Commit eace75cf authored by Srinivas Kandagatla's avatar Srinivas Kandagatla Committed by Greg Kroah-Hartman

nvmem: Add a simple NVMEM framework for nvmem providers

This patch adds just providers part of the framework just to enable easy
review.

Up until now, NVMEM drivers like eeprom were stored in drivers/misc,
where they all had to duplicate pretty much the same code to register
a sysfs file, allow in-kernel users to access the content of the devices
they were driving, etc.

This was also a problem as far as other in-kernel users were involved,
since the solutions used were pretty much different from on driver to
another, there was a rather big abstraction leak.

This introduction of this framework aims at solving this. It also
introduces DT representation for consumer devices to go get the data
they require (MAC Addresses, SoC/Revision ID, part numbers, and so on)
from the nvmems.

Having regmap interface to this framework would give much better
abstraction for nvmems on different buses.
Signed-off-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
[Maxime Ripard: intial version of eeprom framework]
Signed-off-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Tested-by: default avatarStefan Wahren <stefan.wahren@i2se.com>
Tested-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
Tested-by: default avatarRajendra Nayak <rnayak@codeaurora.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4edd70c1
......@@ -184,4 +184,6 @@ source "drivers/android/Kconfig"
source "drivers/nvdimm/Kconfig"
source "drivers/nvmem/Kconfig"
endmenu
......@@ -165,3 +165,4 @@ obj-$(CONFIG_RAS) += ras/
obj-$(CONFIG_THUNDERBOLT) += thunderbolt/
obj-$(CONFIG_CORESIGHT) += hwtracing/coresight/
obj-$(CONFIG_ANDROID) += android/
obj-$(CONFIG_NVMEM) += nvmem/
menuconfig NVMEM
tristate "NVMEM Support"
select REGMAP
help
Support for NVMEM(Non Volatile Memory) devices like EEPROM, EFUSES...
This framework is designed to provide a generic interface to NVMEM
from both the Linux Kernel and the userspace.
This driver can also be built as a module. If so, the module
will be called nvmem_core.
If unsure, say no.
#
# Makefile for nvmem drivers.
#
obj-$(CONFIG_NVMEM) += nvmem_core.o
nvmem_core-y := core.o
/*
* 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/regmap.h>
#include <linux/slab.h>
struct nvmem_device {
const char *name;
struct regmap *regmap;
struct module *owner;
struct device dev;
int stride;
int word_size;
int ncells;
int id;
int users;
size_t size;
bool read_only;
};
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);
#define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
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 = container_of(kobj, struct device, kobj);
struct nvmem_device *nvmem = to_nvmem_device(dev);
int rc;
/* Stop the user from reading */
if (pos > nvmem->size)
return 0;
if (pos + count > nvmem->size)
count = nvmem->size - pos;
count = round_down(count, nvmem->word_size);
rc = regmap_raw_read(nvmem->regmap, pos, buf, count);
if (IS_ERR_VALUE(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 = container_of(kobj, struct device, kobj);
struct nvmem_device *nvmem = to_nvmem_device(dev);
int rc;
/* Stop the user from writing */
if (pos > nvmem->size)
return 0;
if (pos + count > nvmem->size)
count = nvmem->size - pos;
count = round_down(count, nvmem->word_size);
rc = regmap_raw_write(nvmem->regmap, pos, buf, count);
if (IS_ERR_VALUE(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,
};
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]);
if (IS_ERR_VALUE(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]);
return rval;
}
/**
* 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;
struct regmap *rm;
int rval;
if (!config->dev)
return ERR_PTR(-EINVAL);
rm = dev_get_regmap(config->dev, NULL);
if (!rm) {
dev_err(config->dev, "Regmap not found\n");
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->regmap = rm;
nvmem->owner = config->owner;
nvmem->stride = regmap_get_reg_stride(rm);
nvmem->word_size = regmap_get_val_bytes(rm);
nvmem->size = regmap_get_max_register(rm) + nvmem->stride;
nvmem->dev.type = &nvmem_provider_type;
nvmem->dev.bus = &nvmem_bus_type;
nvmem->dev.parent = config->dev;
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;
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) {
ida_simple_remove(&nvmem_ida, nvmem->id);
kfree(nvmem);
return ERR_PTR(rval);
}
if (config->cells)
nvmem_add_cells(nvmem, config);
return nvmem;
}
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)
{
if (nvmem->users)
return -EBUSY;
nvmem_device_remove_all_cells(nvmem);
device_del(&nvmem->dev);
return 0;
}
EXPORT_SYMBOL_GPL(nvmem_unregister);
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");
/*
* nvmem framework consumer.
*
* Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
* Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#ifndef _LINUX_NVMEM_CONSUMER_H
#define _LINUX_NVMEM_CONSUMER_H
struct nvmem_cell_info {
const char *name;
unsigned int offset;
unsigned int bytes;
unsigned int bit_offset;
unsigned int nbits;
};
#endif /* ifndef _LINUX_NVMEM_CONSUMER_H */
/*
* nvmem framework provider.
*
* Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
* Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#ifndef _LINUX_NVMEM_PROVIDER_H
#define _LINUX_NVMEM_PROVIDER_H
struct nvmem_device;
struct nvmem_cell_info;
struct nvmem_config {
struct device *dev;
const char *name;
int id;
struct module *owner;
const struct nvmem_cell_info *cells;
int ncells;
bool read_only;
};
#if IS_ENABLED(CONFIG_NVMEM)
struct nvmem_device *nvmem_register(const struct nvmem_config *cfg);
int nvmem_unregister(struct nvmem_device *nvmem);
#else
static inline struct nvmem_device *nvmem_register(const struct nvmem_config *c)
{
return ERR_PTR(-ENOSYS);
}
static inline int nvmem_unregister(struct nvmem_device *nvmem)
{
return -ENOSYS;
}
#endif /* CONFIG_NVMEM */
#endif /* ifndef _LINUX_NVMEM_PROVIDER_H */
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