Commit ae0c2d72 authored by Srinivas Kandagatla's avatar Srinivas Kandagatla Committed by Greg Kroah-Hartman
Browse files

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: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: default avatarMika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: default avatarGaurav Kohli <gkohli@codeaurora.org>
Tested-by: default avatarGaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fc1eb6eb

Documentation/ABI/stable/sysfs-bus-nvmem

+2 −0
Original line number Diff line number Diff line
@@ -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

drivers/nvmem/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -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

drivers/nvmem/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -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

drivers/nvmem/core.c

+4 −260
Original line number Diff line number Diff line
@@ -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:

drivers/nvmem/nvmem-sysfs.c

0 → 100644
+256 −0
Original line number Diff line number Diff line 
// 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);

}