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linux/sound/core/sound.c

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/*
* Advanced Linux Sound Architecture
* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
*
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/time.h>
#include <linux/device.h>
#include <linux/moduleparam.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/info.h>
#include <sound/version.h>
#include <sound/control.h>
#include <sound/initval.h>
#include <linux/kmod.h>
#include <linux/mutex.h>
static int major = CONFIG_SND_MAJOR;
int snd_major;
EXPORT_SYMBOL(snd_major);
static int cards_limit = 1;
MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
MODULE_LICENSE("GPL");
module_param(major, int, 0444);
MODULE_PARM_DESC(major, "Major # for sound driver.");
module_param(cards_limit, int, 0444);
MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
/* this one holds the actual max. card number currently available.
* as default, it's identical with cards_limit option. when more
* modules are loaded manually, this limit number increases, too.
*/
int snd_ecards_limit;
EXPORT_SYMBOL(snd_ecards_limit);
static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
static DEFINE_MUTEX(sound_mutex);
#ifdef CONFIG_MODULES
/**
* snd_request_card - try to load the card module
* @card: the card number
*
* Tries to load the module "snd-card-X" for the given card number
* via request_module. Returns immediately if already loaded.
*/
void snd_request_card(int card)
{
if (snd_card_locked(card))
return;
if (card < 0 || card >= cards_limit)
return;
request_module("snd-card-%i", card);
}
EXPORT_SYMBOL(snd_request_card);
static void snd_request_other(int minor)
{
char *str;
switch (minor) {
case SNDRV_MINOR_SEQUENCER: str = "snd-seq"; break;
case SNDRV_MINOR_TIMER: str = "snd-timer"; break;
default: return;
}
request_module(str);
}
#endif /* modular kernel */
/**
* snd_lookup_minor_data - get user data of a registered device
* @minor: the minor number
* @type: device type (SNDRV_DEVICE_TYPE_XXX)
*
* Checks that a minor device with the specified type is registered, and returns
* its user data pointer.
*/
void *snd_lookup_minor_data(unsigned int minor, int type)
{
struct snd_minor *mreg;
void *private_data;
if (minor >= ARRAY_SIZE(snd_minors))
return NULL;
mutex_lock(&sound_mutex);
mreg = snd_minors[minor];
if (mreg && mreg->type == type)
private_data = mreg->private_data;
else
private_data = NULL;
mutex_unlock(&sound_mutex);
return private_data;
}
EXPORT_SYMBOL(snd_lookup_minor_data);
#ifdef CONFIG_MODULES
static struct snd_minor *autoload_device(unsigned int minor)
{
int dev;
mutex_unlock(&sound_mutex); /* release lock temporarily */
dev = SNDRV_MINOR_DEVICE(minor);
if (dev == SNDRV_MINOR_CONTROL) {
/* /dev/aloadC? */
int card = SNDRV_MINOR_CARD(minor);
if (snd_cards[card] == NULL)
snd_request_card(card);
} else if (dev == SNDRV_MINOR_GLOBAL) {
/* /dev/aloadSEQ */
snd_request_other(minor);
}
mutex_lock(&sound_mutex); /* reacuire lock */
return snd_minors[minor];
}
#else /* !CONFIG_MODULES */
#define autoload_device(minor) NULL
#endif /* CONFIG_MODULES */
static int snd_open(struct inode *inode, struct file *file)
{
unsigned int minor = iminor(inode);
struct snd_minor *mptr = NULL;
const struct file_operations *old_fops;
int err = 0;
if (minor >= ARRAY_SIZE(snd_minors))
return -ENODEV;
mutex_lock(&sound_mutex);
mptr = snd_minors[minor];
if (mptr == NULL) {
mptr = autoload_device(minor);
if (!mptr) {
mutex_unlock(&sound_mutex);
return -ENODEV;
}
}
old_fops = file->f_op;
file->f_op = fops_get(mptr->f_ops);
if (file->f_op == NULL) {
file->f_op = old_fops;
err = -ENODEV;
}
mutex_unlock(&sound_mutex);
