fpga manager: Add Xilinx slave serial SPI driver

The driver loads FPGA firmware over SPI, using the "slave serial"
configuration interface on Xilinx FPGAs.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Moritz Fischer <mdf@kernel.org>
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index dee470f..c81cb7d 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -46,6 +46,13 @@
 	  FPGA manager driver support for the Altera Cyclone II FPGA
 	  present on the TS-73xx SBC boards.
 
+config FPGA_MGR_XILINX_SPI
+	tristate "Xilinx Configuration over Slave Serial (SPI)"
+	depends on SPI
+	help
+	  FPGA manager driver support for Xilinx FPGA configuration
+	  over slave serial interface.
+
 config FPGA_MGR_ZYNQ_FPGA
 	tristate "Xilinx Zynq FPGA"
 	depends on ARCH_ZYNQ || COMPILE_TEST