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 
cancel_autoload_drivers(void)137 static inline void cancel_autoload_drivers(void)
138 {
139 	cancel_work_sync(&autoload_work);
140 }
141 #else
queue_autoload_drivers(void)142 static inline void queue_autoload_drivers(void)
143 {
144 }
145 
cancel_autoload_drivers(void)146 static inline void cancel_autoload_drivers(void)
147 {
148 }
149 #endif
150 
151 /*
152  * device management
153  */
snd_seq_device_dev_free(struct snd_device * device)154 static 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 
snd_seq_device_dev_register(struct snd_device * device)165 static 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 
snd_seq_device_dev_disconnect(struct snd_device * device)178 static 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 
snd_seq_dev_release(struct device * dev)186 static 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  */
snd_seq_device_new(struct snd_card * card,int device,const char * id,int argsize,struct snd_seq_device ** result)198 int 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 }
243 EXPORT_SYMBOL(snd_seq_device_new);
244 
245 /*
246  * driver registration
247  */
__snd_seq_driver_register(struct snd_seq_driver * drv,struct module * mod)248 int __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 }
256 EXPORT_SYMBOL_GPL(__snd_seq_driver_register);
257 
snd_seq_driver_unregister(struct snd_seq_driver * drv)258 void snd_seq_driver_unregister(struct snd_seq_driver *drv)
259 {
260 	driver_unregister(&drv->driver);
261 }
262 EXPORT_SYMBOL_GPL(snd_seq_driver_unregister);
263 
264 /*
265  * module part
266  */
267 
seq_dev_proc_init(void)268 static 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 
alsa_seq_device_init(void)285 static 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 
alsa_seq_device_exit(void)298 static 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 
309 subsys_initcall(alsa_seq_device_init)
310 module_exit(alsa_seq_device_exit)
311