nvmem: core: Fix a conflict between MTD and NVMEM on wp-gpios property

Wp-gpios property can be used on NVMEM nodes and the same property can
be also used on MTD NAND nodes. In case of the wp-gpios property is
defined at NAND level node, the GPIO management is done at NAND driver
level. Write protect is disabled when the driver is probed or resumed
and is enabled when the driver is released or suspended.

When no partitions are defined in the NAND DT node, then the NAND DT node
will be passed to NVMEM framework. If wp-gpios property is defined in
this node, the GPIO resource is taken twice and the NAND controller
driver fails to probe.

It would be possible to set config->wp_gpio at MTD level before calling
nvmem_register function but NVMEM framework will toggle this GPIO on
each write when this GPIO should only be controlled at NAND level driver
to ensure that the Write Protect has not been enabled.

A way to fix this conflict is to add a new boolean flag in nvmem_config
named ignore_wp. In case ignore_wp is set, the GPIO resource will
be managed by the provider.

Fixes: 2a127da461a9 ("nvmem: add support for the write-protect pin")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220220151432.16605-2-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 23a38dcf0fc4dc8419fbb333e188339b3c7ba4d6..9fd1602b539d97a1c896aedbe29f068b25a689a9 100644 (file)
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -771,7 +771,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 
        if (config->wp_gpio)
                nvmem->wp_gpio = config->wp_gpio;
-       else
+       else if (!config->ignore_wp)
                nvmem->wp_gpio = gpiod_get_optional(config->dev, "wp",
                                                    GPIOD_OUT_HIGH);
        if (IS_ERR(nvmem->wp_gpio)) {

diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index 98efb7b5660d9bb7596e41413d5ea3c04fb63436..c9a3ac9efeaa9af0086ac39249c2b55aec36c85a 100644 (file)
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -70,7 +70,8 @@ struct nvmem_keepout {
  * @word_size: Minimum read/write access granularity.
  * @stride:    Minimum read/write access stride.
  * @priv:      User context passed to read/write callbacks.
- * @wp-gpio:   Write protect pin
+ * @wp-gpio:   Write protect pin
+ * @ignore_wp:  Write Protect pin is managed by the provider.
  *
  * 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
@@ -92,6 +93,7 @@ struct nvmem_config {
        enum nvmem_type         type;
        bool                    read_only;
        bool                    root_only;
+       bool                    ignore_wp;
        struct device_node      *of_node;
        bool                    no_of_node;
        nvmem_reg_read_t        reg_read;