[PATCH 2/4] gpio: sifive: Add DT documentation for SiFive GPIO

[Yash Shah <yash.shah@xxxxxxxxxx>]

DT documentation for GPIO controller added.

Signed-off-by: Wesley W. Terpstra <wesley@xxxxxxxxxx>
[Atish: Compatible string update]
Signed-off-by: Atish Patra <atish.patra@xxxxxxx>
Signed-off-by: Yash Shah <yash.shah@xxxxxxxxxx>
---
 .../devicetree/bindings/gpio/gpio-sifive.txt       | 33 ++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/gpio/gpio-sifive.txt

diff --git a/Documentation/devicetree/bindings/gpio/gpio-sifive.txt b/Documentation/devicetree/bindings/gpio/gpio-sifive.txt
new file mode 100644
index 0000000..d3416d5
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-sifive.txt
@@ -0,0 +1,33 @@
+SiFive GPIO controller bindings
+
+Required properties:
+- compatible: Should be "sifive,<chip>-gpio" and "sifive,gpio<version>".
+  Supported compatible strings are: "sifive,fu540-c000-gpio" for the SiFive
+  GPIO v0 as integrated onto the SiFive FU540 chip, and "sifive,gpio0" for the
+  SiFive GPIO v0 IP block with no chip integration tweaks.
+  Please refer to sifive-blocks-ip-versioning.txt for details.
+- reg: Physical base address and length of the controller's registers.
+- clocks: Should contain a clock identifier for the GPIO's parent clock.
+- #gpio-cells : Should be 2
+  - The first cell is the GPIO offset number.
+  - The second cell indicates the polarity of the GPIO
+- gpio-controller : Marks the device node as a GPIO controller.
+- interrupt-controller: Marks the device node as an interrupt controller.
+- #interrupt-cells : Should be 2.
+  - The first cell is the GPIO offset number within the GPIO controller.
+  - The second cell is the edge/level to use for interrupt generation.
+- interrupts: Specify the interrupts, one per GPIO
+
+Example:
+
+gpio: gpio@10060000 {
+	compatible = "sifive,fu540-c000-gpio","sifive,gpio0";
+	interrupt-parent = <&plic>;
+	interrupts = <7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22>;
+	reg = <0x0 0x10060000 0x0 0x1000>;
+	clocks = <&tlclk>;
+	gpio-controller;
+	#gpio-cells = <2>;
+	interrupt-controller;
+	#interrupt-cells = <2>;
+};
-- 
2.7.4