ALSA: rawmidi: UMP support

This patch adds the support helpers for UMP (Universal MIDI Packet) in
ALSA core.

The basic design is that a rawmidi instance is assigned to each UMP
Endpoint.  A UMP Endpoint provides a UMP stream, typically
bidirectional (but can be also uni-directional, too), which may hold
up to 16 UMP Groups, where each UMP (input/output) Group corresponds
to the traditional MIDI I/O Endpoint.

Additionally, the ALSA UMP abstraction provides the multiple UMP
Blocks that can be assigned to each UMP Endpoint.  A UMP Block is a
metadata to hold the UMP Group clusters, and can represent the
functions assigned to each UMP Group.  A typical implementation of UMP
Block is the Group Terminal Blocks of USB MIDI 2.0 specification.

For distinguishing from the legacy byte-stream MIDI device, a new
device "umpC*D*" will be created, instead of the standard (MIDI 1.0)
devices "midiC*D*".  The UMP instance can be identified by the new
rawmidi info bit SNDRV_RAWMIDI_INFO_UMP, too.

A UMP rawmidi device reads/writes only in 4-bytes words alignment,
stored in CPU native endianness.

The transmit and receive functions take care of the input/out data
alignment, and may return zero or aligned size, and the params ioctl
may return -EINVAL when the given input/output buffer size isn't
aligned.

A few new UMP-specific ioctls are added for obtaining the new UMP
endpoint and block information.

As of this commit, no ALSA sequencer instance is attached to UMP
devices yet.  They will be supported by later patches.

Along with those changes, the protocol version for rawmidi is bumped
to 2.0.3.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230523075358.9672-4-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/sound/rawmidi.h b/include/sound/rawmidi.h
index 84413cfcdcb5..b8a230a7583b 100644
--- a/include/sound/rawmidi.h
+++ b/include/sound/rawmidi.h
@@ -63,6 +63,7 @@ struct snd_rawmidi_runtime {
 	size_t avail_min;	/* min avail for wakeup */
 	size_t avail;		/* max used buffer for wakeup */
 	size_t xruns;		/* over/underruns counter */
+	size_t align;		/* alignment (0 = byte stream, 3 = UMP) */
 	int buffer_ref;		/* buffer reference count */
 	/* misc */
 	wait_queue_head_t sleep;
@@ -148,6 +149,13 @@ int snd_rawmidi_new(struct snd_card *card, char *id, int device,
 void snd_rawmidi_set_ops(struct snd_rawmidi *rmidi, int stream,
 			 const struct snd_rawmidi_ops *ops);
 
+/* internal */
+int snd_rawmidi_init(struct snd_rawmidi *rmidi,
+		     struct snd_card *card, char *id, int device,
+		     int output_count, int input_count,
+		     unsigned int info_flags);
+int snd_rawmidi_free(struct snd_rawmidi *rmidi);
+
 /* callbacks */
 
 int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,