Documentation/devicetree/bindings/dma/st,stm32-dma.yaml

# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/dma/st,stm32-dma.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: STMicroelectronics STM32 DMA Controller

description: |
  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.
  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
       -bit 2: DMA direct mode
         0x0: FIFO mode with threshold selectable with bit 0-1
         0x1: Direct mode: each DMA request immediately initiates a transfer
              from/to the memory, FIFO is bypassed.
       -bit 4: alternative DMA request/acknowledge protocol
         0x0: Use standard DMA ACK management, where ACK signal is maintained
              up to the removal of request and transfer completion
         0x1: Use alternative DMA ACK management, where ACK de-assertion does
              not wait for the de-assertion of the REQuest, ACK is only managed
              by transfer completion. This must only be used on channels
              managing transfers for STM32 USART/UART.


maintainers:
  - Amelie Delaunay <amelie.delaunay@foss.st.com>

allOf:
  - $ref: dma-controller.yaml#

properties:
  "#dma-cells":
    const: 4

  compatible:
    const: st,stm32-dma

  reg:
    maxItems: 1

  clocks:
    maxItems: 1

  interrupts:
    maxItems: 8
    description: Should contain all of the per-channel DMA
      interrupts in ascending order with respect to the
      DMA channel index.

  resets:
    maxItems: 1

  st,mem2mem:
    $ref: /schemas/types.yaml#/definitions/flag
    description: if defined, it indicates that the controller
      supports memory-to-memory transfer

required:
  - compatible
  - reg
  - clocks
  - interrupts

unevaluatedProperties: false

examples:
  - |
    #include <dt-bindings/interrupt-controller/arm-gic.h>
    #include <dt-bindings/clock/stm32mp1-clks.h>
    #include <dt-bindings/reset/stm32mp1-resets.h>
    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>;
    };

...