[alsa-devel] [PATCH 03/17] ASoC: Add a generic dmaengine_pcm driver

[Peter Ujfalusi]

On 04/15/2013 07:19 PM, Lars-Peter Clausen wrote:
> This patch adds a generic dmaengine PCM driver. It builds on top of the
> dmaengine PCM library and adds the missing pieces like DMA channel management,
> buffer management and channel configuration. It will be able to replace the
> majority of the existing platform specific dmaengine based PCM drivers.
> Devicetree is used to map the DMA channels to the PCM device.
> 
> Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
> ---
> +static const char * const dmaengine_pcm_dma_channel_names[] = {
> +	[SNDRV_PCM_STREAM_PLAYBACK] = "tx",
> +	[SNDRV_PCM_STREAM_CAPTURE] = "rx",
> +};

> +
> +/**
> + * snd_dmaengine_pcm_register - Register a dmaengine based PCM device
> + * @dev: The parent device for the PCM device
> + * @config: Platform specific PCM configuration
> + * @flags: Platform specific quirks
> + */
> +int snd_dmaengine_pcm_register(struct device *dev,
> +	const struct snd_dmaengine_pcm_config *config, unsigned int flags)
> +{
> +	struct dmaengine_pcm *pcm;
> +	unsigned int i;
> +
> +	if (!dev->of_node)
> +		return -EINVAL;
> +
> +	pcm = kzalloc(sizeof(*pcm), GFP_KERNEL);
> +	if (!pcm)
> +		return -ENOMEM;
> +
> +	pcm->config = config;
> +
> +	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
> +		pcm->chan[i] = of_dma_request_slave_channel(dev->of_node,
> +					dmaengine_pcm_dma_channel_names[i]);

Here we should have flexibility to provide custom DMA channel names. For OMAP4
AESS support (which I'm cleaning up right now for upstream) will need such a
flexibility since we will have 8 DMA channels and none of them is dedicated tx
or rx.

> +	}
> +
> +	return snd_soc_add_platform(dev, &pcm->platform,
> +				&dmaengine_pcm_platform);
> +}
> +EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_register);
> +
> +/**
> + * snd_dmaengine_pcm_unregister - Removes a dmaengine based PCM device
> + * @dev: Parent device the PCM was register with
> + *
> + * Removes a dmaengine based PCM device previously registered with
> + * snd_dmaengine_pcm_register.
> + */
> +void snd_dmaengine_pcm_unregister(struct device *dev)
> +{
> +	struct snd_soc_platform *platform;
> +	struct dmaengine_pcm *pcm;
> +	unsigned int i;
> +
> +	platform = snd_soc_lookup_platform(dev);
> +	if (!platform)
> +		return;
> +
> +	pcm = soc_platform_to_pcm(platform);
> +
> +	for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
> +		if (pcm->chan[i])
> +			dma_release_channel(pcm->chan[i]);
> +	}
> +
> +	snd_soc_remove_platform(platform);
> +	kfree(pcm);
> +}
> +EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_unregister);
> +
> +MODULE_LICENSE("GPL");
> 


-- 
Péter