// SPDX-License-Identifier: GPL-2.0-or-later/* *  ALSA sequencer device management *  Copyright (c) 1999 by Takashi Iwai <tiwai@suse.de> * *---------------------------------------------------------------- * * This device handler separates the card driver module from sequencer * stuff (sequencer core, synth drivers, etc), so that user can avoid * to spend unnecessary resources e.g. if he needs only listening to * MP3s. * * The card (or lowlevel) driver creates a sequencer device entry * via snd_seq_device_new().  This is an entry pointer to communicate * with the sequencer device "driver", which is involved with the * actual part to communicate with the sequencer core. * Each sequencer device entry has an id string and the corresponding * driver with the same id is loaded when required.  For example, * lowlevel codes to access emu8000 chip on sbawe card are included in * emu8000-synth module.  To activate this module, the hardware * resources like i/o port are passed via snd_seq_device argument. */ #include <linux/device.h>#include <linux/init.h>#include <linux/module.h>#include <sound/core.h>#include <sound/info.h>#include <sound/seq_device.h>#include <sound/seq_kernel.h>#include <sound/initval.h>#include <linux/kmod.h>#include <linux/slab.h>#include <linux/mutex.h> MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");MODULE_DESCRIPTION("ALSA sequencer device management");MODULE_LICENSE("GPL"); /* * bus definition */static int snd_seq_bus_match(struct device *dev, const struct device_driver *drv){	struct snd_seq_device *sdev = to_seq_dev(dev);	const struct snd_seq_driver *sdrv = to_seq_drv(drv); 	return strcmp(sdrv->id, sdev->id) == 0 &&		sdrv->argsize == sdev->argsize;} static int snd_seq_bus_probe(struct device *dev){	struct snd_seq_device *sdev = to_seq_dev(dev);	const struct snd_seq_driver *sdrv = to_seq_drv(dev->driver); 	if (sdrv->probe)		return sdrv->probe(sdev);	else		return 0;} static void snd_seq_bus_remove(struct device *dev){	struct snd_seq_device *sdev = to_seq_dev(dev);	const struct snd_seq_driver *sdrv = to_seq_drv(dev->driver); 	if (sdrv->remove)		sdrv->remove(sdev);} static const struct bus_type snd_seq_bus_type = {	.name = "snd_seq",	.match = snd_seq_bus_match,	.probe = snd_seq_bus_probe,	.remove = snd_seq_bus_remove,}; /* * proc interface -- just for compatibility */#ifdef CONFIG_SND_PROC_FSstatic struct snd_info_entry *info_entry; static int print_dev_info(struct device *dev, void *data){	struct snd_seq_device *sdev = to_seq_dev(dev);	struct snd_info_buffer *buffer = data; 	snd_iprintf(buffer, "snd-%s,%s,%d\n", sdev->id,		    dev->driver ? "loaded" : "empty",		    dev->driver ? 1 : 0);	return 0;} static void snd_seq_device_info(struct snd_info_entry *entry,				struct snd_info_buffer *buffer){	bus_for_each_dev(&snd_seq_bus_type, NULL, buffer, print_dev_info);}#endif /* * load all registered drivers (called from seq_clientmgr.c) */ #ifdef CONFIG_MODULES/* flag to block auto-loading */static atomic_t snd_seq_in_init = ATOMIC_INIT(1); /* blocked as default */ static int request_seq_drv(struct device *dev, void *data){	struct snd_seq_device *sdev = to_seq_dev(dev); 	if (!dev->driver)		request_module("snd-%s", sdev->id);	return 0;} static void autoload_drivers(struct work_struct *work){	/* avoid reentrance */	if (atomic_inc_return(&snd_seq_in_init) == 1)		bus_for_each_dev(&snd_seq_bus_type, NULL, NULL,				 request_seq_drv);	atomic_dec(&snd_seq_in_init);} static DECLARE_WORK(autoload_work, autoload_drivers); static void queue_autoload_drivers(void){	schedule_work(&autoload_work);} void snd_seq_autoload_init(void){	atomic_dec(&snd_seq_in_init);#ifdef CONFIG_SND_SEQUENCER_MODULE	/* initial autoload only when snd-seq is a module */	queue_autoload_drivers();#endif}EXPORT_SYMBOL(snd_seq_autoload_init); void