[U-Boot] [PATCH 02/21] dm: exynos: Bring in GPIO device tree binding

[Simon Glass]

At present the exynos GPIO driver does not fully support the existing device
tree binding, but add the binding file to cover the existing partial support.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 doc/device-tree-bindings/gpio/gpio-samsung.txt | 41 ++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 doc/device-tree-bindings/gpio/gpio-samsung.txt

diff --git a/doc/device-tree-bindings/gpio/gpio-samsung.txt b/doc/device-tree-bindings/gpio/gpio-samsung.txt
new file mode 100644
index 0000000..5375625
--- /dev/null
+++ b/doc/device-tree-bindings/gpio/gpio-samsung.txt
@@ -0,0 +1,41 @@
+Samsung Exynos4 GPIO Controller
+
+Required properties:
+- compatible: Compatible property value should be "samsung,exynos4-gpio>".
+
+- reg: Physical base address of the controller and length of memory mapped
+  region.
+
+- #gpio-cells: Should be 4. The syntax of the gpio specifier used by client nodes
+  should be the following with values derived from the SoC user manual.
+     <[phandle of the gpio controller node]
+      [pin number within the gpio controller]
+      [mux function]
+      [flags and pull up/down]
+      [drive strength]>
+
+  Values for gpio specifier:
+  - Pin number: is a value between 0 to 7.
+  - Flags and Pull Up/Down: 0 - Pull Up/Down Disabled.
+                            1 - Pull Down Enabled.
+                            3 - Pull Up Enabled.
+          Bit 16 (0x00010000) - Input is active low.
+  - Drive Strength: 0 - 1x,
+                    1 - 3x,
+                    2 - 2x,
+                    3 - 4x
+
+- gpio-controller: Specifies that the node is a gpio controller.
+- #address-cells: should be 1.
+- #size-cells: should be 1.
+
+Example:
+
+	gpa0: gpio-controller at 11400000 {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "samsung,exynos4-gpio";
+		reg = <0x11400000 0x20>;
+		#gpio-cells = <4>;
+		gpio-controller;
+	};
-- 
2.2.0.rc0.207.ga3a616c