xref: /kernel/linux/linux-6.6/Documentation/devicetree/bindings/dma/st_fdma.txt

* STMicroelectronics Flexible Direct Memory Access Device Tree bindings

The FDMA is a general-purpose direct memory access controller capable of
supporting 16 independent DMA channels. It accepts up to 32 DMA requests.
The FDMA is based on a Slim processor which requires a firmware.

* FDMA Controller

Required properties:
- compatible	: Should be one of
		 - st,stih407-fdma-mpe31-11, "st,slim-rproc";
		 - st,stih407-fdma-mpe31-12, "st,slim-rproc";
		 - st,stih407-fdma-mpe31-13, "st,slim-rproc";
- reg		: Should contain an entry for each name in reg-names
- reg-names	: Must contain "slimcore", "dmem", "peripherals", "imem" entries
- interrupts	: Should contain one interrupt shared by all channels
- dma-channels	: Number of channels supported by the controller
- #dma-cells	: Must be <3>. See DMA client section below
- clocks	: Must contain an entry for each clock
See: Documentation/devicetree/bindings/clock/clock-bindings.txt


Example:

	fdma0: dma-controller@8e20000 {
		compatible = "st,stih407-fdma-mpe31-11", "st,slim-rproc";
		reg = <0x8e20000 0x8000>,
		      <0x8e30000 0x3000>,
		      <0x8e37000 0x1000>,
		      <0x8e38000 0x8000>;
		reg-names = "slimcore", "dmem", "peripherals", "imem";
		clocks = <&clk_s_c0_flexgen CLK_FDMA>,
			 <&clk_s_c0_flexgen CLK_EXT2F_A9>,
			 <&clk_s_c0_flexgen CLK_EXT2F_A9>,
			 <&clk_s_c0_flexgen CLK_EXT2F_A9>;
		interrupts = <GIC_SPI 5 IRQ_TYPE_NONE>;
		dma-channels = <16>;
		#dma-cells = <3>;
	};

* DMA client

Required properties:
- dmas: Comma separated list of dma channel requests
- dma-names: Names of the aforementioned requested channels

Each dmas request consists of 4 cells:
1. A phandle pointing to the FDMA controller
2. The request line number
3. A 32bit mask specifying (see include/linux/platform_data/dma-st-fdma.h)
 -bit 2-0: Holdoff value, dreq will be masked for
	0x0: 0-0.5us
	0x1: 0.5-1us
	0x2: 1-1.5us
 -bit 17: data swap
	0x0: disabled
	0x1: enabled
 -bit 21: Increment Address
	0x0: no address increment between transfers
	0x1: increment address between transfers
 -bit 22: 2 STBus Initiator Coprocessor interface
	0x0: high priority port
	0x1: low priority port
4. transfers type
 0 free running
 1 paced

Example:

	sti_uni_player2: sti-uni-player@2 {
		compatible = "st,sti-uni-player";
		#sound-dai-cells = <0>;
		st,syscfg = <&syscfg_core>;
		clocks = <&clk_s_d0_flexgen CLK_PCM_2>;
		assigned-clocks = <&clk_s_d0_flexgen CLK_PCM_2>;
		assigned-clock-parents = <&clk_s_d0_quadfs 2>;
		assigned-clock-rates = <50000000>;
		reg = <0x8D82000 0x158>;
		interrupts = <GIC_SPI 86 IRQ_TYPE_NONE>;
		dmas = <&fdma0 4 0 1>;
		dai-name = "Uni Player #1 (DAC)";
		dma-names = "tx";
		st,uniperiph-id = <2>;
		st,version = <5>;
		st,mode = "PCM";
	};