nvmem: core: add NVMEM_SYSFS Kconfig

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

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

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

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

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@ -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
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@ -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
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@ -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 */