Re: [PATCH v4 1/4] dt-bindings: Document the STM32 DMA bindings

[Rob Herring]

On Fri, Oct 16, 2015 at 8:59 AM, M'boumba Cedric Madianga
<cedric.madianga@xxxxxxxxx> wrote:
> This patch adds documentation of device tree bindings for the STM32 dma
> controller.
>
> Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx>
> ---
>  .../devicetree/bindings/dma/stm32-dma.txt          | 82 ++++++++++++++++++++++

Acked-by: Rob Herring <robh@xxxxxxxxxx>

>  1 file changed, 82 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/stm32-dma.txt
>
> diff --git a/Documentation/devicetree/bindings/dma/stm32-dma.txt b/Documentation/devicetree/bindings/dma/stm32-dma.txt
> new file mode 100644
> index 0000000..70cd13f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/stm32-dma.txt
> @@ -0,0 +1,82 @@
> +* STMicroelectronics STM32 DMA controller
> +
> +The STM32 DMA is a general-purpose direct memory access controller capable of
> +supporting 8 independent DMA channels. Each channel can have up to 8 requests.
> +
> +Required properties:
> +- compatible: Should be "st,stm32-dma"
> +- reg: Should contain DMA registers location and length. This should include
> +  all of the per-channel registers.
> +- interrupts: Should contain all of the per-channel DMA interrupts in
> +  ascending order with respect to the DMA channel index.
> +- clocks: Should contain the input clock of the DMA instance.
> +- #dma-cells : Must be <4>. See DMA client paragraph for more details.
> +
> +Optional properties:
> +- resets: Reference to a reset controller asserting the DMA controller
> +- st,mem2mem: boolean; if defined, it indicates that the controller supports
> +  memory-to-memory transfer
> +
> +Example:
> +
> +       dma2: dma-controller@40026400 {
> +               compatible = "st,stm32-dma";
> +               reg = <0x40026400 0x400>;
> +               interrupts = <56>,
> +                            <57>,
> +                            <58>,
> +                            <59>,
> +                            <60>,
> +                            <68>,
> +                            <69>,
> +                            <70>;
> +               clocks = <&clk_hclk>;
> +               #dma-cells = <4>;
> +               st,mem2mem;
> +               resets = <&rcc 150>;
> +       };
> +
> +* DMA client
> +
> +DMA clients connected to the STM32 DMA controller must use the format
> +described in the dma.txt file, using a five-cell specifier for each
> +channel: a phandle plus four integer cells.
> +The four cells in order are:
> +
> +1. The channel id
> +2. The request line number
> +3. A 32bit mask specifying the DMA channel configuration which are device
> +   dependent:
> +  -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 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
> +5. A 32bit mask specifying the DMA FIFO threshold configuration which are device
> +   dependent:
> + -bit 0-1: Fifo threshold
> +       0x0: 1/4 full FIFO
> +       0x1: 1/2 full FIFO
> +       0x2: 3/4 full FIFO
> +       0x3: full FIFO
> +
> +Example:
> +
> +       usart1: serial@40011000 {
> +               compatible = "st,stm32-usart", "st,stm32-uart";
> +               reg = <0x40011000 0x400>;
> +               interrupts = <37>;
> +               clocks = <&clk_pclk2>;
> +               dmas = <&dma2 2 4 0x10400 0x3>,
> +                      <&dma2 7 5 0x10200 0x3>;
> +               dma-names = "rx", "tx";
> +       };
> --
> 1.9.1
>
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