// SPDX-License-Identifier: GPL-2.0-or-later

  /*

   *	Sound core.  This file is composed of two parts.  sound_class
   *	which is common to both OSS and ALSA and OSS sound core which
   *	is used OSS or emulation of it.
   */
  
  /*
   * First, the common part.
   */
  #include <linux/module.h>
  #include <linux/device.h>
  #include <linux/err.h>

  #include <linux/kdev_t.h>
  #include <linux/major.h>

  #include <sound/core.h>

  
  #ifdef CONFIG_SOUND_OSS_CORE
  static int __init init_oss_soundcore(void);

  static void cleanup_oss_soundcore(void);

  #else
  static inline int init_oss_soundcore(void)	{ return 0; }
  static inline void cleanup_oss_soundcore(void)	{ }
  #endif
  
  struct class *sound_class;
  EXPORT_SYMBOL(sound_class);
  
  MODULE_DESCRIPTION("Core sound module");
  MODULE_AUTHOR("Alan Cox");
  MODULE_LICENSE("GPL");

  static char *sound_devnode(struct device *dev, umode_t *mode)

  {

  	if (MAJOR(dev->devt) == SOUND_MAJOR)
  		return NULL;

  	return kasprintf(GFP_KERNEL, "snd/%s", dev_name(dev));
  }

  static int __init init_soundcore(void)
  {
  	int rc;
  
  	rc = init_oss_soundcore();
  	if (rc)
  		return rc;
  
  	sound_class = class_create(THIS_MODULE, "sound");
  	if (IS_ERR(sound_class)) {
  		cleanup_oss_soundcore();
  		return PTR_ERR(sound_class);
  	}

  	sound_class->devnode = sound_devnode;

  	return 0;
  }
  
  static void __exit cleanup_soundcore(void)
  {
  	cleanup_oss_soundcore();
  	class_destroy(sound_class);
  }

  subsys_initcall(init_soundcore);

  module_exit(cleanup_soundcore);
  
  
  #ifdef CONFIG_SOUND_OSS_CORE
  /*
   *	OSS sound core handling. Breaks out sound functions to submodules

   *	

   *	Author:		Alan Cox <alan@lxorguk.ukuu.org.uk>

   *
   *	Fixes:
   *

   *                         --------------------
   * 
   *	Top level handler for the sound subsystem. Various devices can
   *	plug into this. The fact they don't all go via OSS doesn't mean 
   *	they don't have to implement the OSS API. There is a lot of logic
   *	to keeping much of the OSS weight out of the code in a compatibility
   *	module, but it's up to the driver to rember to load it...
   *
   *	The code provides a set of functions for registration of devices
   *	by type. This is done rather than providing a single call so that
   *	we can hide any future changes in the internals (eg when we go to
   *	32bit dev_t) from the modules and their interface.
   *
   *	Secondly we need to allocate the dsp, dsp16 and audio devices as
   *	one. Thus we misuse the chains a bit to simplify this.
   *
   *	Thirdly to make it more fun and for 2.3.x and above we do all
   *	of this using fine grained locking.
   *
   *	FIXME: we have to resolve modules and fine grained load/unload
   *	locking at some point in 2.3.x.
   */

  #include <linux/init.h>
  #include <linux/slab.h>
  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/sound.h>

  #include <linux/kmod.h>

  
  #define SOUND_STEP 16

  struct sound_unit
  {
  	int unit_minor;

  	const struct file_operations *unit_fops;

  	struct sound_unit *next;
  	char name[32];
  };

  /*

   * By default, OSS sound_core claims full legacy minor range (0-255)
   * of SOUND_MAJOR to trap open attempts to any sound minor and
   * requests modules using custom sound-slot/service-* module aliases.
   * The only benefit of doing this is allowing use of custom module
   * aliases instead of the standard char-major-* ones.  This behavior
   * prevents alternative OSS implementation and is scheduled to be
   * removed.
   *
   * CONFIG_SOUND_OSS_CORE_PRECLAIM and soundcore.preclaim_oss kernel
   * parameter are added to allow distros and developers to try and
   * switch to alternative implementations without needing to rebuild
   * the kernel in the meantime.  If preclaim_oss is non-zero, the
   * kernel will behave the same as before.  All SOUND_MAJOR minors are
   * preclaimed and the custom module aliases along with standard chrdev
   * ones are emitted if a missing device is opened.  If preclaim_oss is
   * zero, sound_core only grabs what's actually in use and for missing
   * devices only the standard chrdev aliases are requested.
   *
   * All these clutters are scheduled to be removed along with

   * sound-slot/service-* module aliases.

