1Samsung Exynos4 GPIO Controller 2 3Required properties: 4- compatible: Compatible property value should be "samsung,exynos4-gpio>". 5 6- reg: Physical base address of the controller and length of memory mapped 7 region. 8 9- #gpio-cells: Should be 4. The syntax of the gpio specifier used by client nodes 10 should be the following with values derived from the SoC user manual. 11 <[phandle of the gpio controller node] 12 [pin number within the gpio controller] 13 [mux function] 14 [flags and pull up/down] 15 [drive strength]> 16 17 Values for gpio specifier: 18 - Pin number: is a value between 0 to 7. 19 - Flags and Pull Up/Down: 0 - Pull Up/Down Disabled. 20 1 - Pull Down Enabled. 21 3 - Pull Up Enabled. 22 Bit 16 (0x00010000) - Input is active low. 23 - Drive Strength: 0 - 1x, 24 1 - 3x, 25 2 - 2x, 26 3 - 4x 27 28- gpio-controller: Specifies that the node is a gpio controller. 29- #address-cells: should be 1. 30- #size-cells: should be 1. 31 32Example: 33 34 gpa0: gpio-controller@11400000 { 35 #address-cells = <1>; 36 #size-cells = <1>; 37 compatible = "samsung,exynos4-gpio"; 38 reg = <0x11400000 0x20>; 39 #gpio-cells = <4>; 40 gpio-controller; 41 }; 42