xref: /openbmc/linux/sound/core/seq_device.c (revision 2359ccdd)
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