MIPS: Add driver for the built-in PCI controller of the RT3883 SoC

The Ralink RT3883 SoCs have a built-in PCI Host Controller
device. The patch adds a platform driver and device tree
binding documentation for that.

The patch also enables the HW_HAS_PCI config option. This
is required in order to be able to enable the PCI support.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Acked-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/5758/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Documentation/devicetree/bindings/pci/ralink,rt3883-pci.txt

@@ -0,0 +1,190 @@
+* Mediatek/Ralink RT3883 PCI controller
+
+1) Main node
+
+   Required properties:
+
+   - compatible: must be "ralink,rt3883-pci"
+
+   - reg: specifies the physical base address of the controller and
+     the length of the memory mapped region.
+
+   - #address-cells: specifies the number of cells needed to encode an
+     address. The value must be 1.
+
+   - #size-cells: specifies the number of cells used to represent the size
+     of an address. The value must be 1.
+
+   - ranges: specifies the translation between child address space and parent
+     address space
+
+  Optional properties:
+
+   - status: indicates the operational status of the device.
+     Value must be either "disabled" or "okay".
+
+2) Child nodes
+
+   The main node must have two child nodes which describes the built-in
+   interrupt controller and the PCI host bridge.
+
+   a) Interrupt controller:
+
+   Required properties:
+
+   - interrupt-controller: identifies the node as an interrupt controller
+
+   - #address-cells: specifies the number of cells needed to encode an
+     address. The value must be 0. As such, 'interrupt-map' nodes do not
+     have to specify a parent unit address.
+
+   - #interrupt-cells: specifies the number of cells needed to encode an
+     interrupt source. The value must be 1.
+
+   - interrupt-parent: the phandle for the interrupt controller that
+     services interrupts for this device.
+
+   - interrupts: specifies the interrupt source of the parent interrupt
+     controller. The format of the interrupt specifier depends on the
+     parent interrupt controller.
+
+   b) PCI host bridge:
+
+   Required properties:
+
+   - #address-cells: specifies the number of cells needed to encode an
+     address. The value must be 0.
+
+   - #size-cells: specifies the number of cells used to represent the size
+     of an address. The value must be 2.
+
+   - #interrupt-cells: specifies the number of cells needed to encode an
+     interrupt source. The value must be 1.
+
+   - device_type: must be "pci"
+
+   - bus-range: PCI bus numbers covered
+
+   - ranges: specifies the ranges for the PCI memory and I/O regions
+
+   - interrupt-map-mask,
+   - interrupt-map: standard PCI properties to define the mapping of the
+     PCI interface to interrupt numbers.
+
+   The PCI host bridge node migh have additional sub-nodes representing
+   the onboard PCI devices/PCI slots. Each such sub-node must have the
+   following mandatory properties:
+
+     - reg: used only for interrupt mapping, so only the first four bytes
+       are used to refer to the correct bus number and device number.
+
+     - device_type: must be "pci"
+
+   If a given sub-node represents a PCI bridge it must have following
+   mandatory properties as well:
+
+     - #address-cells: must be set to <3>
+
+     - #size-cells: must set to <2>
+
+     - #interrupt-cells: must be set to <1>
+
+     - interrupt-map-mask,
+     - interrupt-map: standard PCI properties to define the mapping of the
+       PCI interface to interrupt numbers.
+
+   Besides the required properties the sub-nodes may have these optional
+   properties:
+
+     - status: indicates the operational status of the sub-node.
+       Value must be either "disabled" or "okay".
+
+3) Example:
+
+   a) SoC specific dtsi file:
+
+	pci@10140000 {
+		compatible = "ralink,rt3883-pci";
+		reg = <0x10140000 0x20000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges; /* direct mapping */
+
+		status = "disabled";
+
+		pciintc: interrupt-controller {
+			interrupt-controller;
+			#address-cells = <0>;
+			#interrupt-cells = <1>;
+
+			interrupt-parent = <&cpuintc>;
+			interrupts = <4>;
+		};
+
+		host-bridge {
+			#address-cells = <3>;
+			#size-cells = <2>;
+			#interrupt-cells = <1>;
+
+			device_type = "pci";
+
+			bus-range = <0 255>;
+			ranges = <
+				0x02000000 0 0x00000000 0x20000000 0 0x10000000 /* pci memory */
+				0x01000000 0 0x00000000 0x10160000 0 0x00010000 /* io space */
+			>;
+
+			interrupt-map-mask = <0xf800 0 0 7>;
+			interrupt-map = <
+				/* IDSEL 17 */
+				0x8800 0 0 1 &pciintc 18
+				0x8800 0 0 2 &pciintc 18
+				0x8800 0 0 3 &pciintc 18
+				0x8800 0 0 4 &pciintc 18
+				/* IDSEL 18 */
+				0x9000 0 0 1 &pciintc 19
+				0x9000 0 0 2 &pciintc 19
+				0x9000 0 0 3 &pciintc 19
+				0x9000 0 0 4 &pciintc 19
+			>;
+
+			pci-bridge@1 {
+				reg = <0x0800 0 0 0 0>;
+				device_type = "pci";
+				#interrupt-cells = <1>;
+				#address-cells = <3>;
+				#size-cells = <2>;
+
+				interrupt-map-mask = <0x0 0 0 0>;
+				interrupt-map = <0x0 0 0 0 &pciintc 20>;
+
+				status = "disabled";
+			};
+
+			pci-slot@17 {
+				reg = <0x8800 0 0 0 0>;
+				device_type = "pci";
+
+				status = "disabled";
+			};
+
+			pci-slot@18 {
+				reg = <0x9000 0 0 0 0>;
+				device_type = "pci";
+
+				status = "disabled";
+			};
+		};
+	};
+
+   b) Board specific dts file:
+
+	pci@10140000 {
+		status = "okay";
+
+		host-bridge {
+			pci-bridge@1 {
+				status = "okay";
+			};
+		};
+	};

arch/mips/pci/Makefile

@@ -41,6 +41,7 @@ obj-$(CONFIG_SIBYTE_BCM1x80)	+= pci-bcm1480.o pci-bcm1480ht.o
 obj-$(CONFIG_SNI_RM)		+= fixup-sni.o ops-sni.o
 obj-$(CONFIG_LANTIQ)		+= fixup-lantiq.o
 obj-$(CONFIG_PCI_LANTIQ)	+= pci-lantiq.o ops-lantiq.o
+obj-$(CONFIG_SOC_RT3883)	+= pci-rt3883.o
 obj-$(CONFIG_TANBAC_TB0219)	+= fixup-tb0219.o
 obj-$(CONFIG_TANBAC_TB0226)	+= fixup-tb0226.o
 obj-$(CONFIG_TANBAC_TB0287)	+= fixup-tb0287.o

arch/mips/ralink/Kconfig

@@ -26,6 +26,7 @@ choice
 		bool "RT3883"
 		select USB_ARCH_HAS_OHCI
 		select USB_ARCH_HAS_EHCI
+		select HW_HAS_PCI
 
 	config SOC_MT7620
 		bool "MT7620"