1 files changed, 106 insertions, 0 deletions

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 9c411b82a218..9fb8726a6c93 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -118,6 +118,95 @@ MODULE_PARM_DESC(skip_validation, "Skip unit descriptor validation (default: no)
 static DEFINE_MUTEX(register_mutex);
 static struct snd_usb_audio *usb_chip[SNDRV_CARDS];
 static struct usb_driver usb_audio_driver;
+static struct snd_usb_platform_ops *platform_ops;
+
+/*
+ * Register platform specific operations that will be notified on events
+ * which occur in USB SND.  The platform driver can utilize this path to
+ * enable features, such as USB audio offloading, which allows for audio data
+ * to be queued by an audio DSP.
+ *
+ * Only one set of platform operations can be registered to USB SND.  The
+ * platform register operation is protected by the register_mutex.
+ */
+int snd_usb_register_platform_ops(struct snd_usb_platform_ops *ops)
+{
+	guard(mutex)(&register_mutex);
+	if (platform_ops)
+		return -EEXIST;
+
+	platform_ops = ops;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_usb_register_platform_ops);
+
+/*
+ * Unregisters the current set of platform operations.  This allows for
+ * a new set to be registered if required.
+ *
+ * The platform unregister operation is protected by the register_mutex.
+ */
+int snd_usb_unregister_platform_ops(void)
+{
+	guard(mutex)(&register_mutex);
+	platform_ops = NULL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_usb_unregister_platform_ops);
+
+/*
+ * in case the platform driver was not ready at the time of USB SND
+ * device connect, expose an API to discover all connected USB devices
+ * so it can populate any dependent resources/structures.
+ */
+void snd_usb_rediscover_devices(void)
+{
+	int i;
+
+	guard(mutex)(&register_mutex);
+
+	if (!platform_ops || !platform_ops->connect_cb)
+		return;
+
+	for (i = 0; i < SNDRV_CARDS; i++) {
+		if (usb_chip[i])
+			platform_ops->connect_cb(usb_chip[i]);
+	}
+}
+EXPORT_SYMBOL_GPL(snd_usb_rediscover_devices);
+
+/*
+ * Checks to see if requested audio profile, i.e sample rate, # of
+ * channels, etc... is supported by the substream associated to the
+ * USB audio device.
+ */
+struct snd_usb_stream *
+snd_usb_find_suppported_substream(int card_idx, struct snd_pcm_hw_params *params,
+				  int direction)
+{
+	struct snd_usb_audio *chip;
+	struct snd_usb_substream *subs;
+	struct snd_usb_stream *as;
+
+	/*
+	 * Register mutex is held when populating and clearing usb_chip
+	 * array.
+	 */
+	guard(mutex)(&register_mutex);
+	chip = usb_chip[card_idx];
+
+	if (chip && enable[card_idx]) {
+		list_for_each_entry(as, &chip->pcm_list, list) {
+			subs = &as->substream[direction];
+			if (snd_usb_find_substream_format(subs, params))
+				return as;
+		}
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(snd_usb_find_suppported_substream);
 
 /*
  * disconnect streams
@@ -922,7 +1011,11 @@ static int usb_audio_probe(struct usb_interface *intf,
 	chip->num_interfaces++;
 	usb_set_intfdata(intf, chip);
 	atomic_dec(&chip->active);
+
+	if (platform_ops && platform_ops->connect_cb)
+		platform_ops->connect_cb(chip);
 	mutex_unlock(&register_mutex);
+
 	return 0;
 
  __error:
@@ -959,6 +1052,9 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 	card = chip->card;
 
 	mutex_lock(&register_mutex);
+	if (platform_ops && platform_ops->disconnect_cb)
+		platform_ops->disconnect_cb(chip);
+
 	if (atomic_inc_return(&chip->shutdown) == 1) {
 		struct snd_usb_stream *as;
 		struct snd_usb_endpoint *ep;
@@ -1030,6 +1126,7 @@ 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 +1135,7 @@ 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 +1158,7 @@ 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 +1172,7 @@ 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)
 {
@@ -1102,6 +1202,9 @@ static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
 		chip->system_suspend = chip->num_suspended_intf;
 	}
 
+	if (platform_ops && platform_ops->suspend_cb)
+		platform_ops->suspend_cb(intf, message);
+
 	return 0;
 }
 
@@ -1142,6 +1245,9 @@ static int usb_audio_resume(struct usb_interface *intf)
 
 	snd_usb_midi_v2_resume_all(chip);
 
+	if (platform_ops && platform_ops->resume_cb)
+		platform_ops->resume_cb(intf);
+
  out:
 	if (chip->num_suspended_intf == chip->system_suspend) {
 		snd_power_change_state(chip->card, SNDRV_CTL_POWER_D0);