linux/sound/sound_core.c

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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: automatically add .llseek fop All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
2010-08-15 18:52:59 +02:00
.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 + SOUND_STEP;
goto retry;
}
spin_unlock(&sound_loader_lock);
return -EBUSY;
}
}
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, S_IRUSR | S_IWUSR, 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", S_IRUSR | S_IWUSR, NULL);
}
EXPORT_SYMBOL(register_sound_mixer);
/**
* register_sound_midi - register a midi device
* @fops: File operations for the driver
* @dev: Unit number to allocate
*
* Allocate a midi device. Unit is the number of the midi device requested.
* Pass -1 to request the next free midi unit.
*
* Return: On success, the allocated number is returned. On failure,
* a negative error code is returned.
*/
int register_sound_midi(const struct file_operations *fops, int dev)
{
return sound_insert_unit(&chains[2], fops, dev, 2, 130,
"midi", S_IRUSR | S_IWUSR, NULL);
}
EXPORT_SYMBOL(register_sound_midi);
/*
* 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", S_IWUSR | S_IRUSR, 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_midi - unregister a midi device
* @unit: unit number to allocate
*
* Release a sound device that was allocated with register_sound_midi().
* The unit passed is the return value from the register function.
*/
void unregister_sound_midi(int unit)
{
sound_remove_unit(&chains[2], unit);
}
EXPORT_SYMBOL(unregister_sound_midi);
/**
* 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) == -1) {
printk(KERN_ERR "soundcore: sound device already in use.\n");
return -EBUSY;
}
return 0;
}
#endif /* CONFIG_SOUND_OSS_CORE */