This commit adds a new framing mode that frames all MIDI data into
16-byte frames with a timestamp from the monotonic_raw clock.
The main benefit is that we can get accurate timestamps even if
userspace wakeup and processing is not immediate.
---
include/sound/rawmidi.h | 1 +
include/uapi/sound/asound.h | 18 ++++++++++++++-
sound/core/rawmidi.c | 45 ++++++++++++++++++++++++++++++++++++-
3 files changed, 62 insertions(+), 2 deletions(-)
diff --git a/include/sound/rawmidi.h b/include/sound/rawmidi.h
index 334842daa904..ea4d88d513e1 100644
--- a/include/sound/rawmidi.h
+++ b/include/sound/rawmidi.h
@@ -81,6 +81,7 @@ struct snd_rawmidi_substream {
bool opened; /* open flag */
bool append; /* append flag (merge more streams) */
bool active_sensing; /* send active sensing when close */
+ u8 framing; /* whether to frame data (for input) */
int use_count; /* use counter (for output) */
size_t bytes;
struct snd_rawmidi *rmidi;
diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 535a7229e1d9..13c3865a818e 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -736,12 +736,28 @@ struct snd_rawmidi_info {
unsigned char reserved[64]; /* reserved for future use */
};
+enum {
+ SNDRV_RAWMIDI_FRAMING_NONE = 0,
+ SNDRV_RAWMIDI_FRAMING_TSTAMP_MONOTONIC_RAW,
+ SNDRV_RAWMIDI_FRAMING_LAST = SNDRV_RAWMIDI_FRAMING_TSTAMP_MONOTONIC_RAW,
+};
+
+#define SND_RAWMIDI_FRAMING_DATA_LENGTH 7
+
+struct snd_rawmidi_framing_tstamp {
+ unsigned int tv_sec; /* seconds */
+ unsigned int tv_nsec; /* nanoseconds */
+ unsigned char length;
+ unsigned char data[SND_RAWMIDI_FRAMING_DATA_LENGTH];
+};
+
struct snd_rawmidi_params {
int stream;
size_t buffer_size; /* queue size in bytes */
size_t avail_min; /* minimum avail bytes for wakeup */
unsigned int no_active_sensing: 1; /* do not send active sensing byte in close() */
- unsigned char reserved[16]; /* reserved for future use */
+ unsigned char framing; /* For input data only, frame incoming data */
+ unsigned char reserved[15]; /* reserved for future use */
};
#ifndef __KERNEL__
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index aca00af93afe..fefa7d9b70a6 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -721,6 +721,7 @@ int snd_rawmidi_input_params(struct snd_rawmidi_substream *substream,
struct snd_rawmidi_params *params)
{
snd_rawmidi_drain_input(substream);
+ substream->framing = params->framing;
return resize_runtime_buffer(substream->runtime, params, true);
}
EXPORT_SYMBOL(snd_rawmidi_input_params);
@@ -963,6 +964,44 @@ static int snd_rawmidi_control_ioctl(struct snd_card *card,
return -ENOIOCTLCMD;
}
+static int receive_with_tstamp_framing(struct snd_rawmidi_substream *substream,
+ const unsigned char *buffer, int src_count, struct timespec64 *tstamp)
+{
+ struct snd_rawmidi_runtime *runtime = substream->runtime;
+ struct snd_rawmidi_framing_tstamp frame;
+ struct snd_rawmidi_framing_tstamp *dest_ptr;
+
+ int dest_frames = 0;
+ int frame_size = sizeof(struct snd_rawmidi_framing_tstamp);
+ frame.tv_sec = tstamp->tv_sec;
+ frame.tv_nsec = tstamp->tv_nsec;
+
+ if (snd_BUG_ON(runtime->hw_ptr & 15 || runtime->buffer_size & 15 || frame_size != 16))
+ return -EINVAL;
+ while (src_count > 0) {
+ if ((int)(runtime->buffer_size - runtime->avail) < frame_size) {
+ runtime->xruns += src_count;
+ return dest_frames * frame_size;
+ }
+ if (SND_RAWMIDI_FRAMING_DATA_LENGTH < src_count)
+ frame.length = SND_RAWMIDI_FRAMING_DATA_LENGTH;
+ else {
+ frame.length = src_count;
+ memset(frame.data, 0, SND_RAWMIDI_FRAMING_DATA_LENGTH);
+ }
+ memcpy(frame.data, buffer, frame.length);
+ buffer += frame.length;
+ src_count -= frame.length;
+ dest_ptr = (struct snd_rawmidi_framing_tstamp *) (runtime->buffer + runtime->hw_ptr);
+ *dest_ptr = frame;
+ runtime->avail += frame_size;
+ runtime->hw_ptr += frame_size;
+ runtime->hw_ptr %= runtime->buffer_size;
+ dest_frames++;
+ }
+ return dest_frames * frame_size;
+}
+
/**
* snd_rawmidi_receive - receive the input data from the device
* @substream: the rawmidi substream
@@ -988,7 +1027,11 @@ int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
return -EINVAL;
}
spin_lock_irqsave(&runtime->lock, flags);
- if (count == 1) { /* special case, faster code */
+ if (substream->framing == SNDRV_RAWMIDI_FRAMING_TSTAMP_MONOTONIC_RAW) {
+ struct timespec64 ts64;
+ ktime_get_raw_ts64(&ts64);
+ result = receive_with_tstamp_framing(substream, buffer, count, &ts64);
+ } else if (count == 1) { /* special case, faster code */
substream->bytes++;
if (runtime->avail < runtime->buffer_size) {
runtime->buffer[runtime->hw_ptr++] = buffer[0];
--
2.25.1
