linux-kernel - [PATCH 1/4] dt-bindings: nvmem: new optional property write-protect-gpios

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Date:   Wed, 20 Nov 2019 15:20:35 +0100
From:   Khouloud Touil <ktouil@...libre.com>
To:     bgolaszewski@...libre.com, robh+dt@...nel.org,
        mark.rutland@....com, srinivas.kandagatla@...aro.org,
        baylibre-upstreaming@...ups.io
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        linux-i2c@...r.kernel.org, linus.walleij@...aro.org,
        Khouloud Touil <ktouil@...libre.com>
Subject: [PATCH 1/4] dt-bindings: nvmem: new optional property write-protect-gpios

Many nvmem memory chips have a write-protect pin which, when pulled
high, blocks the write operations.

On some boards, this pin is connected to a GPIO and pulled high by
default, which forces the user to manually change its state before
writing.

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.

Add a new optional property to the device tree binding document, which
allows to specify the GPIO line to which the write-protect pin is
connected.

Signed-off-by: Khouloud Touil <ktouil@...libre.com>
---
 Documentation/devicetree/bindings/nvmem/nvmem.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/nvmem/nvmem.yaml b/Documentation/devicetree/bindings/nvmem/nvmem.yaml
index 1c75a059206c..6724764af794 100644
--- a/Documentation/devicetree/bindings/nvmem/nvmem.yaml
+++ b/Documentation/devicetree/bindings/nvmem/nvmem.yaml
@@ -34,6 +34,11 @@ properties:
     description:
       Mark the provider as read only.

+  wp-gpios:
+    description:
+      GPIO to which the write-protect pin of the chip is connected.
+    maxItems: 1
+
 patternProperties:
   "^.*@[0-9a-f]+$":
     type: object
@@ -66,6 +71,7 @@ examples:
       qfprom: eeprom@...000 {
           #address-cells = <1>;
           #size-cells = <1>;
+          wp-gpios = <&gpio1 3 0>;

           /* ... */

-- 
2.17.1