tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ALSA sequencer MIDI-through client
4 * Copyright (c) 1999-2000 by Takashi Iwai <tiwai@suse.de>
5 */
6
7#include <linux/init.h>
8#include <linux/slab.h>
9#include <linux/module.h>
10#include <sound/core.h>
11#include "seq_clientmgr.h"
12#include <sound/initval.h>
13#include <sound/asoundef.h>
14
15/*
16
17 Sequencer MIDI-through client
18
19 This gives a simple midi-through client. All the normal input events
20 are redirected to output port immediately.
21 The routing can be done via aconnect program in alsa-utils.
22
23 Each client has a static client number 62 (= SNDRV_SEQ_CLIENT_DUMMY).
24 If you want to auto-load this module, you may add the following alias
25 in your /etc/conf.modules file.
26
27 alias snd-seq-client-62 snd-seq-dummy
28
29 The module is loaded on demand for client 62, or /proc/asound/seq/
30 is accessed. If you don't need this module to be loaded, alias
31 snd-seq-client-62 as "off". This will help modprobe.
32
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/:
36
37 option snd-seq-dummy ports=4
38
39 The model option "duplex=1" enables duplex operation to the port.
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
42 port A is sent to output port of another port B and vice versa.
43 In duplex mode, each port has DUPLEX capability.
44
45 */
46
47
48MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
49MODULE_DESCRIPTION("ALSA sequencer MIDI-through client");
50MODULE_LICENSE("GPL");
51MODULE_ALIAS("snd-seq-client-" __stringify(SNDRV_SEQ_CLIENT_DUMMY));
52
53static int ports = 1;
54static bool duplex;
55
56module_param(ports, int, 0444);
57MODULE_PARM_DESC(ports, "number of ports to be created");
58module_param(duplex, bool, 0444);
59MODULE_PARM_DESC(duplex, "create DUPLEX ports");
60
61struct snd_seq_dummy_port {
62 int client;
63 int port;
64 int duplex;
65 int connect;
66};
67
68static int my_client = -1;
69
70/*
71 * event input callback - just redirect events to subscribers
72 */
73static int
74dummy_input(struct snd_seq_event *ev, int direct, void *private_data,
75 int atomic, int hop)
76{
77 struct snd_seq_dummy_port *p;
78 struct snd_seq_event tmpev;
79
80 p = private_data;
81 if (ev->source.client == SNDRV_SEQ_CLIENT_SYSTEM ||
82 ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR)
83 return 0; /* ignore system messages */
84 tmpev = *ev;
85 if (p->duplex)
86 tmpev.source.port = p->connect;
87 else
88 tmpev.source.port = p->port;
89 tmpev.dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
90 return snd_seq_kernel_client_dispatch(p->client, &tmpev, atomic, hop);
91}
92
93/*
94 * free_private callback
95 */
96static void
97dummy_free(void *private_data)
98{
99 kfree(private_data);
100}
101
102/*
103 * create a port
104 */
105static struct snd_seq_dummy_port __init *
106create_port(int idx, int type)
107{
108 struct snd_seq_port_info pinfo;
109 struct snd_seq_port_callback pcb;
110 struct snd_seq_dummy_port *rec;
111
112 if ((rec = kzalloc(sizeof(*rec), GFP_KERNEL)) == NULL)
113 return NULL;
114
115 rec->client = my_client;
116 rec->duplex = duplex;
117 rec->connect = 0;
118 memset(&pinfo, 0, sizeof(pinfo));
119 pinfo.addr.client = my_client;
120 if (duplex)
121 sprintf(pinfo.name, "Midi Through Port-%d:%c", idx,
122 (type ? 'B' : 'A'));
123 else
124 sprintf(pinfo.name, "Midi Through Port-%d", idx);
125 pinfo.capability = SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ;
126 pinfo.capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE;
127 if (duplex)
128 pinfo.capability |= SNDRV_SEQ_PORT_CAP_DUPLEX;
129 pinfo.type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC
130 | SNDRV_SEQ_PORT_TYPE_SOFTWARE
131 | SNDRV_SEQ_PORT_TYPE_PORT;
132 memset(&pcb, 0, sizeof(pcb));
133 pcb.owner = THIS_MODULE;
134 pcb.event_input = dummy_input;
135 pcb.private_free = dummy_free;
136 pcb.private_data = rec;
137 pinfo.kernel = &pcb;
138 if (snd_seq_kernel_client_ctl(my_client, SNDRV_SEQ_IOCTL_CREATE_PORT, &pinfo) < 0) {
139 kfree(rec);
140 return NULL;
141 }
142 rec->port = pinfo.addr.port;
143 return rec;
144}
145
146/*
147 * register client and create ports
148 */
149static int __init
150register_client(void)
151{
152 struct snd_seq_dummy_port *rec1, *rec2;
153 int i;
154
155 if (ports < 1) {
156 pr_err("ALSA: seq_dummy: invalid number of ports %d\n", ports);
157 return -EINVAL;
158 }
159
160 /* create client */
161 my_client = snd_seq_create_kernel_client(NULL, SNDRV_SEQ_CLIENT_DUMMY,
162 "Midi Through");
163 if (my_client < 0)
164 return my_client;
165
166 /* create ports */
167 for (i = 0; i < ports; i++) {
168 rec1 = create_port(i, 0);
169 if (rec1 == NULL) {
170 snd_seq_delete_kernel_client(my_client);
171 return -ENOMEM;
172 }
173 if (duplex) {
174 rec2 = create_port(i, 1);
175 if (rec2 == NULL) {
176 snd_seq_delete_kernel_client(my_client);
177 return -ENOMEM;
178 }
179 rec1->connect = rec2->port;
180 rec2->connect = rec1->port;
181 }
182 }
183
184 return 0;
185}
186
187/*
188 * delete client if exists
189 */
190static void __exit
191delete_client(void)
192{
193 if (my_client >= 0)
194 snd_seq_delete_kernel_client(my_client);
195}
196
197/*
198 * Init part
199 */
200
201static int __init alsa_seq_dummy_init(void)
202{
203 return register_client();
204}
205
206static void __exit alsa_seq_dummy_exit(void)
207{
208 delete_client();
209}
210
211module_init(alsa_seq_dummy_init)
212module_exit(alsa_seq_dummy_exit)