ALSA: seq: Add UMP support

Starting from this commit, we add the basic support of UMP (Universal
MIDI Packet) events on ALSA sequencer infrastructure.  The biggest
change here is that, for transferring UMP packets that are up to 128
bits, we extend the data payload of ALSA sequencer event record when
the client is declared to support for the new UMP events.

A new event flag bit, SNDRV_SEQ_EVENT_UMP, is defined and it shall be
set for the UMP packet events that have the larger payload of 128
bits, defined as struct snd_seq_ump_event.

For controlling the UMP feature enablement in kernel, a new Kconfig,
CONFIG_SND_SEQ_UMP is introduced.  The extended event for UMP is
available only when this Kconfig item is set.  Similarly, the size of
the internal snd_seq_event_cell also increases (in 4 bytes) when the
Kconfig item is set.  (But the size increase is effective only for
32bit architectures; 64bit archs already have padding there.)
Overall, when CONFIG_SND_SEQ_UMP isn't set, there is no change in the
event and cell, keeping the old sizes.

For applications that want to access the UMP packets, first of all, a
sequencer client has to declare the user-protocol to match with the
latest one via the new SNDRV_SEQ_IOCTL_USER_PVERSION; otherwise it's
treated as if a legacy client without UMP support.

Then the client can switch to the new UMP mode (MIDI 1.0 or MIDI 2.0)
with a new field, midi_version, in snd_seq_client_info.  When switched
to UMP mode (midi_version = 1 or 2), the client can write the UMP
events with SNDRV_SEQ_EVENT_UMP flag.  For reads, the alignment size
is changed from snd_seq_event (28 bytes) to snd_seq_ump_event (32
bytes).  When a UMP sequencer event is delivered to a legacy sequencer
client, it's ignored or handled as an error.

Conceptually, ALSA sequencer client and port correspond to the UMP
Endpoint and Group, respectively; each client may have multiple ports
and each port has the fixed number (16) of channels, total up to 256
channels.

As of this commit, ALSA sequencer core just sends and receives the UMP
events as-is from/to clients.  The automatic conversions between the
legacy events and the new UMP events will be implemented in a later
patch.

Along with this commit, bump the sequencer protocol version to 1.0.3.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230523075358.9672-26-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

5 files changed, 144 insertions, 47 deletions

diff --git a/sound/core/seq/Kconfig b/sound/core/seq/Kconfig
index f84718a44980..c69d8beb09fa 100644
--- a/sound/core/seq/Kconfig
+++ b/sound/core/seq/Kconfig
@@ -60,4 +60,11 @@ config SND_SEQ_MIDI_EMUL
 config SND_SEQ_VIRMIDI
 	tristate
 
+config SND_SEQ_UMP
+	bool "Support for UMP events"
+	help
+	  Say Y here to enable the support for handling UMP (Universal MIDI
+	  Packet) events via ALSA sequencer infrastructure, which is an
+	  essential feature for enabling MIDI 2.0 support.
+
 endif # SND_SEQUENCER
diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
index 89a8d14df83b..801d5eee21eb 100644
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -387,6 +387,15 @@ static int snd_seq_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static bool event_is_compatible(const struct snd_seq_client *client,
+				const struct snd_seq_event *ev)
+{
+	if (snd_seq_ev_is_ump(ev) && !client->midi_version)
+		return false;
+	if (snd_seq_ev_is_ump(ev) && snd_seq_ev_is_variable(ev))
+		return false;
+	return true;
+}
 
 /* handle client read() */
 /* possible error values:
@@ -400,6 +409,7 @@ static ssize_t snd_seq_read(struct file *file, char __user *buf, size_t count,
 {
 	struct snd_seq_client *client = file->private_data;
 	struct snd_seq_fifo *fifo;
+	size_t aligned_size;
 	int err;
 	long result = 0;
 	struct snd_seq_event_cell *cell;
@@ -431,43 +441,54 @@ static ssize_t snd_seq_read(struct file *file, char __user *buf, size_t count,
 	err = 0;
 	snd_seq_fifo_lock(fifo);
 
