Re: [PATCH v3 2/2] ARM: dts: at_xdmac: add bindings documentation

[Vinod Koul <vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

On Tue, Jul 08, 2014 at 03:11:36PM +0200, Ludovic Desroches wrote:
> Add bindings documentation for the new Atmel DMA controller (XDMAC)
> introduced with SAMA5D4.
> 
> Signed-off-by: Ludovic Desroches <ludovic.desroches-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org>
> ---
>  .../devicetree/bindings/dma/atmel-xdma.txt         |   48 ++++++++++++++++++++
>  1 file changed, 48 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/atmel-xdma.txt

I dont see delta with current atmel-dma bindings. Shouldn't we reuse that
here too?

Surely we dont want to add binding per contoller even if they are similar!

-- 
~Vinod

> 
> diff --git a/Documentation/devicetree/bindings/dma/atmel-xdma.txt b/Documentation/devicetree/bindings/dma/atmel-xdma.txt
> new file mode 100644
> index 0000000..647f099
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/atmel-xdma.txt
> @@ -0,0 +1,48 @@
> +* Atmel Extensible Direct Memory Access Controller (XDMAC)
> +
> +* XDMA Controller
> +Required properties:
> +- compatible: Should be "atmel,<chip>-dma".
> +- reg: Should contain DMA registers location and length.
> +- interrupts: Should contain DMA interrupt.
> +- #dma-cells: Must be <2>, used to represent the number of integer cells in
> +the dmas property of client devices.
> +  - The 1st cell specifies the memory interface (16 most significant bits) and
> +  the peripheral interface (16 less significant bits) to use.
> +  - The 2nd cell specifies the channel configuration register:
> +    - bit 30-24: PERID, peripheral identifier.
> +
> +Example:
> +
> +dma1: dma-controller@f0004000 {
> +	compatible = "atmel,sama5d4-dma";
> +	reg = <0xf0004000 0x200>;
> +	interrupts = <50 4 0>;
> +	#dma-cells = <2>;
> +};
> +
> +
> +* DMA clients
> +DMA clients connected to the Atmel XDMA controller must use the format
> +described in the dma.txt file, using a two-cell specifier for each channel.
> +The three cells in order are:
> +1. A phandle pointing to the DMA controller.
> +2. The memory interface (16 most significant bits), the peripheral interface
> +(16 less significant bits).
> +3. Channel configuration register. Configurable fields are:
> +  - bit 30-24: PERID, peripheral identifier.
> +
> +Example:
> +
> +i2c2: i2c@f8024000 {
> +	compatible = "atmel,at91sam9x5-i2c";
> +	reg = <0xf8024000 0x4000>;
> +	interrupts = <34 4 6>;
> +	dmas = <&dma1
> +		(AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1))
> +		AT91_XDMAC_DT_PERID(6)>,
> +	       <&dma1
> +		(AT91_XDMAC_DT_MEM_IF(0) | AT91_XDMAC_DT_PER_IF(1))
> +		AT91_XDMAC_DT_PERID(7)>;
> +	dma-names = "tx", "rx";
> +};
> -- 
> 1.7.9.5
> 

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