drivers: dma: Add SAM0 DMAC driver

This adds support for the SAM0 DMA Controller (DMAC).  Chained
transfer are not currently implemented.

Tested with tests/drivers/dma/loop_transfer and custom modifications
to that test using three parallel reloading channels.  Also tested
with a trivial program that did memory->serial.

Signed-off-by: Michael Hope <[email protected]>

[[email protected]: Rebased and updated commit message]
Signed-off-by: Derek Hageman <[email protected]>

Author: nzmichaelh

drivers/dma/CMakeLists.txt

@@ -7,4 +7,5 @@ zephyr_library_sources_ifdef(CONFIG_DMA_SAM_XDMAC	dma_sam_xdmac.c)
 zephyr_library_sources_ifdef(CONFIG_DMA_STM32F4X	dma_stm32f4x.c)
 zephyr_library_sources_ifdef(CONFIG_DMA_CAVS		dma_cavs.c)
 zephyr_library_sources_ifdef(CONFIG_DMA_NIOS2_MSGDMA	dma_nios2_msgdma.c)
+zephyr_library_sources_ifdef(CONFIG_DMA_SAM0		dma_sam0.c)
 zephyr_library_sources_ifdef(CONFIG_USERSPACE		dma_handlers.c)

drivers/dma/Kconfig

@@ -63,4 +63,6 @@ source "drivers/dma/Kconfig.cavs"
 
 source "drivers/dma/Kconfig.nios2_msgdma"
 
+source "drivers/dma/Kconfig.sam0"
+
 endif # DMA

drivers/dma/Kconfig.sam0

@@ -0,0 +1,11 @@
+# Kconfig - Atmel SAM DMAC configuration options
+#
+# Copyright (c) 2018 Google LLC.
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig DMA_SAM0
+	bool "Atmel SAM0 series DMAC driver"
+	default y
+	depends on SOC_FAMILY_SAM0
+	help
+	DMA driver for Atmel SAM0 series MCUs.