if (err < 0)
return err;
if (file->f_op->open) {
err = file->f_op->open(inode, file);
if (err) {
fops_put(file->f_op);
file->f_op = fops_get(old_fops);
}
}
fops_put(old_fops);
return err;
}
static const struct file_operations snd_fops =
{
.owner = THIS_MODULE,
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 16:52:59 +00:00
.open = snd_open,
.llseek = noop_llseek,
};
#ifdef CONFIG_SND_DYNAMIC_MINORS
static int snd_find_free_minor(void)
{
int minor;
for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
/* skip minors still used statically for autoloading devices */
if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL ||
minor == SNDRV_MINOR_SEQUENCER)
continue;
if (!snd_minors[minor])
return minor;
}
return -EBUSY;
}
#else
static int snd_kernel_minor(int type, struct snd_card *card, int dev)
{
int minor;
switch (type) {
case SNDRV_DEVICE_TYPE_SEQUENCER:
case SNDRV_DEVICE_TYPE_TIMER:
minor = type;
break;
case SNDRV_DEVICE_TYPE_CONTROL:
if (snd_BUG_ON(!card))
return -EINVAL;
minor = SNDRV_MINOR(card->number, type);
break;
case SNDRV_DEVICE_TYPE_HWDEP:
case SNDRV_DEVICE_TYPE_RAWMIDI:
case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
if (snd_BUG_ON(!card))
return -EINVAL;
minor = SNDRV_MINOR(card->number, type + dev);
break;
default:
return -EINVAL;
}
if (snd_BUG_ON(minor < 0 || minor >= SNDRV_OS_MINORS))
return -EINVAL;
return minor;
}
#endif
/**
* snd_register_device_for_dev - Register the ALSA device file for the card
* @type: the device type, SNDRV_DEVICE_TYPE_XXX
* @card: the card instance
* @dev: the device index
* @f_ops: the file operations
* @private_data: user pointer for f_ops->open()
* @name: the device file name
* @device: the &struct device to link this new device to
*
* Registers an ALSA device file for the given card.
* The operators have to be set in reg parameter.
*
* Returns zero if successful, or a negative error code on failure.
*/
int snd_register_device_for_dev(int type, struct snd_card *card, int dev,
const struct file_operations *f_ops,
void *private_data,
const char *name, struct device *device)
{
int minor;
struct snd_minor *preg;
if (snd_BUG_ON(!name))
return -EINVAL;
preg = kmalloc(sizeof *preg, GFP_KERNEL);
if (preg == NULL)
return -ENOMEM;
preg->type = type;
preg->card = card ? card->number : -1;
preg->device = dev;
preg->f_ops = f_ops;
preg->private_data = private_data;
mutex_lock(&sound_mutex);
#ifdef CONFIG_SND_DYNAMIC_MINORS
minor = snd_find_free_minor();
#else
minor = snd_kernel_minor(type, card, dev);
if (minor >= 0 && snd_minors[minor])
minor = -EBUSY;
#endif
if (minor < 0) {
mutex_unlock(&sound_mutex);
kfree(preg);
return minor;
}
snd_minors[minor] = preg;
preg->dev = device_create(sound_class, device, MKDEV(major, minor),
private_data, "%s", name);
if (IS_ERR(preg->dev)) {
snd_minors[minor] = NULL;
mutex_unlock(&sound_mutex);
minor = PTR_ERR(preg->dev);
kfree(preg);
return minor;
}
mutex_unlock(&sound_mutex);
return 0;
}
EXPORT_SYMBOL(snd_register_device_for_dev);
/* find the matching minor record
* return the index of snd_minor, or -1 if not found
*/
static int find_snd_minor(int type, struct snd_card *card, int dev)
{
int cardnum, minor;
struct snd_minor *mptr;
cardnum = card ? card->number : -1;
for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor)
if ((mptr = snd_minors[minor]) != NULL &&
mptr->type == type &&
mptr->card == cardnum &&
mptr->device == dev)
return minor;
return -1;
}
/**
* snd_unregister_device - unregister the device on the given card
* @type: the device type, SNDRV_DEVICE_TYPE_XXX
* @card: the card instance
* @dev: the device index
*
* Unregisters the device file already registered via
* snd_register_device().
