# Copyright (c) 2019, STMicroelectronics
# SPDX-License-Identifier: Apache-2.0

description: |
  STM32 DMAMUX controller

  The STM32 DMAMUX is a direct memory access multiplexer
  capable of supporting independent DMA channels.
  DMAMUX clients connected to the STM32 DMA ultiplexer must use a two-cell specifier
  for each dmamux channel: a phandle to the DMA multiplexer plus the following 2 integer cells:
    1. channel: the mux channel from 0 to <dma-channels> - 1
    2. slot: the request line Multiplexer ID
    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 not USED for DMA V2
               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
   example for stm32wb55x
     dmamux1: dmamux@40020800 {
         compatible = "st,stm32-dmamux";
         ...
         dma-channels = <14>;
         dma-generators = <4>;
         dma-requests= <36>;
         status = "disabled";
        };
    for client SPI of stm32wb55x
     spi1: spi@40013000 {
         compatible = "st,stm32-spi";
         dmas = <&dmamux1 11 7 0x20440
                  &dmamux1 1 6 0x20480>;
         dma-names = "tx", "rx";
        };

compatible: "st,stm32-dmamux"

include: dmamux-controller.yaml

properties:
  reg:
    required: true

  "#dma-cells":
    const: 3

# 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-dmamux.yaml

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