300 lines
6.9 KiB
C
300 lines
6.9 KiB
C
/*
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* linux/drivers/char/misc.c
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*
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* Generic misc open routine by Johan Myreen
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*
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* Based on code from Linus
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*
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* Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's
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* changes incorporated into 0.97pl4
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* by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92)
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* See busmouse.c for particulars.
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*
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* Made things a lot mode modular - easy to compile in just one or two
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* of the misc drivers, as they are now completely independent. Linus.
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*
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* Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
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*
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* Fixed a failing symbol register to free the device registration
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* Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
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*
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* Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
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*
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* Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
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*
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* Handling of mouse minor numbers for kerneld:
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* Idea by Jacques Gelinas <jack@solucorp.qc.ca>,
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* adapted by Bjorn Ekwall <bj0rn@blox.se>
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* corrected by Alan Cox <alan@lxorguk.ukuu.org.uk>
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*
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* Changes for kmod (from kerneld):
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* Cyrus Durgin <cider@speakeasy.org>
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*
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* Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/errno.h>
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#include <linux/miscdevice.h>
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#include <linux/kernel.h>
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#include <linux/major.h>
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#include <linux/mutex.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/stat.h>
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#include <linux/init.h>
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#include <linux/device.h>
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#include <linux/tty.h>
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#include <linux/kmod.h>
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#include <linux/gfp.h>
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/*
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* Head entry for the doubly linked miscdevice list
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*/
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static LIST_HEAD(misc_list);
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static DEFINE_MUTEX(misc_mtx);
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/*
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* Assigned numbers, used for dynamic minors
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*/
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#define DYNAMIC_MINORS 64 /* like dynamic majors */
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static DECLARE_BITMAP(misc_minors, DYNAMIC_MINORS);
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#ifdef CONFIG_PROC_FS
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static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
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{
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mutex_lock(&misc_mtx);
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return seq_list_start(&misc_list, *pos);
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}
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static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
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{
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return seq_list_next(v, &misc_list, pos);
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}
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static void misc_seq_stop(struct seq_file *seq, void *v)
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{
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mutex_unlock(&misc_mtx);
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}
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static int misc_seq_show(struct seq_file *seq, void *v)
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{
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const struct miscdevice *p = list_entry(v, struct miscdevice, list);
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seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
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return 0;
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}
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static const struct seq_operations misc_seq_ops = {
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.start = misc_seq_start,
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.next = misc_seq_next,
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.stop = misc_seq_stop,
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.show = misc_seq_show,
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};
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static int misc_seq_open(struct inode *inode, struct file *file)
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{
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return seq_open(file, &misc_seq_ops);
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}
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static const struct file_operations misc_proc_fops = {
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.owner = THIS_MODULE,
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.open = misc_seq_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = seq_release,
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};
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#endif
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static int misc_open(struct inode * inode, struct file * file)
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{
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int minor = iminor(inode);
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struct miscdevice *c;
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int err = -ENODEV;
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const struct file_operations *old_fops, *new_fops = NULL;
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mutex_lock(&misc_mtx);
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list_for_each_entry(c, &misc_list, list) {
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if (c->minor == minor) {
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new_fops = fops_get(c->fops);
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break;
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}
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}
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if (!new_fops) {
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mutex_unlock(&misc_mtx);
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request_module("char-major-%d-%d", MISC_MAJOR, minor);
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mutex_lock(&misc_mtx);
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list_for_each_entry(c, &misc_list, list) {
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if (c->minor == minor) {
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new_fops = fops_get(c->fops);
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break;
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}
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}
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if (!new_fops)
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goto fail;
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}
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err = 0;
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old_fops = file->f_op;
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file->f_op = new_fops;
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if (file->f_op->open) {
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file->private_data = c;
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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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}
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fops_put(old_fops);
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fail:
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mutex_unlock(&misc_mtx);
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return err;
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}
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static struct class *misc_class;
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static const struct file_operations misc_fops = {
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.owner = THIS_MODULE,
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.open = misc_open,
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.llseek = noop_llseek,
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};
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/**
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* misc_register - register a miscellaneous device
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* @misc: device structure
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*
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* Register a miscellaneous device with the kernel. If the minor
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* number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
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* and placed in the minor field of the structure. For other cases
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* the minor number requested is used.
