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|
/*
* 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:
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* --------------------
*
* 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];
};
#ifdef CONFIG_SOUND_MSNDCLAS
extern int msnd_classic_init(void);
#endif
#ifdef CONFIG_SOUND_MSNDPIN
extern int msnd_pinnacle_init(void);
#endif
/*
* 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!\n", 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
|