xref: /openbmc/linux/sound/core/seq/seq_dummy.c (revision c819e2cf)
1 /*
2  * ALSA sequencer MIDI-through client
3  * Copyright (c) 1999-2000 by Takashi Iwai <tiwai@suse.de>
4  *
5  *   This program is free software; you can redistribute it and/or modify
6  *   it under the terms of the GNU General Public License as published by
7  *   the Free Software Foundation; either version 2 of the License, or
8  *   (at your option) any later version.
9  *
10  *   This program is distributed in the hope that it will be useful,
11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  *   GNU General Public License for more details.
14  *
15  *   You should have received a copy of the GNU General Public License
16  *   along with this program; if not, write to the Free Software
17  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
18  *
19  */
20 
21 #include <linux/init.h>
22 #include <linux/slab.h>
23 #include <linux/module.h>
24 #include <sound/core.h>
25 #include "seq_clientmgr.h"
26 #include <sound/initval.h>
27 #include <sound/asoundef.h>
28 
29 /*
30 
31   Sequencer MIDI-through client
32 
33   This gives a simple midi-through client.  All the normal input events
34   are redirected to output port immediately.
35   The routing can be done via aconnect program in alsa-utils.
36 
37   Each client has a static client number 62 (= SNDRV_SEQ_CLIENT_DUMMY).
38   If you want to auto-load this module, you may add the following alias
39   in your /etc/conf.modules file.
40 
41 	alias snd-seq-client-62  snd-seq-dummy
42 
43   The module is loaded on demand for client 62, or /proc/asound/seq/
44   is accessed.  If you don't need this module to be loaded, alias
45   snd-seq-client-62 as "off".  This will help modprobe.
46 
47   The number of ports to be created can be specified via the module
48   parameter "ports".  For example, to create four ports, add the
49   following option in a configuration file under /etc/modprobe.d/:
50 
51 	option snd-seq-dummy ports=4
52 
53   The model option "duplex=1" enables duplex operation to the port.
54   In duplex mode, a pair of ports are created instead of single port,
55   and events are tunneled between pair-ports.  For example, input to
56   port A is sent to output port of another port B and vice versa.
57   In duplex mode, each port has DUPLEX capability.
58 
59  */
60 
61 
62 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
63 MODULE_DESCRIPTION("ALSA sequencer MIDI-through client");
64 MODULE_LICENSE("GPL");
65 MODULE_ALIAS("snd-seq-client-" __stringify(SNDRV_SEQ_CLIENT_DUMMY));
66 
67 static int ports = 1;
68 static bool duplex;
69 
70 module_param(ports, int, 0444);
71 MODULE_PARM_DESC(ports, "number of ports to be created");
72 module_param(duplex, bool, 0444);
73 MODULE_PARM_DESC(duplex, "create DUPLEX ports");
74 
75 struct snd_seq_dummy_port {
76 	int client;
77 	int port;
78 	int duplex;
79 	int connect;
80 };
81 
82 static int my_client = -1;
83 
84 /*
85  * event input callback - just redirect events to subscribers
86  */
87 static int
88 dummy_input(struct snd_seq_event *ev, int direct, void *private_data,
89 	    int atomic, int hop)
90 {
91 	struct snd_seq_dummy_port *p;
92 	struct snd_seq_event tmpev;
93 
94 	p = private_data;
95 	if (ev->source.client == SNDRV_SEQ_CLIENT_SYSTEM ||
96 	    ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR)
