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authorRalf Schlatterbeck <rsc@runtux.com>2021-05-19 13:54:51 +0200
committerMiguel Ojeda <ojeda@kernel.org>2021-06-09 15:52:36 +0200
commitc784e46c8445635afd81bd4089fc5e87271a8f3b (patch)
tree154b0b7d6dc4c05d15fba6818c1003a0afe3abef /Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml
parent614124bea77e452aa6df7a8714e8bc820b489922 (diff)
downloadlinux-sh-c784e46c8445635afd81bd4089fc5e87271a8f3b.tar.gz
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/devicetree/bindings/auxdisplay/hit,hd44780.yaml')
-rw-r--r--Documentation/devicetree/bindings/auxdisplay/hit,hd44780.yaml31
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>;
+ };