![Arjan van de Ven](/assets/img/avatar_default.png)
Many struct file_operations in the kernel can be "const". Marking them const moves these to the .rodata section, which avoids false sharing with potential dirty data. In addition it'll catch accidental writes at compile time to these shared resources. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
455 lines
11 KiB
C
455 lines
11 KiB
C
/*
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* Advanced Linux Sound Architecture
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* Copyright (c) by Jaroslav Kysela <perex@suse.cz>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <sound/driver.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/time.h>
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#include <linux/device.h>
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#include <linux/moduleparam.h>
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#include <sound/core.h>
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#include <sound/minors.h>
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#include <sound/info.h>
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#include <sound/version.h>
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#include <sound/control.h>
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#include <sound/initval.h>
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#include <linux/kmod.h>
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#include <linux/mutex.h>
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#define SNDRV_OS_MINORS 256
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static int major = CONFIG_SND_MAJOR;
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int snd_major;
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EXPORT_SYMBOL(snd_major);
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static int cards_limit = 1;
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MODULE_AUTHOR("Jaroslav Kysela <perex@suse.cz>");
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MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
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MODULE_LICENSE("GPL");
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module_param(major, int, 0444);
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MODULE_PARM_DESC(major, "Major # for sound driver.");
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module_param(cards_limit, int, 0444);
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MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
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MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
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/* this one holds the actual max. card number currently available.
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* as default, it's identical with cards_limit option. when more
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* modules are loaded manually, this limit number increases, too.
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*/
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int snd_ecards_limit;
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EXPORT_SYMBOL(snd_ecards_limit);
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static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
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static DEFINE_MUTEX(sound_mutex);
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#ifdef CONFIG_KMOD
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/**
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* snd_request_card - try to load the card module
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* @card: the card number
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*
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* Tries to load the module "snd-card-X" for the given card number
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* via KMOD. Returns immediately if already loaded.
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*/
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void snd_request_card(int card)
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{
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if (! current->fs->root)
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return;
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if (snd_card_locked(card))
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return;
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if (card < 0 || card >= cards_limit)
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return;
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request_module("snd-card-%i", card);
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}
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EXPORT_SYMBOL(snd_request_card);
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static void snd_request_other(int minor)
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{
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char *str;
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if (! current->fs->root)
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return;
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switch (minor) {
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case SNDRV_MINOR_SEQUENCER: str = "snd-seq"; break;
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case SNDRV_MINOR_TIMER: str = "snd-timer"; break;
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default: return;
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}
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request_module(str);
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}
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#endif /* request_module support */
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/**
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* snd_lookup_minor_data - get user data of a registered device
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* @minor: the minor number
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* @type: device type (SNDRV_DEVICE_TYPE_XXX)
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*
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* Checks that a minor device with the specified type is registered, and returns
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* its user data pointer.
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*/
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void *snd_lookup_minor_data(unsigned int minor, int type)
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{
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struct snd_minor *mreg;
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void *private_data;
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if (minor >= ARRAY_SIZE(snd_minors))
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return NULL;
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mutex_lock(&sound_mutex);
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mreg = snd_minors[minor];
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if (mreg && mreg->type == type)
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private_data = mreg->private_data;
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else
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private_data = NULL;
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mutex_unlock(&sound_mutex);
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return private_data;
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}
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EXPORT_SYMBOL(snd_lookup_minor_data);
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static int snd_open(struct inode *inode, struct file *file)
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{
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unsigned int minor = iminor(inode);
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struct snd_minor *mptr = NULL;
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const struct file_operations *old_fops;
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int err = 0;
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if (minor >= ARRAY_SIZE(snd_minors))
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return -ENODEV;
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mptr = snd_minors[minor];
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if (mptr == NULL) {
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#ifdef CONFIG_KMOD
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int dev = SNDRV_MINOR_DEVICE(minor);
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if (dev == SNDRV_MINOR_CONTROL) {
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/* /dev/aloadC? */
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int card = SNDRV_MINOR_CARD(minor);
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if (snd_cards[card] == NULL)
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snd_request_card(card);
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} else if (dev == SNDRV_MINOR_GLOBAL) {
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/* /dev/aloadSEQ */
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snd_request_other(minor);
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}
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#ifndef CONFIG_SND_DYNAMIC_MINORS
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/* /dev/snd/{controlC?,seq} */
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mptr = snd_minors[minor];
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if (mptr == NULL)
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#endif
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#endif
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return -ENODEV;
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}
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old_fops = file->f_op;
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file->f_op = fops_get(mptr->f_ops);
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if (file->f_op->open)
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err = file->f_op->open(inode, file);
