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authorKhouloud Touil <ktouil@baylibre.com>2020-01-07 12:29:19 +0300
committerBartosz Golaszewski <bgolaszewski@baylibre.com>2020-01-09 12:48:54 +0300
commit2a127da461a9d8d97782d6e82b227041393eb4d2 (patch)
tree909764a234c16d372e7f5b332777f90d1355cae0 /drivers/nvmem
parent14f4957313fbf575c7bbd37d45cb148e11fdbc20 (diff)
downloadlinux-2a127da461a9d8d97782d6e82b227041393eb4d2.tar.xz
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: Khouloud Touil <ktouil@baylibre.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Diffstat (limited to 'drivers/nvmem')
-rw-r--r--drivers/nvmem/core.c19
-rw-r--r--drivers/nvmem/nvmem.h2
2 files changed, 19 insertions, 2 deletions
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 9f1ee9c766ec..3e1c94c4eee8 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -15,6 +15,7 @@
#include <linux/module.h>
#include <linux/nvmem-consumer.h>
#include <linux/nvmem-provider.h>
+#include <linux/gpio/consumer.h>
#include <linux/of.h>
#include <linux/slab.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,
void *val, size_t bytes)
{
- if (nvmem->reg_write)
- return nvmem->reg_write(nvmem->priv, offset, val, bytes);
+ int ret;
+
+ 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;
}
@@ -338,6 +345,14 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
kfree(nvmem);
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);
INIT_LIST_HEAD(&nvmem->cells);
diff --git a/drivers/nvmem/nvmem.h b/drivers/nvmem/nvmem.h
index eb8ed7121fa3..be0d66d75c8a 100644
--- a/drivers/nvmem/nvmem.h
+++ b/drivers/nvmem/nvmem.h
@@ -9,6 +9,7 @@
#include <linux/list.h>
#include <linux/nvmem-consumer.h>
#include <linux/nvmem-provider.h>
+#include <linux/gpio/consumer.h>
struct nvmem_device {
struct module *owner;
@@ -26,6 +27,7 @@ struct nvmem_device {
struct list_head cells;
nvmem_reg_read_t reg_read;
nvmem_reg_write_t reg_write;
+ struct gpio_desc *wp_gpio;
void *priv;
};