1Lantiq SoC Serial To Parallel (STP) GPIO controller
2
3The Serial To Parallel (STP) is found on MIPS based Lantiq socs. It is a
4peripheral controller used to drive external shift register cascades. At most
53 groups of 8 bits can be driven. The hardware is able to allow the DSL modem
6to drive the 2 LSBs of the cascade automatically.
7
8
9Required properties:
10- compatible : Should be "lantiq,gpio-stp-xway"
11- reg : Address and length of the register set for the device
12- #gpio-cells : Should be two.  The first cell is the pin number and
13  the second cell is used to specify optional parameters (currently
14  unused).
15- gpio-controller : Marks the device node as a gpio controller.
16
17Optional properties:
18- lantiq,shadow : The default value that we shall assume as already set on the
19  shift register cascade.
20- lantiq,groups : Set the 3 bit mask to select which of the 3 groups are enabled
21  in the shift register cascade.
22- lantiq,dsl : The dsl core can control the 2 LSBs of the gpio cascade. This 2 bit
23  property can enable this feature.
24- lantiq,phy1 : The gphy1 core can control 3 bits of the gpio cascade.
25- lantiq,phy2 : The gphy2 core can control 3 bits of the gpio cascade.
26- lantiq,rising : use rising instead of falling edge for the shift register
27
28Example:
29
30gpio1: stp@E100BB0 {
31	compatible = "lantiq,gpio-stp-xway";
32	reg = <0xE100BB0 0x40>;
33	#gpio-cells = <2>;
34	gpio-controller;
35
36	lantiq,shadow = <0xffff>;
37	lantiq,groups = <0x7>;
38	lantiq,dsl = <0x3>;
39	lantiq,phy1 = <0x7>;
40	lantiq,phy2 = <0x7>;
41	/* lantiq,rising; */
42};
43