Re: [ECOS] SPI and USB support for the STM32

[Chris Holgate <chris at zynaptic dot com>]

Hi Martin,

On Sat, 2008-11-15 at 01:38 +0000, Martin Davey wrote:
> Hi Chris,
> 
> Once I get a working compiler (cygwin issues at the mo) I was going to start 
> looking at an SPI driver. The STM32 has SPI capable of I2S also, and I need 
> this functionality so I was going to look at it.

I think that there is a case for implementing separate SPI and I2S
drivers, since they provide very different functionality at the
application level.  We could then just put a CDL 'mutex' on them so that
only one is active for a given interface.  I don't know if you're
familiar with the ALSA SoC driver model, but the way they separate the
codec and interface drivers is pretty neat and might provide a bit of
inspiration for the I2S framework.

> One of the things about the STM32 is that the peripherals have no FIFO's 
> (with exception of CAN and USB). The DMA is often heavily used to do 
> background transfers etc. Were you planning to implement DMA support?

Yes, I was planning on using the DMA.  Again, I'd expect the SPI and I2S
models for using this would be quite different, with SPI using one-shot
transfers and I2S using the rather nice circular buffer feature.

Chris.


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