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nvmem: core: add NVMEM_SYSFS Kconfig

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Many nvmem providers are not very keen on having default sysfs
nvmem entry, as most of the usecases for them are inside kernel
itself. And in some cases read/writes to some areas in nvmem are
restricted and trapped at secure monitor level, so accessing them
from userspace would result in board reboots.

This patch adds new NVMEM_SYSFS Kconfig to make binary sysfs entry
an optional one. This provision will give more flexibility to users.
This patch also moves existing sysfs code to a new file so that its
not compiled in when its not really required.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Gaurav Kohli <gkohli@codeaurora.org>
Tested-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Srinivas Kandagatla 2019-04-16 10:59:24 +01:00 committed by Greg Kroah-Hartman
parent fc1eb6ebbd
commit ae0c2d7255
6 changed files with 337 additions and 260 deletions
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2
Documentation/ABI/stable/sysfs-bus-nvmem
View File

@ -6,6 +6,8 @@ Description:
This file allows user to read/write the raw NVMEM contents.
Permissions for write to this file depends on the nvmem
provider configuration.
Note: This file is only present if CONFIG_NVMEM_SYSFS
is enabled
ex:
hexdump /sys/bus/nvmem/devices/qfprom0/nvmem

10
drivers/nvmem/Kconfig
View File

@ -13,6 +13,16 @@ menuconfig NVMEM
if NVMEM
config NVMEM_SYSFS
bool "/sys/bus/nvmem/devices/*/nvmem (sysfs interface)"
depends on SYSFS
default y
help
Say Y here to add a sysfs interface for NVMEM.
This interface is mostly used by userspace applications to
read/write directly into nvmem.
config NVMEM_IMX_IIM
tristate "i.MX IC Identification Module support"
depends on ARCH_MXC || COMPILE_TEST

3
drivers/nvmem/Makefile
View File

@ -6,6 +6,9 @@
obj-$(CONFIG_NVMEM) += nvmem_core.o
nvmem_core-y := core.o
obj-$(CONFIG_NVMEM_SYSFS) += nvmem_sysfs.o
nvmem_sysfs-y := nvmem-sysfs.o
# Devices
obj-$(CONFIG_NVMEM_BCM_OCOTP) += nvmem-bcm-ocotp.o
nvmem-bcm-ocotp-y := bcm-ocotp.o

264
drivers/nvmem/core.c
View File

@ -17,27 +17,7 @@
#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)
#include "nvmem.h"
struct nvmem_cell {
const char *name;
@ -61,18 +41,7 @@ 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)
{
@ -91,187 +60,6 @@ static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
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 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);
@ -422,43 +210,6 @@ static int nvmem_add_cells(struct nvmem_device *nvmem,
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_notifier() - Register a notifier block for nvmem events.
*
@ -651,14 +402,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
nvmem->read_only = device_property_present(config->dev, "read-only") ||
config->read_only || !nvmem->reg_write;
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;
nvmem->dev.groups = nvmem_sysfs_get_groups(nvmem, config);
device_initialize(&nvmem->dev);
@ -669,7 +413,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
goto err_put_device;
if (config->compat) {
rval = nvmem_setup_compat(nvmem, config);
rval = nvmem_sysfs_setup_compat(nvmem, config);
if (rval)
goto err_device_del;
}
@ -696,7 +440,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
nvmem_device_remove_all_cells(nvmem);
err_teardown_compat:
if (config->compat)
device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
nvmem_sysfs_remove_compat(nvmem, config);
err_device_del:
device_del(&nvmem->dev);
err_put_device:

256
drivers/nvmem/nvmem-sysfs.c Normal file
View File

@ -0,0 +1,256 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2019, Linaro Limited
*/
#include "nvmem.h"
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);
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 >= 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->priv, 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 attribute_group *nvmem_ro_root_dev_groups[] = {
&nvmem_bin_ro_root_group,
NULL,
};
const struct attribute_group **nvmem_sysfs_get_groups(
struct nvmem_device *nvmem,
const struct nvmem_config *config)
{
if (config->root_only)
return nvmem->read_only ?
nvmem_ro_root_dev_groups :
nvmem_rw_root_dev_groups;
return nvmem->read_only ? nvmem_ro_dev_groups : nvmem_rw_dev_groups;
}
/*
* nvmem_setup_compat() - Create an additional binary entry in
* drivers sys directory, to be backwards compatible with the older
* drivers/misc/eeprom drivers.
*/
int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
const struct nvmem_config *config)
{
int rval;
if (!config->compat)
return 0;
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;
}
void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
const struct nvmem_config *config)
{
if (config->compat)
device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
}

62
drivers/nvmem/nvmem.h Normal file
View File

@ -0,0 +1,62 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _DRIVERS_NVMEM_H
#define _DRIVERS_NVMEM_H
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/nvmem-consumer.h>
#include <linux/nvmem-provider.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 to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
#define FLAG_COMPAT BIT(0)
#ifdef CONFIG_NVMEM_SYSFS
const struct attribute_group **nvmem_sysfs_get_groups(
struct nvmem_device *nvmem,
const struct nvmem_config *config);
int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
const struct nvmem_config *config);
void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
const struct nvmem_config *config);
#else
static inline const struct attribute_group **nvmem_sysfs_get_groups(
struct nvmem_device *nvmem,
const struct nvmem_config *config)
{
return NULL;
}
static inline int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
const struct nvmem_config *config)
{
return -ENOSYS;
}
static inline void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
const struct nvmem_config *config)
{
}
#endif /* CONFIG_NVMEM_SYSFS */
#endif /* _DRIVERS_NVMEM_H */