+	if (client->midi_version > 0)
+		aligned_size = sizeof(struct snd_seq_ump_event);
+	else
+		aligned_size = sizeof(struct snd_seq_event);
+
 	/* while data available in queue */
-	while (count >= sizeof(struct snd_seq_event)) {
+	while (count >= aligned_size) {
 		int nonblock;
 
 		nonblock = (file->f_flags & O_NONBLOCK) || result > 0;
 		err = snd_seq_fifo_cell_out(fifo, &cell, nonblock);
 		if (err < 0)
 			break;
+		if (!event_is_compatible(client, &cell->event)) {
+			snd_seq_cell_free(cell);
+			cell = NULL;
+			continue;
+		}
 		if (snd_seq_ev_is_variable(&cell->event)) {
-			struct snd_seq_event tmpev;
-			tmpev = cell->event;
+			struct snd_seq_ump_event tmpev;
+
+			memcpy(&tmpev, &cell->event, aligned_size);
 			tmpev.data.ext.len &= ~SNDRV_SEQ_EXT_MASK;
-			if (copy_to_user(buf, &tmpev, sizeof(struct snd_seq_event))) {
+			if (copy_to_user(buf, &tmpev, aligned_size)) {
 				err = -EFAULT;
 				break;
 			}
-			count -= sizeof(struct snd_seq_event);
-			buf += sizeof(struct snd_seq_event);
+			count -= aligned_size;
+			buf += aligned_size;
 			err = snd_seq_expand_var_event(&cell->event, count,
 						       (char __force *)buf, 0,
-						       sizeof(struct snd_seq_event));
+						       aligned_size);
 			if (err < 0)
 				break;
 			result += err;
 			count -= err;
 			buf += err;
 		} else {
-			if (copy_to_user(buf, &cell->event, sizeof(struct snd_seq_event))) {
+			if (copy_to_user(buf, &cell->event, aligned_size)) {
 				err = -EFAULT;
 				break;
 			}
-			count -= sizeof(struct snd_seq_event);
-			buf += sizeof(struct snd_seq_event);
+			count -= aligned_size;
+			buf += aligned_size;
 		}
 		snd_seq_cell_free(cell);
 		cell = NULL; /* to be sure */
-		result += sizeof(struct snd_seq_event);
+		result += aligned_size;
 	}
 
 	if (err < 0) {
@@ -665,15 +686,17 @@ static int deliver_to_subscribers(struct snd_seq_client *client,
 {
 	struct snd_seq_subscribers *subs;
 	int err, result = 0, num_ev = 0;
-	struct snd_seq_event event_saved;
 	struct snd_seq_client_port *src_port;
+	union __snd_seq_event event_saved;
+	size_t saved_size;
 	struct snd_seq_port_subs_info *grp;
 
 	src_port = snd_seq_port_use_ptr(client, event->source.port);
 	if (src_port == NULL)
 		return -EINVAL; /* invalid source port */
 	/* save original event record */
-	event_saved = *event;
+	saved_size = snd_seq_event_packet_size(event);
+	memcpy(&event_saved, event, saved_size);
 	grp = &src_port->c_src;
 	
 	/* lock list */
@@ -700,14 +723,13 @@ static int deliver_to_subscribers(struct snd_seq_client *client,
 		}
 		num_ev++;
 		/* restore original event record */
-		*event = event_saved;
+		memcpy(event, &event_saved, saved_size);
 	}
 	if (atomic)
 		read_unlock(&grp->list_lock);
 	else
 		up_read(&grp->list_mutex);
-	*event = event_saved; /* restore */
-	snd_seq_port_unlock(src_port);
+	memcpy(event, &event_saved, saved_size);
 	return (result < 0) ? result : num_ev;
 }
 
@@ -769,7 +791,8 @@ int snd_seq_dispatch_event(struct snd_seq_event_cell *cell, int atomic, int hop)
 		return -EINVAL;
 	}
 