   */
  #ifdef CONFIG_SOUND_OSS_CORE_PRECLAIM
  static int preclaim_oss = 1;
  #else
  static int preclaim_oss = 0;
  #endif
  
  module_param(preclaim_oss, int, 0444);
  
  static int soundcore_open(struct inode *, struct file *);
  
  static const struct file_operations soundcore_fops =
  {
  	/* We must have an owner or the module locking fails */
  	.owner	= THIS_MODULE,
  	.open	= soundcore_open,

  	.llseek = noop_llseek,

  };
  
  /*

   *	Low level list operator. Scan the ordered list, find a hole and
   *	join into it. Called with the lock asserted
   */

  static int __sound_insert_unit(struct sound_unit * s, struct sound_unit **list, const struct file_operations *fops, int index, int low, int top)

  {
  	int n=low;
  
  	if (index < 0) {	/* first free */
  
  		while (*list && (*list)->unit_minor<n)
  			list=&((*list)->next);
  
  		while(n<top)
  		{
  			/* Found a hole ? */
  			if(*list==NULL || (*list)->unit_minor>n)
  				break;
  			list=&((*list)->next);
  			n+=SOUND_STEP;
  		}
  
  		if(n>=top)
  			return -ENOENT;
  	} else {
  		n = low+(index*16);
  		while (*list) {
  			if ((*list)->unit_minor==n)
  				return -EBUSY;
  			if ((*list)->unit_minor>n)
  				break;
  			list=&((*list)->next);
  		}
  	}	
  		
  	/*
  	 *	Fill it in
  	 */
  	 
  	s->unit_minor=n;
  	s->unit_fops=fops;
  	
  	/*
  	 *	Link it
  	 */
  	 
  	s->next=*list;
  	*list=s;
  	
  	
  	return n;
  }
  
  /*
   *	Remove a node from the chain. Called with the lock asserted
   */
   
  static struct sound_unit *__sound_remove_unit(struct sound_unit **list, int unit)
  {
  	while(*list)
  	{
  		struct sound_unit *p=*list;
  		if(p->unit_minor==unit)
  		{
  			*list=p->next;
  			return p;
  		}
  		list=&(p->next);
  	}
  	printk(KERN_ERR "Sound device %d went missing!
  ", unit);
  	return NULL;
  }
  
  /*
   *	This lock guards the sound loader list.
   */
  
  static DEFINE_SPINLOCK(sound_loader_lock);
  
  /*
   *	Allocate the controlling structure and add it to the sound driver
   *	list. Acquires locks as needed
   */

  static int sound_insert_unit(struct sound_unit **list, const struct file_operations *fops, int index, int low, int top, const char *name, umode_t mode, struct device *dev)

  {
  	struct sound_unit *s = kmalloc(sizeof(*s), GFP_KERNEL);
  	int r;
  
  	if (!s)
  		return -ENOMEM;

  	spin_lock(&sound_loader_lock);

  retry:

  	r = __sound_insert_unit(s, list, fops, index, low, top);
  	spin_unlock(&sound_loader_lock);
  	
  	if (r < 0)
  		goto fail;
  	else if (r < SOUND_STEP)
  		sprintf(s->name, "sound/%s", name);
  	else
  		sprintf(s->name, "sound/%s%d", name, r / SOUND_STEP);

  	if (!preclaim_oss) {
  		/*
  		 * Something else might have grabbed the minor.  If
  		 * first free slot is requested, rescan with @low set
  		 * to the next unit; otherwise, -EBUSY.
  		 */
  		r = __register_chrdev(SOUND_MAJOR, s->unit_minor, 1, s->name,
  				      &soundcore_fops);
  		if (r < 0) {
  			spin_lock(&sound_loader_lock);
  			__sound_remove_unit(list, s->unit_minor);
  			if (index < 0) {
  				low = s->unit_minor + SOUND_STEP;
  				goto retry;
  			}
  			spin_unlock(&sound_loader_lock);

  			r = -EBUSY;
  			goto fail;

