Re: DMA driver for BCM2835/Raspberry Pi

[Stephan <stephanwib%googlemail.com@localhost>]

And why not use bus_dma(9)?

I think most of the register definitions, some data structures and the
electrical part could be ripped off the FreeBSD driver once it is
clear what interface to use for NetBSD.

2014-08-25 10:30 GMT+02:00 Nick Hudson <skrll%netbsd.org@localhost>:
> On 08/24/14 16:36, Stephan wrote:
>>
>> Well, I´m trying to get an overview about this topic. I´ve looked at
>> another SoCs DMA driver from NetBSD (s3c2440_dma.c) and at the FreeBSD
>> DMA driver for the BCM2835 SoC.
>>
>> The NetBSD Wiki states a DMA driver and/with a dmover(9) backend is
>> needed.
>
>
> Ideally we'd have a generic interface available for dmac users to request
> channels/transfers and initially I thought dmover could do this for us. I'm
> not so sure now.
>
>
>>   The s3c2440 DMA driver does not seem to offer a dmover(9)
>> backend, it looks to me like a bus_dma(9) inerface.
>
>
> The s3c2440 model isn't exactly what I had in mind either.
>
>> Can somebody explain what is needed and to what extent the FreeBSD
>> driver could serve as a template?
>
>
> I think we need to invent a new interface here. The FreeBSD driver is
> probably only good for register definitions.
>
> Nick
>