soundwire: stream: add helper to startup/shutdown streams

To handle streams at the dailink level, expose two helpers that will
be called from machine drivers.

Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20200630184356.24939-3-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/driver-api/soundwire/stream.rst

@@ -293,6 +293,10 @@ per stream. From ASoC DPCM framework, this stream state maybe linked to
 
   int sdw_alloc_stream(char * stream_name);
 
+The SoundWire core provides a sdw_startup_stream() helper function,
+typically called during a dailink .startup() callback, which performs
+stream allocation and sets the stream pointer for all DAIs
+connected to a stream.
 
 SDW_STREAM_CONFIGURED
 ~~~~~~~~~~~~~~~~~~~~~
@@ -509,7 +513,12 @@ In .shutdown() the data structure maintaining stream state are freed up.
 
   void sdw_release_stream(struct sdw_stream_runtime * stream);
 
-Not Supported
+The SoundWire core provides a sdw_shutdown_stream() helper function,
+typically called during a dailink .shutdown() callback, which clears
+the stream pointer for all DAIS connected to a stream and releases the
+memory allocated for the stream.
+
+  Not Supported
 =============
 
 1. A single port with multiple channels supported cannot be used between two

drivers/soundwire/stream.c

@@ -13,6 +13,7 @@
 #include <linux/slab.h>
 #include <linux/soundwire/sdw_registers.h>
 #include <linux/soundwire/sdw.h>
+#include <sound/soc.h>
 #include "bus.h"
 
 /*
@@ -1826,3 +1827,100 @@ state_err:
 	return ret;
 }
 EXPORT_SYMBOL(sdw_deprepare_stream);
+
+static int set_stream(struct snd_pcm_substream *substream,
+		      struct sdw_stream_runtime *sdw_stream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_dai *dai;
+	int ret = 0;
+	int i;
+
+	/* Set stream pointer on all DAIs */
+	for_each_rtd_dais(rtd, i, dai) {
+		ret = snd_soc_dai_set_sdw_stream(dai, sdw_stream, substream->stream);
+		if (ret < 0) {
+			dev_err(rtd->dev, "failed to set stream pointer on dai %s", dai->name);
+			break;
+		}
+	}
+
+	return ret;
+}
+
+/**
+ * sdw_startup_stream() - Startup SoundWire stream
+ *
+ * @stream: Soundwire stream
+ *
+ * Documentation/driver-api/soundwire/stream.rst explains this API in detail
+ */
+int sdw_startup_stream(void *sdw_substream)
+{
+	struct snd_pcm_substream *substream = sdw_substream;
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct sdw_stream_runtime *sdw_stream;
+	char *name;
+	int ret;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		name = kasprintf(GFP_KERNEL, "%s-Playback", substream->name);
+	else
+		name = kasprintf(GFP_KERNEL, "%s-Capture", substream->name);
+
+	if (!name)
+		return -ENOMEM;
+
+	sdw_stream = sdw_alloc_stream(name);
+	if (!sdw_stream) {
+		dev_err(rtd->dev, "alloc stream failed for substream DAI %s", substream->name);
+		ret = -ENOMEM;
+		goto error;
+	}
+
+	ret = set_stream(substream, sdw_stream);
+	if (ret < 0)
+		goto release_stream;
+	return 0;
+
+release_stream:
+	sdw_release_stream(sdw_stream);
+	set_stream(substream, NULL);
+error:
+	kfree(name);
+	return ret;
+}
+EXPORT_SYMBOL(sdw_startup_stream);
+
+/**
+ * sdw_shutdown_stream() - Shutdown SoundWire stream
+ *
+ * @stream: Soundwire stream
+ *
+ * Documentation/driver-api/soundwire/stream.rst explains this API in detail
+ */
+void sdw_shutdown_stream(void *sdw_substream)
+{
+	struct snd_pcm_substream *substream = sdw_substream;
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct sdw_stream_runtime *sdw_stream;
+	struct snd_soc_dai *dai;
+
+	/* Find stream from first CPU DAI */
+	dai = asoc_rtd_to_cpu(rtd, 0);
+
+	sdw_stream = snd_soc_dai_get_sdw_stream(dai, substream->stream);
+
+	if (!sdw_stream) {
+		dev_err(rtd->dev, "no stream found for DAI %s", dai->name);
+		return;
+	}
+
+	/* release memory */
+	kfree(sdw_stream->name);
+	sdw_release_stream(sdw_stream);
+
+	/* clear DAI data */
+	set_stream(substream, NULL);
+}
+EXPORT_SYMBOL(sdw_shutdown_stream);

include/linux/soundwire/sdw.h

@@ -955,10 +955,12 @@ int sdw_stream_remove_master(struct sdw_bus *bus,
 		struct sdw_stream_runtime *stream);
 int sdw_stream_remove_slave(struct sdw_slave *slave,
 		struct sdw_stream_runtime *stream);
+int sdw_startup_stream(void *sdw_substream);
 int sdw_prepare_stream(struct sdw_stream_runtime *stream);
 int sdw_enable_stream(struct sdw_stream_runtime *stream);
 int sdw_disable_stream(struct sdw_stream_runtime *stream);
 int sdw_deprepare_stream(struct sdw_stream_runtime *stream);
+void sdw_shutdown_stream(void *sdw_substream);
 int sdw_bus_prep_clk_stop(struct sdw_bus *bus);
 int sdw_bus_clk_stop(struct sdw_bus *bus);
 int sdw_bus_exit_clk_stop(struct sdw_bus *bus);