[PATCH 3/3] [POWERPC] Add docs for Freescale DMA & DMA channel device tree nodes

[Kumar Gala]

On Nov 21, 2007, at 8:59 AM, Timur Tabi wrote:

> Kumar Gala wrote:
>
>> +   * Freescale 83xx DMA Controller
>> +
>> +    Freescale PowerPC 83xx have on chip general purpose DMA  
>> controllers.
>> +
>> +    Required properties:
>> +
>> +    - compatible        : compatible list, contains 2 entries,  
>> first is
>> +			 "fsl,CHIP-dma", where CHIP is the processor
>> +			 (mpc8349, mpc8360, etc.) and the second is
>> +			 "fsl,elo-dma"
>
> Shouldn't we put some text somewhere that we're calling it the Elo  
> controller even though that word isn't used in the reference manual?

we don't really have a place to put that.  its effectively documented  
right here.

>
>
>> +   * Freescale 85xx DMA Controller
>
> And 86xx.

yes, true.

>> +
>> +    Freescale PowerPC 85xx have on chip general purpose DMA  
>> controllers.
>> +
>> +    Required properties:
>> +
>> +    - compatible        : compatible list, contains 2 entries,  
>> first is
>> +			 "fsl,CHIP-dma", where CHIP is the processor
>> +			 (mpc8540, mpc8540, etc.) and the second is
>> +			 "fsl,eloplus-dma"
>> +    - reg               : <registers mapping for DMA general  
>> status reg>
>> +    - ranges 		: Should be defined as specified in 1) to describe  
>> the
>> +			  DMA controller channels.
>> +
>> +    - DMA channel nodes:
>> +	    - compatible        : compatible list, contains 2 entries,  
>> first is
>> +				 "fsl,CHIP-dma-channel", where CHIP is the processor
>> +				 (mpc8540, mpc8560, etc.) and the second is
>> +				 "fsl,eloplus-dma-channel"
>> +	    - reg               : <registers mapping for channel>
>> +	    - interrupts        : <interrupt mapping for DMA channel IRQ>
>> +	    - interrupt-parent  : optional, if needed for interrupt mapping
>> +
>> +  Example:
>> +	dma at 21000 {
>
> Shouldn't this be dma at 21300?

its an example that has not basis is reality :)

>> +		#address-cells = <1>;
>> +		#size-cells = <1>;
>> +		compatible = "fsl,mpc8540-dma", "fsl,eloplus-dma";
>> +		reg = <21300 4>;
>> +		ranges = <0 21100 200>;
>> +		dma-channel at 0 {
>> +			compatible = "fsl,mpc8540-dma-channel", "fsl,eloplus-dma- 
>> channel";
>> +			reg = <0 80>;
>> +			interrupt-parent = <&mpic>;
>> +			interrupts = <14 2>;
>> +		};
>
> The DMA controller and the DMA channels need a "device-id", so that  
> they can be identified by number.  Some peripherals, like the SSI,  
> can only use the controller and channel number.  This is what I have  
> in my 8610 DTS:

Why not use reg for this?  I don't see any reason to add another  
"unique id" when there is already one.

>                dma at 21300 {
>                        #address-cells = <1>;
>                        #size-cells = <1>;
>                        compatible = "fsl,mpc8610-dma", "fsl,mpc8540- 
> dma";
>        -->             device-id = <0>;
>                        reg = <21300 4>; /* DMA general status  
> register */
>                        ranges = <0 21100 200>;
>
>                        dma-channel at 0 {
>                                compatible = "fsl,mpc8610-dma-channel",
>                                        "fsl,mpc8540-dma-channel";
>        -->                     device-id = <0>;
>                                reg = <0 80>;
>                                interrupt-parent = <&mpic>;
>                                interrupts = <14 2>;
>                        };
>

- k