dmaengine: Add STM32 DMA3 support

STM32 DMA3 driver supports the 3 hardware configurations of the STM32 DMA3
controller:
- LPDMA (Low Power): 4 channels, no FIFO
- GPDMA (General Purpose): 16 channels, FIFO from 8 to 32 bytes
- HPDMA (High Performance): 16 channels, FIFO from 8 to 256 bytes
Hardware configuration of the channels is retrieved from the hardware
configuration registers.

The client can specify its channel requirements through device tree.
STM32 DMA3 channels can be individually reserved either because they are
secure, or dedicated to another CPU.
Indeed, channels availability depends on Resource Isolation Framework
(RIF) configuration. RIF grants access to buses with Compartment ID (CID)
filtering, secure and privilege level. It also assigns DMA channels to one
or several processors.
DMA channels used by Linux should be CID-filtered and statically assigned
to CID1 or shared with other CPUs but using semaphore. In case CID
filtering is not configured, dma-channel-mask property can be used to
specify available DMA channels to the kernel, otherwise such channels
will be marked as reserved and can't be used by Linux.

STM32 DMA3 is a new STM32 DMA controller, not a new version of an existing
one.
stm32-dma is not considered for reuse because register layout is completely
different and doesn't rely on descriptors mechanism.
stm32-mdma is based on descriptors mechanism but there are significant
differences in register layout and descriptors structure.

Signed-off-by: Amelie Delaunay <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

Author: ADESTM

drivers/dma/stm32/Kconfig

@@ -34,4 +34,14 @@ config STM32_MDMA
 	  If you have a board based on STM32 SoC with such DMA controller
 	  and want to use MDMA say Y here.
 
+config STM32_DMA3
+	tristate "STMicroelectronics STM32 DMA3 support"
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the on-chip DMA3 controller on STMicroelectronics
+	  STM32 platforms.
+	  If you have a board based on STM32 SoC with such DMA3 controller
+	  and want to use DMA3, say Y here.
+
 endif

drivers/dma/stm32/Makefile

@@ -2,3 +2,4 @@
 obj-$(CONFIG_STM32_DMA) += stm32-dma.o
 obj-$(CONFIG_STM32_DMAMUX) += stm32-dmamux.o
 obj-$(CONFIG_STM32_MDMA) += stm32-mdma.o
+obj-$(CONFIG_STM32_DMA3) += stm32-dma3.o