Document the Cadence I3C gpio expander bindings.
Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>
---
.../devicetree/bindings/gpio/gpio-cdns-i3c.txt | 38 ++++++++++++++++++++++
1 file changed, 38 insertions(+)
create mode 100644 Documentation/devicetree/bindings/gpio/gpio-cdns-i3c.txt
diff --git a/Documentation/devicetree/bindings/gpio/gpio-cdns-i3c.txt b/Documentation/devicetree/bindings/gpio/gpio-cdns-i3c.txt
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+* Cadence I3C GPIO expander
+
+The Cadence I3C GPIO expander provides 8 GPIOs controllable over I3C.
+This GPIOs can be configured in output or input mode and if they are in input
+mode they can generate IBIs (In Band Interrupts).
+
+Required properties for GPIO node:
+- reg : 3 cells encoding the I3C static address (none in our case) and the I3C
+ Provisional ID. See Documentation/devicetree/bindings/i3c/i3c.txt for
+ more details.
+ Should be <0x0 0x392 0x0>.
+- gpio-controller : Marks the device node as a gpio controller.
+- #gpio-cells : Should be two. The first cell is the pin number and
+ the second cell is used to specify the gpio polarity:
+ 0 = active high
+ 1 = active low
+- interrupt-controller: Marks the device node as an interrupt controller.
+- #interrupt-cells : Should be 2. The first cell is the GPIO number.
+ The second cell bits[3:0] is used to specify trigger type and level flags:
+ 1 = low-to-high edge triggered.
+ 2 = high-to-low edge triggered.
+ 3 = triggered on both edges.
+ 4 = active high level-sensitive.
+ 8 = active low level-sensitive.
+
+Example:
+
+ i3c-master@xxx {
+ ...
+ i3c_gpio_expander: gpio@0,1c9,0 {
+ reg = <0 0x392 0x0>;
+ gpio-controller;
+ #gpio-cells = <2>;
+ interrupt-controller;
+ #interrupt-cells = <2>;
+ };
+ ...
+ };
--
2.14.1
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