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 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(&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
137static inline void cancel_autoload_drivers(void)
138{
139	cancel_work_sync(&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);
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);
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);
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);
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, "%s-%d-%d", dev->id, card->number, device);
230
231	/* add this device to the list */
232	err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops);
233	if (err < 0) {
234		put_device(&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->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->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, "drivers",
272						  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(info_entry) < 0) {
278		snd_info_free_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(&snd_seq_bus_type);
290	if (err < 0)
291		return err;
292	err = seq_dev_proc_init();
293	if (err < 0)
294		bus_unregister(&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(&autoload_work);
302#endif
303#ifdef CONFIG_SND_PROC_FS
304	snd_info_free_entry(info_entry);
305#endif
306	bus_unregister(&snd_seq_bus_type);
307}
308
309subsys_initcall(alsa_seq_device_init)
310module_exit(alsa_seq_device_exit)
311