1 Lantiq SoC External Bus memory mapped GPIO controller
2
3 By attaching hardware latches to the EBU it is possible to create output
4 only gpios. This driver configures a special memory address, which when
5 written to outputs 16 bit to the latches.
6
7 The node describing the memory mapped GPIOs needs to be a child of the node
8 describing the "lantiq,localbus".
9
10 Required 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
18 Optional properties:
19 - lantiq,shadow : The default value that we shall assume as already set on the
20 shift register cascade.
21
22 Example:
23
24 localbus@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 }
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