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Linux/sound/core/seq/seq_device.c

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  1 /*
  2  *  ALSA sequencer device management
  3  *  Copyright (c) 1999 by Takashi Iwai <tiwai@suse.de>
  4  *
  5  *   This program is free software; you can redistribute it and/or modify
  6  *   it under the terms of the GNU General Public License as published by
  7  *   the Free Software Foundation; either version 2 of the License, or
  8  *   (at your option) any later version.
  9  *
 10  *   This program is distributed in the hope that it will be useful,
 11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13  *   GNU General Public License for more details.
 14  *
 15  *   You should have received a copy of the GNU General Public License
 16  *   along with this program; if not, write to the Free Software
 17  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 18  *
 19  *
 20  *----------------------------------------------------------------
 21  *
 22  * This device handler separates the card driver module from sequencer
 23  * stuff (sequencer core, synth drivers, etc), so that user can avoid
 24  * to spend unnecessary resources e.g. if he needs only listening to
 25  * MP3s.
 26  *
 27  * The card (or lowlevel) driver creates a sequencer device entry
 28  * via snd_seq_device_new().  This is an entry pointer to communicate
 29  * with the sequencer device "driver", which is involved with the
 30  * actual part to communicate with the sequencer core.
 31  * Each sequencer device entry has an id string and the corresponding
 32  * driver with the same id is loaded when required.  For example,
 33  * lowlevel codes to access emu8000 chip on sbawe card are included in
 34  * emu8000-synth module.  To activate this module, the hardware
 35  * resources like i/o port are passed via snd_seq_device argument.
 36  *
 37  */
 38 
 39 #include <linux/init.h>
 40 #include <linux/module.h>
 41 #include <sound/core.h>
 42 #include <sound/info.h>
 43 #include <sound/seq_device.h>
 44 #include <sound/seq_kernel.h>
 45 #include <sound/initval.h>
 46 #include <linux/kmod.h>
 47 #include <linux/slab.h>
 48 #include <linux/mutex.h>
 49 
 50 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
 51 MODULE_DESCRIPTION("ALSA sequencer device management");
 52 MODULE_LICENSE("GPL");
 53 
 54 /* driver state */
 55 #define DRIVER_EMPTY            0
 56 #define DRIVER_LOADED           (1<<0)
 57 #define DRIVER_REQUESTED        (1<<1)
 58 #define DRIVER_LOCKED           (1<<2)
 59 #define DRIVER_REQUESTING       (1<<3)
 60 
 61 struct ops_list {
 62         char id[ID_LEN];        /* driver id */
 63         int driver;             /* driver state */
 64         int used;               /* reference counter */
 65         int argsize;            /* argument size */
 66 
 67         /* operators */
 68         struct snd_seq_dev_ops ops;
 69 
 70         /* registered devices */
 71         struct list_head dev_list;      /* list of devices */
 72         int num_devices;        /* number of associated devices */
 73         int num_init_devices;   /* number of initialized devices */
 74         struct mutex reg_mutex;
 75 
 76         struct list_head list;  /* next driver */
 77 };
 78 
 79 
 80 static LIST_HEAD(opslist);
 81 static int num_ops;
 82 static DEFINE_MUTEX(ops_mutex);
 83 #ifdef CONFIG_PROC_FS
 84 static struct snd_info_entry *info_entry;
 85 #endif
 86 
 87 /*
 88  * prototypes
 89  */
 90 static int snd_seq_device_free(struct snd_seq_device *dev);
 91 static int snd_seq_device_dev_free(struct snd_device *device);
 92 static int snd_seq_device_dev_register(struct snd_device *device);
 93 static int snd_seq_device_dev_disconnect(struct snd_device *device);
 94 
 95 static int init_device(struct snd_seq_device *dev, struct ops_list *ops);
 96 static int free_device(struct snd_seq_device *dev, struct ops_list *ops);
 97 static struct ops_list *find_driver(char *id, int create_if_empty);
 98 static struct ops_list *create_driver(char *id);
 99 static void unlock_driver(struct ops_list *ops);
