[PATCH v6 2/3] ARM: dts: at_xdmac: add bindings documentation

[Ludovic Desroches]

On Wed, Oct 15, 2014 at 07:11:34PM +0530, Vinod Koul wrote:
> On Wed, Oct 01, 2014 at 04:59:24PM +0200, Ludovic Desroches wrote:
> > Add bindings documentation for the new Atmel DMA controller (XDMAC)
> > introduced with SAMA5D4.
> Seeing the example below, it doesnt seem to me that we cant reuse existing
> atmel binding, can you explain why we cnat reuse

We have discussed this in v3 but I didn't get answer:

"
Bindings have changed through the revisions, I didn't notice they were so
close to the hdmac bindings. The only difference is the content of the
second cell.

I don't know if it's a sufficient reason to add a new binding.
"

It makes me thinking that I should merge the two cells since the memory
and peripheral interface have been moved to the configuration register
in xdmac. So the number of cells won't be the same.

Ludovic

> 
> -- 
> ~Vinod
> 
> > 
> > Signed-off-by: Ludovic Desroches <ludovic.desroches at atmel.com>
> > Acked-by: Nicolas Ferre <nicolas.ferre at atmel.com>
> > ---
> >  .../devicetree/bindings/dma/atmel-xdma.txt         | 50 ++++++++++++++++++++++
> >  1 file changed, 50 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/dma/atmel-xdma.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/dma/atmel-xdma.txt b/Documentation/devicetree/bindings/dma/atmel-xdma.txt
> > new file mode 100644
> > index 0000000..ae587ad
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/dma/atmel-xdma.txt
> > @@ -0,0 +1,50 @@
> > +* Atmel Extensible Direct Memory Access Controller (XDMAC)
> > +
> > +* XDMA Controller
> > +Required properties:
> > +- compatible: Should be "atmel,<chip>-dma".
> > +  <chip> compatible description:
> > +  - sama5d4: first SoC adding the XDMAC
> > +- 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 at 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 at 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";
> > +};
> > -- 
> > 2.0.3
> > 
> 
> --