ASoC: apple: mca: Separate data & clock port setup

Up until now FEs were always the clock providers -- feeding the clocks
on any ports (BEs) they are attached to. This will soon change and FEs
will be allowed to be clock consumers. Once that happens, the routing
of clocks and data will to some degree decouple.

In advance of the change, make preparations:

 * Narrow down semantics of what was formerly the 'port_driver' field
   to refer to clocks only.

 * On 'startup' of BEs, separate the clock and data aspects of the port
   setup.

Signed-off-by: Martin Povišer <povik+lin@cutebit.org>

Author: povik

sound/soc/apple/mca.c

@@ -133,8 +133,8 @@ struct mca_cluster {
 	struct clk *clk_parent;
 	struct dma_chan *dma_chans[SNDRV_PCM_STREAM_LAST + 1];
 
-	bool port_started[SNDRV_PCM_STREAM_LAST + 1];
-	int port_driver; /* The cluster driving this cluster's port */
+	bool port_clk_started[SNDRV_PCM_STREAM_LAST + 1];
+	int port_clk_driver; /* The cluster driving this cluster's port */
 
 	bool clocks_in_use[SNDRV_PCM_STREAM_LAST + 1];
 	struct device_link *pd_link;
@@ -157,7 +157,7 @@ struct mca_data {
 	struct reset_control *rstc;
 	struct device_link *pd_link;
 
-	/* Mutex for accessing port_driver of foreign clusters */
+	/* Mutex for accessing port_clk_driver of foreign clusters */
 	struct mutex port_mutex;
 
 	int nclusters;
@@ -311,7 +311,7 @@ static bool mca_fe_clocks_in_use(struct mca_cluster *cl)
 	for (i = 0; i < mca->nclusters; i++) {
 		be_cl = &mca->clusters[i];
 
-		if (be_cl->port_driver != cl->no)
+		if (be_cl->port_clk_driver != cl->no)
 			continue;
 
 		for_each_pcm_streams(stream) {
@@ -333,10 +333,10 @@ static int mca_be_prepare(struct snd_pcm_substream *substream,
 	struct mca_cluster *fe_cl;
 	int ret;
 
-	if (cl->port_driver < 0)
+	if (cl->port_clk_driver < 0)
 		return -EINVAL;
 
-	fe_cl = &mca->clusters[cl->port_driver];
+	fe_cl = &mca->clusters[cl->port_clk_driver];
 
 	/*
 	 * Typically the CODECs we are paired with will require clocks
@@ -683,12 +683,15 @@ static const struct snd_soc_dai_ops mca_fe_ops = {
 	.trigger = mca_fe_trigger,
 };
 
-static bool mca_be_started(struct mca_cluster *cl)
+/*
+ * Is there a FE attached which will be feeding this port's clocks?
+ */
+static bool mca_be_clk_started(struct mca_cluster *cl)
 {
 	int stream;
 
 	for_each_pcm_streams(stream)
-		if (cl->port_started[stream])
+		if (cl->port_clk_started[stream])
 			return true;
 	return false;
 }
@@ -719,29 +722,35 @@ static int mca_be_startup(struct snd_pcm_substream *substream,
 
 	fe_cl = mca_dai_to_cluster(snd_soc_rtd_to_cpu(fe, 0));
 
-	if (mca_be_started(cl)) {
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		writel_relaxed(PORT_DATA_SEL_TXA(fe_cl->no),
+			       cl->base + REG_PORT_DATA_SEL);
+		mca_modify(cl, REG_PORT_ENABLES, PORT_ENABLES_TX_DATA,
+			   PORT_ENABLES_TX_DATA);
+	}
+
+	if (mca_be_clk_started(cl)) {
 		/*
 		 * Port is already started in the other direction.
 		 * Make sure there isn't a conflict with another cluster
-		 * driving the port.
+		 * driving the port clocks.
 		 */
-		if (cl->port_driver != fe_cl->no)
+		if (cl->port_clk_driver != fe_cl->no)
 			return -EINVAL;
 
-		cl->port_started[substream->stream] = true;
+		cl->port_clk_started[substream->stream] = true;
 		return 0;
 	}
 
-	writel_relaxed(PORT_ENABLES_CLOCKS | PORT_ENABLES_TX_DATA,
-		       cl->base + REG_PORT_ENABLES);
 	writel_relaxed(FIELD_PREP(PORT_CLOCK_SEL, fe_cl->no + 1),
 		       cl->base + REG_PORT_CLOCK_SEL);
-	writel_relaxed(PORT_DATA_SEL_TXA(fe_cl->no),
-		       cl->base + REG_PORT_DATA_SEL);
+	mca_modify(cl, REG_PORT_ENABLES, PORT_ENABLES_CLOCKS,
+		   PORT_ENABLES_CLOCKS);
+
 	mutex_lock(&mca->port_mutex);
-	cl->port_driver = fe_cl->no;
+	cl->port_clk_driver = fe_cl->no;
 	mutex_unlock(&mca->port_mutex);
-	cl->port_started[substream->stream] = true;
+	cl->port_clk_started[substream->stream] = true;
 
 	return 0;
 }
@@ -753,8 +762,8 @@ static void mca_be_shutdown(struct snd_pcm_substream *substream,
 	struct mca_data *mca = cl->host;
 
 	if (cl->clocks_in_use[substream->stream] &&
-		!WARN_ON(cl->port_driver < 0)) {
-		struct mca_cluster *fe_cl = &mca->clusters[cl->port_driver];
+		!WARN_ON(cl->port_clk_driver < 0)) {
+		struct mca_cluster *fe_cl = &mca->clusters[cl->port_clk_driver];
 
 		/*
 		 * Typically the CODECs we are paired with will require clocks
@@ -772,17 +781,21 @@ static void mca_be_shutdown(struct snd_pcm_substream *substream,
 			mca_fe_disable_clocks(fe_cl);
 	}
 
-	cl->port_started[substream->stream] = false;
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		mca_modify(cl, REG_PORT_ENABLES, PORT_ENABLES_TX_DATA, 0);
+		writel_relaxed(0, cl->base + REG_PORT_DATA_SEL);
+	}
 
-	if (!mca_be_started(cl)) {
+	cl->port_clk_started[substream->stream] = false;
+	if (!mca_be_clk_started(cl)) {
 		/*
 		 * Were we the last direction to shutdown?
-		 * Turn off the lights.
+		 * Turn off the lights (clocks).
 		 */
-		writel_relaxed(0, cl->base + REG_PORT_ENABLES);
-		writel_relaxed(0, cl->base + REG_PORT_DATA_SEL);
+		mca_modify(cl, REG_PORT_ENABLES, PORT_ENABLES_CLOCKS, 0);
+		writel_relaxed(0, cl->base + REG_PORT_CLOCK_SEL);
 		mutex_lock(&mca->port_mutex);
-		cl->port_driver = -1;
+		cl->port_clk_driver = -1;
 		mutex_unlock(&mca->port_mutex);
 	}
 }
@@ -1088,7 +1101,7 @@ static int apple_mca_probe(struct platform_device *pdev)
 		cl->host = mca;
 		cl->no = i;
 		cl->base = base + CLUSTER_STRIDE * i;
-		cl->port_driver = -1;
+		cl->port_clk_driver = -1;
 		cl->clk_parent = of_clk_get(pdev->dev.of_node, i);
 		if (IS_ERR(cl->clk_parent)) {
 			dev_err(&pdev->dev, "unable to obtain clock %d: %ld\n",