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- 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>;
- };
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