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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * ALSA sequencer device management4 * Copyright (c) 1999 by Takashi Iwai <tiwai@suse.de>5 *6 *----------------------------------------------------------------7 *8 * This device handler separates the card driver module from sequencer9 * stuff (sequencer core, synth drivers, etc), so that user can avoid10 * to spend unnecessary resources e.g. if he needs only listening to11 * MP3s.12 *13 * The card (or lowlevel) driver creates a sequencer device entry14 * via snd_seq_device_new(). This is an entry pointer to communicate15 * with the sequencer device "driver", which is involved with the16 * actual part to communicate with the sequencer core.17 * Each sequencer device entry has an id string and the corresponding18 * driver with the same id is loaded when required. For example,19 * lowlevel codes to access emu8000 chip on sbawe card are included in20 * emu8000-synth module. To activate this module, the hardware21 * 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 definition42 */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 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 compatibility59 */60#ifdef CONFIG_SND_PROC_FS61static 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#endif80 81/*82 * load all registered drivers (called from seq_clientmgr.c)83 */84 85#ifdef CONFIG_MODULES86/* 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_MODULE118 /* initial autoload only when snd-seq is a module */119 queue_autoload_drivers();120#endif121}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#else142static inline void queue_autoload_drivers(void)143{144}145 146static inline void cancel_autoload_drivers(void)147{148}149#endif150 151/*152 * device management153 */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 device193 * card = card info194 * device = device number (if any)195 * id = id of driver196 * 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 registration247 */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 part266 */267 268static int __init seq_dev_proc_init(void)269{270#ifdef CONFIG_SND_PROC_FS271 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#endif282 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_MODULES301 cancel_work_sync(&autoload_work);302#endif303#ifdef CONFIG_SND_PROC_FS304 snd_info_free_entry(info_entry);305#endif306 bus_unregister(&snd_seq_bus_type);307}308 309subsys_initcall(alsa_seq_device_init)310module_exit(alsa_seq_device_exit)311