PCI: thunder: Add driver for ThunderX-pass{1,2} on-chip devices

The cavium,pci-thunder-ecam devices are exactly ECAM-based PCI root
complexes.  These root complexes (loosely referred to as ECAM units in the
hardware manuals) are used to access the Thunder on-chip devices.  They
are special in that all the BARs on devices behind these root complexes are
at fixed addresses.

Add a driver for these devices that synthesizes Enhanced Allocation (EA)
capability entries for each BAR.

Since this EA synthesis is needed for exactly two chip models, we can hard-
code some assumptions about the device topology and the layout of the
config space of specific DEVFNs in the driver.

[bhelgaas: changelog, whitespace]
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/pci/pci-thunder-ecam.txt

+* ThunderX PCI host controller for pass-1.x silicon
+
+Firmware-initialized PCI host controller to on-chip devices found on
+some Cavium ThunderX processors.  These devices have ECAM-based config
+access, but the BARs are all at fixed addresses.  We handle the fixed
+addresses by synthesizing Enhanced Allocation (EA) capabilities for
+these devices.
+
+The properties and their meanings are identical to those described in
+host-generic-pci.txt except as listed below.
+
+Properties of the host controller node that differ from
+host-generic-pci.txt:
+
+- compatible     : Must be "cavium,pci-host-thunder-ecam"
+
+Example:
+
+	pcie@84b000000000 {
+		compatible = "cavium,pci-host-thunder-ecam";
+		device_type = "pci";
+		msi-parent = <&its>;
+		msi-map = <0 &its 0x30000 0x10000>;
+		bus-range = <0 31>;
+		#size-cells = <2>;
+		#address-cells = <3>;
+		#stream-id-cells = <1>;
+		reg = <0x84b0 0x00000000 0 0x02000000>;  /* Configuration space */
+		ranges = <0x03000000 0x8180 0x00000000 0x8180 0x00000000 0x80 0x00000000>; /* mem ranges */
+	};

drivers/pci/host/Kconfig

@@ -202,4 +202,11 @@ config PCI_HOST_THUNDER_PEM
 	help
 	  Say Y here if you want PCIe support for CN88XX Cavium Thunder SoCs.
 
+config PCI_HOST_THUNDER_ECAM
+	bool "Cavium Thunder ECAM controller to on-chip devices on pass-1.x silicon"
+	depends on OF && ARM64
+	select PCI_HOST_COMMON
+	help
+	  Say Y here if you want ECAM support for CN88XX-Pass-1.x Cavium Thunder SoCs.
+
 endmenu

drivers/pci/host/Makefile

@@ -23,4 +23,5 @@ obj-$(CONFIG_PCIE_ALTERA) += pcie-altera.o
 obj-$(CONFIG_PCIE_ALTERA_MSI) += pcie-altera-msi.o
 obj-$(CONFIG_PCI_HISI) += pcie-hisi.o
 obj-$(CONFIG_PCIE_QCOM) += pcie-qcom.o
+obj-$(CONFIG_PCI_HOST_THUNDER_ECAM) += pci-thunder-ecam.o
 obj-$(CONFIG_PCI_HOST_THUNDER_PEM) += pci-thunder-pem.o