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Diffstat (limited to 'Documentation/devicetree/bindings/dma/stm32-mdma.txt')
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diff --git a/Documentation/devicetree/bindings/dma/stm32-mdma.txt b/Documentation/devicetree/bindings/dma/stm32-mdma.txt new file mode 100644 index 000000000..d18772d6b --- /dev/null +++ b/Documentation/devicetree/bindings/dma/stm32-mdma.txt @@ -0,0 +1,94 @@ +* 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"; + }; |