1Rockchip RK3328 GRF (General Register Files) GPIO controller.
 2
 3In Rockchip RK3328, the output only GPIO_MUTE pin, originally for codec mute
 4control, can also be used for general purpose. It is manipulated by the
 5GRF_SOC_CON10 register in GRF. Aside from the GPIO_MUTE pin, the HDMI pins can
 6also be set in the same way.
 7
 8Currently this GPIO controller only supports the mute pin. If needed in the
 9future, the HDMI pins support can also be added.
10
11Required properties:
12- compatible: Should contain "rockchip,rk3328-grf-gpio".
13- gpio-controller: Marks the device node as a gpio controller.
14- #gpio-cells: Should be 2. The first cell is the pin number and
15  the second cell is used to specify the gpio polarity:
16    0 = Active high,
17    1 = Active low.
18
19Example:
20
21	grf: syscon@ff100000 {
22		compatible = "rockchip,rk3328-grf", "syscon", "simple-mfd";
23
24		grf_gpio: grf-gpio {
25			compatible = "rockchip,rk3328-grf-gpio";
26			gpio-controller;
27			#gpio-cells = <2>;
28		};
29	};
30
31Note: The grf_gpio node should be declared as the child of the GRF (General
32Register File) node. The GPIO_MUTE pin is referred to as <&grf_gpio 0>.