gpio: Add support for Qualcomm gpio controller

Add support for gpio controllers on Qualcomm Snapdragon devices.
This devices are usually called Top Level Mode Multiplexing in
Qualcomm documentation.

Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/device-tree-bindings/gpio/gpio-msm.txt b/doc/device-tree-bindings/gpio/gpio-msm.txt
new file mode 100644
index 0000000..966ce0a
--- /dev/null
+++ b/doc/device-tree-bindings/gpio/gpio-msm.txt
@@ -0,0 +1,22 @@
+Qualcomm Snapdragon GPIO controller
+
+Required properties:
+- compatible : "qcom,msm8916-pinctrl" or "qcom,apq8016-pinctrl"
+- reg : Physical base address and length of the controller's registers.
+	This controller is called "Top Level Mode Multiplexing" in
+	Qualcomm documentation.
+- #gpio-cells : Should be one (pin number).
+- gpio-controller : Marks the device node as a GPIO controller.
+- gpio-count: Number of GPIO pins.
+- gpio-bank-name: (optional) name of gpio bank. As default "soc" is used.
+
+Example:
+
+soc_gpios: pinctrl@1000000 {
+	compatible = "qcom,msm8916-pinctrl";
+	reg = <0x1000000 0x300000>;
+	gpio-controller;
+	gpio-count = <122>;
+	gpio-bank-name="soc";
+	#gpio-cells = <1>;
+};