pinctrl: Add DT bindings for PIC32 pin control and GPIO

Document the devicetree bindings for PINCTRL and GPIO found on Microchip
PIC32 class devices.

Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/Documentation/devicetree/bindings/gpio/microchip,pic32-gpio.txt b/Documentation/devicetree/bindings/gpio/microchip,pic32-gpio.txt
new file mode 100644
index 0000000..ef37528
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/microchip,pic32-gpio.txt
@@ -0,0 +1,49 @@
+* Microchip PIC32 GPIO devices (PIO).
+
+Required properties:
+ - compatible: "microchip,pic32mzda-gpio"
+ - reg: Base address and length for the device.
+ - interrupts: The port interrupt shared by all pins.
+ - gpio-controller: Marks the port as GPIO controller.
+ - #gpio-cells: Two. The first cell is the pin number and
+   the second cell is used to specify the gpio polarity as defined in
+   defined in <dt-bindings/gpio/gpio.h>:
+      0 = GPIO_ACTIVE_HIGH
+      1 = GPIO_ACTIVE_LOW
+      2 = GPIO_OPEN_DRAIN
+ - interrupt-controller: Marks the device node as an interrupt controller.
+ - #interrupt-cells: Two. The first cell is the GPIO number and second cell
+   is used to specify the trigger type as defined in
+   <dt-bindings/interrupt-controller/irq.h>:
+      IRQ_TYPE_EDGE_RISING
+      IRQ_TYPE_EDGE_FALLING
+      IRQ_TYPE_EDGE_BOTH
+ - clocks: Clock specifier (see clock bindings for details).
+ - microchip,gpio-bank: Specifies which bank a controller owns.
+ - gpio-ranges: Interaction with the PINCTRL subsystem.
+
+Example:
+
+/* PORTA */
+gpio0: gpio0@1f860000 {
+	compatible = "microchip,pic32mzda-gpio";
+	reg = <0x1f860000 0x100>;
+	interrupts = <118 IRQ_TYPE_LEVEL_HIGH>;
+	#gpio-cells = <2>;
+	gpio-controller;
+	interrupt-controller;
+	#interrupt-cells = <2>;
+	clocks = <&PBCLK4>;
+	microchip,gpio-bank = <0>;
+	gpio-ranges = <&pic32_pinctrl 0 0 16>;
+};
+
+keys {
+	...
+
+	button@sw1 {
+		label = "ESC";
+		linux,code = <1>;
+		gpios = <&gpio0 12 0>;
+	};
+};