100 static void remove_drivers(void);
101 
102 /*
103  * show all drivers and their status
104  */
105 
106 #ifdef CONFIG_PROC_FS
107 static void snd_seq_device_info(struct snd_info_entry *entry,
108                                 struct snd_info_buffer *buffer)
109 {
110         struct ops_list *ops;
111 
112         mutex_lock(&ops_mutex);
113         list_for_each_entry(ops, &opslist, list) {
114                 snd_iprintf(buffer, "snd-%s%s%s%s,%d\n",
115                                 ops->id,
116                                 ops->driver & DRIVER_LOADED ? ",loaded" : (ops->driver == DRIVER_EMPTY ? ",empty" : ""),
117                                 ops->driver & DRIVER_REQUESTED ? ",requested" : "",
118                                 ops->driver & DRIVER_LOCKED ? ",locked" : "",
119                                 ops->num_devices);
120         }
121         mutex_unlock(&ops_mutex);
122 }
123 #endif
124  
125 /*
126  * load all registered drivers (called from seq_clientmgr.c)
127  */
128 
129 #ifdef CONFIG_MODULES
130 /* avoid auto-loading during module_init() */
131 static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */
132 void snd_seq_autoload_lock(void)
133 {
134         atomic_inc(&snd_seq_in_init);
135 }
136 
137 void snd_seq_autoload_unlock(void)
138 {
139         atomic_dec(&snd_seq_in_init);
140 }
141 
142 static void autoload_drivers(void)
143 {
144         /* avoid reentrance */
145         if (atomic_inc_return(&snd_seq_in_init) == 1) {
146                 struct ops_list *ops;
147 
148                 mutex_lock(&ops_mutex);
149                 list_for_each_entry(ops, &opslist, list) {
150                         if ((ops->driver & DRIVER_REQUESTING) &&
151                             !(ops->driver & DRIVER_REQUESTED)) {
152                                 ops->used++;
153                                 mutex_unlock(&ops_mutex);
154                                 ops->driver |= DRIVER_REQUESTED;
155                                 request_module("snd-%s", ops->id);
156                                 mutex_lock(&ops_mutex);
157                                 ops->used--;
158                         }
159                 }
160                 mutex_unlock(&ops_mutex);
161         }
162         atomic_dec(&snd_seq_in_init);
163 }
164 
165 static void call_autoload(struct work_struct *work)
166 {
167         autoload_drivers();
168 }
169 
170 static DECLARE_WORK(autoload_work, call_autoload);
171 
172 static void try_autoload(struct ops_list *ops)
173 {
174         if (!ops->driver) {
175                 ops->driver |= DRIVER_REQUESTING;
176                 schedule_work(&autoload_work);
177         }
178 }
179 
180 static void queue_autoload_drivers(void)
181 {
182         struct ops_list *ops;
183 
184         mutex_lock(&ops_mutex);
185         list_for_each_entry(ops, &opslist, list)
186                 try_autoload(ops);
187         mutex_unlock(&ops_mutex);
188 }
189 
190 void snd_seq_autoload_init(void)
191 {
192         atomic_dec(&snd_seq_in_init);
193 #ifdef CONFIG_SND_SEQUENCER_MODULE
194         /* initial autoload only when snd-seq is a module */
195         queue_autoload_drivers();
196 #endif
197 }
198 #else
199 #define try_autoload(ops) /* NOP */
200 #endif
201 
202 void snd_seq_device_load_drivers(void)
203 {
204 #ifdef CONFIG_MODULES
205         queue_autoload_drivers();
206         flush_work(&autoload_work);
207 #endif
208 }
209 
210 /*
211  * register a sequencer device
212  * card = card info
213  * device = device number (if any)
214  * id = id of driver
215  * result = return pointer (NULL allowed if unnecessary)
216  */
217 int snd_seq_device_new(struct snd_card *card, int device, char *id, int argsize,
218                        struct snd_seq_device **result)
219 {
220         struct snd_seq_device *dev;
221         struct ops_list *ops;
222         int err;
223         static struct snd_device_ops dops = {
224                 .dev_free = snd_seq_device_dev_free,
225                 .dev_register = snd_seq_device_dev_register,
