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 14 (= 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-14 snd-seq-dummy 28 29 The module is loaded on demand for client 14, or /proc/asound/seq/ 30 is accessed. If you don't need this module to be loaded, alias 31 snd-seq-client-14 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 48 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>"); 49 MODULE_DESCRIPTION("ALSA sequencer MIDI-through client"); 50 MODULE_LICENSE("GPL"); 51 MODULE_ALIAS("snd-seq-client-" __stringify(SNDRV_SEQ_CLIENT_DUMMY)); 52 53 static int ports = 1; 54 static bool duplex; 55 56 module_param(ports, int, 0444); 57 MODULE_PARM_DESC(ports, "number of ports to be created"); 58 module_param(duplex, bool, 0444); 59 MODULE_PARM_DESC(duplex, "create DUPLEX ports"); 60 61 struct snd_seq_dummy_port { 62 int client; 63 int port; 64 int duplex; 65 int connect; 66 }; 67 68 static int my_client = -1; 69 70 /* 71 * event input callback - just redirect events to subscribers 72 */ 73 static int 74 dummy_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 */ 96 static void 97 dummy_free(void *private_data) 98 { 99 kfree(private_data); 100 } 101 102 /* 103 * create a port 104 */ 105 static struct snd_seq_dummy_port __init * 106 create_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 rec = kzalloc(sizeof(*rec), GFP_KERNEL); 113 if (!rec) 114 return NULL; 115 116 rec->client = my_client; 117 rec->duplex = duplex; 118 rec->connect = 0; 119 memset(&pinfo, 0, sizeof(pinfo)); 120 pinfo.addr.client = my_client; 121 if (duplex) 122 sprintf(pinfo.name, "Midi Through Port-%d:%c", idx, 123 (type ? 'B' : 'A')); 124 else 125 sprintf(pinfo.name, "Midi Through Port-%d", idx); 126 pinfo.capability = SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ; 127 pinfo.capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE; 128 if (duplex) 129 pinfo.capability |= SNDRV_SEQ_PORT_CAP_DUPLEX; 130 pinfo.direction = SNDRV_SEQ_PORT_DIR_BIDIRECTION; 131 pinfo.type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC 132 | SNDRV_SEQ_PORT_TYPE_SOFTWARE 133 | SNDRV_SEQ_PORT_TYPE_PORT; 134 memset(&pcb, 0, sizeof(pcb)); 135 pcb.owner = THIS_MODULE; 136 pcb.event_input = dummy_input; 137 pcb.private_free = dummy_free; 138 pcb.private_data = rec; 139 pinfo.kernel = &pcb; 140 if (snd_seq_kernel_client_ctl(my_client, SNDRV_SEQ_IOCTL_CREATE_PORT, &pinfo) < 0) { 141 kfree(rec); 142 return NULL; 143 } 144 rec->port = pinfo.addr.port; 145 return rec; 146 } 147 148 /* 149 * register client and create ports 150 */ 151 static int __init 152 register_client(void) 153 { 154 struct snd_seq_dummy_port *rec1, *rec2; 155 struct snd_seq_client *client; 156 int i; 157 158 if (ports < 1) { 159 pr_err("ALSA: seq_dummy: invalid number of ports %d\n", ports); 160 return -EINVAL; 161 } 162 163 /* create client */ 164 my_client = snd_seq_create_kernel_client(NULL, SNDRV_SEQ_CLIENT_DUMMY, 165 "Midi Through"); 166 if (my_client < 0) 167 return my_client; 168 169 /* don't convert events but just pass-through */ 170 client = snd_seq_kernel_client_get(my_client); 171 if (!client) 172 return -EINVAL; 173 client->filter = SNDRV_SEQ_FILTER_NO_CONVERT; 174 snd_seq_kernel_client_put(client); 175 176 /* create ports */ 177 for (i = 0; i < ports; i++) { 178 rec1 = create_port(i, 0); 179 if (rec1 == NULL) { 180 snd_seq_delete_kernel_client(my_client); 181 return -ENOMEM; 182 } 183 if (duplex) { 184 rec2 = create_port(i, 1); 185 if (rec2 == NULL) { 186 snd_seq_delete_kernel_client(my_client); 187 return -ENOMEM; 188 } 189 rec1->connect = rec2->port; 190 rec2->connect = rec1->port; 191 } 192 } 193 194 return 0; 195 } 196 197 /* 198 * delete client if exists 199 */ 200 static void __exit 201 delete_client(void) 202 { 203 if (my_client >= 0) 204 snd_seq_delete_kernel_client(my_client); 205 } 206 207 /* 208 * Init part 209 */ 210 211 static int __init alsa_seq_dummy_init(void) 212 { 213 return register_client(); 214 } 215 216 static void __exit alsa_seq_dummy_exit(void) 217 { 218 delete_client(); 219 } 220 221 module_init(alsa_seq_dummy_init) 222 module_exit(alsa_seq_dummy_exit) 223