Lantiq SoC Serial To Parallel (STP) GPIO controller
The Serial To Parallel (STP) is found on MIPS based Lantiq socs. It is a
peripheral controller used to drive external shift register cascades. At most
3 groups of 8 bits can be driven. The hardware is able to allow the DSL modem
to drive the 2 LSBs of the cascade automatically.
Required properties:
- compatible : Should be “lantiq,gpio-stp-xway”
- reg : Address and length of the register set for the device
- #gpio-cells : Should be two. The first cell is the pin number and
the second cell is used to specify optional parameters (currently
unused). - gpio-controller : Marks the device node as a gpio controller.
Optional properties:
- lantiq,shadow : The default value that we shall assume as already set on the
shift register cascade. - lantiq,groups : Set the 3 bit mask to select which of the 3 groups are enabled
in the shift register cascade. - lantiq,dsl : The dsl core can control the 2 LSBs of the gpio cascade. This 2 bit
property can enable this feature. - lantiq,phy1 : The gphy1 core can control 3 bits of the gpio cascade.
- lantiq,phy2 : The gphy2 core can control 3 bits of the gpio cascade.
- lantiq,rising : use rising instead of falling edge for the shift register
Example:
gpio1: stp@E100BB0 {
compatible = “lantiq,gpio-stp-xway”;
reg = <0xE100BB0 0x40>;
#gpio-cells = <2>;
gpio-controller;
lantiq,shadow = <0xffff>;
lantiq,groups = <0x7>;
lantiq,dsl = <0x3>;
lantiq,phy1 = <0x7>;
lantiq,phy2 = <0x7>;
/* lantiq,rising; */
};