226                 .dev_disconnect = snd_seq_device_dev_disconnect,
227         };
228 
229         if (result)
230                 *result = NULL;
231 
232         if (snd_BUG_ON(!id))
233                 return -EINVAL;
234 
235         ops = find_driver(id, 1);
236         if (ops == NULL)
237                 return -ENOMEM;
238 
239         dev = kzalloc(sizeof(*dev)*2 + argsize, GFP_KERNEL);
240         if (dev == NULL) {
241                 unlock_driver(ops);
242                 return -ENOMEM;
243         }
244 
245         /* set up device info */
246         dev->card = card;
247         dev->device = device;
248         strlcpy(dev->id, id, sizeof(dev->id));
249         dev->argsize = argsize;
250         dev->status = SNDRV_SEQ_DEVICE_FREE;
251 
252         /* add this device to the list */
253         mutex_lock(&ops->reg_mutex);
254         list_add_tail(&dev->list, &ops->dev_list);
255         ops->num_devices++;
256         mutex_unlock(&ops->reg_mutex);
257 
258         if ((err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops)) < 0) {
259                 snd_seq_device_free(dev);
260                 return err;
261         }
262         
263         try_autoload(ops);
264         unlock_driver(ops);
265 
266         if (result)
267                 *result = dev;
268 
269         return 0;
270 }
271 
272 /*
273  * free the existing device
274  */
275 static int snd_seq_device_free(struct snd_seq_device *dev)
276 {
277         struct ops_list *ops;
278 
279         if (snd_BUG_ON(!dev))
280                 return -EINVAL;
281 
282         ops = find_driver(dev->id, 0);
283         if (ops == NULL)
284                 return -ENXIO;
285 
286         /* remove the device from the list */
287         mutex_lock(&ops->reg_mutex);
288         list_del(&dev->list);
289         ops->num_devices--;
290         mutex_unlock(&ops->reg_mutex);
291 
292         free_device(dev, ops);
293         if (dev->private_free)
294                 dev->private_free(dev);
295         kfree(dev);
296 
297         unlock_driver(ops);
298 
299         return 0;
300 }
301 
302 static int snd_seq_device_dev_free(struct snd_device *device)
303 {
304         struct snd_seq_device *dev = device->device_data;
305         return snd_seq_device_free(dev);
306 }
307 
308 /*
309  * register the device
310  */
311 static int snd_seq_device_dev_register(struct snd_device *device)
312 {
313         struct snd_seq_device *dev = device->device_data;
314         struct ops_list *ops;
315 
316         ops = find_driver(dev->id, 0);
317         if (ops == NULL)
318                 return -ENOENT;
319 
320         /* initialize this device if the corresponding driver was
321          * already loaded
322          */
323         if (ops->driver & DRIVER_LOADED)
324                 init_device(dev, ops);
325 
326         unlock_driver(ops);
327         return 0;
328 }
329 
330 /*
331  * disconnect the device
332  */
333 static int snd_seq_device_dev_disconnect(struct snd_device *device)
334 {
335         struct snd_seq_device *dev = device->device_data;
336         struct ops_list *ops;
337 
338         ops = find_driver(dev->id, 0);
339         if (ops == NULL)
340                 return -ENOENT;
341 
342         free_device(dev, ops);
343 
344         unlock_driver(ops);
345         return 0;
346 }
347 
348 /*
349  * register device driver
350  * id = driver id
351  * entry = driver operators - duplicated to each instance
352  */
353 int snd_seq_device_register_driver(char *id, struct snd_seq_dev_ops *entry,
354                                    int argsize)
355 {
356         struct ops_list *ops;
357         struct snd_seq_device *dev;
358 
359         if (id == NULL || entry == NULL ||
360             entry->init_device == NULL || entry->free_device == NULL)
361                 return -EINVAL;
362 
363         ops = find_driver(id, 1);
364         if (ops == NULL)
365                 return -ENOMEM;
366         if (ops->driver & DRIVER_LOADED) {
367                 pr_warn("ALSA: seq: driver_register: driver '%s' already exists\n", id);