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*
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* The structure passed is linked into the kernel and may not be
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* destroyed until it has been unregistered.
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*
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* A zero is returned on success and a negative errno code for
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* failure.
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*/
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int misc_register(struct miscdevice * misc)
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{
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dev_t dev;
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int err = 0;
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INIT_LIST_HEAD(&misc->list);
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mutex_lock(&misc_mtx);
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if (misc->minor == MISC_DYNAMIC_MINOR) {
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int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
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if (i >= DYNAMIC_MINORS) {
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mutex_unlock(&misc_mtx);
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return -EBUSY;
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}
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misc->minor = DYNAMIC_MINORS - i - 1;
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set_bit(i, misc_minors);
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} else {
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struct miscdevice *c;
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list_for_each_entry(c, &misc_list, list) {
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if (c->minor == misc->minor) {
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mutex_unlock(&misc_mtx);
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return -EBUSY;
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}
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}
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}
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dev = MKDEV(MISC_MAJOR, misc->minor);
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misc->this_device = device_create(misc_class, misc->parent, dev,
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misc, "%s", misc->name);
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if (IS_ERR(misc->this_device)) {
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int i = DYNAMIC_MINORS - misc->minor - 1;
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if (i < DYNAMIC_MINORS && i >= 0)
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clear_bit(i, misc_minors);
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err = PTR_ERR(misc->this_device);
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goto out;
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}
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/*
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* Add it to the front, so that later devices can "override"
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* earlier defaults
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*/
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list_add(&misc->list, &misc_list);
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out:
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mutex_unlock(&misc_mtx);
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return err;
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}
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/**
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* misc_deregister - unregister a miscellaneous device
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* @misc: device to unregister
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*
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* Unregister a miscellaneous device that was previously
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* successfully registered with misc_register(). Success
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* is indicated by a zero return, a negative errno code
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* indicates an error.
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*/
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int misc_deregister(struct miscdevice *misc)
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{
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int i = DYNAMIC_MINORS - misc->minor - 1;
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if (WARN_ON(list_empty(&misc->list)))
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return -EINVAL;
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mutex_lock(&misc_mtx);
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list_del(&misc->list);
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device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
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if (i < DYNAMIC_MINORS && i >= 0)
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clear_bit(i, misc_minors);
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mutex_unlock(&misc_mtx);
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return 0;
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}
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EXPORT_SYMBOL(misc_register);
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EXPORT_SYMBOL(misc_deregister);
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static char *misc_devnode(struct device *dev, umode_t *mode)
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{
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struct miscdevice *c = dev_get_drvdata(dev);
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if (mode && c->mode)
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*mode = c->mode;
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if (c->nodename)
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return kstrdup(c->nodename, GFP_KERNEL);
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return NULL;
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}
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static int __init misc_init(void)
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{
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int err;
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#ifdef CONFIG_PROC_FS
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proc_create("misc", 0, NULL, &misc_proc_fops);
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#endif
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misc_class = class_create(THIS_MODULE, "misc");
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err = PTR_ERR(misc_class);
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if (IS_ERR(misc_class))
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goto fail_remove;
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err = -EIO;
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if (register_chrdev(MISC_MAJOR,"misc",&misc_fops))
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goto fail_printk;
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misc_class->devnode = misc_devnode;
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return 0;
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fail_printk:
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printk("unable to get major %d for misc devices\n", MISC_MAJOR);
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class_destroy(misc_class);
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fail_remove:
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remove_proc_entry("misc", NULL);
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return err;
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}
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subsys_initcall(misc_init);
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