dt-bindings: PCI: tegra: Add device tree support for Tegra194

Add support for Tegra194 PCIe controllers. These controllers are based
on Synopsys DesignWare core IP.
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Thierry Reding <treding@nvidia.com>

Documentation/devicetree/bindings/pci/nvidia,tegra194-pcie.txt

+NVIDIA Tegra PCIe controller (Synopsys DesignWare Core based)
+
+This PCIe host controller is based on the Synopsis Designware PCIe IP
+and thus inherits all the common properties defined in designware-pcie.txt.
+
+Required properties:
+- compatible: For Tegra19x, must contain "nvidia,tegra194-pcie".
+- device_type: Must be "pci"
+- power-domains: A phandle to the node that controls power to the respective
+  PCIe controller and a specifier name for the PCIe controller. Following are
+  the specifiers for the different PCIe controllers
+    TEGRA194_POWER_DOMAIN_PCIEX8B: C0
+    TEGRA194_POWER_DOMAIN_PCIEX1A: C1
+    TEGRA194_POWER_DOMAIN_PCIEX1A: C2
+    TEGRA194_POWER_DOMAIN_PCIEX1A: C3
+    TEGRA194_POWER_DOMAIN_PCIEX4A: C4
+    TEGRA194_POWER_DOMAIN_PCIEX8A: C5
+  these specifiers are defined in
+  "include/dt-bindings/power/tegra194-powergate.h" file.
+- reg: A list of physical base address and length pairs for each set of
+  controller registers. Must contain an entry for each entry in the reg-names
+  property.
+- reg-names: Must include the following entries:
+  "appl": Controller's application logic registers
+  "config": As per the definition in designware-pcie.txt
+  "atu_dma": iATU and DMA registers. This is where the iATU (internal Address
+             Translation Unit) registers of the PCIe core are made available
+             for SW access.
+  "dbi": The aperture where root port's own configuration registers are
+         available
+- interrupts: A list of interrupt outputs of the controller. Must contain an
+  entry for each entry in the interrupt-names property.
+- interrupt-names: Must include the following entries:
+  "intr": The Tegra interrupt that is asserted for controller interrupts
+  "msi": The Tegra interrupt that is asserted when an MSI is received
+- bus-range: Range of bus numbers associated with this controller
+- #address-cells: Address representation for root ports (must be 3)
+  - cell 0 specifies the bus and device numbers of the root port:
+    [23:16]: bus number
+    [15:11]: device number
+  - cell 1 denotes the upper 32 address bits and should be 0
+  - cell 2 contains the lower 32 address bits and is used to translate to the
+    CPU address space
+- #size-cells: Size representation for root ports (must be 2)
+- ranges: Describes the translation of addresses for root ports and standard
+  PCI regions. The entries must be 7 cells each, where the first three cells
+  correspond to the address as described for the #address-cells property
+  above, the fourth and fifth cells are for the physical CPU address to
+  translate to and the sixth and seventh cells are as described for the
+  #size-cells property above.
+  - Entries setup the mapping for the standard I/O, memory and
+    prefetchable PCI regions. The first cell determines the type of region
+    that is setup:
+    - 0x81000000: I/O memory region
+    - 0x82000000: non-prefetchable memory region
+    - 0xc2000000: prefetchable memory region
+  Please refer to the standard PCI bus binding document for a more detailed
+  explanation.
+- #interrupt-cells: Size representation for interrupts (must be 1)
+- interrupt-map-mask and interrupt-map: Standard PCI IRQ mapping properties
+  Please refer to the standard PCI bus binding document for a more detailed
