sound/core/seq_device.c - linux - Git at Google

 // 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, struct device_driver *drv)
 {
 	struct snd_seq_device *sdev = to_seq_dev(dev);
 	struct snd_seq_driver *sdrv = to_seq_drv(drv);

 	return strcmp(sdrv->id, sdev->id) == 0 &&
 		sdrv->argsize == sdev->argsize;
 }

 static const struct bus_type snd_seq_bus_type = {
 	.name = "snd_seq",
 	.match = snd_seq_bus_match,
 };

 /*
  * proc interface -- just for compatibility
  */
 #ifdef CONFIG_SND_PROC_FS
 static 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);
 }
 #else
 static 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;

 	dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL);
 	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))
 		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)
	// 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, struct device_driver drv)
	{
	struct snd_seq_device *sdev = to_seq_dev(dev);
	struct snd_seq_driver *sdrv = to_seq_drv(drv);

	return strcmp(sdrv->id, sdev->id) == 0 &&
	sdrv->argsize == sdev->argsize;
	}

	static const struct bus_type snd_seq_bus_type = {
	.name = "snd_seq",
	.match = snd_seq_bus_match,
	};

	/*
	* proc interface -- just for compatibility
	*/
	#ifdef CONFIG_SND_PROC_FS
	static 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);
	}
	#else
	static 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;

	dev = kzalloc(sizeof(*dev) + argsize, GFP_KERNEL);
	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))
	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)