From 2a48c15d2e4d43d6fbac427d03ef73f41d8708ae Mon Sep 17 00:00:00 2001 From: Lars Povlsen Date: Wed, 2 Jan 2019 09:52:22 +0100 Subject: mips: mscc_sgpio: Add DT bindings documentation This add device tree binding documentation for the MSCC serial GPIO driver. Signed-off-by: Lars Povlsen Acked-by: Linus Walleij --- doc/device-tree-bindings/gpio/mscc_sgpio.txt | 45 ++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 doc/device-tree-bindings/gpio/mscc_sgpio.txt (limited to 'doc') diff --git a/doc/device-tree-bindings/gpio/mscc_sgpio.txt b/doc/device-tree-bindings/gpio/mscc_sgpio.txt new file mode 100644 index 0000000..3d344d6 --- /dev/null +++ b/doc/device-tree-bindings/gpio/mscc_sgpio.txt @@ -0,0 +1,45 @@ +Microsemi Corporation (MSCC) Serial GPIO driver + +The MSCC serial GPIO extends the number or GPIO's on the system by +means of 4 dedicated pins: one input, one output, one clock and one +strobe pin. By attaching a number of (external) shift registers, the +effective GPIO count can be extended by up to 128 GPIO's per +controller. + +Required properties: +- compatible : "mscc,luton-sgpio" or "mscc,ocelot-sgpio" +- clock: Reference clock used to generate clock divider setting. See + mscc,sgpio-frequency property. +- reg : Physical base address and length of the controller's registers. +- #gpio-cells : Should be two. The first cell is the pin number and the + second cell is used to specify optional parameters: + - bit 0 specifies polarity (0 for normal, 1 for inverted) +- gpio-controller : Marks the device node as a GPIO controller. +- gpio-ranges: Standard gpio range(s): phandle, gpio base, pinctrl base + and count. + +Optional properties: +- ngpios: See gpio.txt +- mscc,sgpio-frequency: The frequency at which the serial bitstream is + generated and sampled. Default: 12500000 (Hz). +- mscc,sgpio-ports: A bitmask (32 bits) of which ports are enabled in + the serialized gpio stream. One 'port' will transport from 1 to 4 + gpio bits. Default: 0xFFFFFFFF. + +Typically the pinctrl-0 and pinctrl-names properties will also be +present to enable the use of the SIO CLK, LD, DI and DO for some +regular GPIO pins. + +Example: + +sgpio: gpio@10700f8 { + compatible = "mscc,ocelot-sgpio"; + pinctrl-0 = <&sgpio_pins>; + pinctrl-names = "default"; + reg = <0x10700f8 0x100>; + gpio-controller; + #gpio-cells = <2>; + gpio-ranges = <&sgpio 0 0 64>; + mscc,sgpio-frequency = <12500>; + mscc,sgpio-ports = <0x000FFFFF>; +}; -- cgit v1.1