-	if (cell->event.type == SNDRV_SEQ_EVENT_NOTE) {
+	if (!snd_seq_ev_is_ump(&cell->event) &&
+	    cell->event.type == SNDRV_SEQ_EVENT_NOTE) {
 		/* NOTE event:
 		 * the event cell is re-used as a NOTE-OFF event and
 		 * enqueued again.
@@ -793,7 +816,7 @@ int snd_seq_dispatch_event(struct snd_seq_event_cell *cell, int atomic, int hop)
 		/* add the duration time */
 		switch (ev->flags & SNDRV_SEQ_TIME_STAMP_MASK) {
 		case SNDRV_SEQ_TIME_STAMP_TICK:
-			ev->time.tick += ev->data.note.duration;
+			cell->event.time.tick += ev->data.note.duration;
 			break;
 		case SNDRV_SEQ_TIME_STAMP_REAL:
 			/* unit for duration is ms */
@@ -850,7 +873,8 @@ static int snd_seq_client_enqueue_event(struct snd_seq_client *client,
 
 	/* direct event processing without enqueued */
 	if (snd_seq_ev_is_direct(event)) {
-		if (event->type == SNDRV_SEQ_EVENT_NOTE)
+		if (!snd_seq_ev_is_ump(event) &&
+		    event->type == SNDRV_SEQ_EVENT_NOTE)
 			return -EINVAL; /* this event must be enqueued! */
 		return snd_seq_deliver_event(client, event, atomic, hop);
 	}
@@ -920,7 +944,8 @@ static ssize_t snd_seq_write(struct file *file, const char __user *buf,
 	struct snd_seq_client *client = file->private_data;
 	int written = 0, len;
 	int err, handled;
-	struct snd_seq_event event;
+	union __snd_seq_event __event;
+	struct snd_seq_event *ev = &__event.legacy;
 
 	if (!(snd_seq_file_flags(file) & SNDRV_SEQ_LFLG_OUTPUT))
 		return -ENXIO;
@@ -946,49 +971,66 @@ static ssize_t snd_seq_write(struct file *file, const char __user *buf,
 	err = -EINVAL;
 	while (count >= sizeof(struct snd_seq_event)) {
 		/* Read in the event header from the user */
-		len = sizeof(event);
-		if (copy_from_user(&event, buf, len)) {
+		len = sizeof(struct snd_seq_event);
+		if (copy_from_user(ev, buf, len)) {
 			err = -EFAULT;
 			break;
 		}
-		event.source.client = client->number;	/* fill in client number */
+		/* read in the rest bytes for UMP events */
+		if (snd_seq_ev_is_ump(ev)) {
+			if (count < sizeof(struct snd_seq_ump_event))
+				break;
+			if (copy_from_user((char *)ev + len, buf + len,
+					   sizeof(struct snd_seq_ump_event) - len)) {
+				err = -EFAULT;
+				break;
+			}
+			len = sizeof(struct snd_seq_ump_event);
+		}
+
+		ev->source.client = client->number;	/* fill in client number */
 		/* Check for extension data length */
-		if (check_event_type_and_length(&event)) {
+		if (check_event_type_and_length(ev)) {
 			err = -EINVAL;
 			break;
 		}
 
-		/* check for special events */
-		if (event.type == SNDRV_SEQ_EVENT_NONE)
-			goto __skip_event;
-		else if (snd_seq_ev_is_reserved(&event)) {
+		if (!event_is_compatible(client, ev)) {
 			err = -EINVAL;
 			break;
 		}
 
