linux/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt
Geert Uytterhoeven c7c3f096eb auxdisplay: hd44780: Fix DT properties to include units of measurement
DT properties specifying physical properties should contain appropriate
suffices indicating the units of measurement.

Hence amend the HD44780 DT bindings to add "chars" suffixes to the
"display-height" and "display-width" properties, and update the driver
to parse them.

Fixes: dd9502a9e9 ("dt-bindings: auxdisplay: Add bindings for Hitachi HD44780")
Fixes: d47d88361f ("auxdisplay: Add HD44780 Character LCD support")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-04-08 17:48:19 +02:00

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DT bindings for the Hitachi HD44780 Character LCD Controller
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.
Required properties:
- compatible: Must contain "hit,hd44780",
- data-gpios: Must contain an array of either 4 or 8 GPIO specifiers,
referring to the GPIO pins connected to the data signal lines DB0-DB7
(8-bit mode) or DB4-DB7 (4-bit mode) of the LCD Controller's bus interface,
- enable-gpios: Must contain a GPIO specifier, referring to the GPIO pin
connected to the "E" (Enable) signal line of the LCD Controller's bus
interface,
- rs-gpios: Must contain a GPIO specifier, referring to the GPIO pin
connected to the "RS" (Register Select) signal line of the LCD Controller's
bus interface,
- display-height-chars: Height of the display, in character cells,
- display-width-chars: Width of the display, in character cells.
Optional properties:
- rw-gpios: Must contain a GPIO specifier, referring to the GPIO pin
connected to the "RW" (Read/Write) signal line of the LCD Controller's bus
interface,
- backlight-gpios: Must contain a GPIO specifier, referring to the GPIO pin
used for enabling the LCD's backlight,
- internal-buffer-width: Internal buffer width (default is 40 for displays
with 1 or 2 lines, and display-width-chars for displays with more than 2
lines).
Example:
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>;
};