x86: Add a generic Intel pinctrl driver

Recent Intel SoCs share a pinctrl mechanism with many common elements. Add
an implementation of this core functionality, allowing SoC-specific
drivers to avoid adding common code.

As well as a pinctrl driver this provides a GPIO driver based on the same
code.

Once other SoCs use this driver we may consider moving more properties to
the device tree (e.g. the community info and pad definitions).

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/doc/device-tree-bindings/pinctrl/intel,apl-pinctrl.txt b/doc/device-tree-bindings/pinctrl/intel,apl-pinctrl.txt
new file mode 100644
index 0000000..cd7f8a0
--- /dev/null
+++ b/doc/device-tree-bindings/pinctrl/intel,apl-pinctrl.txt
@@ -0,0 +1,39 @@
+* Intel Apollo Lake pin controller
+
+The Apollo Lake (APL) pin controller is used to select the function of a pin
+and to configure it.
+
+Required properties:
+- compatible: "intel,apl-pinctrl"
+- intel,p2sb-port-id: Port ID number within the parent P2SB
+- reg: PCI address of the controller
+
+Please refer to pinctrl-bindings.txt in this directory for details of the
+common pinctrl bindings used by client devices.
+
+Optional subnodes:
+
+GPIO nodes may be added as children of the pinctrl nodes. See intel,apl-gpio
+for the binding.
+
+
+Example:
+
+...
+{
+	p2sb: p2sb@d,0 {
+		reg = <0x02006810 0 0 0 0>;
+		compatible = "intel,apl-p2sb";
+		early-regs = <IOMAP_P2SB_BAR 0x100000>;
+
+		n {
+			compatible = "intel,apl-pinctrl";
+			intel,p2sb-port-id = <PID_GPIO_N>;
+			gpio_n: gpio-n {
+				compatible = "intel,apl-gpio";
+				#gpio-cells = <2>;
+			};
+		};
+	};
+};
+...