linux-kernel - [PATCH v4 1/2] dt-bindings: display: add bindings for pcd8544 displays

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Message-Id: <20230724090713.1489-1-viteosen@gmail.com>
Date:   Mon, 24 Jul 2023 12:07:12 +0300
From:   Viktar Simanenka <viteosen@...il.com>
To:     David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Viktar Simanenka <viteosen@...il.com>,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 1/2] dt-bindings: display: add bindings for pcd8544 displays

Add device tree binding documentation for PCD8544 LCD display controller.

Signed-off-by: Viktar Simanenka <viteosen@...il.com>
---
v4:remove reference to panel/panel-common.yaml
add optional backlight property
v3 link: https://lore.kernel.org/linux-devicetree/20230720124026.356603-1-viteosen@gmail.com/
 .../bindings/display/nxp,pcd8544.yaml         | 100 ++++++++++++++++++
 1 file changed, 100 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/display/nxp,pcd8544.yaml

diff --git a/Documentation/devicetree/bindings/display/nxp,pcd8544.yaml b/Documentation/devicetree/bindings/display/nxp,pcd8544.yaml
new file mode 100644
index 000000000000..236eb4f4b3a8
--- /dev/null
+++ b/Documentation/devicetree/bindings/display/nxp,pcd8544.yaml
@@ -0,0 +1,100 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/display/nxp,pcd8544.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Philips Semiconductors PCD8544 LCD Display Controller
+
+maintainers:
+  - Viktar Simanenka <viteosen@...il.com>
+
+description: |
+  Philips Semiconductors PCD8544 LCD Display Controller with SPI control bus.
+  Designed to drive a graphic display of 48 rows and 84 columns,
+  such as Nokia 5110/3310 LCDs.
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - nxp,pcd8544
+
+  dc-gpios:
+    maxItems: 1
+    description: Data/Command selection pin (D/CX).
+
+  reset-gpios:
+    maxItems: 1
+    description: Display Reset pin (RST).
+
+  backlight:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: |
+      Phandle of the backlight device. The display may have an LED pin that
+      controls the backlight through GPIO or PWM.
+
+  nxp,inverted:
+    type: boolean
+    description: Display color inversion.
+
+  nxp,voltage-op:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 127
+    description: |
+      Liquid crystall voltage operation coefficient. Determines the LCD
+      controlling voltage on display segments. Should be adjusted according
+      to the ambient temperature. Adjusts the contrast of the display.
+
+  nxp,temperature-coeff:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 3
+    description: |
+      Display temperature compensation coefficient. Increases LCD controlling
+      voltage at lower temperatures to maintain optimum contrast.
+
+  nxp,bias:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 7
+    description: |
+      Display bias system coefficient. Should only be changed if an external
+      oscillator is used for the display.
+
+required:
+  - compatible
+  - reg
+  - dc-gpios
+  - reset-gpios
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        display@0 {
+            compatible = "nxp,pcd8544";
+            reg = <0>;
+            spi-max-frequency = <8000000>;
+
+            dc-gpios = <&pio 0 3 GPIO_ACTIVE_HIGH>; /* DC=PA3 */
+            reset-gpios = <&pio 0 1 GPIO_ACTIVE_HIGH>; /* RESET=PA1 */
+            backlight = <&backlight>;
+
+            nxp,inverted;
+            nxp,voltage-op = <0>;
+            nxp,bias = <4>;
+            nxp,temperature-coeff = <0>;
+        };
+    };
+
+...
-- 
2.34.1