ASoC: DaVinci: Update suspend/resume support for McASP driver

Add clock enable and disable calls to resume and suspend respectively.
Also add a member to the audio device data structure which tracks the clock
status.

Tested on DA850/OMAP-L138 EVM. For the purpose of testing, the patches[1] which
add suspend-to-RAM support to DA850/OMAP-L138 SoC were applied.

[1] http://linux.davincidsp.com/pipermail/davinci-linux-open-source/
2009-November/016958.html

Signed-off-by: Chaithrika U S <chaithrika@ti.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/davinci/davinci-mcasp.c

@@ -767,14 +767,27 @@ static int davinci_mcasp_trigger(struct snd_pcm_substream *substream,
 	int ret = 0;
 
 	switch (cmd) {
-	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_RESUME:
+		if (!dev->clk_active) {
+			clk_enable(dev->clk);
+			dev->clk_active = 1;
+		}
+		/* Fall through */
+	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 		davinci_mcasp_start(dev, substream->stream);
 		break;
 
-	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_SUSPEND:
+		davinci_mcasp_stop(dev, substream->stream);
+		if (dev->clk_active) {
+			clk_disable(dev->clk);
+			dev->clk_active = 0;
+		}
+
+		break;
+
+	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 		davinci_mcasp_stop(dev, substream->stream);
 		break;
@@ -866,6 +879,7 @@ static int davinci_mcasp_probe(struct platform_device *pdev)
 	}
 
 	clk_enable(dev->clk);
+	dev->clk_active = 1;
 
 	dev->base = (void __iomem *)IO_ADDRESS(mem->start);
 	dev->op_mode = pdata->op_mode;

sound/soc/davinci/davinci-mcasp.h

@@ -44,6 +44,7 @@ struct davinci_audio_dev {
 	int sample_rate;
 	struct clk *clk;
 	unsigned int codec_fmt;
+	u8 clk_active;
 
 	/* McASP specific data */
 	int	tdm_slots;

sound/soc/davinci/davinci-pcm.c

@@ -49,7 +49,7 @@ static void print_buf_info(int slot, char *name)
 static struct snd_pcm_hardware pcm_hardware_playback = {
 	.info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER |
 		 SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID |
-		 SNDRV_PCM_INFO_PAUSE),
+		 SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME),
 	.formats = (SNDRV_PCM_FMTBIT_S16_LE),
 	.rates = (SNDRV_PCM_RATE_8000 | SNDRV_PCM_RATE_16000 |
 		  SNDRV_PCM_RATE_22050 | SNDRV_PCM_RATE_32000 |