+  explanation.
+- clocks: Must contain an entry for each entry in clock-names.
+  See ../clocks/clock-bindings.txt for details.
+- clock-names: Must include the following entries:
+  - core
+- resets: Must contain an entry for each entry in reset-names.
+  See ../reset/reset.txt for details.
+- reset-names: Must include the following entries:
+  - apb
+  - core
+- phys: Must contain a phandle to P2U PHY for each entry in phy-names.
+- phy-names: Must include an entry for each active lane.
+  "p2u-N": where N ranges from 0 to one less than the total number of lanes
+- nvidia,bpmp: Must contain a pair of phandle to BPMP controller node followed
+  by controller-id. Following are the controller ids for each controller.
+    0: C0
+    1: C1
+    2: C2
+    3: C3
+    4: C4
+    5: C5
+- vddio-pex-ctl-supply: Regulator supply for PCIe side band signals
+
+Optional properties:
+- supports-clkreq: Refer to Documentation/devicetree/bindings/pci/pci.txt
+- nvidia,update-fc-fixup: This is a boolean property and needs to be present to
+    improve performance when a platform is designed in such a way that it
+    satisfies at least one of the following conditions thereby enabling root
+    port to exchange optimum number of FC (Flow Control) credits with
+    downstream devices
+    1. If C0/C4/C5 run at x1/x2 link widths (irrespective of speed and MPS)
+    2. If C0/C1/C2/C3/C4/C5 operate at their respective max link widths and
+       a) speed is Gen-2 and MPS is 256B
+       b) speed is >= Gen-3 with any MPS
+- nvidia,aspm-cmrt-us: Common Mode Restore Time for proper operation of ASPM
+   to be specified in microseconds
+- nvidia,aspm-pwr-on-t-us: Power On time for proper operation of ASPM to be
+   specified in microseconds
+- nvidia,aspm-l0s-entrance-latency-us: ASPM L0s entrance latency to be
+   specified in microseconds
+
+Examples:
+=========
+
+Tegra194:
+--------
+
+	pcie@14180000 {
+		compatible = "nvidia,tegra194-pcie", "snps,dw-pcie";
+		power-domains = <&bpmp TEGRA194_POWER_DOMAIN_PCIEX8B>;
+		reg = <0x00 0x14180000 0x0 0x00020000   /* appl registers (128K)      */
+		       0x00 0x38000000 0x0 0x00040000   /* configuration space (256K) */
+		       0x00 0x38040000 0x0 0x00040000>; /* iATU_DMA reg space (256K)  */
+		reg-names = "appl", "config", "atu_dma";
+
+		#address-cells = <3>;
+		#size-cells = <2>;
+		device_type = "pci";
+		num-lanes = <8>;
+		linux,pci-domain = <0>;
+
+		clocks = <&bpmp TEGRA194_CLK_PEX0_CORE_0>;
+		clock-names = "core";
+
+		resets = <&bpmp TEGRA194_RESET_PEX0_CORE_0_APB>,
+			 <&bpmp TEGRA194_RESET_PEX0_CORE_0>;
+		reset-names = "apb", "core";
+
+		interrupts = <GIC_SPI 72 IRQ_TYPE_LEVEL_HIGH>,	/* controller interrupt */
+			     <GIC_SPI 73 IRQ_TYPE_LEVEL_HIGH>;	/* MSI interrupt */
+		interrupt-names = "intr", "msi";
+
+		#interrupt-cells = <1>;
+		interrupt-map-mask = <0 0 0 0>;
+		interrupt-map = <0 0 0 0 &gic GIC_SPI 72 IRQ_TYPE_LEVEL_HIGH>;
+
+		nvidia,bpmp = <&bpmp 0>;
+
+		supports-clkreq;
+		nvidia,aspm-cmrt-us = <60>;
+		nvidia,aspm-pwr-on-t-us = <20>;
+		nvidia,aspm-l0s-entrance-latency-us = <3>;
+
+		bus-range = <0x0 0xff>;
+		ranges = <0x81000000 0x0  0x38100000 0x0  0x38100000 0x0 0x00100000    /* downstream I/O (1MB) */
+			  0x82000000 0x0  0x38200000 0x0  0x38200000 0x0 0x01E00000    /* non-prefetchable memory (30MB) */
+			  0xc2000000 0x18 0x00000000 0x18 0x00000000 0x4 0x00000000>;  /* prefetchable memory (16GB) */
+
+		vddio-pex-ctl-supply = <&vdd_1v8ao>;
+
+		phys = <&p2u_hsio_2>, <&p2u_hsio_3>, <&p2u_hsio_4>,
+		       <&p2u_hsio_5>;
+		phy-names = "p2u-0", "p2u-1", "p2u-2", "p2u-3";
+	};