*
* Returns zero if sucecessful, or a negative error code on failure
*/
int snd_unregister_device(int type, struct snd_card *card, int dev)
{
int minor;
mutex_lock(&sound_mutex);
minor = find_snd_minor(type, card, dev);
if (minor < 0) {
mutex_unlock(&sound_mutex);
return -EINVAL;
}
device_destroy(sound_class, MKDEV(major, minor));
kfree(snd_minors[minor]);
snd_minors[minor] = NULL;
mutex_unlock(&sound_mutex);
return 0;
}
EXPORT_SYMBOL(snd_unregister_device);
int snd_add_device_sysfs_file(int type, struct snd_card *card, int dev,
struct device_attribute *attr)
{
int minor, ret = -EINVAL;
struct device *d;
mutex_lock(&sound_mutex);
minor = find_snd_minor(type, card, dev);
if (minor >= 0 && (d = snd_minors[minor]->dev) != NULL)
ret = device_create_file(d, attr);
mutex_unlock(&sound_mutex);
return ret;
}
EXPORT_SYMBOL(snd_add_device_sysfs_file);
#ifdef CONFIG_PROC_FS
/*
* INFO PART
*/
static struct snd_info_entry *snd_minor_info_entry;
static const char *snd_device_type_name(int type)
{
switch (type) {
case SNDRV_DEVICE_TYPE_CONTROL:
return "control";
case SNDRV_DEVICE_TYPE_HWDEP:
return "hardware dependent";
case SNDRV_DEVICE_TYPE_RAWMIDI:
return "raw midi";
case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
return "digital audio playback";
case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
return "digital audio capture";
case SNDRV_DEVICE_TYPE_SEQUENCER:
return "sequencer";
case SNDRV_DEVICE_TYPE_TIMER:
return "timer";
default:
return "?";
}
}
static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
{
int minor;
struct snd_minor *mptr;
mutex_lock(&sound_mutex);
for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
if (!(mptr = snd_minors[minor]))
continue;
if (mptr->card >= 0) {
if (mptr->device >= 0)
snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
minor, mptr->card, mptr->device,
snd_device_type_name(mptr->type));
else
snd_iprintf(buffer, "%3i: [%2i] : %s\n",
minor, mptr->card,
snd_device_type_name(mptr->type));
} else
snd_iprintf(buffer, "%3i: : %s\n", minor,
snd_device_type_name(mptr->type));
}
mutex_unlock(&sound_mutex);
}
int __init snd_minor_info_init(void)
{
struct snd_info_entry *entry;
entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
if (entry) {
entry->c.text.read = snd_minor_info_read;
if (snd_info_register(entry) < 0) {
snd_info_free_entry(entry);
entry = NULL;
}
}
snd_minor_info_entry = entry;
return 0;
}
int __exit snd_minor_info_done(void)
{
snd_info_free_entry(snd_minor_info_entry);
return 0;
}
#endif /* CONFIG_PROC_FS */
/*
* INIT PART
*/
static int __init alsa_sound_init(void)
{
snd_major = major;
snd_ecards_limit = cards_limit;
if (register_chrdev(major, "alsa", &snd_fops)) {
snd_printk(KERN_ERR "unable to register native major device number %d\n", major);
return -EIO;
}
if (snd_info_init() < 0) {
unregister_chrdev(major, "alsa");
return -ENOMEM;
}
snd_info_minor_register();
#ifndef MODULE
printk(KERN_INFO "Advanced Linux Sound Architecture Driver Version " CONFIG_SND_VERSION CONFIG_SND_DATE ".\n");
#endif
return 0;
}
static void __exit alsa_sound_exit(void)
{
snd_info_minor_unregister();
snd_info_done();
unregister_chrdev(major, "alsa");
}
subsys_initcall(alsa_sound_init);
module_exit(alsa_sound_exit);