ALSA: seq: Support MIDI 2.0 UMP Endpoint port

This is an extension to ALSA sequencer infrastructure to support the
MIDI 2.0 UMP Endpoint port.  It's a "catch-all" port that is supposed
to be present for each UMP Endpoint.  When this port is read via
subscription, it sends any events from all ports (UMP Groups) found in
the same client.

A UMP Endpoint port can be created with the new capability bit
SNDRV_SEQ_PORT_CAP_UMP_ENDPOINT.  Although the port assignment isn't
strictly defined, it should be the port number 0.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230523075358.9672-28-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 39 insertions, 8 deletions

diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c
index 6508ce63f761..061b3e2bece1 100644
--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -239,6 +239,7 @@ static struct snd_seq_client *seq_create_client1(int client_index, int poolsize)
 	mutex_init(&client->ports_mutex);
 	INIT_LIST_HEAD(&client->ports_list_head);
 	mutex_init(&client->ioctl_mutex);
+	client->ump_endpoint_port = -1;
 
 	/* find free slot in the client table */
 	spin_lock_irq(&clients_lock);
@@ -680,20 +681,17 @@ static int snd_seq_deliver_single_event(struct snd_seq_client *client,
 /*
  * send the event to all subscribers:
  */
-static int deliver_to_subscribers(struct snd_seq_client *client,
-				  struct snd_seq_event *event,
-				  int atomic, int hop)
+static int __deliver_to_subscribers(struct snd_seq_client *client,
+				    struct snd_seq_event *event,
+				    struct snd_seq_client_port *src_port,
+				    int atomic, int hop)
 {
 	struct snd_seq_subscribers *subs;
 	int err, result = 0, num_ev = 0;
-	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 */
 	saved_size = snd_seq_event_packet_size(event);
 	memcpy(&event_saved, event, saved_size);
@@ -733,6 +731,31 @@ static int deliver_to_subscribers(struct snd_seq_client *client,
 	return (result < 0) ? result : num_ev;
 }
 
+static int deliver_to_subscribers(struct snd_seq_client *client,
+				  struct snd_seq_event *event,
+				  int atomic, int hop)
+{
+	struct snd_seq_client_port *src_port;
+	int ret = 0, ret2;
+
+	src_port = snd_seq_port_use_ptr(client, event->source.port);
+	if (src_port) {
+		ret = __deliver_to_subscribers(client, event, src_port, atomic, hop);
+		snd_seq_port_unlock(src_port);
+	}
+
+	if (client->ump_endpoint_port < 0 ||
+	    event->source.port == client->ump_endpoint_port)
+		return ret;
+
+	src_port = snd_seq_port_use_ptr(client, client->ump_endpoint_port);
+	if (!src_port)
+		return ret;
+	ret2 = __deliver_to_subscribers(client, event, src_port, atomic, hop);
+	snd_seq_port_unlock(src_port);
+	return ret2 < 0 ? ret2 : ret;
+}
+
 /* deliver an event to the destination port(s).
  * if the event is to subscribers or broadcast, the event is dispatched
  * to multiple targets.
@@ -1257,6 +1280,9 @@ static int snd_seq_ioctl_create_port(struct snd_seq_client *client, void *arg)
 		return -EPERM;
 	if (client->type == USER_CLIENT && info->kernel)
 		return -EINVAL;
+	if ((info->capability & SNDRV_SEQ_PORT_CAP_UMP_ENDPOINT) &&
+	    client->ump_endpoint_port >= 0)
+		return -EBUSY;
 
 	if (info->flags & SNDRV_SEQ_PORT_FLG_GIVEN_PORT)
 		port_idx = info->addr.port;
@@ -1286,6 +1312,8 @@ static int snd_seq_ioctl_create_port(struct snd_seq_client *client, void *arg)
 	info->addr = port->addr;
 
 	snd_seq_set_port_info(port, info);
+	if (info->capability & SNDRV_SEQ_PORT_CAP_UMP_ENDPOINT)
+		client->ump_endpoint_port = port->addr.port;
 	snd_seq_system_client_ev_port_start(port->addr.client, port->addr.port);
 	snd_seq_port_unlock(port);
 
@@ -1305,8 +1333,11 @@ static int snd_seq_ioctl_delete_port(struct snd_seq_client *client, void *arg)
 		return -EPERM;
 
 	err = snd_seq_delete_port(client, info->addr.port);
-	if (err >= 0)
+	if (err >= 0) {
+		if (client->ump_endpoint_port == info->addr.port)
+			client->ump_endpoint_port = -1;
 		snd_seq_system_client_ev_port_exit(client->number, info->addr.port);
+	}
 	return err;
 }