_SYMBOL_GPL(nvmem_cell_write);

1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118
/**
 * nvmem_device_cell_read() - Read a given nvmem device and cell
 *
 * @nvmem: nvmem device to read from.
 * @info: nvmem cell info to be read.
 * @buf: buffer pointer which will be populated on successful read.
 *
 * Return: length of successful bytes read on success and negative
 * error code on error.
 */
ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
			   struct nvmem_cell_info *info, void *buf)
{
	struct nvmem_cell cell;
	int rc;
	ssize_t len;

1119
	if (!nvmem)
1120 1121 1122
		return -EINVAL;

	rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1123
	if (rc)
1124 1125 1126
		return rc;

	rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
1127
	if (rc)
1128 1129 1130 1131 1132 1133 1134 1135 1136 1137
		return rc;

	return len;
}
EXPORT_SYMBOL_GPL(nvmem_device_cell_read);

/**
 * nvmem_device_cell_write() - Write cell to a given nvmem device
 *
 * @nvmem: nvmem device to be written to.
1138
 * @info: nvmem cell info to be written.
1139 1140 1141 1142 1143 1144 1145 1146 1147 1148
 * @buf: buffer to be written to cell.
 *
 * Return: length of bytes written or negative error code on failure.
 * */
int nvmem_device_cell_write(struct nvmem_device *nvmem,
			    struct nvmem_cell_info *info, void *buf)
{
	struct nvmem_cell cell;
	int rc;

1149
	if (!nvmem)
1150 1151 1152
		return -EINVAL;

	rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
1153
	if (rc)
1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176
		return rc;

	return nvmem_cell_write(&cell, buf, cell.bytes);
}
EXPORT_SYMBOL_GPL(nvmem_device_cell_write);

/**
 * nvmem_device_read() - Read from a given nvmem device
 *
 * @nvmem: nvmem device to read from.
 * @offset: offset in nvmem device.
 * @bytes: number of bytes to read.
 * @buf: buffer pointer which will be populated on successful read.
 *
 * Return: length of successful bytes read on success and negative
 * error code on error.
 */
int nvmem_device_read(struct nvmem_device *nvmem,
		      unsigned int offset,
		      size_t bytes, void *buf)
{
	int rc;

1177
	if (!nvmem)
1178 1179
		return -EINVAL;

1180
	rc = nvmem_reg_read(nvmem, offset, buf, bytes);
1181

1182
	if (rc)
1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204
		return rc;

	return bytes;
}
EXPORT_SYMBOL_GPL(nvmem_device_read);

/**
 * nvmem_device_write() - Write cell to a given nvmem device
 *
 * @nvmem: nvmem device to be written to.
 * @offset: offset in nvmem device.
 * @bytes: number of bytes to write.
 * @buf: buffer to be written.
 *
 * Return: length of bytes written or negative error code on failure.
 * */
int nvmem_device_write(struct nvmem_device *nvmem,
		       unsigned int offset,
		       size_t bytes, void *buf)
{
	int rc;

1205
	if (!nvmem)
1206 1207
		return -EINVAL;

1208
	rc = nvmem_reg_write(nvmem, offset, buf, bytes);
1209

1210
	if (rc)
1211 1212 1213 1214 1215 1216 1217
		return rc;


	return bytes;
}
EXPORT_SYMBOL_GPL(nvmem_device_write);

1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234
static int __init nvmem_init(void)
{
	return bus_register(&nvmem_bus_type);
}

static void __exit nvmem_exit(void)
{
	bus_unregister(&nvmem_bus_type);
}

subsys_initcall(nvmem_init);
module_exit(nvmem_exit);

MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
MODULE_DESCRIPTION("nvmem Driver Core");
MODULE_LICENSE("GPL v2");