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Linux/sound/core/seq/seq_dummy.c

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  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         return register_client();
218 }
219 
220 static void __exit alsa_seq_dummy_exit(void)
221 {
222         delete_client();
223 }
224 
225 module_init(alsa_seq_dummy_init)
226 module_exit(alsa_seq_dummy_exit)
227 

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