1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * ALSA sequencer device management 4 * Copyright (c) 1999 by Takashi Iwai <tiwai@suse.de> 5 * 6 *---------------------------------------------------------------- 7 * 8 * This device handler separates the card driver module from sequencer 9 * stuff (sequencer core, synth drivers, etc), so that user can avoid 10 * to spend unnecessary resources e.g. if he needs only listening to 11 * MP3s. 12 * 13 * The card (or lowlevel) driver creates a sequencer device entry 14 * via snd_seq_device_new(). This is an entry pointer to communicate 15 * with the sequencer device "driver", which is involved with the 16 * actual part to communicate with the sequencer core. 17 * Each sequencer device entry has an id string and the corresponding 18 * driver with the same id is loaded when required. For example, 19 * lowlevel codes to access emu8000 chip on sbawe card are included in 20 * emu8000-synth module. To activate this module, the hardware 21 * resources like i/o port are passed via snd_seq_device argument. 22 */ 23 24 #include <linux/device.h> 25 #include <linux/init.h> 26 #include <linux/module.h> 27 #include <sound/core.h> 28 #include <sound/info.h> 29 #include <sound/seq_device.h> 30 #include <sound/seq_kernel.h> 31 #include <sound/initval.h> 32 #include <linux/kmod.h> 33 #include <linux/slab.h> 34 #include <linux/mutex.h> 35 36 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>"); 37 MODULE_DESCRIPTION("ALSA sequencer device management"); 38 MODULE_LICENSE("GPL"); 39 40 /* 41 * bus definition 42 */ 43 static int snd_seq_bus_match(struct device *dev, struct device_driver *drv) 44 { 45 struct snd_seq_device *sdev = to_seq_dev(dev); 46 struct snd_seq_driver *sdrv = to_seq_drv(drv); 47 48 return strcmp(sdrv->id, sdev->id) == 0 && 49 sdrv->argsize == sdev->argsize; 50 } 51 52 static struct bus_type snd_seq_bus_type = { 53 .name = "snd_seq", 54 .match = snd_seq_bus_match, 55 }; 56 57 /* 58 * proc interface -- just for compatibility 59 */ 60 #ifdef CONFIG_SND_PROC_FS 61 static struct snd_info_entry *info_entry; 62 63 static int print_dev_info(struct device *dev, void *data) 64 { 65 struct snd_seq_device *sdev = to_seq_dev(dev); 66 struct snd_info_buffer *buffer = data; 67 68 snd_iprintf(buffer, "snd-%s,%s,%d\n", sdev->id, 69 dev->driver ? "loaded" : "empty", 70 dev->driver ? 1 : 0); 71 return 0; 72 } 73 74 static void snd_seq_device_info(struct snd_info_entry *entry, 75 struct snd_info_buffer *buffer) 76 { 77 bus_for_each_dev(&snd_seq_bus_type, NULL, buffer, print_dev_info); 78 } 79 #endif 80 81 /* 82 * load all registered drivers (called from seq_clientmgr.c) 83 */ 84 85 #ifdef CONFIG_MODULES 86 /* flag to block auto-loading */ 87 static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */ 88 89 static int request_seq_drv(struct device *dev, void *data) 90 { 91 struct snd_seq_device *sdev = to_seq_dev(dev); 92 93 if (!dev->driver) 94 request_module("snd-%s", sdev->id); 95 return 0; 96 } 97 98 static void autoload_drivers(struct work_struct *work) 99 { 100 /* avoid reentrance */ 101 if (atomic_inc_return(&snd_seq_in_init) == 1) 102 bus_for_each_dev(&snd_seq_bus_type, NULL, NULL, 103 request_seq_drv); 104 atomic_dec(&snd_seq_in_init); 105 } 106 107 static DECLARE_WORK(autoload_work, autoload_drivers); 108 109 static void queue_autoload_drivers(void) 110 { 111 schedule_work(&autoload_work); 112 } 113 114 void snd_seq_autoload_init(void) 115 { 116 atomic_dec(&snd_seq_in_init); 117 #ifdef CONFIG_SND_SEQUENCER_MODULE 118 /* initial autoload only when snd-seq is a module */ 119 queue_autoload_drivers(); 120 #endif 121 } 122 EXPORT_SYMBOL(snd_seq_autoload_init); 123 124 void snd_seq_autoload_exit(void) 125 { 126 atomic_inc(&snd_seq_in_init); 127 } 128 EXPORT_SYMBOL(snd_seq_autoload_exit); 129 130 void snd_seq_device_load_drivers(void) 131 { 132 queue_autoload_drivers(); 133 flush_work(&autoload_work); 134 } 135 EXPORT_SYMBOL(snd_seq_device_load_drivers); 136 #define cancel_autoload_drivers() cancel_work_sync(&autoload_work) 137 #else 138 #define queue_autoload_drivers() /* NOP */ 139 #define cancel_autoload_drivers() /* NOP */ 140 #endif 141 142 /* 143 * device management 144 */ 145 static int snd_seq_device_dev_free(struct snd_device *device) 146 { 147 struct snd_seq_device *dev = device->device_data; 148 149 cancel_autoload_drivers(); 150 put_device(&dev->dev); 151 return 0; 152 } 153 154 static int snd_seq_device_dev_register(struct snd_device *device) 155 { 156 struct snd_seq_device *dev = device->device_data; 157 int err; 158 159 err = device_add(&dev->dev); 160 if (err < 0) 161 return err; 162 if (!dev->dev.driver) 163 queue_autoload_drivers(); 164 return 0; 165 } 166 167 static int snd_seq_device_dev_disconnect(struct snd_device *device) 168 { 169 struct snd_seq_device *dev = device->device_data; 170 171 device_del(&dev->dev); 172 return 0; 173 } 174 175 static void snd_seq_dev_release(struct device *dev) 176 { 177 struct snd_seq_device *sdev = to_seq_dev(dev); 178 179 if (sdev->private_free) 180 sdev->private_free(sdev); 181 kfree(sdev); 182 } 183 184 /* 185 * register a sequencer device 186 * card = card info 187 * device = device number (if any) 188 * id = id of driver 189 * result = return pointer (NULL allowed if unnecessary) 190 */ 191 int snd_seq_device_new(struct snd_card *card, int device, const char *id, 192 int argsize, struct snd_seq_device **result) 193 { 194 struct snd_seq_device *dev; 195 int err; 196 static const struct snd_device_ops dops = { 197 .dev_free = snd_seq_device_dev_free, 198 .dev_register = snd_seq_device_dev_register, 199 .dev_disconnect = snd_seq_device_dev_disconnect, 200 }; 201 202 if (result) 203 *result = NULL; 204 205 if (snd_BUG_ON(!id)) 206 return -EINVAL; 207 208 dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL); 209 if (!dev) 210 return -ENOMEM; 211 212 /* set up device info */ 213 dev->card = card; 214 dev->device = device; 215 dev->id = id; 216 dev->argsize = argsize; 217 218 device_initialize(&dev->dev); 219 dev->dev.parent = &card->card_dev; 220 dev->dev.bus = &snd_seq_bus_type; 221 dev->dev.release = snd_seq_dev_release; 222 dev_set_name(&dev->dev, "%s-%d-%d", dev->id, card->number, device); 223 224 /* add this device to the list */ 225 err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops); 226 if (err < 0) { 227 put_device(&dev->dev); 228 return err; 229 } 230 231 if (result) 232 *result = dev; 233 234 return 0; 235 } 236 EXPORT_SYMBOL(snd_seq_device_new); 237 238 /* 239 * driver registration 240 */ 241 int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod) 242 { 243 if (WARN_ON(!drv->driver.name || !drv->id)) 244 return -EINVAL; 245 drv->driver.bus = &snd_seq_bus_type; 246 drv->driver.owner = mod; 247 return driver_register(&drv->driver); 248 } 249 EXPORT_SYMBOL_GPL(__snd_seq_driver_register); 250 251 void snd_seq_driver_unregister(struct snd_seq_driver *drv) 252 { 253 driver_unregister(&drv->driver); 254 } 255 EXPORT_SYMBOL_GPL(snd_seq_driver_unregister); 256 257 /* 258 * module part 259 */ 260 261 static int __init seq_dev_proc_init(void) 262 { 263 #ifdef CONFIG_SND_PROC_FS 264 info_entry = snd_info_create_module_entry(THIS_MODULE, "drivers", 265 snd_seq_root); 266 if (info_entry == NULL) 267 return -ENOMEM; 268 info_entry->content = SNDRV_INFO_CONTENT_TEXT; 269 info_entry->c.text.read = snd_seq_device_info; 270 if (snd_info_register(info_entry) < 0) { 271 snd_info_free_entry(info_entry); 272 return -ENOMEM; 273 } 274 #endif 275 return 0; 276 } 277 278 static int __init alsa_seq_device_init(void) 279 { 280 int err; 281 282 err = bus_register(&snd_seq_bus_type); 283 if (err < 0) 284 return err; 285 err = seq_dev_proc_init(); 286 if (err < 0) 287 bus_unregister(&snd_seq_bus_type); 288 return err; 289 } 290 291 static void __exit alsa_seq_device_exit(void) 292 { 293 #ifdef CONFIG_MODULES 294 cancel_work_sync(&autoload_work); 295 #endif 296 #ifdef CONFIG_SND_PROC_FS 297 snd_info_free_entry(info_entry); 298 #endif 299 bus_unregister(&snd_seq_bus_type); 300 } 301 302 subsys_initcall(alsa_seq_device_init) 303 module_exit(alsa_seq_device_exit) 304