WSL2-Linux-Kernel/drivers/char/misc.c

332 строки
7.3 KiB
C

/*
* linux/drivers/char/misc.c
*
* Generic misc open routine by Johan Myreen
*
* Based on code from Linus
*
* Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's
* changes incorporated into 0.97pl4
* by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92)
* See busmouse.c for particulars.
*
* Made things a lot mode modular - easy to compile in just one or two
* of the misc drivers, as they are now completely independent. Linus.
*
* Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk>
*
* Fixed a failing symbol register to free the device registration
* Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96
*
* Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96
*
* Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96
*
* Handling of mouse minor numbers for kerneld:
* Idea by Jacques Gelinas <jack@solucorp.qc.ca>,
* adapted by Bjorn Ekwall <bj0rn@blox.se>
* corrected by Alan Cox <alan@lxorguk.ukuu.org.uk>
*
* Changes for kmod (from kerneld):
* Cyrus Durgin <cider@speakeasy.org>
*
* Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998
*/
#include <linux/module.h>
#include <linux/config.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/kmod.h>
/*
* Head entry for the doubly linked miscdevice list
*/
static LIST_HEAD(misc_list);
static DECLARE_MUTEX(misc_sem);
/*
* Assigned numbers, used for dynamic minors
*/
#define DYNAMIC_MINORS 64 /* like dynamic majors */
static unsigned char misc_minors[DYNAMIC_MINORS / 8];
extern int rtc_DP8570A_init(void);
extern int rtc_MK48T08_init(void);
extern int pmu_device_init(void);
extern int tosh_init(void);
extern int i8k_init(void);
#ifdef CONFIG_PROC_FS
static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
{
struct miscdevice *p;
loff_t off = 0;
down(&misc_sem);
list_for_each_entry(p, &misc_list, list) {
if (*pos == off++)
return p;
}
return NULL;
}
static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
struct list_head *n = ((struct miscdevice *)v)->list.next;
++*pos;
return (n != &misc_list) ? list_entry(n, struct miscdevice, list)
: NULL;
}
static void misc_seq_stop(struct seq_file *seq, void *v)
{
up(&misc_sem);
}
static int misc_seq_show(struct seq_file *seq, void *v)
{
const struct miscdevice *p = v;
seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : "");
return 0;
}
static struct seq_operations misc_seq_ops = {
.start = misc_seq_start,
.next = misc_seq_next,
.stop = misc_seq_stop,
.show = misc_seq_show,
};
static int misc_seq_open(struct inode *inode, struct file *file)
{
return seq_open(file, &misc_seq_ops);
}
static struct file_operations misc_proc_fops = {
.owner = THIS_MODULE,
.open = misc_seq_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
#endif
static int misc_open(struct inode * inode, struct file * file)
{
int minor = iminor(inode);
struct miscdevice *c;
int err = -ENODEV;
struct file_operations *old_fops, *new_fops = NULL;
down(&misc_sem);
list_for_each_entry(c, &misc_list, list) {
if (c->minor == minor) {
new_fops = fops_get(c->fops);
break;
}
}
if (!new_fops) {
up(&misc_sem);
request_module("char-major-%d-%d", MISC_MAJOR, minor);
down(&misc_sem);
list_for_each_entry(c, &misc_list, list) {
if (c->minor == minor) {
new_fops = fops_get(c->fops);
break;
}
}
if (!new_fops)
goto fail;
}
err = 0;
old_fops = file->f_op;
file->f_op = new_fops;
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);
fail:
up(&misc_sem);
return err;
}
/*
* TODO for 2.7:
* - add a struct class_device to struct miscdevice and make all usages of
* them dynamic.
*/
static struct class_simple *misc_class;
static struct file_operations misc_fops = {
.owner = THIS_MODULE,
.open = misc_open,
};
/**
* misc_register - register a miscellaneous device
* @misc: device structure
*
* Register a miscellaneous device with the kernel. If the minor
* number is set to %MISC_DYNAMIC_MINOR a minor number is assigned
* and placed in the minor field of the structure. For other cases
* the minor number requested is used.
*
* The structure passed is linked into the kernel and may not be
* destroyed until it has been unregistered.
*
* A zero is returned on success and a negative errno code for
* failure.
*/
int misc_register(struct miscdevice * misc)
{
struct miscdevice *c;
dev_t dev;
int err;
down(&misc_sem);
list_for_each_entry(c, &misc_list, list) {
if (c->minor == misc->minor) {
up(&misc_sem);
return -EBUSY;
}
}
if (misc->minor == MISC_DYNAMIC_MINOR) {
int i = DYNAMIC_MINORS;
while (--i >= 0)
if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
break;
if (i<0) {
up(&misc_sem);
return -EBUSY;
}
misc->minor = i;
}
if (misc->minor < DYNAMIC_MINORS)
misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7);
if (misc->devfs_name[0] == '\0') {
snprintf(misc->devfs_name, sizeof(misc->devfs_name),
"misc/%s", misc->name);
}
dev = MKDEV(MISC_MAJOR, misc->minor);
misc->class = class_simple_device_add(misc_class, dev,
misc->dev, misc->name);
if (IS_ERR(misc->class)) {
err = PTR_ERR(misc->class);
goto out;
}
err = devfs_mk_cdev(dev, S_IFCHR|S_IRUSR|S_IWUSR|S_IRGRP,
misc->devfs_name);
if (err) {
class_simple_device_remove(dev);
goto out;
}
/*
* Add it to the front, so that later devices can "override"
* earlier defaults
*/
list_add(&misc->list, &misc_list);
out:
up(&misc_sem);
return err;
}
/**
* misc_deregister - unregister a miscellaneous device
* @misc: device to unregister
*
* Unregister a miscellaneous device that was previously
* successfully registered with misc_register(). Success
* is indicated by a zero return, a negative errno code
* indicates an error.
*/
int misc_deregister(struct miscdevice * misc)
{
int i = misc->minor;
if (list_empty(&misc->list))
return -EINVAL;
down(&misc_sem);
list_del(&misc->list);
class_simple_device_remove(MKDEV(MISC_MAJOR, misc->minor));
devfs_remove(misc->devfs_name);
if (i < DYNAMIC_MINORS && i>0) {
misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
}
up(&misc_sem);
return 0;
}
EXPORT_SYMBOL(misc_register);
EXPORT_SYMBOL(misc_deregister);
static int __init misc_init(void)
{
#ifdef CONFIG_PROC_FS
struct proc_dir_entry *ent;
ent = create_proc_entry("misc", 0, NULL);
if (ent)
ent->proc_fops = &misc_proc_fops;
#endif
misc_class = class_simple_create(THIS_MODULE, "misc");
if (IS_ERR(misc_class))
return PTR_ERR(misc_class);
#ifdef CONFIG_MVME16x
rtc_MK48T08_init();
#endif
#ifdef CONFIG_BVME6000
rtc_DP8570A_init();
#endif
#ifdef CONFIG_PMAC_PBOOK
pmu_device_init();
#endif
#ifdef CONFIG_TOSHIBA
tosh_init();
#endif
#ifdef CONFIG_I8K
i8k_init();
#endif
if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) {
printk("unable to get major %d for misc devices\n",
MISC_MAJOR);
class_simple_destroy(misc_class);
return -EIO;
}
return 0;
}
subsys_initcall(misc_init);