TPO TPG110 Panel
================

This panel driver is a component that acts as an intermediary
between an RGB output and a variety of panels. The panel
driver is strapped up in electronics to the desired resolution
and other properties, and has a control interface over 3WIRE
SPI. By talking to the TPG110 over SPI, the strapped properties
can be discovered and the hardware is therefore mostly
self-describing.

       +--------+
SPI -> |  TPO   | -> physical display
RGB -> | TPG110 |
       +--------+

If some electrical strap or alternate resolution is desired,
this can be set up by taking software control of the display
over the SPI interface. The interface can also adjust
for properties of the display such as gamma correction and
certain electrical driving levels.

The TPG110 does not know the physical dimensions of the panel
connected, so this needs to be specified in the device tree.

It requires a GPIO line for control of its reset line.

The serial protocol has line names that resemble I2C but the
protocol is not I2C but 3WIRE SPI.

Required properties:
- compatible : one of:
  "ste,nomadik-nhk15-display", "tpo,tpg110"
  "tpo,tpg110"
- grestb-gpios : panel reset GPIO
- width-mm : see display/panel/panel-common.txt
- height-mm : see display/panel/panel-common.txt

The device needs to be a child of an SPI bus, see
spi/spi-bus.txt. The SPI child must set the following
properties:
- spi-3wire
- spi-max-frequency = <3000000>;
as these are characteristics of this device.

The device node can contain one 'port' child node with one child
'endpoint' node, according to the bindings defined in
media/video-interfaces.txt. This node should describe panel's video bus.

Example
-------

panel: display@0 {
	compatible = "tpo,tpg110";
	reg = <0>;
	spi-3wire;
	/* 320 ns min period ~= 3 MHz */
	spi-max-frequency = <3000000>;
	/* Width and height from data sheet */
	width-mm = <116>;
	height-mm = <87>;
	grestb-gpios = <&foo_gpio 5 GPIO_ACTIVE_LOW>;
	backlight = <&bl>;

	port {
		nomadik_clcd_panel: endpoint {
			remote-endpoint = <&foo>;
		};
	};
};