Signed-off-by: Viktar Simanenka <viteosen@xxxxxxxxx> V2: deleted oneOf property from compatible changed prefix from 'philips' to existing vendor prefix 'nxp' placed `reg = <0>` right after `compatible` About parameters exposed for controller: inverted - I had an unbranded display that after reset had all pixels black, while register was in 'normal operation'. The display I have now is opposite: all white after reset in normal mode. This parameter should help user keep same settings in KMS(?) for diverse displays; voltage-op & temperature-coeff - adjusts contrast for display. voltage-op cannot be expressed in real units, because resulting equation looks like V = a + Vop * b, where a and b varies with ambient temperature. Vop is a coefficient. same story for temperature-coeff - it shifts resulting voltage curve depending on display usage invironment; bias - relates to waveforms for LCD segments. default is 4 and should be changed only if you use external oscillator for display. v1 link: https://lore.kernel.org/linux-devicetree/20230719092903.316452-1-viteosen@xxxxxxxxx/ --- .../bindings/display/nxp,pcd8544.yaml | 94 +++++++++++++++++++ 1 file changed, 94 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..52e40fd0eacb --- /dev/null +++ b/Documentation/devicetree/bindings/display/nxp,pcd8544.yaml @@ -0,0 +1,94 @@ +# 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@xxxxxxxxx> + +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: panel/panel-common.yaml# + - $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) + + 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 the display segments. Should be adjusted + depending on the ambient temperature. + + 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. + +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
