projects/linux·blob master · refs

337 lines · 7.7 KiB

1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ALSA sequencer device management
4 * Copyright (c) 1999 by Takashi Iwai <[email protected]>
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
36MODULE_AUTHOR("Takashi Iwai <[email protected]>");
37MODULE_DESCRIPTION("ALSA sequencer device management");
38MODULE_LICENSE("GPL");
39
40/*
41 * bus definition
42 */
43static int snd_seq_bus_match(struct device *dev, const struct device_driver *drv)
44{
45 struct snd_seq_device *sdev = to_seq_dev(dev);
46 const 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
52static int snd_seq_bus_probe(struct device *dev)
53{
54 struct snd_seq_device *sdev = to_seq_dev(dev);
55 const struct snd_seq_driver *sdrv = to_seq_drv(dev->driver);
56
57 if (sdrv->probe)
58 return sdrv->probe(sdev);
59 else
60 return 0;
61}
62
63static void snd_seq_bus_remove(struct device *dev)
64{
65 struct snd_seq_device *sdev = to_seq_dev(dev);
66 const struct snd_seq_driver *sdrv = to_seq_drv(dev->driver);
67
68 if (sdrv->remove)
69 sdrv->remove(sdev);
70}
71
72static const struct bus_type snd_seq_bus_type = {
73 .name = "snd_seq",
74 .match = snd_seq_bus_match,
75 .probe = snd_seq_bus_probe,
76 .remove = snd_seq_bus_remove,
77};
78
79/*
80 * proc interface -- just for compatibility
81 */
82#ifdef CONFIG_SND_PROC_FS
83static struct snd_info_entry *info_entry;
84
85static int print_dev_info(struct device *dev, void *data)
86{
87 struct snd_seq_device *sdev = to_seq_dev(dev);
88 struct snd_info_buffer *buffer = data;
89
90 snd_iprintf(buffer, "snd-%s,%s,%d\n", sdev->id,
91 dev->driver ? "loaded" : "empty",
92 dev->driver ? 1 : 0);
93 return 0;
94}
95
96static void snd_seq_device_info(struct snd_info_entry *entry,
97 struct snd_info_buffer *buffer)
98{
99 bus_for_each_dev(&snd_seq_bus_type, NULL, buffer, print_dev_info);
100}
101#endif
102
103/*
104 * load all registered drivers (called from seq_clientmgr.c)
105 */
106
107#ifdef CONFIG_MODULES
108/* flag to block auto-loading */
109static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */
110
111static int request_seq_drv(struct device *dev, void *data)
112{
113 struct snd_seq_device *sdev = to_seq_dev(dev);
114
115 if (!dev->driver)
116 request_module("snd-%s", sdev->id);
117 return 0;
118}
119
120static void autoload_drivers(struct work_struct *work)
121{
122 /* avoid reentrance */
123 if (atomic_inc_return(&snd_seq_in_init) == 1)
124 bus_for_each_dev(&snd_seq_bus_type, NULL, NULL,
125 request_seq_drv);
126 atomic_dec(&snd_seq_in_init);
127}
128
129static DECLARE_WORK(autoload_work, autoload_drivers);
130
131static void queue_autoload_drivers(void)
132{
133 schedule_work(&autoload_work);
134}
135
136void snd_seq_autoload_init(void)
137{
138 atomic_dec(&snd_seq_in_init);
139#ifdef CONFIG_SND_SEQUENCER_MODULE
140 /* initial autoload only when snd-seq is a module */
141 queue_autoload_drivers();
142#endif
143}
144EXPORT_SYMBOL(snd_seq_autoload_init);
145
146void snd_seq_autoload_exit(void)
147{
148 atomic_inc(&snd_seq_in_init);
149}
150EXPORT_SYMBOL(snd_seq_autoload_exit);
151
152void snd_seq_device_load_drivers(void)
153{
154 queue_autoload_drivers();
155 flush_work(&autoload_work);
156}
157EXPORT_SYMBOL(snd_seq_device_load_drivers);
158
159static inline void cancel_autoload_drivers(void)
160{
161 cancel_work_sync(&autoload_work);
162}
163#else
164static inline void queue_autoload_drivers(void)
165{
166}
167
168static inline void cancel_autoload_drivers(void)
169{
170}
171#endif
172
173/*
174 * device management
175 */
176static int snd_seq_device_dev_free(struct snd_device *device)
177{
178 struct snd_seq_device *dev = device->device_data;
179
180 cancel_autoload_drivers();
