ALSA: pcm - Export snd_pcm_lib_default_mmap() helper

Export the default mmap function, snd_pcm_lib_default_mmap().
The upcoming non-snooping support in HD-audio driver will use this
to override the mmap method.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/pcm.h

@@ -1035,6 +1035,8 @@ static inline void snd_pcm_mmap_data_close(struct vm_area_struct *area)
 	atomic_dec(&substream->mmap_count);
 }
 
+int snd_pcm_lib_default_mmap(struct snd_pcm_substream *substream,
+			     struct vm_area_struct *area);
 /* mmap for io-memory area */
 #if defined(CONFIG_X86) || defined(CONFIG_PPC) || defined(CONFIG_ALPHA)
 #define SNDRV_PCM_INFO_MMAP_IOMEM	SNDRV_PCM_INFO_MMAP

sound/core/pcm_native.c

@@ -3156,7 +3156,7 @@ static const struct vm_operations_struct snd_pcm_vm_ops_data_fault = {
 /*
  * mmap the DMA buffer on RAM
  */
-static int snd_pcm_default_mmap(struct snd_pcm_substream *substream,
+int snd_pcm_lib_default_mmap(struct snd_pcm_substream *substream,
 			     struct vm_area_struct *area)
 {
 	area->vm_flags |= VM_RESERVED;
@@ -3177,6 +3177,7 @@ static int snd_pcm_default_mmap(struct snd_pcm_substream *substream,
 	area->vm_ops = &snd_pcm_vm_ops_data_fault;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(snd_pcm_lib_default_mmap);
 
 /*
  * mmap the DMA buffer on I/O memory area
@@ -3242,7 +3243,7 @@ int snd_pcm_mmap_data(struct snd_pcm_substream *substream, struct file *file,
 	if (substream->ops->mmap)
 		err = substream->ops->mmap(substream, area);
 	else
-		err = snd_pcm_default_mmap(substream, area);
+		err = snd_pcm_lib_default_mmap(substream, area);
 	if (!err)
 		atomic_inc(&substream->mmap_count);
 	return err;