SPI: Add SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs

The Atheros AR71XX/AR724X/AR913X SoCs have a built-in SPI controller. This
patch implements a driver for that.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: spi-devel-general@lists.sourceforge.net
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Cc: linux-mips@linux-mips.org
Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Luis R. Rodriguez <lrodriguez@atheros.com>
Cc: Cliff Holden <Cliff.Holden@Atheros.com>
Cc: Kathy Giori <Kathy.Giori@Atheros.com>
Patchwork: https://patchwork.linux-mips.org/patch/1960/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 13bfa9d..bb233a9c 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -53,6 +53,14 @@
 
 comment "SPI Master Controller Drivers"
 
+config SPI_ATH79
+	tristate "Atheros AR71XX/AR724X/AR913X SPI controller driver"
+	depends on ATH79 && GENERIC_GPIO
+	select SPI_BITBANG
+	help
+	  This enables support for the SPI controller present on the
+	  Atheros AR71XX/AR724X/AR913X SoCs.
+
 config SPI_ATMEL
 	tristate "Atmel SPI Controller"
 	depends on (ARCH_AT91 || AVR32)