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if (err) {
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fops_put(file->f_op);
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file->f_op = fops_get(old_fops);
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}
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fops_put(old_fops);
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return err;
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}
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static const struct file_operations snd_fops =
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{
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.owner = THIS_MODULE,
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.open = snd_open
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};
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#ifdef CONFIG_SND_DYNAMIC_MINORS
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static int snd_find_free_minor(void)
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{
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int minor;
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for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
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/* skip minors still used statically for autoloading devices */
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if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL ||
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minor == SNDRV_MINOR_SEQUENCER)
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continue;
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if (!snd_minors[minor])
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return minor;
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}
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return -EBUSY;
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}
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#else
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static int snd_kernel_minor(int type, struct snd_card *card, int dev)
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{
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int minor;
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switch (type) {
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case SNDRV_DEVICE_TYPE_SEQUENCER:
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case SNDRV_DEVICE_TYPE_TIMER:
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minor = type;
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break;
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case SNDRV_DEVICE_TYPE_CONTROL:
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snd_assert(card != NULL, return -EINVAL);
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minor = SNDRV_MINOR(card->number, type);
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break;
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case SNDRV_DEVICE_TYPE_HWDEP:
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case SNDRV_DEVICE_TYPE_RAWMIDI:
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case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
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case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
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snd_assert(card != NULL, return -EINVAL);
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minor = SNDRV_MINOR(card->number, type + dev);
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break;
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default:
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return -EINVAL;
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}
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snd_assert(minor >= 0 && minor < SNDRV_OS_MINORS, return -EINVAL);
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return minor;
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}
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#endif
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/**
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* snd_register_device_for_dev - Register the ALSA device file for the card
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* @type: the device type, SNDRV_DEVICE_TYPE_XXX
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* @card: the card instance
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* @dev: the device index
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* @f_ops: the file operations
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* @private_data: user pointer for f_ops->open()
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* @name: the device file name
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* @device: the &struct device to link this new device to
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*
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* Registers an ALSA device file for the given card.
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* The operators have to be set in reg parameter.
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*
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* Returns zero if successful, or a negative error code on failure.
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*/
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int snd_register_device_for_dev(int type, struct snd_card *card, int dev,
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const struct file_operations *f_ops,
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void *private_data,
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const char *name, struct device *device)
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{
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int minor;
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struct snd_minor *preg;
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snd_assert(name, return -EINVAL);
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preg = kmalloc(sizeof *preg, GFP_KERNEL);
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if (preg == NULL)
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return -ENOMEM;
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preg->type = type;
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preg->card = card ? card->number : -1;
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preg->device = dev;
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preg->f_ops = f_ops;
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preg->private_data = private_data;
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mutex_lock(&sound_mutex);
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#ifdef CONFIG_SND_DYNAMIC_MINORS
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minor = snd_find_free_minor();
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#else
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minor = snd_kernel_minor(type, card, dev);
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if (minor >= 0 && snd_minors[minor])
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minor = -EBUSY;
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#endif
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if (minor < 0) {
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mutex_unlock(&sound_mutex);
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kfree(preg);
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return minor;
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}
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snd_minors[minor] = preg;
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preg->dev = device_create(sound_class, device, MKDEV(major, minor),
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"%s", name);
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if (preg->dev)
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dev_set_drvdata(preg->dev, private_data);
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mutex_unlock(&sound_mutex);
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return 0;
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}
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EXPORT_SYMBOL(snd_register_device_for_dev);
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/* find the matching minor record
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* return the index of snd_minor, or -1 if not found
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*/
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static int find_snd_minor(int type, struct snd_card *card, int dev)
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{
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int cardnum, minor;
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struct snd_minor *mptr;
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cardnum = card ? card->number : -1;
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for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor)
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if ((mptr = snd_minors[minor]) != NULL &&
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mptr->type == type &&
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mptr->card == cardnum &&
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mptr->device == dev)
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return minor;
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return -1;
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}
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/**
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* snd_unregister_device - unregister the device on the given card
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* @type: the device type, SNDRV_DEVICE_TYPE_XXX
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* @card: the card instance
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* @dev: the device index
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*
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* Unregisters the device file already registered via
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* snd_register_device().
