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); 136 137 static inline void cancel_autoload_drivers(void) 138 { 139 cancel_work_sync(&autoload_work); 140 } 141 #else 142 static inline void queue_autoload_drivers(void) 143 { 144 } 145 146 static inline void cancel_autoload_drivers(void) 147 { 148 } 149 #endif 150 151 /* 152 * device management 153 */ 154 static int snd_seq_device_dev_free(struct snd_device *device) 155 { 156 struct snd_seq_device *dev = device->device_data; 157 158 cancel_autoload_drivers(); 159 put_device(&dev->dev); 160 return 0; 161 } 162 163 static int snd_seq_device_dev_register(struct snd_device *device) 164 { 165 struct snd_seq_device *dev = device->device_data; 166 int err; 167 168 err = device_add(&dev->dev); 169 if (err < 0) 170 return err; 171 if (!dev->dev.driver) 172 queue_autoload_drivers(); 173 return 0; 174 } 175 176 static int snd_seq_device_dev_disconnect(struct snd_device *device) 177 { 178 struct snd_seq_device *dev = device->device_data; 179 180 device_del(&dev->dev); 181 return 0; 182 } 183 184 static void snd_seq_dev_release(struct device *dev) 185 { 186 struct snd_seq_device *sdev = to_seq_dev(dev); 187 188 if (sdev->private_free) 189 sdev->private_free(sdev); 190 kfree(sdev); 191 } 192 193 /* 194 * register a sequencer device 195 * card = card info 196 * device = device number (if any) 197 * id = id of driver 198 * result = return pointer (NULL allowed if unnecessary) 199 */ 200 int snd_seq_device_new(struct snd_card *card, int device, const char *id, 201 int argsize, struct snd_seq_device **result) 202 { 203 struct snd_seq_device *dev; 204 int err; 205 static const struct snd_device_ops dops = { 206 .dev_free = snd_seq_device_dev_free, 207 .dev_register = snd_seq_device_dev_register, 208 .dev_disconnect = snd_seq_device_dev_disconnect, 209 }; 210 211 if (result) 212 *result = NULL; 213 214 if (snd_BUG_ON(!id)) 215 return -EINVAL; 216 217 dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL); 218 if (!dev) 219 return -ENOMEM; 220 221 /* set up device info */ 222 dev->card = card; 223 dev->device = device; 224 dev->id = id; 225 dev->argsize = argsize; 226 227 device_initialize(&dev->dev); 228 dev->dev.parent = &card->card_dev; 229 dev->dev.bus = &snd_seq_bus_type; 230 dev->dev.release = snd_seq_dev_release; 231 dev_set_name(&dev->dev, "%s-%d-%d", dev->id, card->number, device); 232 233 /* add this device to the list */ 234 err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops); 235 if (err < 0) { 236 put_device(&dev->dev); 237 return err; 238 } 239 240 if (result) 241 *result = dev; 242 243 return 0; 244 } 245 EXPORT_SYMBOL(snd_seq_device_new); 246 247 /* 248 * driver registration 249 */ 250 int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod) 251 { 252 if (WARN_ON(!drv->driver.name || !drv->id)) 253 return -EINVAL; 254 drv->driver.bus = &snd_seq_bus_type; 255 drv->driver.owner = mod; 256 return driver_register(&drv->driver); 257 } 258 EXPORT_SYMBOL_GPL(__snd_seq_driver_register); 259 260 void snd_seq_driver_unregister(struct snd_seq_driver *drv) 261 { 262 driver_unregister(&drv->driver); 263 } 264 EXPORT_SYMBOL_GPL(snd_seq_driver_unregister); 265 266 /* 267 * module part 268 */ 269 270 static int __init seq_dev_proc_init(void) 271 { 272 #ifdef CONFIG_SND_PROC_FS 273 info_entry = snd_info_create_module_entry(THIS_MODULE, "drivers", 274 snd_seq_root); 275 if (info_entry == NULL) 276 return -ENOMEM; 277 info_entry->content = SNDRV_INFO_CONTENT_TEXT; 278 info_entry->c.text.read = snd_seq_device_info; 279 if (snd_info_register(info_entry) < 0) { 280 snd_info_free_entry(info_entry); 281 return -ENOMEM; 282 } 283 #endif 284 return 0; 285 } 286 287 static int __init alsa_seq_device_init(void) 288 { 289 int err; 290 291 err = bus_register(&snd_seq_bus_type); 292 if (err < 0) 293 return err; 294 err = seq_dev_proc_init(); 295 if (err < 0) 296 bus_unregister(&snd_seq_bus_type); 297 return err; 298 } 299 300 static void __exit alsa_seq_device_exit(void) 301 { 302 #ifdef CONFIG_MODULES 303 cancel_work_sync(&autoload_work); 304 #endif 305 #ifdef CONFIG_SND_PROC_FS 306 snd_info_free_entry(info_entry); 307 #endif 308 bus_unregister(&snd_seq_bus_type); 309 } 310 311 subsys_initcall(alsa_seq_device_init) 312 module_exit(alsa_seq_device_exit) 313