1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * ALSA sequencer MIDI-through client
4  * Copyright (c) 1999-2000 by Takashi Iwai <tiwai@suse.de>
17   Sequencer MIDI-through client
19   This gives a simple midi-through client.  All the normal input events
21   The routing can be done via aconnect program in alsa-utils.
24   If you want to auto-load this module, you may add the following alias
25   in your /etc/conf.modules file.
27 	alias snd-seq-client-14  snd-seq-dummy
31   snd-seq-client-14 as "off".  This will help modprobe.
33   The number of ports to be created can be specified via the module
34   parameter "ports".  For example, to create four ports, add the
35   following option in a configuration file under /etc/modprobe.d/:
37 	option snd-seq-dummy ports=4
40   In duplex mode, a pair of ports are created instead of single port,
41   and events are tunneled between pair-ports.  For example, input to
43   In duplex mode, each port has DUPLEX capability.
49 MODULE_DESCRIPTION("ALSA sequencer MIDI-through client");
51 MODULE_ALIAS("snd-seq-client-" __stringify(SNDRV_SEQ_CLIENT_DUMMY));
53 static int ports = 1;  variable
56 module_param(ports, int, 0444);
57 MODULE_PARM_DESC(ports, "number of ports to be created");
59 MODULE_PARM_DESC(duplex, "create DUPLEX ports");
74 static int my_client = -1;
77  * event input callback - just redirect events to subscribers
87 	if (ev->source.client == SNDRV_SEQ_CLIENT_SYSTEM ||  in dummy_input()
88 	    ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR)  in dummy_input()
91 	if (p->duplex)  in dummy_input()
92 		tmpev.source.port = p->connect;  in dummy_input()
94 		tmpev.source.port = p->port;  in dummy_input()
96 	return snd_seq_kernel_client_dispatch(p->client, &tmpev, atomic, hop);  in dummy_input()
122 	rec->client = my_client;  in create_port()
123 	rec->duplex = duplex;  in create_port()
124 	rec->connect = 0;  in create_port()
128 		sprintf(pinfo.name, "Midi Through Port-%d:%c", idx,  in create_port()
131 		sprintf(pinfo.name, "Midi Through Port-%d", idx);  in create_port()
150 	rec->port = pinfo.addr.port;  in create_port()
155  * register client and create ports
166 	if (ports < 1) {  in register_client()
167 		pr_err("ALSA: seq_dummy: invalid number of ports %d\n", ports);  in register_client()
168 		return -EINVAL;  in register_client()
180 		return -EINVAL;  in register_client()
183 		client->midi_version = SNDRV_SEQ_CLIENT_UMP_MIDI_1_0;  in register_client()
186 		client->midi_version = SNDRV_SEQ_CLIENT_UMP_MIDI_2_0;  in register_client()
189 		/* don't convert events but just pass-through */  in register_client()
190 		client->filter = SNDRV_SEQ_FILTER_NO_CONVERT;  in register_client()
196 	/* create ports */  in register_client()
197 	for (i = 0; i < ports; i++) {  in register_client()
201 			return -ENOMEM;  in register_client()
207 				return -ENOMEM;  in register_client()
209 			rec1->connect = rec2->port;  in register_client()
210 			rec2->connect = rec1->port;  in register_client()