ALSA: seq: ump: Handle groupless messages

The UMP Utility and Stream messages are "groupless", i.e. an incoming
groupless packet should be sent only to the UMP EP port, and the event
with the groupless message is sent to UMP EP as is without the group
translation per port.

Also, the former reserved bit 0 for the client group filter is now
used for groupless events.  When the bit 0 is set, the groupless
events are filtered out and skipped.

Link: https://lore.kernel.org/r/20230612081054.17200-6-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Author: tiwai

include/sound/ump.h

@@ -255,4 +255,7 @@ static inline u32 ump_stream_compose(unsigned char status, unsigned short form)
 		((u32)status << 16);
 }
 
+#define ump_is_groupless_msg(type) \
+	((type) == UMP_MSG_TYPE_UTILITY || (type) == UMP_MSG_TYPE_STREAM)
+
 #endif /* __SOUND_UMP_H */

include/uapi/sound/asequencer.h

@@ -362,7 +362,10 @@ struct snd_seq_client_info {
 	int card;			/* RO: card number[kernel] */
 	int pid;			/* RO: pid[user] */
 	unsigned int midi_version;	/* MIDI version */
-	unsigned int group_filter;	/* UMP group filter bitmap (for 1-based Group indices) */
+	unsigned int group_filter;	/* UMP group filter bitmap
+					 * (bit 0 = groupless messages,
+					 *  bit 1-16 = messages for groups 1-16)
+					 */
 	char reserved[48];		/* for future use */
 };
 

sound/core/seq/seq_ump_client.c

@@ -73,7 +73,10 @@ static void seq_ump_input_receive(struct snd_ump_endpoint *ump,
 	if (!client->opened[STR_IN])
 		return;
 
-	ev.source.port = ump_group_to_seq_port(ump_message_group(*val));
+	if (ump_is_groupless_msg(ump_message_type(*val)))
+		ev.source.port = 0; /* UMP EP port */
+	else
+		ev.source.port = ump_group_to_seq_port(ump_message_group(*val));
 	ev.dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
 	ev.flags = SNDRV_SEQ_EVENT_UMP;
 	memcpy(ev.ump, val, words << 2);

sound/core/seq/seq_ump_convert.c

@@ -534,6 +534,8 @@ static bool ump_event_filtered(struct snd_seq_client *dest,
 	unsigned char group;
 
 	group = ump_message_group(ev->ump[0]);
+	if (ump_is_groupless_msg(ump_message_type(ev->ump[0])))
+		return dest->group_filter & (1U << 0);
 	/* check the bitmap for 1-based group number */
 	return dest->group_filter & (1U << (group + 1));
 }
@@ -565,6 +567,7 @@ int snd_seq_deliver_from_ump(struct snd_seq_client *source,
 						      event, atomic, hop);
 		/* non-EP port and different group is set? */
 		if (dest_port->ump_group &&
+		    !ump_is_groupless_msg(type) &&
 		    ump_message_group(*ump_ev->ump) + 1 != dest_port->ump_group)
 			return deliver_with_group_convert(dest, dest_port,
 							  ump_ev, atomic, hop);