gd,gd32-dma

Vendor: GigaDevice Semiconductor

Description

These nodes are “dma” bus nodes.

GD32 DMA controller

channel: Select channel for data transmitting

config: A 32bit mask specifying the DMA channel configuration
  - bit 6-7:   Direction  (see dma.h)
               - 0x0: MEMORY to MEMORY
               - 0x1: MEMORY to PERIPH
               - 0x2: PERIPH to MEMORY
               - 0x3: reserved for PERIPH to PERIPH

  - bit 9:     Peripheral address increase
               - 0x0: no address increment between transfers
               - 0x1: increment address between transfers

  - bit 10:    Memory address increase
               - 0x0: no address increase between transfers
               - 0x1: increase address between transfers

  - bit 11-12: Peripheral data width
               - 0x0: 8 bits
               - 0x1: 16 bits
               - 0x2: 32 bits
               - 0x3: reserved

  - bit 13-14: Memory data width
               - 0x0: 8 bits
               - 0x1: 16 bits
               - 0x2: 32 bits
               - 0x3: reserved

  - 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
               - 0x0: low
               - 0x1: medium
               - 0x2: high
               - 0x3: very high

Example of devicetree configuration

&spi0 {
      status = "okay";
      pinctrl-0 = <&spi0_default>;
      pinctrl-names = "default";
      cs-gpios = <&gpioa 4 GPIO_ACTIVE_LOW>;

      dmas = <&dma0 3 0>, <&dma0 5 GD32_DMA_PRIORITY_HIGH>;
      dma-names = "rx", "tx";
};

"spi0" uses dma0 for transmitting and receiving in the example.
Each is named "rx" and "tx".
The channel cell assigns channel 3 to receive and channel 5 to transmit.
The config cell can take various configs.
But the setting used depends on each driver implementation.
Set the priority for the transmitting channel as HIGH, LOW(the default) for receive channel.

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: 2

dma-channels

int

Number of DMA channels supported by the controller

This property is required.

gd,mem2mem

boolean

The DMA controller supporting memory to memory transfer

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-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, config