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	if (dev->private_free)
151		dev->private_free(dev);
152	put_device(&dev->dev);
153	return 0;
154}
155
156static 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
169static 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
177static 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 */
189int 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 const 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}
234EXPORT_SYMBOL(snd_seq_device_new);
235
236/*
237 * driver registration
238 */
239int __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}
247EXPORT_SYMBOL_GPL(__snd_seq_driver_register);
248
249void snd_seq_driver_unregister(struct snd_seq_driver *drv)
250{
251	driver_unregister(&drv->driver);
252}
253EXPORT_SYMBOL_GPL(snd_seq_driver_unregister);
254
255/*
256 * module part
257 */
258
259static 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
276static 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
289static 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
300subsys_initcall(alsa_seq_device_init)
301module_exit(alsa_seq_device_exit)
302