ALSA: pcm: More kerneldoc updates

Add proper kerneldoc comments to the exported functions.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm.c

@@ -218,6 +218,10 @@ static char *snd_pcm_format_names[] = {
 	FORMAT(DSD_U32_LE),
 };
 
+/**
+ * snd_pcm_format_name - Return a name string for the given PCM format
+ * @format: PCM format
+ */
 const char *snd_pcm_format_name(snd_pcm_format_t format)
 {
 	if ((__force unsigned int)format >= ARRAY_SIZE(snd_pcm_format_names))
@@ -707,7 +711,6 @@ int snd_pcm_new_stream(struct snd_pcm *pcm, int stream, int substream_count)
 	}
 	return 0;
 }				
-
 EXPORT_SYMBOL(snd_pcm_new_stream);
 
 static int _snd_pcm_new(struct snd_card *card, const char *id, int device,
@@ -1155,6 +1158,15 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 	return 0;
 }
 
+/**
+ * snd_pcm_notify - Add/remove the notify list
+ * @notify: PCM notify list
+ * @nfree: 0 = register, 1 = unregister
+ *
+ * This adds the given notifier to the global list so that the callback is
+ * called for each registered PCM devices.  This exists only for PCM OSS
+ * emulation, so far.
+ */
 int snd_pcm_notify(struct snd_pcm_notify *notify, int nfree)
 {
 	struct snd_pcm *pcm;
@@ -1177,7 +1189,6 @@ int snd_pcm_notify(struct snd_pcm_notify *notify, int nfree)
 	mutex_unlock(&register_mutex);
 	return 0;
 }
-
 EXPORT_SYMBOL(snd_pcm_notify);
 
 #ifdef CONFIG_PROC_FS

sound/core/pcm_native.c

@@ -74,6 +74,14 @@ static int snd_pcm_open(struct file *file, struct snd_pcm *pcm, int stream);
 static DEFINE_RWLOCK(snd_pcm_link_rwlock);
 static DECLARE_RWSEM(snd_pcm_link_rwsem);
 
+/**
+ * snd_pcm_stream_lock - Lock the PCM stream
+ * @substream: PCM substream
+ *
+ * This locks the PCM stream's spinlock or mutex depending on the nonatomic
+ * flag of the given substream.  This also takes the global link rw lock
+ * (or rw sem), too, for avoiding the race with linked streams.
+ */
 void snd_pcm_stream_lock(struct snd_pcm_substream *substream)
 {
 	if (substream->pcm->nonatomic) {
@@ -86,6 +94,12 @@ void snd_pcm_stream_lock(struct snd_pcm_substream *substream)
 }
 EXPORT_SYMBOL_GPL(snd_pcm_stream_lock);
 
+/**
+ * snd_pcm_stream_lock - Unlock the PCM stream
+ * @substream: PCM substream
+ *
+ * This unlocks the PCM stream that has been locked via snd_pcm_stream_lock().
+ */
 void snd_pcm_stream_unlock(struct snd_pcm_substream *substream)
 {
 	if (substream->pcm->nonatomic) {
@@ -98,6 +112,14 @@ void snd_pcm_stream_unlock(struct snd_pcm_substream *substream)
 }
 EXPORT_SYMBOL_GPL(snd_pcm_stream_unlock);
 
+/**
+ * snd_pcm_stream_lock_irq - Lock the PCM stream
+ * @substream: PCM substream
+ *
+ * This locks the PCM stream like snd_pcm_stream_lock() and disables the local
+ * IRQ (only when nonatomic is false).  In nonatomic case, this is identical
+ * as snd_pcm_stream_lock().
+ */
 void snd_pcm_stream_lock_irq(struct snd_pcm_substream *substream)
 {
 	if (!substream->pcm->nonatomic)
@@ -106,6 +128,12 @@ void snd_pcm_stream_lock_irq(struct snd_pcm_substream *substream)
 }
 EXPORT_SYMBOL_GPL(snd_pcm_stream_lock_irq);
 
+/**
+ * snd_pcm_stream_unlock_irq - Unlock the PCM stream
+ * @substream: PCM substream
+ *
+ * This is a counter-part of snd_pcm_stream_lock_irq().
+ */
 void snd_pcm_stream_unlock_irq(struct snd_pcm_substream *substream)
 {
 	snd_pcm_stream_unlock(substream);
@@ -124,6 +152,13 @@ unsigned long _snd_pcm_stream_lock_irqsave(struct snd_pcm_substream *substream)
 }
 EXPORT_SYMBOL_GPL(_snd_pcm_stream_lock_irqsave);
 
+/**
+ * snd_pcm_stream_unlock_irqrestore - Unlock the PCM stream
+ * @substream: PCM substream
+ * @flags: irq flags
+ *
+ * This is a counter-part of snd_pcm_stream_lock_irqsave().
+ */
 void snd_pcm_stream_unlock_irqrestore(struct snd_pcm_substream *substream,
 				      unsigned long flags)
 {
@@ -3312,6 +3347,15 @@ static const struct vm_operations_struct snd_pcm_vm_ops_data_fault = {
 /*
  * mmap the DMA buffer on RAM
  */
+
+/**
+ * snd_pcm_lib_default_mmap - Default PCM data mmap function
+ * @substream: PCM substream
+ * @area: VMA
+ *
+ * This is the default mmap handler for PCM data.  When mmap pcm_ops is NULL,
+ * this function is invoked implicitly.
+ */
 int snd_pcm_lib_default_mmap(struct snd_pcm_substream *substream,
 			     struct vm_area_struct *area)
 {
@@ -3343,6 +3387,15 @@ EXPORT_SYMBOL_GPL(snd_pcm_lib_default_mmap);
  * mmap the DMA buffer on I/O memory area
  */
 #if SNDRV_PCM_INFO_MMAP_IOMEM
+/**
+ * snd_pcm_lib_mmap_iomem - Default PCM data mmap function for I/O mem
+ * @substream: PCM substream
+ * @area: VMA
+ *
+ * When your hardware uses the iomapped pages as the hardware buffer and
+ * wants to mmap it, pass this function as mmap pcm_ops.  Note that this
+ * is supposed to work only on limited architectures.
+ */
 int snd_pcm_lib_mmap_iomem(struct snd_pcm_substream *substream,
 			   struct vm_area_struct *area)
 {