181 if (dev->private_free)
182 dev->private_free(dev);
183 put_device(&dev->dev);
184 return 0;
185}
186
187static int snd_seq_device_dev_register(struct snd_device *device)
188{
189 struct snd_seq_device *dev = device->device_data;
190 int err;
191
192 err = device_add(&dev->dev);
193 if (err < 0)
194 return err;
195 if (!dev->dev.driver)
196 queue_autoload_drivers();
197 return 0;
198}
199
200static int snd_seq_device_dev_disconnect(struct snd_device *device)
201{
202 struct snd_seq_device *dev = device->device_data;
203
204 device_del(&dev->dev);
205 return 0;
206}
207
208static void snd_seq_dev_release(struct device *dev)
209{
210 kfree(to_seq_dev(dev));
211}
212
213/*
214 * register a sequencer device
215 * card = card info
216 * device = device number (if any)
217 * id = id of driver
218 * result = return pointer (NULL allowed if unnecessary)
219 */
220int snd_seq_device_new(struct snd_card *card, int device, const char *id,
221 int argsize, struct snd_seq_device **result)
222{
223 struct snd_seq_device *dev;
224 int err;
225 static const struct snd_device_ops dops = {
226 .dev_free = snd_seq_device_dev_free,
227 .dev_register = snd_seq_device_dev_register,
228 .dev_disconnect = snd_seq_device_dev_disconnect,
229 };
230
231 if (result)
232 *result = NULL;
233
234 if (snd_BUG_ON(!id))
235 return -EINVAL;
236
237 if (argsize < 0)
238 return -EINVAL;
239
240 dev = kzalloc_flex(*dev, args, argsize);
241 if (!dev)
242 return -ENOMEM;
243
244 /* set up device info */
245 dev->card = card;
246 dev->device = device;
247 dev->id = id;
248 dev->argsize = argsize;
249
250 device_initialize(&dev->dev);
251 dev->dev.parent = &card->card_dev;
252 dev->dev.bus = &snd_seq_bus_type;
253 dev->dev.release = snd_seq_dev_release;
254 dev_set_name(&dev->dev, "%s-%d-%d", dev->id, card->number, device);
255
256 /* add this device to the list */
257 err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops);
258 if (err < 0) {
259 put_device(&dev->dev);
260 return err;
261 }
262
263 if (result)
264 *result = dev;
265
266 return 0;
267}
268EXPORT_SYMBOL(snd_seq_device_new);
269
270/*
271 * driver registration
272 */
273int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod)
274{
275 if (WARN_ON(!drv->driver.name || !drv->id || drv->driver.probe || drv->driver.remove))
276 return -EINVAL;
277
278 drv->driver.bus = &snd_seq_bus_type;
279 drv->driver.owner = mod;
280
281 return driver_register(&drv->driver);
282}
283EXPORT_SYMBOL_GPL(__snd_seq_driver_register);
284
285void snd_seq_driver_unregister(struct snd_seq_driver *drv)
286{
287 driver_unregister(&drv->driver);
288}
289EXPORT_SYMBOL_GPL(snd_seq_driver_unregister);
290
291/*
292 * module part
293 */
294
295static int __init seq_dev_proc_init(void)
296{
297#ifdef CONFIG_SND_PROC_FS
298 info_entry = snd_info_create_module_entry(THIS_MODULE, "drivers",
299 snd_seq_root);
300 if (info_entry == NULL)
301 return -ENOMEM;
302 info_entry->content = SNDRV_INFO_CONTENT_TEXT;
303 info_entry->c.text.read = snd_seq_device_info;
304 if (snd_info_register(info_entry) < 0) {
305 snd_info_free_entry(info_entry);
306 return -ENOMEM;
307 }
308#endif
309 return 0;
310}
311
312static int __init alsa_seq_device_init(void)
313{
314 int err;
315
316 err = bus_register(&snd_seq_bus_type);
317 if (err < 0)
318 return err;
319 err = seq_dev_proc_init();
320 if (err < 0)
321 bus_unregister(&snd_seq_bus_type);
322 return err;
323}
324
325static void __exit alsa_seq_device_exit(void)
326{
327#ifdef CONFIG_MODULES
328 cancel_work_sync(&autoload_work);
329#endif
330#ifdef CONFIG_SND_PROC_FS
331 snd_info_free_entry(info_entry);
332#endif
333 bus_unregister(&snd_seq_bus_type);
334}
335
336subsys_initcall(alsa_seq_device_init)
337module_exit(alsa_seq_device_exit)