ASoC: fsl_sai: Move clock operation to PM runtime

Turn off/on clocks when device enters suspend/resume. This
can help saving power.

As a further optimization, we turn off/on mclk only when SAI
is in master mode because otherwise mclk is externally provided.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Viorel Suman <viorel.suman@nxp.com>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_sai.c

@@ -596,15 +596,8 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream,
 {
 	struct fsl_sai *sai = snd_soc_dai_get_drvdata(cpu_dai);
 	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
-	struct device *dev = &sai->pdev->dev;
 	int ret;
 
-	ret = clk_prepare_enable(sai->bus_clk);
-	if (ret) {
-		dev_err(dev, "failed to enable bus clock: %d\n", ret);
-		return ret;
-	}
-
 	regmap_update_bits(sai->regmap, FSL_SAI_xCR3(tx), FSL_SAI_CR3_TRCE,
 			   FSL_SAI_CR3_TRCE);
 
@@ -621,8 +614,6 @@ static void fsl_sai_shutdown(struct snd_pcm_substream *substream,
 	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
 
 	regmap_update_bits(sai->regmap, FSL_SAI_xCR3(tx), FSL_SAI_CR3_TRCE, 0);
-
-	clk_disable_unprepare(sai->bus_clk);
 }
 
 static const struct snd_soc_dai_ops fsl_sai_pcm_dai_ops = {
@@ -935,6 +926,14 @@ static int fsl_sai_runtime_suspend(struct device *dev)
 {
 	struct fsl_sai *sai = dev_get_drvdata(dev);
 
+	if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_CAPTURE))
+		clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[0]]);
+
+	if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_PLAYBACK))
+		clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[1]]);
+
+	clk_disable_unprepare(sai->bus_clk);
+
 	regcache_cache_only(sai->regmap, true);
 	regcache_mark_dirty(sai->regmap);
 
@@ -944,6 +943,25 @@ static int fsl_sai_runtime_suspend(struct device *dev)
 static int fsl_sai_runtime_resume(struct device *dev)
 {
 	struct fsl_sai *sai = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(sai->bus_clk);
+	if (ret) {
+		dev_err(dev, "failed to enable bus clock: %d\n", ret);
+		return ret;
+	}
+
+	if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_PLAYBACK)) {
+		ret = clk_prepare_enable(sai->mclk_clk[sai->mclk_id[1]]);
+		if (ret)
+			goto disable_bus_clk;
+	}
+
+	if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_CAPTURE)) {
+		ret = clk_prepare_enable(sai->mclk_clk[sai->mclk_id[0]]);
+		if (ret)
+			goto disable_tx_clk;
+	}
 
 	regcache_cache_only(sai->regmap, false);
 	regmap_write(sai->regmap, FSL_SAI_TCSR, FSL_SAI_CSR_SR);
@@ -951,7 +969,23 @@ static int fsl_sai_runtime_resume(struct device *dev)
 	usleep_range(1000, 2000);
 	regmap_write(sai->regmap, FSL_SAI_TCSR, 0);
 	regmap_write(sai->regmap, FSL_SAI_RCSR, 0);
-	return regcache_sync(sai->regmap);
+
+	ret = regcache_sync(sai->regmap);
+	if (ret)
+		goto disable_rx_clk;
+
+	return 0;
+
+disable_rx_clk:
+	if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_CAPTURE))
+		clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[0]]);
+disable_tx_clk:
+	if (sai->mclk_streams & BIT(SNDRV_PCM_STREAM_PLAYBACK))
+		clk_disable_unprepare(sai->mclk_clk[sai->mclk_id[1]]);
+disable_bus_clk:
+	clk_disable_unprepare(sai->bus_clk);
+
+	return ret;
 }
 #endif /* CONFIG_PM */