pci: xilinx: Add a driver for Xilinx AXI to PCIe bridge

This patch adds a driver for the Xilinx AXI bridge for PCI express, an
IP block which can be used on some generations of Xilinx FPGAs. This is
mostly a case of implementing PCIe ECAM specification, but with some
quirks about what devices are valid to access.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 669e37b..9a7c187 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -39,4 +39,11 @@
 	  with a total of 5 lanes. Some boards require this for Ethernet
 	  support to work (e.g. beaver, jetson-tk1).
 
+config PCI_XILINX
+	bool "Xilinx AXI Bridge for PCI Express"
+	depends on DM_PCI
+	help
+	  Enable support for the Xilinx AXI bridge for PCI express, an IP block
+	  which can be used on some generations of Xilinx FPGAs.
+
 endmenu