-		if (snd_seq_ev_is_variable(&event)) {
-			int extlen = event.data.ext.len & ~SNDRV_SEQ_EXT_MASK;
+		/* check for special events */
+		if (!snd_seq_ev_is_ump(ev)) {
+			if (ev->type == SNDRV_SEQ_EVENT_NONE)
+				goto __skip_event;
+			else if (snd_seq_ev_is_reserved(ev)) {
+				err = -EINVAL;
+				break;
+			}
+		}
+
+		if (snd_seq_ev_is_variable(ev)) {
+			int extlen = ev->data.ext.len & ~SNDRV_SEQ_EXT_MASK;
 			if ((size_t)(extlen + len) > count) {
 				/* back out, will get an error this time or next */
 				err = -EINVAL;
 				break;
 			}
 			/* set user space pointer */
-			event.data.ext.len = extlen | SNDRV_SEQ_EXT_USRPTR;
-			event.data.ext.ptr = (char __force *)buf
-						+ sizeof(struct snd_seq_event);
+			ev->data.ext.len = extlen | SNDRV_SEQ_EXT_USRPTR;
+			ev->data.ext.ptr = (char __force *)buf + len;
 			len += extlen; /* increment data length */
 		} else {
 #ifdef CONFIG_COMPAT
-			if (client->convert32 && snd_seq_ev_is_varusr(&event)) {
-				void *ptr = (void __force *)compat_ptr(event.data.raw32.d[1]);
-				event.data.ext.ptr = ptr;
-			}
+			if (client->convert32 && snd_seq_ev_is_varusr(ev))
+				ev->data.ext.ptr =
+					(void __force *)compat_ptr(ev->data.raw32.d[1]);
 #endif
 		}
 
 		/* ok, enqueue it */
-		err = snd_seq_client_enqueue_event(client, &event, file,
+		err = snd_seq_client_enqueue_event(client, ev, file,
 						   !(file->f_flags & O_NONBLOCK),
 						   0, 0, &client->ioctl_mutex);
 		if (err < 0)
@@ -1146,6 +1188,7 @@ static void get_client_info(struct snd_seq_client *cptr,
 	else
 		info->card = -1;
 
+	info->midi_version = cptr->midi_version;
 	memset(info->reserved, 0, sizeof(info->reserved));
 }
 
@@ -1180,12 +1223,19 @@ static int snd_seq_ioctl_set_client_info(struct snd_seq_client *client,
 	if (client->type != client_info->type)
 		return -EINVAL;
 
+	/* check validity of midi_version field */
+	if (client->user_pversion >= SNDRV_PROTOCOL_VERSION(1, 0, 3) &&
+	    client_info->midi_version > SNDRV_SEQ_CLIENT_UMP_MIDI_2_0)
+		return -EINVAL;
+
 	/* fill the info fields */
 	if (client_info->name[0])
 		strscpy(client->name, client_info->name, sizeof(client->name));
 
 	client->filter = client_info->filter;
 	client->event_lost = client_info->event_lost;
+	if (client->user_pversion >= SNDRV_PROTOCOL_VERSION(1, 0, 3))
+		client->midi_version = client_info->midi_version;
 	memcpy(client->event_filter, client_info->event_filter, 32);
 
 	return 0;
@@ -2181,10 +2231,12 @@ int snd_seq_kernel_client_enqueue(int client, struct snd_seq_event *ev,
 	if (snd_BUG_ON(!ev))
 		return -EINVAL;
 
-	if (ev->type == SNDRV_SEQ_EVENT_NONE)
-		return 0; /* ignore this */
-	if (ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR)
-		return -EINVAL; /* quoted events can't be enqueued */
+	if (!snd_seq_ev_is_ump(ev)) {
+		if (ev->type == SNDRV_SEQ_EVENT_NONE)
+			return 0; /* ignore this */
+		if (ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR)
+			return -EINVAL; /* quoted events can't be enqueued */
+	}
 
 	/* fill in client number */
 	ev->source.client = client;
@@ -2376,6 +2428,19 @@ static void snd_seq_info_dump_ports(struct snd_info_buffer *buffer,
 	mutex_unlock(&client->ports_mutex);
 }
 
+static const char *midi_version_string(unsigned int version)
+{
+	switch (version) {
+	case SNDRV_SEQ_CLIENT_LEGACY_MIDI:
+		return "Legacy";
+	case SNDRV_SEQ_CLIENT_UMP_MIDI_1_0:
+		return "UMP MIDI1";
+	case SNDRV_SEQ_CLIENT_UMP_MIDI_2_0:
+		return "UMP MIDI2";
+	default:
+		return "Unknown";
+	}
+}
 
