Commit 2a127da4 authored by Khouloud Touil's avatar Khouloud Touil Committed by Bartosz Golaszewski
Browse files

nvmem: add support for the write-protect pin 

The write-protect pin handling looks like a standard property that
could benefit other users if available in the core nvmem framework.

Instead of modifying all the memory drivers to check this pin, make
the NVMEM subsystem check if the write-protect GPIO being passed
through the nvmem_config or defined in the device tree and pull it
low whenever writing to the memory.

There was a suggestion for introducing the gpiodesc from pdata, but
as pdata is already removed it could be replaced by adding it to
nvmem_config.

Reference: https://lists.96boards.org/pipermail/dev/2018-August/001056.html



Signed-off-by: default avatarKhouloud Touil <ktouil@baylibre.com>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Acked-by: default avatarSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
parent 14f49573

drivers/nvmem/core.c

+17 −2
Original line number Original line Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <linux/module.h>

#include <linux/module.h>

#include <linux/nvmem-consumer.h>

#include <linux/nvmem-consumer.h>

#include <linux/nvmem-provider.h>

#include <linux/nvmem-provider.h>

#include <linux/gpio/consumer.h>

#include <linux/of.h>

#include <linux/of.h>

#include <linux/slab.h>

#include <linux/slab.h>

#include "nvmem.h"

#include "nvmem.h"
@@ -54,8 +55,14 @@ static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset, 
static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,

static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,

			   void *val, size_t bytes)

			   void *val, size_t bytes)

{

{

	if (nvmem->reg_write)

	int ret;

		return nvmem->reg_write(nvmem->priv, offset, val, bytes);



	if (nvmem->reg_write) {

		gpiod_set_value_cansleep(nvmem->wp_gpio, 0);

		ret = nvmem->reg_write(nvmem->priv, offset, val, bytes);

		gpiod_set_value_cansleep(nvmem->wp_gpio, 1);

		return ret;

	}





	return -EINVAL;

	return -EINVAL;

}

}
@@ -338,6 +345,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) 
		kfree(nvmem);

		kfree(nvmem);

		return ERR_PTR(rval);

		return ERR_PTR(rval);

	}

	}

	if (config->wp_gpio)

		nvmem->wp_gpio = config->wp_gpio;

	else

		nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",

						    GPIOD_OUT_HIGH);

	if (IS_ERR(nvmem->wp_gpio))

		return PTR_ERR(nvmem->wp_gpio);







	kref_init(&nvmem->refcnt);

	kref_init(&nvmem->refcnt);

	INIT_LIST_HEAD(&nvmem->cells);

	INIT_LIST_HEAD(&nvmem->cells);

drivers/nvmem/nvmem.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/list.h>

#include <linux/list.h>

#include <linux/nvmem-consumer.h>

#include <linux/nvmem-consumer.h>

#include <linux/nvmem-provider.h>

#include <linux/nvmem-provider.h>

#include <linux/gpio/consumer.h>





struct nvmem_device {

struct nvmem_device {

	struct module		*owner;

	struct module		*owner;
@@ -26,6 +27,7 @@ struct nvmem_device { 
	struct list_head	cells;

	struct list_head	cells;

	nvmem_reg_read_t	reg_read;

	nvmem_reg_read_t	reg_read;

	nvmem_reg_write_t	reg_write;

	nvmem_reg_write_t	reg_write;

	struct gpio_desc	*wp_gpio;

	void *priv;

	void *priv;

};

};

include/linux/nvmem-provider.h

+3 −0
Original line number Original line Diff line number Diff line
@@ -11,6 +11,7 @@ 




#include <linux/err.h>

#include <linux/err.h>

#include <linux/errno.h>

#include <linux/errno.h>

#include <linux/gpio/consumer.h>





struct nvmem_device;

struct nvmem_device;

struct nvmem_cell_info;

struct nvmem_cell_info;
@@ -45,6 +46,7 @@ enum nvmem_type { 
 * @word_size:	Minimum read/write access granularity.

 * @word_size:	Minimum read/write access granularity.

 * @stride:	Minimum read/write access stride.

 * @stride:	Minimum read/write access stride.

 * @priv:	User context passed to read/write callbacks.

 * @priv:	User context passed to read/write callbacks.

 * @wp-gpio:   Write protect pin

 *

 *

 * Note: A default "nvmem<id>" name will be assigned to the device if

 * Note: A default "nvmem<id>" name will be assigned to the device if

 * no name is specified in its configuration. In such case "<id>" is

 * no name is specified in its configuration. In such case "<id>" is
@@ -58,6 +60,7 @@ struct nvmem_config { 
	const char		*name;

	const char		*name;

	int			id;

	int			id;

	struct module		*owner;

	struct module		*owner;

	struct gpio_desc	*wp_gpio;

	const struct nvmem_cell_info	*cells;

	const struct nvmem_cell_info	*cells;

	int			ncells;

	int			ncells;

	enum nvmem_type		type;

	enum nvmem_type		type;

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