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)