368                 unlock_driver(ops);
369                 return -EBUSY;
370         }
371 
372         mutex_lock(&ops->reg_mutex);
373         /* copy driver operators */
374         ops->ops = *entry;
375         ops->driver |= DRIVER_LOADED;
376         ops->argsize = argsize;
377 
378         /* initialize existing devices if necessary */
379         list_for_each_entry(dev, &ops->dev_list, list) {
380                 init_device(dev, ops);
381         }
382         mutex_unlock(&ops->reg_mutex);
383 
384         unlock_driver(ops);
385 
386         return 0;
387 }
388 
389 
390 /*
391  * create driver record
392  */
393 static struct ops_list * create_driver(char *id)
394 {
395         struct ops_list *ops;
396 
397         ops = kzalloc(sizeof(*ops), GFP_KERNEL);
398         if (ops == NULL)
399                 return ops;
400 
401         /* set up driver entry */
402         strlcpy(ops->id, id, sizeof(ops->id));
403         mutex_init(&ops->reg_mutex);
404         /*
405          * The ->reg_mutex locking rules are per-driver, so we create
406          * separate per-driver lock classes:
407          */
408         lockdep_set_class(&ops->reg_mutex, (struct lock_class_key *)id);
409 
410         ops->driver = DRIVER_EMPTY;
411         INIT_LIST_HEAD(&ops->dev_list);
412         /* lock this instance */
413         ops->used = 1;
414 
415         /* register driver entry */
416         mutex_lock(&ops_mutex);
417         list_add_tail(&ops->list, &opslist);
418         num_ops++;
419         mutex_unlock(&ops_mutex);
420 
421         return ops;
422 }
423 
424 
425 /*
426  * unregister the specified driver
427  */
428 int snd_seq_device_unregister_driver(char *id)
429 {
430         struct ops_list *ops;
431         struct snd_seq_device *dev;
432 
433         ops = find_driver(id, 0);
434         if (ops == NULL)
435                 return -ENXIO;
436         if (! (ops->driver & DRIVER_LOADED) ||
437             (ops->driver & DRIVER_LOCKED)) {
438                 pr_err("ALSA: seq: driver_unregister: cannot unload driver '%s': status=%x\n",
439                            id, ops->driver);
440                 unlock_driver(ops);
441                 return -EBUSY;
442         }
443 
444         /* close and release all devices associated with this driver */
445         mutex_lock(&ops->reg_mutex);
446         ops->driver |= DRIVER_LOCKED; /* do not remove this driver recursively */
447         list_for_each_entry(dev, &ops->dev_list, list) {
448                 free_device(dev, ops);
449         }
450 
451         ops->driver = 0;
452         if (ops->num_init_devices > 0)
453                 pr_err("ALSA: seq: free_driver: init_devices > 0!! (%d)\n",
454                            ops->num_init_devices);
455         mutex_unlock(&ops->reg_mutex);
456 
457         unlock_driver(ops);
458 
459         /* remove empty driver entries */
460         remove_drivers();
461 
462         return 0;
463 }
464 
465 
466 /*
467  * remove empty driver entries
468  */
469 static void remove_drivers(void)
470 {
471         struct list_head *head;
472 
473         mutex_lock(&ops_mutex);
474         head = opslist.next;
475         while (head != &opslist) {
476                 struct ops_list *ops = list_entry(head, struct ops_list, list);
477                 if (! (ops->driver & DRIVER_LOADED) &&
478                     ops->used == 0 && ops->num_devices == 0) {
479                         head = head->next;
480                         list_del(&ops->list);
481                         kfree(ops);
482                         num_ops--;
483                 } else
484                         head = head->next;
485         }
486         mutex_unlock(&ops_mutex);
487 }
488 
489 /*
490  * initialize the device - call init_device operator
491  */
492 static int init_device(struct snd_seq_device *dev, struct ops_list *ops)
493 {
494         if (! (ops->driver & DRIVER_LOADED))
495                 return 0; /* driver is not loaded yet */
496         if (dev->status != SNDRV_SEQ_DEVICE_FREE)