 /* exported to seq_info.c */
 void snd_seq_info_clients_read(struct snd_info_entry *entry, 
@@ -2400,9 +2465,10 @@ void snd_seq_info_clients_read(struct snd_info_entry *entry,
 			continue;
 		}
 
-		snd_iprintf(buffer, "Client %3d : \"%s\" [%s]\n",
+		snd_iprintf(buffer, "Client %3d : \"%s\" [%s %s]\n",
 			    c, client->name,
-			    client->type == USER_CLIENT ? "User" : "Kernel");
+			    client->type == USER_CLIENT ? "User" : "Kernel",
+			    midi_version_string(client->midi_version));
 		snd_seq_info_dump_ports(buffer, client);
 		if (snd_seq_write_pool_allocated(client)) {
 			snd_iprintf(buffer, "  Output pool :\n");
diff --git a/sound/core/seq/seq_clientmgr.h b/sound/core/seq/seq_clientmgr.h
index abe0ceadf3da..5657f8091835 100644
--- a/sound/core/seq/seq_clientmgr.h
+++ b/sound/core/seq/seq_clientmgr.h
@@ -35,6 +35,7 @@ struct snd_seq_client {
 	snd_seq_client_type_t type;
 	unsigned int accept_input: 1,
 		accept_output: 1;
+	unsigned int midi_version;
 	unsigned int user_pversion;
 	char name[64];		/* client name */
 	int number;		/* client number */
diff --git a/sound/core/seq/seq_memory.c b/sound/core/seq/seq_memory.c
index a8d2db439f86..174585bf59d2 100644
--- a/sound/core/seq/seq_memory.c
+++ b/sound/core/seq/seq_memory.c
@@ -340,6 +340,7 @@ int snd_seq_event_dup(struct snd_seq_pool *pool, struct snd_seq_event *event,
 	int ncells, err;
 	unsigned int extlen;
 	struct snd_seq_event_cell *cell;
+	int size;
 
 	*cellp = NULL;
 
@@ -357,7 +358,12 @@ int snd_seq_event_dup(struct snd_seq_pool *pool, struct snd_seq_event *event,
 		return err;
 
 	/* copy the event */
-	cell->event = *event;
+	size = snd_seq_event_packet_size(event);
+	memcpy(&cell->ump, event, size);
+#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
+	if (size < sizeof(cell->event))
+		cell->ump.raw.extra = 0;
+#endif
 
 	/* decompose */
 	if (snd_seq_ev_is_variable(event)) {
@@ -375,7 +381,7 @@ int snd_seq_event_dup(struct snd_seq_pool *pool, struct snd_seq_event *event,
 		tail = NULL;
 
 		while (ncells-- > 0) {
-			int size = sizeof(struct snd_seq_event);
+			size = sizeof(struct snd_seq_event);
 			if (len < size)
 				size = len;
 			err = snd_seq_cell_alloc(pool, &tmp, nonblock, file,
diff --git a/sound/core/seq/seq_memory.h b/sound/core/seq/seq_memory.h
index 7d7ff80f915e..7f7a2c0b187d 100644
--- a/sound/core/seq/seq_memory.h
+++ b/sound/core/seq/seq_memory.h
@@ -11,9 +11,26 @@
 
 struct snd_info_buffer;
 
+/* aliasing for legacy and UMP event packet handling */
+union __snd_seq_event {
+	struct snd_seq_event legacy;
+#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
+	struct snd_seq_ump_event ump;
+#endif
+	struct {
+		struct snd_seq_event event;
+#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
+		u32 extra;
+#endif
+	} __packed raw;
+};
+
 /* container for sequencer event (internal use) */
 struct snd_seq_event_cell {
-	struct snd_seq_event event;
+	union {
+		struct snd_seq_event event;
+		union __snd_seq_event ump;
+	};
 	struct snd_seq_pool *pool;				/* used pool */
 	struct snd_seq_event_cell *next;	/* next cell */
 };