On Fri, 2007-09-28 at 16:14 -0500, Timur Tabi wrote:
I'm writing an ASOC driver. When my machine driver loads, it determines some hardware information for the DMA controllers, some other hardware information for the I2S controller, and even more information for the codec.
I want to be able to pass all this information to each of the three other drivers. Unfortunately, it doesn't appear that I have enough "private_data" pointers available to me.
The current ASOC drivers all use statically defined global structures and indexes into arrays of these structures to identify individual devices, such associating I2S controller #2 with DMA channels 3 and 4. On PowerPC, this doesn't work. The actual hardware configuration is determined at runtime (see arch/powerpc/boot/dts/), and so the machine driver needs to collect all the information and make all the device-to-device associations.
For example, the PCM driver has an open function:
static struct snd_pcm_ops fsl_dma_ops = { .open = fsl_dma_open, ...
static int fsl_dma_open(struct snd_pcm_substream *substream) { ...
What I would like is for fsl_dma_open() to be able to obtain pointers to the DMA controller's registers (there are two controllers with 4 channels each) by looking inside 'substream'. How can I do that?
I think we have addressed this now in ASoC V2. Every component driver now registers as a standard Linux device driver. It would probably be possible to read the dts configuration at probe() and then configure the driver with the correct DMA pointers before calling driver_register().
http://opensource.wolfsonmicro.com/cgi-bin/gitweb/gitweb.cgi?p=linux-2.6-aso...
Could you have a look at the V2 i.mx31 SSI driver and let me know if we need further changes for better dts support.
Thanks
Liam