ASoC: Provide a more complete DMA driver stub

Allow userspace applications to do more parameter setting by providing a
more complete stub DMA driver specifying a wildcard set of formats and
channels and essentially random values for the DMA parameters. This is
required for useful runtime operation of the dummy DMA driver until we
are able to figure out how to power up links and do hw_params() from DAPM.

Sending to stable as without this the dummy driver is not terribly
useful.
Reported-by: Kyung-Kwee Ryu <Kyung-Kwee.Ryu@wolfsonmicro.com>
Tested-by: Kyung-Kwee Ryu <Kyung-Kwee.Ryu@wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@kernel.org

sound/soc/soc-utils.c

@@ -58,7 +58,36 @@ int snd_soc_params_to_bclk(struct snd_pcm_hw_params *params)
 }
 EXPORT_SYMBOL_GPL(snd_soc_params_to_bclk);
 
-static struct snd_soc_platform_driver dummy_platform;
+static const struct snd_pcm_hardware dummy_dma_hardware = {
+	.formats		= 0xffffffff,
+	.channels_min		= 1,
+	.channels_max		= UINT_MAX,
+
+	/* Random values to keep userspace happy when checking constraints */
+	.info			= SNDRV_PCM_INFO_INTERLEAVED |
+				  SNDRV_PCM_INFO_BLOCK_TRANSFER,
+	.buffer_bytes_max	= 128*1024,
+	.period_bytes_min	= PAGE_SIZE,
+	.period_bytes_max	= PAGE_SIZE*2,
+	.periods_min		= 2,
+	.periods_max		= 128,
+};
+
+static int dummy_dma_open(struct snd_pcm_substream *substream)
+{
+	snd_soc_set_runtime_hwparams(substream, &dummy_dma_hardware);
+
+	return 0;
+}
+
+static struct snd_pcm_ops dummy_dma_ops = {
+	.open		= dummy_dma_open,
+	.ioctl		= snd_pcm_lib_ioctl,
+};
+
+static struct snd_soc_platform_driver dummy_platform = {
+	.ops = &dummy_dma_ops,
+};
 
 static __devinit int snd_soc_dummy_probe(struct platform_device *pdev)
 {