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/gpio/consumer.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;
	bool			root_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;
	struct gpio_desc	*wp_gpio;
	void *priv;
};

#define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)

#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);

#ifdef CONFIG_NVMEM_SYSFS
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

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);

	if (!nvmem->reg_read)
		return -EPERM;

	rc = nvmem->reg_read(nvmem->priv, 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 >=