linux-arkmicro/linux/Documentation/devicetree/bindings/dma/stm32-mdma.txt

* STMicroelectronics STM32 MDMA controller

The STM32 MDMA is a general-purpose direct memory access controller capable of
supporting 64 independent DMA channels with 256 HW requests.

Required properties:
- compatible: Should be "st,stm32h7-mdma"
- reg: Should contain MDMA registers location and length. This should include
  all of the per-channel registers.
- interrupts: Should contain the MDMA interrupt.
- clocks: Should contain the input clock of the DMA instance.
- resets: Reference to a reset controller asserting the DMA controller.
- #dma-cells : Must be <5>. See DMA client paragraph for more details.

Optional properties:
- dma-channels: Number of DMA channels supported by the controller.
- dma-requests: Number of DMA request signals supported by the controller.
- st,ahb-addr-masks: Array of u32 mask to list memory devices addressed via
  AHB bus.

Example:

	mdma1: dma@52000000 {
		compatible = "st,stm32h7-mdma";
		reg = <0x52000000 0x1000>;
		interrupts = <122>;
		clocks = <&timer_clk>;
		resets = <&rcc 992>;
		#dma-cells = <5>;
		dma-channels = <16>;
		dma-requests = <32>;
		st,ahb-addr-masks = <0x20000000>, <0x00000000>;
	};

* DMA client

DMA clients connected to the STM32 MDMA controller must use the format
described in the dma.txt file, using a five-cell specifier for each channel:
a phandle to the MDMA controller plus the following five integer cells:

1. The request line number
2. The priority level
	0x00: Low
	0x01: Medium
	0x10: High
	0x11: Very high
3. A 32bit mask specifying the DMA channel configuration
 -bit 0-1: Source increment mode
	0x00: Source address pointer is fixed
	0x10: Source address pointer is incremented after each data transfer
	0x11: Source address pointer is decremented after each data transfer
 -bit 2-3: Destination increment mode
	0x00: Destination address pointer is fixed
	0x10: Destination address pointer is incremented after each data
	transfer
	0x11: Destination address pointer is decremented after each data
	transfer
 -bit 8-9: Source increment offset size
	0x00: byte (8bit)
	0x01: half-word (16bit)
	0x10: word (32bit)
	0x11: double-word (64bit)
 -bit 10-11: Destination increment offset size
	0x00: byte (8bit)
	0x01: half-word (16bit)
	0x10: word (32bit)
	0x11: double-word (64bit)
-bit 25-18: The number of bytes to be transferred in a single transfer
	(min = 1 byte, max = 128 bytes)
-bit 29:28: Trigger Mode
	0x00: Each MDMA request triggers a buffer transfer (max 128 bytes)
	0x01: Each MDMA request triggers a block transfer (max 64K bytes)
	0x10: Each MDMA request triggers a repeated block transfer
	0x11: Each MDMA request triggers a linked list transfer
4. A 32bit value specifying the register to be used to acknowledge the request
   if no HW ack signal is used by the MDMA client
5. A 32bit mask specifying the value to be written to acknowledge the request
   if no HW ack signal is used by the MDMA client

Example:

	i2c4: i2c@5c002000 {
		compatible = "st,stm32f7-i2c";
		reg = <0x5c002000 0x400>;
		interrupts = <95>,
			     <96>;
		clocks = <&timer_clk>;
		#address-cells = <1>;
		#size-cells = <0>;
		dmas = <&mdma1 36 0x0 0x40008 0x0 0x0>,
		       <&mdma1 37 0x0 0x40002 0x0 0x0>;
		dma-names = "rx", "tx";
		status = "disabled";
	};