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
36 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
37 MODULE_DESCRIPTION("ALSA sequencer device management");
38 MODULE_LICENSE("GPL");
39
40 /*
41 * bus definition
42 */
snd_seq_bus_match(struct device * dev,struct device_driver * drv)43 static 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
52 static 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
61 static struct snd_info_entry *info_entry;
62
print_dev_info(struct device * dev,void * data)63 static 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
snd_seq_device_info(struct snd_info_entry * entry,struct snd_info_buffer * buffer)74 static 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 */
87 static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */
88
request_seq_drv(struct device * dev,void * data)89 static 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
autoload_drivers(struct work_struct * work)98 static 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
107 static DECLARE_WORK(autoload_work, autoload_drivers);
108
queue_autoload_drivers(void)109 static void queue_autoload_drivers(void)
110 {
111 schedule_work(&autoload_work);
112 }
113
snd_seq_autoload_init(void)114 void 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 }
122 EXPORT_SYMBOL(snd_seq_autoload_init);
123
snd_seq_autoload_exit(void)124 void snd_seq_autoload_exit(void)
125 {
126 atomic_inc(&snd_seq_in_init);
127 }
128 EXPORT_SYMBOL(snd_seq_autoload_exit);
129
snd_seq_device_load_drivers(void)130 void snd_seq_device_load_drivers(void)
131 {
132 queue_autoload_drivers();
133 flush_work(&autoload_work);
134 }
135 EXPORT_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 */
snd_seq_device_dev_free(struct snd_device * device)145 static 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 if (dev->private_free)
151 dev->private_free(dev);
152 put_device(&dev->dev);
153 return 0;
154 }
155
snd_seq_device_dev_register(struct snd_device * device)156 static int snd_seq_device_dev_register(struct snd_device *device)
157 {
158 struct snd_seq_device *dev = device->device_data;
159 int err;
160
161 err = device_add(&dev->dev);
162 if (err < 0)
163 return err;
164 if (!dev->dev.driver)
165 queue_autoload_drivers();
166 return 0;
167 }
168
snd_seq_device_dev_disconnect(struct snd_device * device)169 static int snd_seq_device_dev_disconnect(struct snd_device *device)
170 {
171 struct snd_seq_device *dev = device->device_data;
172
173 device_del(&dev->dev);
174 return 0;
175 }
176
snd_seq_dev_release(struct device * dev)177 static void snd_seq_dev_release(struct device *dev)
178 {
179 kfree(to_seq_dev(dev));
180 }
181
182 /*
183 * register a sequencer device
184 * card = card info
185 * device = device number (if any)
186 * id = id of driver
187 * result = return pointer (NULL allowed if unnecessary)
188 */
snd_seq_device_new(struct snd_card * card,int device,const char * id,int argsize,struct snd_seq_device ** result)189 int snd_seq_device_new(struct snd_card *card, int device, const char *id,
190 int argsize, struct snd_seq_device **result)
191 {
192 struct snd_seq_device *dev;
193 int err;
194 static struct snd_device_ops dops = {
195 .dev_free = snd_seq_device_dev_free,
196 .dev_register = snd_seq_device_dev_register,
197 .dev_disconnect = snd_seq_device_dev_disconnect,
198 };
199
200 if (result)
201 *result = NULL;
202
203 if (snd_BUG_ON(!id))
204 return -EINVAL;
205
206 dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL);
207 if (!dev)
208 return -ENOMEM;
209
210 /* set up device info */
211 dev->card = card;
212 dev->device = device;
213 dev->id = id;
214 dev->argsize = argsize;
215
216 device_initialize(&dev->dev);
217 dev->dev.parent = &card->card_dev;
218 dev->dev.bus = &snd_seq_bus_type;
219 dev->dev.release = snd_seq_dev_release;
220 dev_set_name(&dev->dev, "%s-%d-%d", dev->id, card->number, device);
221
222 /* add this device to the list */
223 err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops);
224 if (err < 0) {
225 put_device(&dev->dev);
226 return err;
227 }
228
229 if (result)
230 *result = dev;
231
232 return 0;
233 }
234 EXPORT_SYMBOL(snd_seq_device_new);
235
236 /*
237 * driver registration
238 */
__snd_seq_driver_register(struct snd_seq_driver * drv,struct module * mod)239 int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod)
240 {
241 if (WARN_ON(!drv->driver.name || !drv->id))
242 return -EINVAL;
243 drv->driver.bus = &snd_seq_bus_type;
244 drv->driver.owner = mod;
245 return driver_register(&drv->driver);
246 }
247 EXPORT_SYMBOL_GPL(__snd_seq_driver_register);
248
snd_seq_driver_unregister(struct snd_seq_driver * drv)249 void snd_seq_driver_unregister(struct snd_seq_driver *drv)
250 {
251 driver_unregister(&drv->driver);
252 }
253 EXPORT_SYMBOL_GPL(snd_seq_driver_unregister);
254
255 /*
256 * module part
257 */
258
seq_dev_proc_init(void)259 static int __init seq_dev_proc_init(void)
260 {
261 #ifdef CONFIG_SND_PROC_FS
262 info_entry = snd_info_create_module_entry(THIS_MODULE, "drivers",
263 snd_seq_root);
264 if (info_entry == NULL)
265 return -ENOMEM;
266 info_entry->content = SNDRV_INFO_CONTENT_TEXT;
267 info_entry->c.text.read = snd_seq_device_info;
268 if (snd_info_register(info_entry) < 0) {
269 snd_info_free_entry(info_entry);
270 return -ENOMEM;
271 }
272 #endif
273 return 0;
274 }
275
alsa_seq_device_init(void)276 static int __init alsa_seq_device_init(void)
277 {
278 int err;
279
280 err = bus_register(&snd_seq_bus_type);
281 if (err < 0)
282 return err;
283 err = seq_dev_proc_init();
284 if (err < 0)
285 bus_unregister(&snd_seq_bus_type);
286 return err;
287 }
288
alsa_seq_device_exit(void)289 static void __exit alsa_seq_device_exit(void)
290 {
291 #ifdef CONFIG_MODULES
292 cancel_work_sync(&autoload_work);
293 #endif
294 #ifdef CONFIG_SND_PROC_FS
295 snd_info_free_entry(info_entry);
296 #endif
297 bus_unregister(&snd_seq_bus_type);
298 }
299
300 subsys_initcall(alsa_seq_device_init)
301 module_exit(alsa_seq_device_exit)
302