path: root/drivers/nvmem/core.c

// SPDX-License-Identifier: GPL-2.0
/*
 * nvmem framework core.
 *
 * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
 * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
 */

#include <linux/device.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/kref.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 {
	struct module		*owner;
	struct device		dev;
	int			stride;
	int			word_size;
	int			id;
	struct kref		refcnt;
	size_t			size;
	bool			read_only;
	int			flags;
	enum nvmem_type		type;
	struct bin_attribute	eeprom;
	struct device		*base_dev;
	struct list_head	cells;
	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 device_node	*np;
	struct nvmem_device	*nvmem;
	struct list_head	node;
};

static DEFINE_MUTEX(nvmem_mutex);
static DEFINE_IDA(nvmem_ida);

static DEFINE_MUTEX(nvmem_cell_mutex);
static LIST_HEAD(nvmem_cell_tables);

static DEFINE_MUTEX(nvmem_lookup_mutex);
static LIST_HEAD(nvmem_lookup_list);

static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);

static const char * const nvmem_type_str[] = {
	[NVMEM_TYPE_UNKNOWN] = "Unknown",
	[NVMEM_TYPE_EEPROM] = "EEPROM",
	[NVMEM_TYPE_OTP] = "OTP",
	[NVMEM_TYPE_BATTERY_BACKED] = "Battery backed",
};

#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 type_show(struct device *dev,
			 struct device_attribute *attr, char *buf)
{
	struct nvmem_device *nvmem = to_nvmem_device(dev);

	return sprintf(buf, "%s\n", nvmem_type_str[nvmem->type]);
}

static DEVICE_ATTR_RO(type);

static struct attribute *nvmem_attrs[] = {
	&dev_attr_type.attr,
	NULL,
};

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	= 0644,
	},
	.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,
	.attrs		= nvmem_attrs,
};

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	= 0444,
	},
	.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,
	.attrs		= nvmem_attrs,
};

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	= 0600,
	},
	.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,
	.attrs		= nvmem_attrs,
};

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	= 0400,
	},
	.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,
	.attrs		= nvmem_attrs,
};

static const struct a