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| author | Ralf Schlatterbeck <rsc@runtux.com> | 2021-05-19 13:54:51 +0200 |
|---|---|---|
| committer | Miguel Ojeda <ojeda@kernel.org> | 2021-06-09 15:52:36 +0200 |
| commit | c784e46c8445635afd81bd4089fc5e87271a8f3b (patch) | |
| tree | 154b0b7d6dc4c05d15fba6818c1003a0afe3abef /Documentation | |
| parent | Linux 5.13-rc5 (diff) | |
| download | linux-c784e46c8445635afd81bd4089fc5e87271a8f3b.tar.xz linux-c784e46c8445635afd81bd4089fc5e87271a8f3b.zip | |
auxdisplay: Add I2C gpio expander example
The hd44780 displays are often used with pcf8574 based I/O expanders.
Add example to documentation.
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Ralf Schlatterbeck <rsc@runtux.com>
[Added Suggested-by tag]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml | 31 |
1 files changed, 30 insertions, 1 deletions
diff --git a/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml b/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml index 9222b06e93a0..fde07e4b119d 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: @@ -94,3 +97,29 @@ examples: display-height-chars = <2>; display-width-chars = <16>; }; + - | + #include <dt-bindings/gpio/gpio.h> + i2c { + #address-cells = <1>; + #size-cells = <0>; + + pcf8574: pcf8574@27 { + compatible = "nxp,pcf8574"; + reg = <0x27>; + gpio-controller; + #gpio-cells = <2>; + }; + }; + hd44780 { + compatible = "hit,hd44780"; + display-height-chars = <2>; + display-width-chars = <16>; + data-gpios = <&pcf8574 4 0>, + <&pcf8574 5 0>, + <&pcf8574 6 0>, + <&pcf8574 7 0>; + enable-gpios = <&pcf8574 2 0>; + rs-gpios = <&pcf8574 0 0>; + rw-gpios = <&pcf8574 1 0>; + backlight-gpios = <&pcf8574 3 0>; + }; |