# Copyright (c) 2019, Song Qiang <songqiang1304521@gmail.com>
# SPDX-License-Identifier: Apache-2.0

description: |
  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 between <dma-generators>+1  ..  <dma-generators>+<dma-requests>
    3. channel-config: A 32bit mask specifying the DMA channel configuration
    which is device dependent. See stm32_dma.h:
        -bit 6-7 : Direction  (see dma.h)
               0x0: STM32_DMA_MEMORY_TO_MEMORY: MEM to MEM
               0x1: STM32_DMA_MEMORY_TO_PERIPH: MEM to PERIPH
               0x2: STM32_DMA_PERIPH_TO_MEMORY: PERIPH to MEM
               0x3: reserved for PERIPH to PERIPH
        -bit 9 : Peripheral Increment Address
               0x0: STM32_DMA_PERIPH_NO_INC: no address increment between transfers
               0x1: STM32_DMA_PERIPH_INC: increment address between transfers
        -bit 10 : Memory Increment Address
               0x0: STM32_DMA_MEM_NO_INC: no address increment between transfers
               0x1: STM32_DMA_MEM_INC: increment address between transfers
        -bit 11-12 : Peripheral data size
               0x0: STM32_DMA_PERIPH_8BITS: Byte (8 bits)
               0x1: STM32_DMA_PERIPH_16BITS: Half-word (16 bits)
               0x2: STM32_DMA_PERIPH_32BITS: Word (32 bits)
               0x3: reserved
        -bit 13-14 : Memory data size
               0x0: STM32_DMA_MEM_8BITS: Byte (8 bits)
               0x1: STM32_DMA_MEM_16BITS: Half-word (16 bits)
               0x2: STM32_DMA_MEM_32BITS: Word (32 bits)
               0x3: reserved
        -bit 15: Peripheral Increment Offset Size
               0x0: STM32_DMA_OFFSET_LINKED_BUS: offset size is linked to the peripheral bus width
               0x1: STM32_DMA_OFFSET_FIXED_4: offset size is fixed to 4 (32-bit alignment)
        -bit 16-17 : Priority level
               0x0: STM32_DMA_PRIORITY_LOW: low
               0x1: STM32_DMA_PRIORITY_MEDIUM: medium
               0x2: hSTM32_DMA_PRIORITY_HIGH: high
               0x3: STM32_DMA_PRIORITY_VERY_HIGH: very high
    4. features: A 32bit bitfield value specifying DMA features
        -bit 0-1: DMA FIFO threshold selection
               0x0: STM32_DMA_FIFO_1_4: 1/4 full FIFO
               0x1: STM32_DMA_FIFO_HALF: 1/2 full FIFO
               0x2: STM32_DMA_FIFO_3_4: 3/4 full FIFO
               0x3: STM32_DMA_FIFO_FULL: full FIFO

  Example of dma usual combination for peripheral transfer
       #define STM32_DMA_PERIPH_TX	(STM32_DMA_MEMORY_TO_PERIPH | STM32_DMA_MEM_INC)
       #define STM32_DMA_PERIPH_RX	(STM32_DMA_PERIPH_TO_MEMORY | STM32_DMA_MEM_INC)

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

  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 STM32_DMA_PERIPH_TX STM32_DMA_FIFO_FULL>,
           <&dma2 2 3 STM32_DMA_PERIPH_RX STM32_DMA_FIFO_FULL>;
     dma-names = "tx", "rx";
     };

compatible: "st,stm32-dma-v1"

include: st,stm32-dma.yaml

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

# Parameter syntax of stm32 follows the dma client dts syntax
# in the Linux kernel declared in
# https://git.kernel.org/pub/scm/linux/kernel/git/devicetree/devicetree-rebasing.git/plain/Bindings/dma/st,stm32-dma.yaml

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