ALSA: usb-audio: Export USB SND APIs for modules

Some vendor modules will utilize useful parsing and endpoint management
APIs to start audio playback/capture.

Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Tested-by: Puma Hsu <pumahsu@google.com>
Tested-by: Daehwan Jung <dh10.jung@samsung.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Acked-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20250409194804.3773260-9-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sound/usb/card.c

@@ -1030,6 +1030,7 @@ int snd_usb_lock_shutdown(struct snd_usb_audio *chip)
 		wake_up(&chip->shutdown_wait);
 	return err;
 }
+EXPORT_SYMBOL_GPL(snd_usb_lock_shutdown);
 
 /* autosuspend and unlock the shutdown */
 void snd_usb_unlock_shutdown(struct snd_usb_audio *chip)
@@ -1038,6 +1039,7 @@ void snd_usb_unlock_shutdown(struct snd_usb_audio *chip)
 	if (atomic_dec_and_test(&chip->usage_count))
 		wake_up(&chip->shutdown_wait);
 }
+EXPORT_SYMBOL_GPL(snd_usb_unlock_shutdown);
 
 int snd_usb_autoresume(struct snd_usb_audio *chip)
 {
@@ -1060,6 +1062,7 @@ int snd_usb_autoresume(struct snd_usb_audio *chip)
 	}
 	return 0;
 }
+EXPORT_SYMBOL_GPL(snd_usb_autoresume);
 
 void snd_usb_autosuspend(struct snd_usb_audio *chip)
 {
@@ -1073,6 +1076,7 @@ void snd_usb_autosuspend(struct snd_usb_audio *chip)
 	for (i = 0; i < chip->num_interfaces; i++)
 		usb_autopm_put_interface(chip->intf[i]);
 }
+EXPORT_SYMBOL_GPL(snd_usb_autosuspend);
 
 static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
 {

sound/usb/endpoint.c

@@ -1524,6 +1524,7 @@ unlock:
 	mutex_unlock(&chip->mutex);
 	return err;
 }
+EXPORT_SYMBOL_GPL(snd_usb_endpoint_prepare);
 
 /* get the current rate set to the given clock by any endpoint */
 int snd_usb_endpoint_get_clock_rate(struct snd_usb_audio *chip, int clock)

sound/usb/helper.c

@@ -62,6 +62,7 @@ void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype
 	}
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(snd_usb_find_csint_desc);
 
 /*
  * Wrapper for usb_control_msg().

sound/usb/pcm.c

@@ -148,6 +148,16 @@ find_format(struct list_head *fmt_list_head, snd_pcm_format_t format,
 	return found;
 }
 
+const struct audioformat *
+snd_usb_find_format(struct list_head *fmt_list_head, snd_pcm_format_t format,
+		    unsigned int rate, unsigned int channels, bool strict_match,
+		    struct snd_usb_substream *subs)
+{
+	return find_format(fmt_list_head, format, rate, channels, strict_match,
+			subs);
+}
+EXPORT_SYMBOL_GPL(snd_usb_find_format);
+
 static const struct audioformat *
 find_substream_format(struct snd_usb_substream *subs,
 		      const struct snd_pcm_hw_params *params)
@@ -157,6 +167,14 @@ find_substream_format(struct snd_usb_substream *subs,
 			   true, subs);
 }
 
+const struct audioformat *
+snd_usb_find_substream_format(struct snd_usb_substream *subs,
+			      const struct snd_pcm_hw_params *params)
+{
+	return find_substream_format(subs, params);
+}
+EXPORT_SYMBOL_GPL(snd_usb_find_substream_format);
+
 bool snd_usb_pcm_has_fixed_rate(struct snd_usb_substream *subs)
 {
 	const struct audioformat *fp;
@@ -461,20 +479,9 @@ static void close_endpoints(struct snd_usb_audio *chip,
 	}
 }
 
