Linux kernel mirror (for testing)
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linux
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
36MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
37MODULE_DESCRIPTION("ALSA sequencer device management");
38MODULE_LICENSE("GPL");
39
40/*
41 * bus definition
42 */
43static 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
52static 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
61static struct snd_info_entry *info_entry;
62
63static 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
74static 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 */
87static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */
88
89static 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
98static 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
107static DECLARE_WORK(autoload_work, autoload_drivers);
108
109static void queue_autoload_drivers(void)
110{
111 schedule_work(&autoload_work);
112}
113
114void 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}
122EXPORT_SYMBOL(snd_seq_autoload_init);
123
124void snd_seq_autoload_exit(void)
125{
126 atomic_inc(&snd_seq_in_init);
127}
128EXPORT_SYMBOL(snd_seq_autoload_exit);
129
130void snd_seq_device_load_drivers(void)
131{
132 queue_autoload_drivers();
133 flush_work(&autoload_work);
134}
135EXPORT_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 */
145static 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
154static 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
167static 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
175static 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 */
191int 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 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}
236EXPORT_SYMBOL(snd_seq_device_new);
237
238/*
239 * driver registration
240 */
241int __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}
249EXPORT_SYMBOL_GPL(__snd_seq_driver_register);
250
251void snd_seq_driver_unregister(struct snd_seq_driver *drv)
252{
253 driver_unregister(&drv->driver);
254}
255EXPORT_SYMBOL_GPL(snd_seq_driver_unregister);
256
257/*
258 * module part
259 */
260
261static 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
278static 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
291static 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
302subsys_initcall(alsa_seq_device_init)
303module_exit(alsa_seq_device_exit)