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Lantiq SoC External Bus memory mapped GPIO controller
By attaching hardware latches to the EBU it is possible to create output
only gpios. This driver configures a special memory address, which when
written to outputs 16 bit to the latches.
The node describing the memory mapped GPIOs needs to be a child of the node
describing the "lantiq,localbus".
Required properties:
- compatible : Should be "lantiq,gpio-mm-lantiq"
- 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.
Example:
localbus@0 {
#address-cells = <2>;
#size-cells = <1>;
ranges = <0 0 0x0 0x3ffffff /* addrsel0 */
1 0 0x4000000 0x4000010>; /* addsel1 */
compatible = "lantiq,localbus", "simple-bus";
gpio_mm0: gpio@4000000 {
compatible = "lantiq,gpio-mm";
reg = <1 0x0 0x10>;
gpio-controller;
#gpio-cells = <2>;
lantiq,shadow = <0x77f>
};
}
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