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

commit f6c052afe6f802d87c74153b7a57c43b2e9faf07 upstream.

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 9aecb83021a2dc2c6b1e3733644c4564ef3de00f..fb7840c73765a4c1dfc4fa210684d03e25585284 100644 (file)
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -768,7 +768,7 @@ 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 104505e9028f7bb65bc530688b6d52812d3c9e9a..87932bdb25d7b95b351d315ee96481087e6cc199 100644 (file)
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -66,7 +66,8 @@ 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
@@ -88,6 +89,7 @@ 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;