  		}
  	}

  	device_create(sound_class, dev, MKDEV(SOUND_MAJOR, s->unit_minor),

  		      NULL, "%s", s->name+6);

  	return s->unit_minor;

  fail:

  	kfree(s);
  	return r;
  }
  
  /*
   *	Remove a unit. Acquires locks as needed. The drivers MUST have
   *	completed the removal before their file operations become
   *	invalid.
   */
   	
  static void sound_remove_unit(struct sound_unit **list, int unit)
  {
  	struct sound_unit *p;
  
  	spin_lock(&sound_loader_lock);
  	p = __sound_remove_unit(list, unit);
  	spin_unlock(&sound_loader_lock);
  	if (p) {

  		if (!preclaim_oss)
  			__unregister_chrdev(SOUND_MAJOR, p->unit_minor, 1,
  					    p->name);

  		device_destroy(sound_class, MKDEV(SOUND_MAJOR, p->unit_minor));

  		kfree(p);
  	}
  }
  
  /*
   *	Allocations
   *
   *	0	*16		Mixers
   *	1	*8		Sequencers
   *	2	*16		Midi
   *	3	*16		DSP
   *	4	*16		SunDSP
   *	5	*16		DSP16
   *	6	--		sndstat (obsolete)
   *	7	*16		unused
   *	8	--		alternate sequencer (see above)
   *	9	*16		raw synthesizer access
   *	10	*16		unused
   *	11	*16		unused
   *	12	*16		unused
   *	13	*16		unused
   *	14	*16		unused
   *	15	*16		unused
   */
  
  static struct sound_unit *chains[SOUND_STEP];
  
  /**

   *	register_sound_special_device - register a special sound node

   *	@fops: File operations for the driver
   *	@unit: Unit number to allocate

   *      @dev: device pointer

   *
   *	Allocate a special sound device by minor number from the sound

   *	subsystem.
   *
   *	Return: The allocated number is returned on success. On failure,

   *	a negative error code is returned.
   */
   

  int register_sound_special_device(const struct file_operations *fops, int unit,

  				  struct device *dev)

  {
  	const int chain = unit % SOUND_STEP;

  	int max_unit = 256;

  	const char *name;
  	char _name[16];
  
  	switch (chain) {
  	    case 0:
  		name = "mixer";
  		break;
  	    case 1:
  		name = "sequencer";
  		if (unit >= SOUND_STEP)
  			goto __unknown;
  		max_unit = unit + 1;
  		break;
  	    case 2:
  		name = "midi";
  		break;
  	    case 3:
  		name = "dsp";
  		break;
  	    case 4:
  		name = "audio";
  		break;

  	    case 5:
  		name = "dspW";
  		break;

  	    case 8:
  		name = "sequencer2";
  		if (unit >= SOUND_STEP)
  			goto __unknown;
  		max_unit = unit + 1;
  		break;
  	    case 9:
  		name = "dmmidi";
  		break;
  	    case 10:
  		name = "dmfm";
  		break;
  	    case 12:
  		name = "adsp";
  		break;
  	    case 13:
  		name = "amidi";
  		break;
  	    case 14:
  		name = "admmidi";
  		break;
  	    default:
  	    	{
  		    __unknown:
  			sprintf(_name, "unknown%d", chain);
  		    	if (unit >= SOUND_STEP)
  		    		strcat(_name, "-");
  		    	name = _name;
  		}
  		break;
  	}
  	return sound_insert_unit(&chains[chain], fops, -1, unit, max_unit,

  				 name, 0600, dev);

  }
   

  EXPORT_SYMBOL(register_sound_special_device);

  int register_sound_special(const struct file_operations *fops, int unit)

  {
  	return register_sound_special_device(fops, unit, NULL);
  }

  EXPORT_SYMBOL(register_sound_special);
  
  /**
   *	register_sound_mixer - register a mixer device
   *	@fops: File operations for the driver
   *	@dev: Unit number to allocate
   *
   *	Allocate a mixer device. Unit is the number of the mixer requested.

   *	Pass -1 to request the next free mixer unit.
   *
   *	Return: On success, the allocated number is returned. On failure,
   *	a negative error code is returned.

   */

  int register_sound_mixer(const struct file_operations *fops, int dev)

  {
  	return sound_insert_unit(&chains[0], fops, dev, 0, 128,

  				 "mixer", 0600, NULL);

  }
  
  EXPORT_SYMBOL(register_sound_mixer);

  /*
   *	DSP's are registered as a triple. Register only one and cheat
   *	in open - see below.
   */
   
  /**
   *	register_sound_dsp - register a DSP device
   *	@fops: File operations for the driver
   *	@dev: Unit number to allocate
   *
   *	Allocate a DSP device. Unit is the number of the DSP requested.

   *	Pass -1 to request the next free DSP unit.

   *
   *	This function allocates both the audio and dsp device entries together
   *	and will always allocate them as a matching pair - eg dsp3/audio3

   *
   *	Return: On success, the allocated number is returned. On failure,
   *	a negative error code is returned.

