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