sound/core/seq_device.c

   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)