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Linux/sound/core/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/device.h>
 40 #include <linux/init.h>
 41 #include <linux/module.h>
 42 #include <sound/core.h>
 43 #include <sound/info.h>
 44 #include <sound/seq_device.h>
 45 #include <sound/seq_kernel.h>
 46 #include <sound/initval.h>
 47 #include <linux/kmod.h>
 48 #include <linux/slab.h>
 49 #include <linux/mutex.h>
 50 
 51 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
 52 MODULE_DESCRIPTION("ALSA sequencer device management");
 53 MODULE_LICENSE("GPL");
 54 
 55 /*
 56  * bus definition
 57  */
 58 static int snd_seq_bus_match(struct device *dev, struct device_driver *drv)
 59 {
 60         struct snd_seq_device *sdev = to_seq_dev(dev);
 61         struct snd_seq_driver *sdrv = to_seq_drv(drv);
 62 
 63         return strcmp(sdrv->id, sdev->id) == 0 &&
 64                 sdrv->argsize == sdev->argsize;
 65 }
 66 
 67 static struct bus_type snd_seq_bus_type = {
 68         .name = "snd_seq",
 69         .match = snd_seq_bus_match,
 70 };
 71 
 72 /*
 73  * proc interface -- just for compatibility
 74  */
 75 #ifdef CONFIG_SND_PROC_FS
 76 static struct snd_info_entry *info_entry;
 77 
 78 static int print_dev_info(struct device *dev, void *data)
 79 {
 80         struct snd_seq_device *sdev = to_seq_dev(dev);
 81         struct snd_info_buffer *buffer = data;
 82 
 83         snd_iprintf(buffer, "snd-%s,%s,%d\n", sdev->id,
 84                     dev->driver ? "loaded" : "empty",
 85                     dev->driver ? 1 : 0);
 86         return 0;
 87 }
 88 
 89 static void snd_seq_device_info(struct snd_info_entry *entry,
 90                                 struct snd_info_buffer *buffer)
 91 {
 92         bus_for_each_dev(&snd_seq_bus_type, NULL, buffer, print_dev_info);
 93 }
 94 #endif
 95 
 96 /*
 97  * load all registered drivers (called from seq_clientmgr.c)
 98  */
 99 
100 #ifdef CONFIG_MODULES
101 /* flag to block auto-loading */
102 static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */
103 
104 static int request_seq_drv(struct device *dev, void *data)
105 {
106         struct snd_seq_device *sdev = to_seq_dev(dev);
107 
108         if (!dev->driver)
109                 request_module("snd-%s", sdev->id);
110         return 0;
111 }
112 
113 static void autoload_drivers(struct work_struct *work)
114 {
115         /* avoid reentrance */
116         if (atomic_inc_return(&snd_seq_in_init) == 1)
117                 bus_for_each_dev(&snd_seq_bus_type, NULL, NULL,
118                                  request_seq_drv);
119         atomic_dec(&snd_seq_in_init);
120 }
121 
122 static DECLARE_WORK(autoload_work, autoload_drivers);
123 
124 static void queue_autoload_drivers(void)
125 {
126         schedule_work(&autoload_work);
127 }
128 
129 void snd_seq_autoload_init(void)
130 {
131         atomic_dec(&snd_seq_in_init);
132 #ifdef CONFIG_SND_SEQUENCER_MODULE
133         /* initial autoload only when snd-seq is a module */
134         queue_autoload_drivers();
135 #endif
136 }
137 EXPORT_SYMBOL(snd_seq_autoload_init);
138 
139 void snd_seq_autoload_exit(void)
140 {
141         atomic_inc(&snd_seq_in_init);
142 }
143 EXPORT_SYMBOL(snd_seq_autoload_exit);
144 
145 void snd_seq_device_load_drivers(void)
146 {
147         queue_autoload_drivers();
148         flush_work(&autoload_work);
149 }
150 EXPORT_SYMBOL(snd_seq_device_load_drivers);
151 #define cancel_autoload_drivers()       cancel_work_sync(&autoload_work)
152 #else
153 #define queue_autoload_drivers() /* NOP */
154 #define cancel_autoload_drivers() /* NOP */
155 #endif
156 
157 /*
158  * device management
159  */
160 static int snd_seq_device_dev_free(struct snd_device *device)
161 {
162         struct snd_seq_device *dev = device->device_data;
163 
164         cancel_autoload_drivers();
165         put_device(&dev->dev);
166         return 0;
167 }
168 
169 static int snd_seq_device_dev_register(struct snd_device *device)
170 {
171         struct snd_seq_device *dev = device->device_data;
172         int err;
173 
174         err = device_add(&dev->dev);
175         if (err < 0)
176                 return err;
177         if (!dev->dev.driver)
178                 queue_autoload_drivers();