snd_seq_autoload_exit(void){	atomic_inc(&snd_seq_in_init);}EXPORT_SYMBOL(snd_seq_autoload_exit); void snd_seq_device_load_drivers(void){	queue_autoload_drivers();	flush_work(&autoload_work);}EXPORT_SYMBOL(snd_seq_device_load_drivers); static inline void cancel_autoload_drivers(void){	cancel_work_sync(&autoload_work);}#elsestatic inline void queue_autoload_drivers(void){} static inline void cancel_autoload_drivers(void){}#endif /* * device management */static int snd_seq_device_dev_free(struct snd_device *device){	struct snd_seq_device *dev = device->device_data; 	cancel_autoload_drivers();	if (dev->private_free)		dev->private_free(dev);	put_device(&dev->dev);	return 0;} static int snd_seq_device_dev_register(struct snd_device *device){	struct snd_seq_device *dev = device->device_data;	int err; 	err = device_add(&dev->dev);	if (err < 0)		return err;	if (!dev->dev.driver)		queue_autoload_drivers();	return 0;} static int snd_seq_device_dev_disconnect(struct snd_device *device){	struct snd_seq_device *dev = device->device_data; 	device_del(&dev->dev);	return 0;} static void snd_seq_dev_release(struct device *dev){	kfree(to_seq_dev(dev));} /* * register a sequencer device * card = card info * device = device number (if any) * id = id of driver * result = return pointer (NULL allowed if unnecessary) */int snd_seq_device_new(struct snd_card *card, int device, const char *id,		       int argsize, struct snd_seq_device **result){	struct snd_seq_device *dev;	int err;	static const struct snd_device_ops dops = {		.dev_free = snd_seq_device_dev_free,		.dev_register = snd_seq_device_dev_register,		.dev_disconnect = snd_seq_device_dev_disconnect,	}; 	if (result)		*result = NULL; 	if (snd_BUG_ON(!id))		return -EINVAL; 	if (argsize < 0)		return -EINVAL; 	dev = kzalloc_flex(*dev, args, argsize);	if (!dev)		return -ENOMEM; 	/* set up device info */	dev->card = card;	dev->device = device;	dev->id = id;	dev->argsize = argsize; 	device_initialize(&dev->dev);	dev->dev.parent = &card->card_dev;	dev->dev.bus = &snd_seq_bus_type;	dev->dev.release = snd_seq_dev_release;	dev_set_name(&dev->dev, "%s-%d-%d", dev->id, card->number, device); 	/* add this device to the list */	err = snd_device_new(card, SNDRV_DEV_SEQUENCER, dev, &dops);	if (err < 0) {		put_device(&dev->dev);		return err;	} 	if (result)		*result = dev; 	return 0;}EXPORT_SYMBOL(snd_seq_device_new); /* * driver registration */int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod){	if (WARN_ON(!drv->driver.name || !drv->id || drv->driver.probe || drv->driver.remove))		return -EINVAL; 	drv->driver.bus = &snd_seq_bus_type;	drv->driver.owner = mod; 	return driver_register(&drv->driver);}EXPORT_SYMBOL_GPL(__snd_seq_driver_register); void snd_seq_driver_unregister(struct snd_seq_driver *drv){	driver_unregister(&drv->driver);}EXPORT_SYMBOL_GPL(snd_seq_driver_unregister); /* * module part */ static int __init seq_dev_proc_init(void){#ifdef CONFIG_SND_PROC_FS	info_entry = snd_info_create_module_entry(THIS_MODULE, "drivers",						  snd_seq_root);	if (info_entry == NULL)		return -ENOMEM;	info_entry->content = SNDRV_INFO_CONTENT_TEXT;	info_entry->c.text.read = snd_seq_device_info;	if (snd_info_register(info_entry) < 0) {		snd_info_free_entry(info_entry);		return -ENOMEM;	}#endif	return 0;} static int __init alsa_seq_device_init(void){	int err; 	err = bus_register(&snd_seq_bus_type);	if (err < 0)		return err;	err = seq_dev_proc_init();	if (err < 0)		bus_unregister(&snd_seq_bus_type);	return err;} static void __exit alsa_seq_device_exit(void){#ifdef CONFIG_MODULES	cancel_work_sync(&autoload_work);#endif#ifdef CONFIG_SND_PROC_FS	snd_info_free_entry(info_entry);#endif	bus_unregister(&snd_seq_bus_type);} subsys_initcall(alsa_seq_device_init)module_exit(alsa_seq_device_exit)