497                 return 0; /* already initialized */
498         if (ops->argsize != dev->argsize) {
499                 pr_err("ALSA: seq: incompatible device '%s' for plug-in '%s' (%d %d)\n",
500                            dev->name, ops->id, ops->argsize, dev->argsize);
501                 return -EINVAL;
502         }
503         if (ops->ops.init_device(dev) >= 0) {
504                 dev->status = SNDRV_SEQ_DEVICE_REGISTERED;
505                 ops->num_init_devices++;
506         } else {
507                 pr_err("ALSA: seq: init_device failed: %s: %s\n",
508                            dev->name, dev->id);
509         }
510 
511         return 0;
512 }
513 
514 /*
515  * release the device - call free_device operator
516  */
517 static int free_device(struct snd_seq_device *dev, struct ops_list *ops)
518 {
519         int result;
520 
521         if (! (ops->driver & DRIVER_LOADED))
522                 return 0; /* driver is not loaded yet */
523         if (dev->status != SNDRV_SEQ_DEVICE_REGISTERED)
524                 return 0; /* not registered */
525         if (ops->argsize != dev->argsize) {
526                 pr_err("ALSA: seq: incompatible device '%s' for plug-in '%s' (%d %d)\n",
527                            dev->name, ops->id, ops->argsize, dev->argsize);
528                 return -EINVAL;
529         }
530         if ((result = ops->ops.free_device(dev)) >= 0 || result == -ENXIO) {
531                 dev->status = SNDRV_SEQ_DEVICE_FREE;
532                 dev->driver_data = NULL;
533                 ops->num_init_devices--;
534         } else {
535                 pr_err("ALSA: seq: free_device failed: %s: %s\n",
536                            dev->name, dev->id);
537         }
538 
539         return 0;
540 }
541 
542 /*
543  * find the matching driver with given id
544  */
545 static struct ops_list * find_driver(char *id, int create_if_empty)
546 {
547         struct ops_list *ops;
548 
549         mutex_lock(&ops_mutex);
550         list_for_each_entry(ops, &opslist, list) {
551                 if (strcmp(ops->id, id) == 0) {
552                         ops->used++;
553                         mutex_unlock(&ops_mutex);
554                         return ops;
555                 }
556         }
557         mutex_unlock(&ops_mutex);
558         if (create_if_empty)
559                 return create_driver(id);
560         return NULL;
561 }
562 
563 static void unlock_driver(struct ops_list *ops)
564 {
565         mutex_lock(&ops_mutex);
566         ops->used--;
567         mutex_unlock(&ops_mutex);
568 }
569 
570 
571 /*
572  * module part
573  */
574 
575 static int __init alsa_seq_device_init(void)
576 {
577 #ifdef CONFIG_PROC_FS
578         info_entry = snd_info_create_module_entry(THIS_MODULE, "drivers",
579                                                   snd_seq_root);
580         if (info_entry == NULL)
581                 return -ENOMEM;
582         info_entry->content = SNDRV_INFO_CONTENT_TEXT;
583         info_entry->c.text.read = snd_seq_device_info;
584         if (snd_info_register(info_entry) < 0) {
585                 snd_info_free_entry(info_entry);
586                 return -ENOMEM;
587         }
588 #endif
589         return 0;
590 }
591 
592 static void __exit alsa_seq_device_exit(void)
593 {
594 #ifdef CONFIG_MODULES
595         cancel_work_sync(&autoload_work);
596 #endif
597         remove_drivers();
598 #ifdef CONFIG_PROC_FS
599         snd_info_free_entry(info_entry);
600 #endif
601         if (num_ops)
602                 pr_err("ALSA: seq: drivers not released (%d)\n", num_ops);
603 }
604 
605 module_init(alsa_seq_device_init)
606 module_exit(alsa_seq_device_exit)
607 
608 EXPORT_SYMBOL(snd_seq_device_load_drivers);
609 EXPORT_SYMBOL(snd_seq_device_new);
610 EXPORT_SYMBOL(snd_seq_device_register_driver);
611 EXPORT_SYMBOL(snd_seq_device_unregister_driver);
612 #ifdef CONFIG_MODULES
613 EXPORT_SYMBOL(snd_seq_autoload_init);
614 EXPORT_SYMBOL(snd_seq_autoload_lock);
615 EXPORT_SYMBOL(snd_seq_autoload_unlock);
616 #endif
617 

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