   */

  int register_sound_dsp(const struct file_operations *fops, int dev)

  {
  	return sound_insert_unit(&chains[3], fops, dev, 3, 131,

  				 "dsp", 0600, NULL);

  }
  
  EXPORT_SYMBOL(register_sound_dsp);
  
  /**

   *	unregister_sound_special - unregister a special sound device
   *	@unit: unit number to allocate
   *
   *	Release a sound device that was allocated with
   *	register_sound_special(). The unit passed is the return value from
   *	the register function.
   */
  
  
  void unregister_sound_special(int unit)
  {
  	sound_remove_unit(&chains[unit % SOUND_STEP], unit);
  }
   
  EXPORT_SYMBOL(unregister_sound_special);
  
  /**
   *	unregister_sound_mixer - unregister a mixer
   *	@unit: unit number to allocate
   *
   *	Release a sound device that was allocated with register_sound_mixer().
   *	The unit passed is the return value from the register function.
   */
  
  void unregister_sound_mixer(int unit)
  {
  	sound_remove_unit(&chains[0], unit);
  }
  
  EXPORT_SYMBOL(unregister_sound_mixer);
  
  /**

   *	unregister_sound_dsp - unregister a DSP device
   *	@unit: unit number to allocate
   *
   *	Release a sound device that was allocated with register_sound_dsp().
   *	The unit passed is the return value from the register function.
   *
   *	Both of the allocated units are released together automatically.
   */
  
  void unregister_sound_dsp(int unit)
  {

  	sound_remove_unit(&chains[3], unit);

  }
  
  
  EXPORT_SYMBOL(unregister_sound_dsp);

  static struct sound_unit *__look_for_unit(int chain, int unit)
  {
  	struct sound_unit *s;
  	
  	s=chains[chain];
  	while(s && s->unit_minor <= unit)
  	{
  		if(s->unit_minor==unit)
  			return s;
  		s=s->next;
  	}
  	return NULL;
  }

  static int soundcore_open(struct inode *inode, struct file *file)

  {
  	int chain;
  	int unit = iminor(inode);
  	struct sound_unit *s;

  	const struct file_operations *new_fops = NULL;

  
  	chain=unit&0x0F;
  	if(chain==4 || chain==5)	/* dsp/audio/dsp16 */
  	{
  		unit&=0xF0;
  		unit|=3;
  		chain=3;
  	}
  	
  	spin_lock(&sound_loader_lock);
  	s = __look_for_unit(chain, unit);
  	if (s)
  		new_fops = fops_get(s->unit_fops);

  	if (preclaim_oss && !new_fops) {

  		spin_unlock(&sound_loader_lock);

  		/*
  		 *  Please, don't change this order or code.
  		 *  For ALSA slot means soundcard and OSS emulation code
  		 *  comes as add-on modules which aren't depend on
  		 *  ALSA toplevel modules for soundcards, thus we need
  		 *  load them at first.	  [Jaroslav Kysela <perex@jcu.cz>]
  		 */
  		request_module("sound-slot-%i", unit>>4);
  		request_module("sound-service-%i-%i", unit>>4, chain);

  
  		/*
  		 * sound-slot/service-* module aliases are scheduled
  		 * for removal in favor of the standard char-major-*
  		 * module aliases.  For the time being, generate both
  		 * the legacy and standard module aliases to ease
  		 * transition.
  		 */
  		if (request_module("char-major-%d-%d", SOUND_MAJOR, unit) > 0)
  			request_module("char-major-%d", SOUND_MAJOR);

  		spin_lock(&sound_loader_lock);
  		s = __look_for_unit(chain, unit);
  		if (s)
  			new_fops = fops_get(s->unit_fops);
  	}

  	spin_unlock(&sound_loader_lock);

  	if (new_fops) {
  		/*
  		 * We rely upon the fact that we can't be unloaded while the

  		 * subdriver is there.

  		 */
  		int err = 0;

  		replace_fops(file, new_fops);

  		if (file->f_op->open)

  			err = file->f_op->open(inode,file);

  		return err;
  	}

  	return -ENODEV;
  }

  MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);

  static void cleanup_oss_soundcore(void)

  {
  	/* We have nothing to really do here - we know the lists must be
  	   empty */
  	unregister_chrdev(SOUND_MAJOR, "sound");

  }

  static int __init init_oss_soundcore(void)

  {

  	if (preclaim_oss &&

  	    register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops) < 0) {

  		printk(KERN_ERR "soundcore: sound device already in use.
  ");
  		return -EBUSY;
  	}

  
  	return 0;
  }

  #endif /* CONFIG_SOUND_OSS_CORE */