dt-bindings: PCI: dra7xx: Add DT bindings for PCI dra7xx EP mode

TI PCI Controllers

PCIe Designware Controller

 - compatible: Should be "ti,dra7-pcie""

 - reg : Two register ranges as listed in the reg-names property

 - reg-names : The first entry must be "ti-conf" for the TI specific registers

	       The second entry must be "rc-dbics" for the designware pcie

	       registers

	       The third entry must be "config" for the PCIe configuration space

 - compatible: Should be "ti,dra7-pcie" for RC

	       Should be "ti,dra7-pcie-ep" for EP

 - phys : list of PHY specifiers (used by generic PHY framework)

 - phy-names : must be "pcie-phy0", "pcie-phy1", "pcie-phyN".. based on the

	       number of PHYs as specified in *phys* property.

 - ti,hwmods : Name of the hwmod associated to the pcie, "pcie<X>",

	       where <X> is the instance number of the pcie from the HW spec.

 - num-lanes as specified in ../designware-pcie.txt

HOST MODE

=========

 - reg : Two register ranges as listed in the reg-names property

 - reg-names : The first entry must be "ti-conf" for the TI specific registers

	       The second entry must be "rc-dbics" for the DesignWare PCIe

	       registers

	       The third entry must be "config" for the PCIe configuration space

 - interrupts : Two interrupt entries must be specified. The first one is for

		main interrupt line and the second for MSI interrupt line.

 - #address-cells,

   #interrupt-cells,

   device_type,

   ranges,

   num-lanes,

   interrupt-map-mask,

   interrupt-map : as specified in ../designware-pcie.txt

DEVICE MODE

===========

 - reg : Four register ranges as listed in the reg-names property

 - reg-names : "ti-conf" for the TI specific registers

	       "ep_dbics" for the standard configuration registers as

		they are locally accessed within the DIF CS space

	       "ep_dbics2" for the standard configuration registers as

		they are locally accessed within the DIF CS2 space

	       "addr_space" used to map remote RC address space

 - interrupts : one interrupt entries must be specified for main interrupt.

 - num-ib-windows : number of inbound address translation windows

 - num-ob-windows : number of outbound address translation windows

Optional Property:

 - gpios : Should be added if a gpio line is required to drive PERST# line

NOTE: Two DT nodes may be added for each PCI controller; one for host

mode and another for device mode. So in order for PCI to

work in host mode, EP mode DT node should be disabled and in order to PCI to

work in EP mode, host mode DT node should be disabled. Host mode and EP

mode are mutually exclusive.

Example:

axi {

	compatible = "simple-bus";