Now all materials are ready, let's allow the direct in-kernel
read/write, i.e. a kernel-space buffer is passed for read or write,
instead of the normal user-space buffer. This feature is used by OSS
layer and UAC1 driver, for example.
The __snd_pcm_lib_xfer() takes in_kernel argument that indicates the
in-kernel buffer copy. When this flag is set, another transfer code
is used. It's either via copy_kernel PCM ops or the normal memcpy(),
depending on the driver setup.
As external API, snd_pcm_kernel_read(), *_write() and other variants
are provided.
That's all. This support is really simple because of the code
refactoring until now.
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
include/sound/pcm.h | 38 +++++++++++++++++++++++++++++++++-----
sound/core/pcm_lib.c | 26 +++++++++++++++++++++++++-
2 files changed, 58 insertions(+), 6 deletions(-)
diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 173c6a6ebf35..e3a7269824c7 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -1090,34 +1090,62 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram
void snd_pcm_period_elapsed(struct snd_pcm_substream *substream);
snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
void *buf, bool interleaved,
- snd_pcm_uframes_t frames);
+ snd_pcm_uframes_t frames, bool in_kernel);
static inline snd_pcm_sframes_t
snd_pcm_lib_write(struct snd_pcm_substream *substream,
const void __user *buf, snd_pcm_uframes_t frames)
{
- return __snd_pcm_lib_xfer(substream, (void *)buf, true, frames);
+ return __snd_pcm_lib_xfer(substream, (void *)buf, true, frames, false);
}
static inline snd_pcm_sframes_t
snd_pcm_lib_read(struct snd_pcm_substream *substream,
void __user *buf, snd_pcm_uframes_t frames)
{
- return __snd_pcm_lib_xfer(substream, (void *)buf, true, frames);
+ return __snd_pcm_lib_xfer(substream, (void *)buf, true, frames, false);
}
static inline snd_pcm_sframes_t
snd_pcm_lib_writev(struct snd_pcm_substream *substream,
void __user **bufs, snd_pcm_uframes_t frames)
{
- return __snd_pcm_lib_xfer(substream, (void *)bufs, false, frames);
+ return __snd_pcm_lib_xfer(substream, (void *)bufs, false, frames, false);
}
static inline snd_pcm_sframes_t
snd_pcm_lib_readv(struct snd_pcm_substream *substream,
void __user **bufs, snd_pcm_uframes_t frames)
{
- return __snd_pcm_lib_xfer(substream, (void *)bufs, false, frames);
+ return __snd_pcm_lib_xfer(substream, (void *)bufs, false, frames, false);
+}
+
+static inline snd_pcm_sframes_t
+snd_pcm_kernel_write(struct snd_pcm_substream *substream,
+ const void *buf, snd_pcm_uframes_t frames)
+{
+ return __snd_pcm_lib_xfer(substream, (void *)buf, true, frames, true);
+}
+
+static inline snd_pcm_sframes_t
+snd_pcm_kernel_read(struct snd_pcm_substream *substream,
+ void *buf, snd_pcm_uframes_t frames)
+{
+ return __snd_pcm_lib_xfer(substream, buf, true, frames, true);
+}
+
+static inline snd_pcm_sframes_t
+snd_pcm_kernel_writev(struct snd_pcm_substream *substream,
+ void **bufs, snd_pcm_uframes_t frames)
+{
+ return __snd_pcm_lib_xfer(substream, bufs, false, frames, true);
+}
+
+static inline snd_pcm_sframes_t
+snd_pcm_kernel_readv(struct snd_pcm_substream *substream,
+ void **bufs, snd_pcm_uframes_t frames)
+{
+ return __snd_pcm_lib_xfer(substream, bufs, false, frames, true);
}
extern const struct snd_pcm_hw_constraint_list snd_pcm_known_rates;
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index a592d3308474..ba08b246d153 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -1992,6 +1992,15 @@ static int default_write_copy(struct snd_pcm_substream *substream,
return 0;
}
+/* default copy_kernel ops for write */
+static int default_write_copy_kernel(struct snd_pcm_substream *substream,
+ int channel, unsigned long hwoff,
+ void *buf, unsigned long bytes)
+{
+ memcpy(get_dma_ptr(substream->runtime, channel, hwoff), buf, bytes);
+ return 0;
+}
+
/* fill silence instead of copy data; called as a transfer helper
* from __snd_pcm_lib_write() or directly from noninterleaved_copy() when
* a NULL buffer is passed
@@ -2025,6 +2034,15 @@ static int default_read_copy(struct snd_pcm_substream *substream,
return 0;
}
+/* default copy_kernel ops for read */
+static int default_read_copy_kernel(struct snd_pcm_substream *substream,
+ int channel, unsigned long hwoff,
+ void *buf, unsigned long bytes)
+{
+ memcpy(buf, get_dma_ptr(substream->runtime, channel, hwoff), bytes);
+ return 0;
+}
+
/* call transfer function with the converted pointers and sizes;
* for interleaved mode, it's one shot for all samples
*/
@@ -2124,7 +2142,7 @@ static int pcm_accessible_state(struct snd_pcm_runtime *runtime)
/* the common loop for read/write data */
snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
void *data, bool interleaved,
- snd_pcm_uframes_t size)
+ snd_pcm_uframes_t size, bool in_kernel)
{
struct snd_pcm_runtime *runtime = substream->runtime;
snd_pcm_uframes_t xfer = 0;
@@ -2157,6 +2175,12 @@ snd_pcm_sframes_t __snd_pcm_lib_xfer(struct snd_pcm_substream *substream,
transfer = fill_silence;
else
return -EINVAL;
+ } else if (in_kernel) {
+ if (substream->ops->copy_kernel)
+ transfer = substream->ops->copy_kernel;
+ else
+ transfer = is_playback ?
+ default_write_copy_kernel : default_read_copy_kernel;
} else {
if (substream->ops->copy_user)
transfer = (pcm_transfer_f)substream->ops->copy_user;
--
2.13.0
