dmaengine: Add STM32 MDMA driver

This patch adds the driver for the STM32 MDMA controller.

Master Direct memory access (MDMA) is used in order to provide high-speed
data transfer between memory and memory or between peripherals and memory.

MDMA controller provides a master AXI interface for main memory and
peripheral registers access (system access port) and a master AHB
interface only for Cortex-M7 TCM memory access (TCM access port).

MDMA works in conjunction with the standard DMA controllers (DMA1 or DMA2).
It offers up to 64 channels, each dedicated to managing memory access
requests from one of the DMA stream memory buffer or other peripherals
(w/ integrated FIFO).

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
Signed-off-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/Kconfig

@@ -492,6 +492,18 @@ config STM32_DMAMUX
 	  If you have a board based on such a MCU and wish to use DMAMUX say Y
 	  here.
 
+config STM32_MDMA
+	bool "STMicroelectronics STM32 master dma support"
+	depends on ARCH_STM32 || COMPILE_TEST
+	select DMA_ENGINE
+	select DMA_OF
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the on-chip MDMA controller on STMicroelectronics
+	  STM32 platforms.
+	  If you have a board based on STM32 SoC and wish to use the master DMA
+	  say Y here.
+
 config S3C24XX_DMAC
 	bool "Samsung S3C24XX DMA support"
 	depends on ARCH_S3C24XX || COMPILE_TEST

drivers/dma/Makefile

@@ -60,6 +60,7 @@ obj-$(CONFIG_SIRF_DMA) += sirf-dma.o
 obj-$(CONFIG_STE_DMA40) += ste_dma40.o ste_dma40_ll.o
 obj-$(CONFIG_STM32_DMA) += stm32-dma.o
 obj-$(CONFIG_STM32_DMAMUX) += stm32-dmamux.o
+obj-$(CONFIG_STM32_MDMA) += stm32-mdma.o
 obj-$(CONFIG_S3C24XX_DMAC) += s3c24xx-dma.o
 obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
 obj-$(CONFIG_TEGRA20_APB_DMA) += tegra20-apb-dma.o