seq_device.c | Explore in Territory

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  ALSA sequencer device management
 *  Copyright (c) 1999 by Takashi Iwai <[email protected]>
 *
 *----------------------------------------------------------------
 *
 * 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(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;

/*
 * bus definition
 */
static int snd_seq_bus_match(struct device *dev, const struct device_driver *drv)
{ … }

static const struct bus_type snd_seq_bus_type = …;

/*
 * 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)
{ … }

static void snd_seq_device_info(struct snd_info_entry *entry,
				struct snd_info_buffer *buffer)
{ … }
#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 = …; /* blocked as default */

static int request_seq_drv(struct device *dev, void *data)
{ … }

static void autoload_drivers(struct work_struct *work)
{ … }

static DECLARE_WORK(autoload_work, autoload_drivers);

static void queue_autoload_drivers(void)
{ … }

void snd_seq_autoload_init(void)
{ … }
EXPORT_SYMBOL(…);

void snd_seq_autoload_exit(void)
{ … }
EXPORT_SYMBOL(…);

void snd_seq_device_load_drivers(void)
{ … }
EXPORT_SYMBOL(…);

static inline void cancel_autoload_drivers(void)
{ … }
#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)
{ … }

static int snd_seq_device_dev_register(struct snd_device *device)
{ … }

static int snd_seq_device_dev_disconnect(struct snd_device *device)
{ … }

static void snd_seq_dev_release(struct device *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)
{ … }
EXPORT_SYMBOL(…);

/*
 * driver registration
 */
int __snd_seq_driver_register(struct snd_seq_driver *drv, struct module *mod)
{ … }
EXPORT_SYMBOL_GPL(…);

void snd_seq_driver_unregister(struct snd_seq_driver *drv)
{ … }
EXPORT_SYMBOL_GPL(…);

/*
 * module part
 */

static int __init seq_dev_proc_init(void)
{ … }

static int __init alsa_seq_device_init(void)
{ … }

static void __exit alsa_seq_device_exit(void)
{ … }

subsys_initcall(…) …
module_exit(…)
linux/sound/core/seq_device.c
