PCI: ixp4xx: Add device tree bindings for IXP4xx

This adds device tree bindings for the Intel IXP4xx
PCI controller which can be used as both host and
option.

Cc: devicetree@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Krzysztof Halasa <khalasa@piap.pl>
Cc: Zoltan HERPAI <wigyori@uid0.hu>
Cc: Raylynn Knight <rayknight@me.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pci/intel,ixp4xx-pci.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pci/intel,ixp4xx-pci.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Intel IXP4xx PCI controller
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+description: PCI host controller found in the Intel IXP4xx SoC series.
+
+allOf:
+  - $ref: /schemas/pci/pci-bus.yaml#
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - intel,ixp42x-pci
+          - intel,ixp43x-pci
+    description: The two supported variants are ixp42x and ixp43x,
+      though more variants may exist.
+
+  reg:
+    items:
+      - description: IXP4xx-specific registers
+
+  interrupts:
+    items:
+      - description: Main PCI interrupt
+      - description: PCI DMA interrupt 1
+      - description: PCI DMA interrupt 2
+
+  ranges:
+    maxItems: 2
+    description: Typically one memory range of 64MB and one IO
+      space range of 64KB.
+
+  dma-ranges:
+    maxItems: 1
+    description: The DMA range tells the PCI host which addresses
+      the RAM is at. It can map only 64MB so if the RAM is bigger
+      than 64MB the DMA access has to be restricted to these
+      addresses.
+
+  "#interrupt-cells": true
+
+  interrupt-map: true
+
+  interrupt-map-mask:
+    items:
+      - const: 0xf800
+      - const: 0
+      - const: 0
+      - const: 7
+
+required:
+  - compatible
+  - reg
+  - dma-ranges
+  - "#interrupt-cells"
+  - interrupt-map
+  - interrupt-map-mask
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    pci@c0000000 {
+      compatible = "intel,ixp43x-pci";
+      reg = <0xc0000000 0x1000>;
+      #address-cells = <3>;
+      #size-cells = <2>;
+      device_type = "pci";
+      bus-range = <0x00 0xff>;
+
+      ranges =
+        <0x02000000 0 0x48000000 0x48000000 0 0x04000000>,
+        <0x01000000 0 0x00000000 0x4c000000 0 0x00010000>;
+      dma-ranges =
+        <0x02000000 0 0x00000000 0x00000000 0 0x04000000>;
+
+      #interrupt-cells = <1>;
+      interrupt-map-mask = <0xf800 0 0 7>;
+      interrupt-map =
+        <0x0800 0 0 1 &gpio0 11 3>, /* INT A on slot 1 is irq 11 */
+        <0x0800 0 0 2 &gpio0 10 3>, /* INT B on slot 1 is irq 10 */
+        <0x0800 0 0 3 &gpio0 9  3>, /* INT C on slot 1 is irq 9 */
+        <0x0800 0 0 4 &gpio0 8  3>, /* INT D on slot 1 is irq 8 */
+        <0x1000 0 0 1 &gpio0 10 3>, /* INT A on slot 2 is irq 10 */
+        <0x1000 0 0 2 &gpio0 9  3>, /* INT B on slot 2 is irq 9 */
+        <0x1000 0 0 3 &gpio0 8  3>, /* INT C on slot 2 is irq 8 */
+        <0x1000 0 0 4 &gpio0 11 3>, /* INT D on slot 2 is irq 11 */
+        <0x1800 0 0 1 &gpio0 9  3>, /* INT A on slot 3 is irq 9 */
+        <0x1800 0 0 2 &gpio0 8  3>, /* INT B on slot 3 is irq 8 */
+        <0x1800 0 0 3 &gpio0 11 3>, /* INT C on slot 3 is irq 11 */
+        <0x1800 0 0 4 &gpio0 10 3>; /* INT D on slot 3 is irq 10 */
+    };