1Lantiq SoC External Bus memory mapped GPIO controller 2 3By attaching hardware latches to the EBU it is possible to create output 4only gpios. This driver configures a special memory address, which when 5written to outputs 16 bit to the latches. 6 7The node describing the memory mapped GPIOs needs to be a child of the node 8describing the "lantiq,localbus". 9 10Required properties: 11- compatible : Should be "lantiq,gpio-mm-lantiq" 12- reg : Address and length of the register set for the device 13- #gpio-cells : Should be two. The first cell is the pin number and 14 the second cell is used to specify optional parameters (currently 15 unused). 16- gpio-controller : Marks the device node as a gpio controller. 17 18Optional properties: 19- lantiq,shadow : The default value that we shall assume as already set on the 20 shift register cascade. 21 22Example: 23 24localbus@0 { 25 #address-cells = <2>; 26 #size-cells = <1>; 27 ranges = <0 0 0x0 0x3ffffff /* addrsel0 */ 28 1 0 0x4000000 0x4000010>; /* addsel1 */ 29 compatible = "lantiq,localbus", "simple-bus"; 30 31 gpio_mm0: gpio@4000000 { 32 compatible = "lantiq,gpio-mm"; 33 reg = <1 0x0 0x10>; 34 gpio-controller; 35 #gpio-cells = <2>; 36 lantiq,shadow = <0x77f> 37 }; 38} 39