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, 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 const 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(bus: &snd_seq_bus_type, NULL, data: buffer, fn: 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(v: &snd_seq_in_init) == 1)
102 bus_for_each_dev(bus: &snd_seq_bus_type, NULL, NULL,
103 fn: request_seq_drv);
104 atomic_dec(v: &snd_seq_in_init);
105}
106
107static DECLARE_WORK(autoload_work, autoload_drivers);
108
109static void queue_autoload_drivers(void)
110{
111 schedule_work(work: &autoload_work);
112}
113
114void snd_seq_autoload_init(void)
115{
116 atomic_dec(v: &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(v: &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(work: &autoload_work);
134}
135EXPORT_SYMBOL(snd_seq_device_load_drivers);
136
137static inline void cancel_autoload_drivers(void)
138{
139 cancel_work_sync(work: &autoload_work);
140}
141#else
142static inline void queue_autoload_drivers(void)
143{
144}
145
146static inline void cancel_autoload_drivers(void)
147{
148}
149#endif
150
151/*
152 * device management
153 */
154static int snd_seq_device_dev_free(struct snd_device *device)
155{
156 struct snd_seq_device *dev = device->device_data;
157
158 cancel_autoload_drivers();
159 if (dev->private_free)
160 dev->private_free(dev);
161 put_device(dev: &dev->dev);
162 return 0;
163}
164
165static int snd_seq_device_dev_register(struct snd_device *device)
166{
167 struct snd_seq_device *dev = device->device_data;
168 int err;
169
170 err = device_add(dev: &dev->dev);
171 if (err < 0)
172 return err;
173 if (!dev->dev.driver)
174 queue_autoload_drivers();
175 return 0;
176}
177
178static int snd_seq_device_dev_disconnect(struct snd_device *device)
179{
180 struct snd_seq_device *dev = device->device_data;
181
182 device_del(dev: &dev->dev);
183 return 0;
184}
185
186static void snd_seq_dev_release(struct device *dev)
187{
188 kfree(to_seq_dev(dev));
189}
190
191/*
192 * register a sequencer device
193 * card = card info
194 * device = device number (if any)
195 * id = id of driver
196 * result = return pointer (NULL allowed if unnecessary)
197 */
198int snd_seq_device_new(struct snd_card *card, int device, const char *id,
199 int argsize, struct snd_seq_device **result)
200{
201 struct snd_seq_device *dev;
202 int err;
203 static const struct snd_device_ops dops = {
204 .dev_free = snd_seq_device_dev_free,
205 .dev_register = snd_seq_device_dev_register,
206 .dev_disconnect = snd_seq_device_dev_disconnect,
207 };
208
209 if (result)
210 *result = NULL;
211
212 if (snd_BUG_ON(!id))
213 return -EINVAL;
214
215 dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL);
216 if (!dev)
217 return -ENOMEM;
218
219 /* set up device info */
220 dev->card = card;
221 dev->device = device;
222 dev->id = id;
223 dev->argsize = argsize;
224
225 device_initialize(dev: &dev->dev);
226 dev->dev.parent = &card->card_dev;
227 dev->dev.bus = &snd_seq_bus_type;
228 dev->dev.release = snd_seq_dev_release;
229 dev_set_name(dev: &dev->dev, name: "%s-%d-%d", dev->id, card->number, device);
230
231 /* add this device to the list */
232 err = snd_device_new(card, type: SNDRV_DEV_SEQUENCER, device_data: dev, ops: &dops);
233 if (err < 0) {
234 put_device(dev: &dev->dev);
235 return err;
236 }
237
238 if (result)
239 *result = dev;
240
241 return 0;
242}
243EXPORT_SYMBOL(snd_seq_device_new);
244
245/*
246 * driver registration
247 */
248int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod)
249{
250 if (WARN_ON(!drv->driver.name || !drv->id))
251 return -EINVAL;
252 drv->driver.bus = &snd_seq_bus_type;
253 drv->driver.owner = mod;
254 return driver_register(drv: &drv->driver);
255}
256EXPORT_SYMBOL_GPL(__snd_seq_driver_register);
257
258void snd_seq_driver_unregister(struct snd_seq_driver *drv)
259{
260 driver_unregister(drv: &drv->driver);
261}
262EXPORT_SYMBOL_GPL(snd_seq_driver_unregister);
263
264/*
265 * module part
266 */
267
268static int __init seq_dev_proc_init(void)
269{
270#ifdef CONFIG_SND_PROC_FS
271 info_entry = snd_info_create_module_entry(THIS_MODULE, name: "drivers",
272 parent: snd_seq_root);
273 if (info_entry == NULL)
274 return -ENOMEM;
275 info_entry->content = SNDRV_INFO_CONTENT_TEXT;
276 info_entry->c.text.read = snd_seq_device_info;
277 if (snd_info_register(entry: info_entry) < 0) {
278 snd_info_free_entry(entry: info_entry);
279 return -ENOMEM;
280 }
281#endif
282 return 0;
283}
284
285static int __init alsa_seq_device_init(void)
286{
287 int err;
288
289 err = bus_register(bus: &snd_seq_bus_type);
290 if (err < 0)
291 return err;
292 err = seq_dev_proc_init();
293 if (err < 0)
294 bus_unregister(bus: &snd_seq_bus_type);
295 return err;
296}
297
298static void __exit alsa_seq_device_exit(void)
299{
300#ifdef CONFIG_MODULES
301 cancel_work_sync(work: &autoload_work);
302#endif
303#ifdef CONFIG_SND_PROC_FS
304 snd_info_free_entry(entry: info_entry);
305#endif
306 bus_unregister(bus: &snd_seq_bus_type);
307}
308
309subsys_initcall(alsa_seq_device_init)
310module_exit(alsa_seq_device_exit)
311