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st,stm32-dma-v2

Vendor: STMicroelectronics

Description

These nodes are “dma” bus nodes.

STM32 DMA controller (V2)

It is present on stm32 devices like stm32L4 or stm32WB.
This DMA controller includes several channels with different 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
capable of supporting 5 or 6 or 7 or 8 independent DMA channels.
DMA clients connected to the STM32 DMA controller must use the format
described in the dma.txt file, using a 3-cell specifier for each
channel: a phandle to the DMA controller plus the following four integer cells:
  1. channel: the dma stream from 1 to <dma-requests>
  2. slot: DMA periph request ID, which is written in the DMAREQ_ID of the DMAMUX_CxCR
  this value is 0 for Memory-to-memory transfers
  or a value between <1> .. <dma-generators> (not supported yet)
  or a value beweeen <dma-generators>+1  ..  <dma-generators>+<dma-requests>
  3. channel-config: A 32bit mask specifying the DMA channel configuration
  which is device dependent:
      -bit 6-7 : Direction  (see dma.h)
             0x0: MEM to MEM
             0x1: MEM to PERIPH
             0x2: PERIPH to MEM
             0x3: reserved for PERIPH to PERIPH
      -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 11-12 : Peripheral data size
             0x0: Byte (8 bits)
             0x1: Half-word (16 bits)
             0x2: Word (32 bits)
             0x3: reserved
      -bit 13-14 : Memory data size
             0x0: Byte (8 bits)
             0x1: Half-word (16 bits)
             0x2: Word (32 bits)
             0x3: reserved
      -bit 15: Reserved
      -bit 16-17 : Priority level
             0x0: low
             0x1: medium
             0x2: high
             0x3: very high
Example of dma node for stm32wb55x
   dma2: dma-controller@40020400 {
       compatible = "st,stm32-dma-v2";
       ...
       dma-requests = <7>;
       status = "disabled";
      };

For the client part, example for stm32l476 on DMA1 instance
  Tx using channel 3 with request 1
  Rx using channel 2 with request 1
  spi1 {
   compatible = "st,stm32-spi";
   dmas = <&dma1 3 1 0x20440>,
          <&dma1 2 1 0x20480>;
   dma-names = "tx", "rx";
  };

Properties

Properties not inherited from the base binding file.

Name

Type

Details

#dma-cells

int

Number of items to expect in a DMA specifier

This property is required.

Constant value: 3

st,mem2mem

boolean

If the DMA controller V1 supports memory to memory transfer

dma-offset

int

offset in the table of channels when mapping to a DMAMUX
for 1st dma instance, offset is 0,
for 2nd dma instance, offset is the nb of dma channels of the 1st dma,
for 3rd dma instance, offset is the nb of dma channels of the 2nd dma
plus the nb of dma channels of the 1st dma instance, etc.

dma-channel-mask

int

Bitmask of available DMA channels in ascending order that are
not reserved by firmware and are available to the
kernel. i.e. first channel corresponds to LSB.

dma-channels

int

Number of DMA channels supported by the controller

dma-requests

int

Number of DMA request signals supported by the controller.

dma-buf-addr-alignment

int

Memory address alignment requirement for DMA buffers used by the controller.

dma-buf-size-alignment

int

Memory size alignment requirement for DMA buffers used by the controller.

dma-copy-alignment

int

Minimal chunk of data possible to be copied by the controller.

Specifier cell names

  • dma cells: channel, slot, channel-config