spi: sunxi: Add Allwinner A31 SPI controller driver

The Allwinner A31 has a new SPI controller IP compared to the older Allwinner
SoCs.

It supports DMA, but the driver only does PIO for now, and DMA will be
supported eventually.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index ba9310b..7cfe0ee 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -446,6 +446,12 @@
 	help
 	  SPI driver for CSR SiRFprimaII SoCs
 
+config SPI_SUN6I
+	tristate "Allwinner A31 SPI controller"
+	depends on ARCH_SUNXI || COMPILE_TEST
+	help
+	  This enables using the SPI controller on the Allwinner A31 SoCs.
+
 config SPI_MXS
 	tristate "Freescale MXS SPI controller"
 	depends on ARCH_MXS