dts: arm: Add base DTS and YAML definitions

This patch adds the base DTS and YAML files that may be referenced by
SoCs.  The device tree files provide base definitions for the more well
known ARMV7M device nodes.  These files are meant to be included in
SoC vendor specific device tree files.

The YAML files provide definitions for the contents of device tree node
that contain information that will be parsed and used for configuration
in the system.

DTS files define hardware and software configuration and YAML files
provide the markers for knowing which pieces need to be extracted.

Change-Id: I7e90fe19f09afb269b7b2988c2c19c0f26d7ee7c
Signed-off-by: Andy Gross <andy.gross@linaro.org>

dts/arm/armv7-m.dtsi

@@ -0,0 +1,25 @@
+#include "skeleton.dtsi"
+
+/ {
+	soc {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		compatible = "simple-bus";
+		interrupt-parent = <&nvic>;
+		ranges;
+
+		nvic: interrupt-controller@e000e100  {
+			compatible = "arm,armv7m-nvic";
+			reg = <0xe000e100 0xc00>;
+			interrupt-controller;
+			#interrupt-cells = <1>;
+		};
+
+		systick: timer@e000e010 {
+			compatible = "arm,armv7m-systick";
+			reg = <0xe000e010 0x10>;
+			status = "disabled";
+		};
+	};
+};
+

dts/arm/yaml/arm_cortex_m4_nvic.yaml

@@ -0,0 +1,37 @@
+---
+title: ARM Cortex M4 NVIC Interrupt Controller
+version: 0.1
+
+description: >
+    This binding describes the ARM Cortex M4 NVIC IRQ controller
+
+properties:
+  - compatible:
+      category: required
+      type: string
+      description: compatible strings
+      constraint: "arm,armv7m-nvic"
+
+  - reg:
+      category: required
+      type: int
+      description: mmio register space
+      generation: define
+
+  - num-irq-prio-bits:
+      category: required
+      type: int
+      description: number of bits of IRQ priorities
+      generation: define
+
+  - num-irqs:
+      category: required
+      type: int
+      description: number of interrupts controlled by controller
+      generation: define
+
+cell_prefix: IRQ
+
+"#cells":
+  - irq
+...

dts/common/skeleton.dtsi

@@ -0,0 +1,13 @@
+/*
+ * Skeleton device tree; the bare minimum needed to boot; just include and
+ * add a compatible value.  The bootloader will typically populate the memory
+ * node.
+ */
+
+/ {
+	#address-cells = <1>;
+	#size-cells = <1>;
+	chosen { };
+	aliases { };
+	memory { device_type = "memory"; reg = <0 0>; };
+};

dts/common/yaml/uart.yaml

@@ -0,0 +1,25 @@
+---
+title: Uart Base Structure
+id: uart
+version: 0.1
+
+description: >
+    This binding gives the base structures for all UART devices
+
+properties:
+  - clock-frequency:
+      type: int
+      category: optional
+      description: Clock frequency information for UART operation
+      generation: define
+  - baud-rate:
+      type: int
+      category: required
+      description: Initial baud rate setting for UART
+      generation: define
+  - clocks:
+      type: array
+      category: required
+      description: Clock gate information
+      generation: define
+...

dts/common/yaml/zephyr_devices.yaml

@@ -0,0 +1,14 @@
+---
+title: Zephyr Device Specific Properties
+version: 0.1
+
+description: >
+    This binding describes Zephyr device specific properties
+
+properties:
+  - zephyr,irq-prio:
+      category: optional
+      type: int
+      description: priority setting
+      generation: define
+...