dt-binding: can: mcp25xxfd: document device tree bindings

This patch adds the device-tree binding documentation for the Microchip
MCP25xxFD SPI CAN controller family.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20200918172536.2074504-2-mkl@pengutronix.de

Documentation/devicetree/bindings/net/can/microchip,mcp25xxfd.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/can/microchip,mcp25xxfd.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title:
+  Microchip MCP2517FD and MCP2518FD stand-alone CAN controller device tree
+  bindings
+
+maintainers:
+  - Marc Kleine-Budde <mkl@pengutronix.de>
+
+properties:
+  compatible:
+    oneOf:
+      - const: microchip,mcp2517fd
+        description: for MCP2517FD
+      - const: microchip,mcp2518fd
+        description: for MCP2518FD
+      - const: microchip,mcp25xxfd
+        description: to autodetect chip variant
+
+  reg:
+    maxItems: 1
+
+  interrupts-extended:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  vdd-supply:
+    description: Regulator that powers the CAN controller.
+    maxItems: 1
+
+  xceiver-supply:
+    description: Regulator that powers the CAN transceiver.
+    maxItems: 1
+
+  microchip,rx-int-gpios:
+    description:
+      GPIO phandle of GPIO connected to to INT1 pin of the MCP25XXFD, which
+      signals a pending RX interrupt.
+    maxItems: 1
+
+  spi-max-frequency:
+    description:
+      Must be half or less of "clocks" frequency.
+    maximum: 20000000
+
+required:
+  - compatible
+  - reg
+  - interrupts-extended
+  - clocks
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    spi0 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        can@0 {
+            compatible = "microchip,mcp25xxfd";
+            reg = <0>;
+            clocks = <&can0_osc>;
+            pinctrl-names = "default";
+            pinctrl-0 = <&can0_pins>;
+            spi-max-frequency = <20000000>;
+            interrupts-extended = <&gpio 13 IRQ_TYPE_LEVEL_LOW>;
+            microchip,rx-int-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
+            vdd-supply = <&reg5v0>;
+            xceiver-supply = <&reg5v0>;
+        };
+    };