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/*
* drivers/usb/file.c
*
* (C) Copyright Linus Torvalds 1999
* (C) Copyright Johannes Erdfelt 1999-2001
* (C) Copyright Andreas Gal 1999
* (C) Copyright Gregory P. Smith 1999
* (C) Copyright Deti Fliegl 1999 (new USB architecture)
* (C) Copyright Randy Dunlap 2000
* (C) Copyright David Brownell 2000-2001 (kernel hotplug, usb_device_id,
more docs, etc)
* (C) Copyright Yggdrasil Computing, Inc. 2000
* (usb_device_id matching changes by Adam J. Richter)
* (C) Copyright Greg Kroah-Hartman 2002
*
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#ifdef CONFIG_USB_DEBUG
#define DEBUG
#else
#undef DEBUG
#endif
#include <linux/usb.h>
devfs_handle_t usb_devfs_handle; /* /dev/usb dir. */
EXPORT_SYMBOL(usb_devfs_handle);
#define MAX_USB_MINORS 256
static struct file_operations *usb_minors[MAX_USB_MINORS];
static spinlock_t minor_lock = SPIN_LOCK_UNLOCKED;
static int usb_open(struct inode * inode, struct file * file)
{
int minor = minor(inode->i_rdev);
struct file_operations *c;
int err = -ENODEV;
struct file_operations *old_fops, *new_fops = NULL;
spin_lock (&minor_lock);
c = usb_minors[minor];
if (!c || !(new_fops = fops_get(c))) {
spin_unlock(&minor_lock);
return err;
}
spin_unlock(&minor_lock);
old_fops = file->f_op;
file->f_op = new_fops;
/* Curiouser and curiouser... NULL ->open() as "no device" ? */
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 struct file_operations usb_fops = {
.owner = THIS_MODULE,
.open = usb_open,
};
int usb_major_init(void)
{
if (register_chrdev(USB_MAJOR, "usb", &usb_fops)) {
err("unable to get major %d for usb devices", USB_MAJOR);
return -EBUSY;
}
usb_devfs_handle = devfs_mk_dir(NULL, "usb", NULL);
return 0;
}
void usb_major_cleanup(void)
{
devfs_unregister(usb_devfs_handle);
unregister_chrdev(USB_MAJOR, "usb");
}
/**
* usb_register_dev - register a USB device, and ask for a minor number
* @fops: the file operations for this USB device
* @minor: the requested starting minor for this device.
* @num_minors: number of minor numbers requested for this device
* @start_minor: place to put the new starting minor number
*
* This should be called by all USB drivers that use the USB major number.
* If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
* dynamically allocated out of the list of available ones. If it is not
* enabled, the minor number will be based on the next available free minor,
* starting at the requested @minor.
*
* usb_deregister_dev() must be called when the driver is done with
* the minor numbers given out by this function.
*
* Returns -EINVAL if something bad happens with trying to register a
* device, and 0 on success, alone with a value that the driver should
* use in start_minor.
*/
int usb_register_dev (struct file_operations *fops, int minor, int num_minors, int *start_minor)
{
int i;
int j;
int good_spot;
int retval = -EINVAL;
#ifdef CONFIG_USB_DYNAMIC_MINORS
/*
* We don't care what the device tries to start at, we want to start
* at zero to pack the devices into the smallest available space with
* no holes in the minor range.
*/
minor = 0;
#endif
dbg ("asking for %d minors, starting at %d", num_minors, minor);
if (fops == NULL)
goto exit;
*start_minor = 0;
spin_lock (&minor_lock);
for (i = minor; i < MAX_USB_MINORS; ++i) {
if (usb_minors[i])
continue;
good_spot = 1;
for (j = 1; j <= num_minors-1; ++j)
if (usb_minors[i+j]) {
good_spot = 0;
break;
}
if (good_spot == 0)
continue;
*start_minor = i;
dbg("found a minor chunk free, starting at %d", i);
for (i = *start_minor; i < (*start_minor + num_minors); ++i)
usb_minors[i] = fops;
retval = 0;
goto exit;
}
exit:
spin_unlock (&minor_lock);
return retval;
}
EXPORT_SYMBOL(usb_register_dev);
/**
* usb_deregister_dev - deregister a USB device's dynamic minor.
* @num_minors: number of minor numbers to put back.
* @start_minor: the starting minor number
*
* Used in conjunction with usb_register_dev(). This function is called
* when the USB driver is finished with the minor numbers gotten from a
* call to usb_register_dev() (usually when the device is disconnected
* from the system.)
*
* This should be called by all drivers that use the USB major number.
*/
void usb_deregister_dev (int num_minors, int start_minor)
{
int i;
dbg ("removing %d minors starting at %d", num_minors, start_minor);
spin_lock (&minor_lock);
for (i = start_minor; i < (start_minor + num_minors); ++i)
usb_minors[i] = NULL;
spin_unlock (&minor_lock);
}
EXPORT_SYMBOL(usb_deregister_dev);
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