diff options
Diffstat (limited to 'Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml')
| -rw-r--r-- | Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml | 57 |
1 files changed, 44 insertions, 13 deletions
diff --git a/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml b/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml index 9222b06e93a0..3ca0e9863d83 100644 --- a/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml +++ b/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml @@ -12,7 +12,10 @@ maintainers: description: The Hitachi HD44780 Character LCD Controller is commonly used on character LCDs that can display one or more lines of text. It exposes an M6800 bus - interface, which can be used in either 4-bit or 8-bit mode. + interface, which can be used in either 4-bit or 8-bit mode. By using a + GPIO expander it is possible to use the driver with one of the popular I2C + expander boards based on the PCF8574 available for these displays. For + an example see below. properties: compatible: @@ -81,16 +84,44 @@ additionalProperties: false examples: - | #include <dt-bindings/gpio/gpio.h> - auxdisplay { - compatible = "hit,hd44780"; - - data-gpios = <&hc595 0 GPIO_ACTIVE_HIGH>, - <&hc595 1 GPIO_ACTIVE_HIGH>, - <&hc595 2 GPIO_ACTIVE_HIGH>, - <&hc595 3 GPIO_ACTIVE_HIGH>; - enable-gpios = <&hc595 4 GPIO_ACTIVE_HIGH>; - rs-gpios = <&hc595 5 GPIO_ACTIVE_HIGH>; - - display-height-chars = <2>; - display-width-chars = <16>; + display-controller { + compatible = "hit,hd44780"; + + data-gpios = <&hc595 0 GPIO_ACTIVE_HIGH>, + <&hc595 1 GPIO_ACTIVE_HIGH>, + <&hc595 2 GPIO_ACTIVE_HIGH>, + <&hc595 3 GPIO_ACTIVE_HIGH>; + enable-gpios = <&hc595 4 GPIO_ACTIVE_HIGH>; + rs-gpios = <&hc595 5 GPIO_ACTIVE_HIGH>; + + display-height-chars = <2>; + display-width-chars = <16>; + }; + + - | + #include <dt-bindings/gpio/gpio.h> + i2c { + #address-cells = <1>; + #size-cells = <0>; + + pcf8574: gpio-expander@27 { + compatible = "nxp,pcf8574"; + reg = <0x27>; + gpio-controller; + #gpio-cells = <2>; + }; + }; + + display-controller { + compatible = "hit,hd44780"; + display-height-chars = <2>; + display-width-chars = <16>; + data-gpios = <&pcf8574 4 GPIO_ACTIVE_HIGH>, + <&pcf8574 5 GPIO_ACTIVE_HIGH>, + <&pcf8574 6 GPIO_ACTIVE_HIGH>, + <&pcf8574 7 GPIO_ACTIVE_HIGH>; + enable-gpios = <&pcf8574 2 GPIO_ACTIVE_HIGH>; + rs-gpios = <&pcf8574 0 GPIO_ACTIVE_HIGH>; + rw-gpios = <&pcf8574 1 GPIO_ACTIVE_HIGH>; + backlight-gpios = <&pcf8574 3 GPIO_ACTIVE_HIGH>; }; |