-/*
+int snd_usb_hw_params(struct snd_usb_substream *subs,
- * hw_params callback
- *
- * allocate a buffer and set the given audio format.
- *
- * so far we use a physically linear buffer although packetize transfer
- * doesn't need a continuous area.
- * if sg buffer is supported on the later version of alsa, we'll follow
- * that.
- */
-static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 		      struct snd_pcm_hw_params *hw_params)
 {
-	struct snd_usb_substream *subs = substream->runtime->private_data;
 	struct snd_usb_audio *chip = subs->stream->chip;
 	const struct audioformat *fmt;
 	const struct audioformat *sync_fmt;
@@ -499,7 +506,7 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 	if (fmt->implicit_fb) {
 		sync_fmt = snd_usb_find_implicit_fb_sync_format(chip, fmt,
 								hw_params,
-								!substream->stream,
+								!subs->direction,
 								&sync_fixed_rate);
 		if (!sync_fmt) {
 			usb_audio_dbg(chip,
@@ -579,15 +586,28 @@ static int snd_usb_hw_params(struct snd_pcm_substream *substream,
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(snd_usb_hw_params);
 
 /*
- * hw_free callback
+ * hw_params callback
  *
- * reset the audio format and release the buffer
+ * allocate a buffer and set the given audio format.
+ *
+ * so far we use a physically linear buffer although packetize transfer
+ * doesn't need a continuous area.
+ * if sg buffer is supported on the later version of alsa, we'll follow
+ * that.
  */
-static int snd_usb_hw_free(struct snd_pcm_substream *substream)
+static int snd_usb_pcm_hw_params(struct snd_pcm_substream *substream,
+				 struct snd_pcm_hw_params *hw_params)
 {
 	struct snd_usb_substream *subs = substream->runtime->private_data;
+
+	return snd_usb_hw_params(subs, hw_params);
+}
+
+int snd_usb_hw_free(struct snd_usb_substream *subs)
+{
 	struct snd_usb_audio *chip = subs->stream->chip;
 
 	snd_media_stop_pipeline(subs);
@@ -603,6 +623,19 @@ static int snd_usb_hw_free(struct snd_pcm_substream *substream)
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(snd_usb_hw_free);
+
+/*
+ * hw_free callback
+ *
+ * reset the audio format and release the buffer
+ */
+static int snd_usb_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+	struct snd_usb_substream *subs = substream->runtime->private_data;
+
+	return snd_usb_hw_free(subs);
+}
 
 /* free-wheeling mode? (e.g. dmix) */
 static int in_free_wheeling_mode(struct snd_pcm_runtime *runtime)
@@ -1746,8 +1779,8 @@ static int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream
 static const struct snd_pcm_ops snd_usb_playback_ops = {
 	.open =		snd_usb_pcm_open,
 	.close =	snd_usb_pcm_close,
-	.hw_params =	snd_usb_hw_params,
+	.hw_params =	snd_usb_pcm_hw_params,
-	.hw_free =	snd_usb_hw_free,
+	.hw_free =	snd_usb_pcm_hw_free,
 	.prepare =	snd_usb_pcm_prepare,
 	.trigger =	snd_usb_substream_playback_trigger,
 	.sync_stop =	snd_usb_pcm_sync_stop,
@@ -1758,8 +1791,8 @@ static const struct snd_pcm_ops snd_usb_playback_ops = {
 static const struct snd_pcm_ops snd_usb_capture_ops = {
 	.open =		snd_usb_pcm_open,
 	.close =	snd_usb_pcm_close,
-	.hw_params =	snd_usb_hw_params,
+	.hw_params =	snd_usb_pcm_hw_params,
-	.hw_free =	snd_usb_hw_free,
+	.hw_free =	snd_usb_pcm_hw_free,
 	.prepare =	snd_usb_pcm_prepare,
 	.trigger =	snd_usb_substream_capture_trigger,
 	.sync_stop =	snd_usb_pcm_sync_stop,

sound/usb/pcm.h

@@ -15,4 +15,15 @@ void snd_usb_preallocate_buffer(struct snd_usb_substream *subs);
 int snd_usb_audioformat_set_sync_ep(struct snd_usb_audio *chip,
 				    struct audioformat *fmt);
 
+const struct audioformat *
+snd_usb_find_format(struct list_head *fmt_list_head, snd_pcm_format_t format,
+		    unsigned int rate, unsigned int channels, bool strict_match,
+		    struct snd_usb_substream *subs);
+const struct audioformat *
+snd_usb_find_substream_format(struct snd_usb_substream *subs,
+			      const struct snd_pcm_hw_params *params);
+
+int snd_usb_hw_params(struct snd_usb_substream *subs,
+		      struct snd_pcm_hw_params *hw_params);
+int snd_usb_hw_free(struct snd_usb_substream *subs);
 #endif /* __USBAUDIO_PCM_H */