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* STMicroelectronics STM32 DMA controller
The STM32 DMA is a general-purpose direct memory access controller capable of
supporting 8 independent DMA channels. Each channel can have up to 8 requests.
Required properties:
- compatible: Should be "st,stm32-dma"
- reg: Should contain DMA registers location and length. This should include
all of the per-channel registers.
- interrupts: Should contain all of the per-channel DMA interrupts in
ascending order with respect to the DMA channel index.
- clocks: Should contain the input clock of the DMA instance.
- #dma-cells : Must be <4>. See DMA client paragraph for more details.
Optional properties:
- dma-requests : Number of DMA requests supported.
- resets: Reference to a reset controller asserting the DMA controller
- st,mem2mem: boolean; if defined, it indicates that the controller supports
memory-to-memory transfer
Example:
dma2: dma-controller@40026400 {
compatible = "st,stm32-dma";
reg = <0x40026400 0x400>;
interrupts = <56>,
<57>,
<58>,
<59>,
<60>,
<68>,
<69>,
<70>;
clocks = <&clk_hclk>;
#dma-cells = <4>;
st,mem2mem;
resets = <&rcc 150>;
dma-requests = <8>;
};
* DMA client
DMA clients connected to the STM32 DMA controller must use the format
described in the dma.txt file, using a four-cell specifier for each
channel: a phandle to the DMA controller plus the following four integer cells:
1. The channel id
2. The request line number
3. A 32bit mask specifying the DMA channel configuration which are device
dependent:
-bit 9: Peripheral Increment Address
0x0: no address increment between transfers
0x1: increment address between transfers
-bit 10: Memory Increment Address
0x0: no address increment between transfers
0x1: increment address between transfers
-bit 15: Peripheral Increment Offset Size
0x0: offset size is linked to the peripheral bus width
0x1: offset size is fixed to 4 (32-bit alignment)
-bit 16-17: Priority level
0x0: low
0x1: medium
0x2: high
0x3: very high
4. A 32bit bitfield value specifying DMA features which are device dependent:
-bit 0-1: DMA FIFO threshold selection
0x0: 1/4 full FIFO
0x1: 1/2 full FIFO
0x2: 3/4 full FIFO
0x3: full FIFO
Example:
usart1: serial@40011000 {
compatible = "st,stm32-uart";
reg = <0x40011000 0x400>;
interrupts = <37>;
clocks = <&clk_pclk2>;
dmas = <&dma2 2 4 0x10400 0x3>,
<&dma2 7 5 0x10200 0x3>;
dma-names = "rx", "tx";
};
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