179         return 0;
180 }
181 
182 static int snd_seq_device_dev_disconnect(struct snd_device *device)
183 {
184         struct snd_seq_device *dev = device->device_data;
185 
186         device_del(&dev->dev);
187         return 0;
188 }
189 
190 static void snd_seq_dev_release(struct device *dev)
191 {
192         struct snd_seq_device *sdev = to_seq_dev(dev);
193 
194         if (sdev->private_free)
195                 sdev->private_free(sdev);
196         kfree(sdev);
197 }
198 
199 /*
200  * register a sequencer device
201  * card = card info
202  * device = device number (if any)
203  * id = id of driver
204  * result = return pointer (NULL allowed if unnecessary)
205  */
206 int snd_seq_device_new(struct snd_card *card, int device, const char *id,
207                        int argsize, struct snd_seq_device **result)
208 {
209         struct snd_seq_device *dev;
210         int err;
211         static struct snd_device_ops dops = {
212                 .dev_free = snd_seq_device_dev_free,
213                 .dev_register = snd_seq_device_dev_register,
214                 .dev_disconnect = snd_seq_device_dev_disconnect,
215         };
216 
217         if (result)
218                 *result = NULL;
219 
220         if (snd_BUG_ON(!id))
221                 return -EINVAL;
222 
223         dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL);
224         if (!dev)
225                 return -ENOMEM;
226 
227         /* set up device info */
228         dev->card = card;
229         dev->device = device;
230         dev->id = id;
231         dev->argsize = argsize;
232 
233         device_initialize(&dev->dev);
234         dev->dev.parent = &card->card_dev;
235         dev->dev.bus = &snd_seq_bus_type;
236         dev->dev.release = snd_seq_dev_release;
237         dev_set_name(&dev->dev, "%s-%d-%d", dev->id, card->number, device);
238 
239         /* add this device to the list */
240         err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops);
241         if (err < 0) {
242                 put_device(&dev->dev);
243                 return err;
244         }
245         
246         if (result)
247                 *result = dev;
248 
249         return 0;
250 }
251 EXPORT_SYMBOL(snd_seq_device_new);
252 
253 /*
254  * driver registration
255  */
256 int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod)
257 {
258         if (WARN_ON(!drv->driver.name || !drv->id))
259                 return -EINVAL;
260         drv->driver.bus = &snd_seq_bus_type;
261         drv->driver.owner = mod;
262         return driver_register(&drv->driver);
263 }
264 EXPORT_SYMBOL_GPL(__snd_seq_driver_register);
265 
266 void snd_seq_driver_unregister(struct snd_seq_driver *drv)
267 {
268         driver_unregister(&drv->driver);
269 }
270 EXPORT_SYMBOL_GPL(snd_seq_driver_unregister);
271 
272 /*
273  * module part
274  */
275 
276 static int __init seq_dev_proc_init(void)
277 {
278 #ifdef CONFIG_SND_PROC_FS
279         info_entry = snd_info_create_module_entry(THIS_MODULE, "drivers",
280                                                   snd_seq_root);
281         if (info_entry == NULL)
282                 return -ENOMEM;
283         info_entry->content = SNDRV_INFO_CONTENT_TEXT;
284         info_entry->c.text.read = snd_seq_device_info;
285         if (snd_info_register(info_entry) < 0) {
286                 snd_info_free_entry(info_entry);
287                 return -ENOMEM;
288         }
289 #endif
290         return 0;
291 }
292 
293 static int __init alsa_seq_device_init(void)
294 {
295         int err;
296 
297         err = bus_register(&snd_seq_bus_type);
298         if (err < 0)
299                 return err;
300         err = seq_dev_proc_init();
301         if (err < 0)
302                 bus_unregister(&snd_seq_bus_type);
303         return err;
304 }
305 
306 static void __exit alsa_seq_device_exit(void)
307 {
308 #ifdef CONFIG_MODULES
309         cancel_work_sync(&autoload_work);
310 #endif
311 #ifdef CONFIG_SND_PROC_FS
312         snd_info_free_entry(info_entry);
313 #endif
314         bus_unregister(&snd_seq_bus_type);
315 }
316 
317 subsys_initcall(alsa_seq_device_init)
318 module_exit(alsa_seq_device_exit)
319 

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