spi: add driver for STM32 SPI controller

The STM32 Serial Peripheral Interface (SPI) can be used to communicate
with external devices while using the specific synchronous protocol. It
supports a half-duplex, full-duplex and simplex synchronous, serial
communication with external devices with 4-bit to 16/32-bit per word. It
has two 8x/16x 8-bit embedded Rx and TxFIFOs with DMA capability. It can
operate in master or slave mode.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/Kconfig

@@ -619,6 +619,16 @@ config SPI_SIRF
 	help
 	  SPI driver for CSR SiRFprimaII SoCs
 
+config SPI_STM32
+	tristate "STMicroelectronics STM32 SPI controller"
+	depends on ARCH_STM32 || COMPILE_TEST
+	help
+	  SPI driver for STMicroelectonics STM32 SoCs.
+
+	  STM32 SPI controller supports DMA and PIO modes. When DMA
+	  is not available, the driver automatically falls back to
+	  PIO mode.
+
 config SPI_ST_SSC4
 	tristate "STMicroelectronics SPI SSC-based driver"
 	depends on ARCH_STI || COMPILE_TEST

drivers/spi/Makefile

@@ -89,6 +89,7 @@ obj-$(CONFIG_SPI_SH_HSPI)		+= spi-sh-hspi.o
 obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIRF)		+= spi-sirf.o
+obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o
 obj-$(CONFIG_SPI_ST_SSC4)		+= spi-st-ssc4.o
 obj-$(CONFIG_SPI_SUN4I)			+= spi-sun4i.o
 obj-$(CONFIG_SPI_SUN6I)			+= spi-sun6i.o