dt-bindings: PCI: Add UniPhier PCIe host controller description

Add DT bindings for PCIe controller implemented in UniPhier SoCs when
configured in Root Complex (host) mode. This controller is based on
the DesignWare PCIe core.
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/pci/uniphier-pcie.txt

+Socionext UniPhier PCIe host controller bindings
+
+This describes the devicetree bindings for PCIe host controller implemented
+on Socionext UniPhier SoCs.
+
+UniPhier PCIe host controller is based on the Synopsys DesignWare PCI core.
+It shares common functions with the PCIe DesignWare core driver and inherits
+common properties defined in
+Documentation/devicetree/bindings/pci/designware-pcie.txt.
+
+Required properties:
+- compatible: Should be "socionext,uniphier-pcie".
+- reg: Specifies offset and length of the register set for the device.
+	According to the reg-names, appropriate register sets are required.
+- reg-names: Must include the following entries:
+    "dbi"    - controller configuration registers
+    "link"   - SoC-specific glue layer registers
+    "config" - PCIe configuration space
+- clocks: A phandle to the clock gate for PCIe glue layer including
+	the host controller.
+- resets: A phandle to the reset line for PCIe glue layer including
+	the host controller.
+- interrupts: A list of interrupt specifiers. According to the
+	interrupt-names, appropriate interrupts are required.
+- interrupt-names: Must include the following entries:
+    "dma" - DMA interrupt
+    "msi" - MSI interrupt
+
+Optional properties:
+- phys: A phandle to generic PCIe PHY. According to the phy-names, appropriate
+	phys are required.
+- phy-names: Must be "pcie-phy".
+
+Required sub-node:
+- legacy-interrupt-controller: Specifies interrupt controller for legacy PCI
+	interrupts.
+
+Required properties for legacy-interrupt-controller:
+- interrupt-controller: identifies the node as an interrupt controller.
+- #interrupt-cells: specifies the number of cells needed to encode an
+	interrupt source. The value must be 1.
+- interrupt-parent: Phandle to the parent interrupt controller.
+- interrupts: An interrupt specifier for legacy interrupt.
+
+Example:
+
+	pcie: pcie@66000000 {
+		compatible = "socionext,uniphier-pcie", "snps,dw-pcie";
+		status = "disabled";
+		reg-names = "dbi", "link", "config";
+		reg = <0x66000000 0x1000>, <0x66010000 0x10000>,
+		      <0x2fff0000 0x10000>;
+		#address-cells = <3>;
+		#size-cells = <2>;
+		clocks = <&sys_clk 24>;
+		resets = <&sys_rst 24>;
+		num-lanes = <1>;
+		num-viewport = <1>;
+		bus-range = <0x0 0xff>;
+		device_type = "pci";
+		ranges =
+		/* downstream I/O */
+			<0x81000000 0 0x00000000  0x2ffe0000  0 0x00010000
+		/* non-prefetchable memory */
+			 0x82000000 0 0x00000000  0x20000000  0 0x0ffe0000>;
+		#interrupt-cells = <1>;
+		interrupt-names = "dma", "msi";
+		interrupts = <0 224 4>, <0 225 4>;
+		interrupt-map-mask = <0 0 0  7>;
+		interrupt-map = <0 0 0  1  &pcie_intc 0>,	/* INTA */
+				<0 0 0  2  &pcie_intc 1>,	/* INTB */
+				<0 0 0  3  &pcie_intc 2>,	/* INTC */
+				<0 0 0  4  &pcie_intc 3>;	/* INTD */
+
+		pcie_intc: legacy-interrupt-controller {
+			interrupt-controller;
+			#interrupt-cells = <1>;
+			interrupt-parent = <&gic>;
+			interrupts = <0 226 4>;
+		};
+	};