97 		return 0; /* ignore system messages */
98 	tmpev = *ev;
99 	if (p->duplex)
100 		tmpev.source.port = p->connect;
101 	else
102 		tmpev.source.port = p->port;
103 	tmpev.dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
104 	return snd_seq_kernel_client_dispatch(p->client, &tmpev, atomic, hop);
105 }
106 
107 /*
108  * free_private callback
109  */
110 static void
111 dummy_free(void *private_data)
112 {
113 	kfree(private_data);
114 }
115 
116 /*
117  * create a port
118  */
119 static struct snd_seq_dummy_port __init *
120 create_port(int idx, int type)
121 {
122 	struct snd_seq_port_info pinfo;
123 	struct snd_seq_port_callback pcb;
124 	struct snd_seq_dummy_port *rec;
125 
126 	if ((rec = kzalloc(sizeof(*rec), GFP_KERNEL)) == NULL)
127 		return NULL;
128 
129 	rec->client = my_client;
130 	rec->duplex = duplex;
131 	rec->connect = 0;
132 	memset(&pinfo, 0, sizeof(pinfo));
133 	pinfo.addr.client = my_client;
134 	if (duplex)
135 		sprintf(pinfo.name, "Midi Through Port-%d:%c", idx,
136 			(type ? 'B' : 'A'));
137 	else
138 		sprintf(pinfo.name, "Midi Through Port-%d", idx);
139 	pinfo.capability = SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ;
140 	pinfo.capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE;
141 	if (duplex)
142 		pinfo.capability |= SNDRV_SEQ_PORT_CAP_DUPLEX;
143 	pinfo.type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC
144 		| SNDRV_SEQ_PORT_TYPE_SOFTWARE
145 		| SNDRV_SEQ_PORT_TYPE_PORT;
146 	memset(&pcb, 0, sizeof(pcb));
147 	pcb.owner = THIS_MODULE;
148 	pcb.event_input = dummy_input;
149 	pcb.private_free = dummy_free;
150 	pcb.private_data = rec;
151 	pinfo.kernel = &pcb;
152 	if (snd_seq_kernel_client_ctl(my_client, SNDRV_SEQ_IOCTL_CREATE_PORT, &pinfo) < 0) {
153 		kfree(rec);
154 		return NULL;
155 	}
156 	rec->port = pinfo.addr.port;
157 	return rec;
158 }
159 
160 /*
161  * register client and create ports
162  */
163 static int __init
164 register_client(void)
165 {
166 	struct snd_seq_dummy_port *rec1, *rec2;
167 	int i;
168 
169 	if (ports < 1) {
170 		pr_err("ALSA: seq_dummy: invalid number of ports %d\n", ports);
171 		return -EINVAL;
172 	}
173 
174 	/* create client */
175 	my_client = snd_seq_create_kernel_client(NULL, SNDRV_SEQ_CLIENT_DUMMY,
176 						 "Midi Through");
177 	if (my_client < 0)
178 		return my_client;
179 
180 	/* create ports */
181 	for (i = 0; i < ports; i++) {
182 		rec1 = create_port(i, 0);
183 		if (rec1 == NULL) {
184 			snd_seq_delete_kernel_client(my_client);
185 			return -ENOMEM;
186 		}
187 		if (duplex) {
188 			rec2 = create_port(i, 1);
189 			if (rec2 == NULL) {
190 				snd_seq_delete_kernel_client(my_client);
191 				return -ENOMEM;
192 			}
193 			rec1->connect = rec2->port;
194 			rec2->connect = rec1->port;
195 		}
196 	}
197 
198 	return 0;
199 }
200 
201 /*
202  * delete client if exists
203  */
204 static void __exit
205 delete_client(void)
206 {
207 	if (my_client >= 0)
208 		snd_seq_delete_kernel_client(my_client);
209 }
210 
211 /*
212  *  Init part
213  */
214 
215 static int __init alsa_seq_dummy_init(void)
216 {
217 	int err;
218 	snd_seq_autoload_lock();
219 	err = register_client();
220 	snd_seq_autoload_unlock();
221 	return err;
222 }
223 
224 static void __exit alsa_seq_dummy_exit(void)
225 {
226 	delete_client();
227 }
228 
229 module_init(alsa_seq_dummy_init)
230 module_exit(alsa_seq_dummy_exit)
231