Re: DMA driver for BCM2835/Raspberry Pi

[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