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*
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* Returns zero if sucecessful, or a negative error code on failure
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*/
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int snd_unregister_device(int type, struct snd_card *card, int dev)
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{
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int minor;
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mutex_lock(&sound_mutex);
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minor = find_snd_minor(type, card, dev);
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if (minor < 0) {
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mutex_unlock(&sound_mutex);
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return -EINVAL;
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}
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device_destroy(sound_class, MKDEV(major, minor));
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kfree(snd_minors[minor]);
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snd_minors[minor] = NULL;
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mutex_unlock(&sound_mutex);
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return 0;
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}
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EXPORT_SYMBOL(snd_unregister_device);
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int snd_add_device_sysfs_file(int type, struct snd_card *card, int dev,
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struct device_attribute *attr)
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{
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int minor, ret = -EINVAL;
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struct device *d;
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mutex_lock(&sound_mutex);
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minor = find_snd_minor(type, card, dev);
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if (minor >= 0 && (d = snd_minors[minor]->dev) != NULL)
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ret = device_create_file(d, attr);
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mutex_unlock(&sound_mutex);
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return ret;
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}
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EXPORT_SYMBOL(snd_add_device_sysfs_file);
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#ifdef CONFIG_PROC_FS
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/*
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* INFO PART
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*/
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static struct snd_info_entry *snd_minor_info_entry;
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static const char *snd_device_type_name(int type)
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{
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switch (type) {
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case SNDRV_DEVICE_TYPE_CONTROL:
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return "control";
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case SNDRV_DEVICE_TYPE_HWDEP:
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return "hardware dependent";
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case SNDRV_DEVICE_TYPE_RAWMIDI:
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return "raw midi";
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case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
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return "digital audio playback";
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case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
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return "digital audio capture";
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case SNDRV_DEVICE_TYPE_SEQUENCER:
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return "sequencer";
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case SNDRV_DEVICE_TYPE_TIMER:
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return "timer";
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default:
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return "?";
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}
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}
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static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
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{
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int minor;
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struct snd_minor *mptr;
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mutex_lock(&sound_mutex);
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for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
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if (!(mptr = snd_minors[minor]))
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continue;
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if (mptr->card >= 0) {
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if (mptr->device >= 0)
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snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
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minor, mptr->card, mptr->device,
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snd_device_type_name(mptr->type));
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else
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snd_iprintf(buffer, "%3i: [%2i] : %s\n",
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minor, mptr->card,
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snd_device_type_name(mptr->type));
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} else
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snd_iprintf(buffer, "%3i: : %s\n", minor,
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snd_device_type_name(mptr->type));
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}
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mutex_unlock(&sound_mutex);
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}
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int __init snd_minor_info_init(void)
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{
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struct snd_info_entry *entry;
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entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
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if (entry) {
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entry->c.text.read = snd_minor_info_read;
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if (snd_info_register(entry) < 0) {
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snd_info_free_entry(entry);
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entry = NULL;
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}
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}
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snd_minor_info_entry = entry;
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return 0;
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}
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int __exit snd_minor_info_done(void)
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{
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snd_info_free_entry(snd_minor_info_entry);
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return 0;
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}
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#endif /* CONFIG_PROC_FS */
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/*
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* INIT PART
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*/
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static int __init alsa_sound_init(void)
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{
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snd_major = major;
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snd_ecards_limit = cards_limit;
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if (register_chrdev(major, "alsa", &snd_fops)) {
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snd_printk(KERN_ERR "unable to register native major device number %d\n", major);
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return -EIO;
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}
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if (snd_info_init() < 0) {
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unregister_chrdev(major, "alsa");
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return -ENOMEM;
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}
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snd_info_minor_register();
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#ifndef MODULE
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printk(KERN_INFO "Advanced Linux Sound Architecture Driver Version " CONFIG_SND_VERSION CONFIG_SND_DATE ".\n");
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#endif
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return 0;
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}
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static void __exit alsa_sound_exit(void)
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{
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snd_info_minor_unregister();
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snd_info_done();
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if (unregister_chrdev(major, "alsa") != 0)
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snd_printk(KERN_ERR "unable to unregister major device number %d\n", major);
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}
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module_init(alsa_sound_init)
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module_exit(alsa_sound_exit)
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