spi: add xtfpga SPI controller driver

This simple SPI master controller is built into xtfpga bitstreams. It
always transfers 16 bit words in SPI mode 0, automatically asserting CS
on transfer start and deasserting on end.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index ba9310b..c87475d 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -520,6 +520,19 @@
 
 	  Or for the DS570, see "XPS Serial Peripheral Interface (SPI) (v2.00b)"
 
+config SPI_XTENSA_XTFPGA
+	tristate "Xtensa SPI controller for xtfpga"
+	depends on XTENSA && XTENSA_PLATFORM_XTFPGA
+	select SPI_BITBANG
+	help
+	  SPI driver for xtfpga SPI master controller.
+
+	  This simple SPI master controller is built into xtfpga bitstreams
+	  and is used to control daughterboard audio codec. It always transfers
+	  16 bit words in SPI mode 0, automatically asserting CS on transfer
+	  start and deasserting on end.
+
+
 config SPI_NUC900
 	tristate "Nuvoton NUC900 series SPI"
 	depends on ARCH_W90X900