drivers: can: Add dts bindings for CAN

This commit adds generic device tree bindings for can devices.

Signed-off-by: Alexander Wachter <alexander.wachter@student.tugraz.at>

dts/bindings/can/can-device.yaml

@@ -0,0 +1,37 @@
+#
+# Copyright (c) 2018 Alexander Wachter
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+---
+title: CAN Device Base Structure
+id: can-device
+version: 0.1
+
+description: >
+    This binding gives the base structures for all can devices
+
+parent:
+    bus: can
+
+properties:
+    compatible:
+      type: string
+      category: required
+      description: compatible strings
+    reg:
+      type: array
+      description: register base address
+      generation: define
+      category: required
+    label:
+      type: string
+      category: required
+      description: Human readable string describing the device (used by Zephyr for API name)
+      generation: define
+    bus-speed:
+      type: int
+      category: required
+      description: bus spees in Baud/s
+      generation: define
+...

dts/bindings/can/can.yaml

@@ -0,0 +1,36 @@
+---
+title: CAN Base Structure
+id: can
+version: 0.1
+
+description: >
+    This binding gives the base structures for all CAN devices
+
+child:
+    bus: can
+
+properties:
+    "#address-cells":
+      type: int
+      category: required
+      description: should be 1.
+    "#size-cells":
+      type: int
+      category: required
+      description: should be 0.
+    label:
+      type: string
+      category: required
+      description: Human readable string describing the device (used by Zephyr for API name)
+      generation: define
+    bus-speed:
+      type: int
+      category: required
+      description: bus spees in Baud/s
+      generation: define
+    pinctrl-\d+:
+      type: array
+      category: optional
+      description: pinmux information for RX, TX
+      generation: structure
+...

dts/bindings/can/st,stm32-can.yaml

@@ -0,0 +1,48 @@
+---
+title: STM32 CAN
+id: st,stm32-can
+version: 0.1
+
+description: >
+    This binding gives a base representation of the STM32 CAN controller
+
+inherits:
+    !include can.yaml
+
+properties:
+    compatible:
+      type: string
+      category: required
+      description: compatible strings
+      constraint: "st,stm32-can"
+
+    reg:
+      type: array
+      description: register base address
+      generation: define
+      category: required
+
+    interrupts:
+      type: array
+      category: required
+      description: required interrupts
+      generation: define
+
+    gpio-port:
+      type: string
+      category: required
+      description: gpio port name
+      generation: define
+
+    rx-pin:
+      type: string
+      category: required
+      description: rx pin name
+      generation: define
+
+    tx-pin:
+      type: string
+      category: required
+      description: tx pin name
+      generation: define
+...