st,stm32-dma-v1

Description

These nodes are “dma” bus nodes.

STM32 DMA controller (V1)

It is present on stm32 devices like stm32F4 or stm32F2.
This DMA controller includes FIFO control registers.
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. channel: the dma stream from 0 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: 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. features: A 32bit bitfield value specifying DMA features
      -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

  examples for stm32f411
   dma2: dma-controller@40020400 {
       compatible = "st,stm32-dma-v1";
       ...
       st,mem2mem;
       dma-requests = <7>;
       status = "disabled";
       label = "DMA_2";
      };

For the client part, example for stm32f411 on DMA2 instance
  Tx using stream 5 on channel 3 (stream 2 on channel 2 is also possible)
  Rx using stream 2 on channel 3 (stream 0 on channel 3 is also possible)
  spi1 {
   dmas = <&dma2 5 3 0x28440 0x03>,
         <&dma2 2 3 0x28480 0x03>;
   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: `4`
`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.

Properties inherited from the base binding file, which defines common properties that may be set on many nodes. Not all of these may apply to the “st,stm32-dma-v1” compatible.

Name	Type	Details
`reg`	`array`	register space This property is required. See Important properties for more information.
`interrupts`	`array`	interrupts for device This property is required. See Important properties for more information.
`label`	`string`	Human readable string describing the device (used as device_get_binding() argument) This property is required. See Important properties for more information.
`status`	`string`	indicates the operational status of a device Legal values: `'ok'`, `'okay'`, `'disabled'`, `'reserved'`, `'fail'`, `'fail-sss'` See Important properties for more information.
`compatible`	`string-array`	compatible strings This property is required. See Important properties for more information.
`reg-names`	`string-array`	name of each register space
`interrupts-extended`	`compound`	extended interrupt specifier for device
`interrupt-names`	`string-array`	name of each interrupt
`interrupt-parent`	`phandle`	phandle to interrupt controller node
`clocks`	`phandle-array`	Clock gate information
`clock-names`	`string-array`	name of each clock
`#address-cells`	`int`	number of address cells in reg property
`#size-cells`	`int`	number of size cells in reg property
`dmas`	`phandle-array`	DMA channels specifiers
`dma-names`	`string-array`	Provided names of DMA channel specifiers
`io-channels`	`phandle-array`	IO channels specifiers
`io-channel-names`	`string-array`	Provided names of IO channel specifiers
`mboxes`	`phandle-array`	mailbox / IPM channels specifiers
`mbox-names`	`string-array`	Provided names of mailbox / IPM channel specifiers
`wakeup-source`	`boolean`	Property to identify that a device can be used as wake up source. When this property is provided a specific flag is set into the device that tells the system that the device is capable of wake up the system. Wake up capable devices are disabled (interruptions will not wake up the system) by default but they can be enabled at runtime if necessary.

Specifier cell names

dma cells: channel, slot, channel-config, features