Hi Rob
On 03/20/2017 10:34 PM, Rob Herring wrote:
> On Mon, Mar 13, 2017 at 03:15:57PM +0100, M'boumba Cedric Madianga wrote:
>> This patch adds the documentation of device tree bindings for the STM32
>> DMAMUX.
>>
>> Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx>
>> ---
>> .../devicetree/bindings/dma/stm32-dmamux.txt | 57 ++++++++++++++++++++++
>> 1 file changed, 57 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/dma/stm32-dmamux.txt
>>
>> diff --git a/Documentation/devicetree/bindings/dma/stm32-dmamux.txt b/Documentation/devicetree/bindings/dma/stm32-dmamux.txt
>> new file mode 100644
>> index 0000000..1039420
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/dma/stm32-dmamux.txt
>> @@ -0,0 +1,57 @@
>> +STM32 DMA MUX (DMA request router)
>> +
>> +Required properties:
>> +- compatible: "st,stm32-dmamux"
>> +- reg: Memory map for accessing module
>> +- #dma-cells: Should be set to <4>.
>> + For more details about the four cells, please see stm32-dma.txt
>> + documentation binding file
>> +- dma-masters: Phandle pointing to the DMA controller
>> +- clocks: Input clock of the DMAMUX instance.
>> +
>> +Optional properties:
>> +- dma-channels : Number of DMA channels supported.
>> +- dma-requests : Number of DMA requests supported.
>> +- resets: Reference to a reset controller asserting the DMA controller
>> +
>> +Example:
>> +
>> +/* DMA controller */
>> +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>;
>> + st,dmamux;
>> + dma-channels = <8>;
>> +};
>> +
>> +/* DMA mux */
>> +dmamux2: dma-router@40020820 {
>> + compatible = "st,stm32-dmamux";
>> + reg = <0x40020800 0x1c>;
>> + #dma-cells = <4>;
>> + dma-requests = <128>;
>> + dma-masters = <&dma2>;
>
> I think this should be modeled after the interrupt-map property (or
> Stephen Boyd's gpio-map support which additionally allows pass thru of
> cell values). Something like this:
>
> dma-map = <0 41 0 0 &dma2 0 <req> 0 0>,
> <1 42 0 0 &dma2 1 <req> 0 0>;
> dma-map-mask = <0xffffffff 0xffffffff 0 0>;
>
> <req> is the request number on dma2 controller.
>
> This is more generic and would work if you have a single mux with
> multiple DMA controllers.
>
Would you mind to detail a little bit more your thoughts please ?
Are dma-map & dma-map-mask part of an existing bindings ? or need to be
developed ?
I'm a little bit confused where come from values you used.
>> +};
>> +
>> +/* DMA client */
>> +usart1: serial@40011000 {
>> + compatible = "st,stm32-usart", "st,stm32-uart";
>> + reg = <0x40011000 0x400>;
>> + interrupts = <37>;
>> + clocks = <&clk_pclk2>;
>> + dmas = <&dmamux2 0 41 0x400 0x00>,
>> + <&dmamux2 1 42 0x400 0x00>;
>> + dma-names = "rx", "tx";
>> +};
>> --
>> 1.9.1
>>
>
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>
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