ALSA: pcm: Introduce copy_user, copy_kernel and fill_silence ops

For supporting the explicit in-kernel copy of PCM buffer data, and
also for further code refactoring, three new PCM ops, copy_user,
copy_kernel and fill_silence, are introduced.  The old copy and
silence ops will be deprecated and removed later once when all callers
are converted.

The copy_kernel ops is the new one, and it's supposed to transfer the
PCM data from the given kernel buffer to the hardware ring-buffer (or
vice-versa depending on the stream direction), while the copy_user ops
is equivalent with the former copy ops, to transfer the data from the
user-space buffer.

The major difference of the new copy_* and fill_silence ops from the
previous ops is that the new ops take bytes instead of frames for size
and position arguments.  It has two merits: first, it allows the
callback implementation often simpler (just call directly memcpy() &
co), and second, it may unify the implementations of both interleaved
and non-interleaved cases, as we'll see in the later patch.

As of this stage, copy_kernel ops isn't referred yet, but only
copy_user is used.

Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 79fedf517070..86b126be49a2 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -83,6 +83,13 @@ struct snd_pcm_ops {
 		    void __user *buf, snd_pcm_uframes_t count);
 	int (*silence)(struct snd_pcm_substream *substream, int channel, 
 		       snd_pcm_uframes_t pos, snd_pcm_uframes_t count);
+	int (*fill_silence)(struct snd_pcm_substream *substream, int channel,
+			    unsigned long pos, unsigned long bytes);
+	int (*copy_user)(struct snd_pcm_substream *substream, int channel,
+			 unsigned long pos, void __user *buf,
+			 unsigned long bytes);
+	int (*copy_kernel)(struct snd_pcm_substream *substream, int channel,
+			   unsigned long pos, void *buf, unsigned long bytes);
 	struct page *(*page)(struct snd_pcm_substream *substream,
 			     unsigned long offset);
 	int (*mmap)(struct snd_pcm_substream *substream, struct vm_area_struct *vma);