blob: ea337a718cc1ca38945d3c42e6d0f75d157083b6 [file] [log] [blame]
* drivers/usb/core/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 2002-2003
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include "usb.h"
#define MAX_USB_MINORS 256
static const struct file_operations *usb_minors[MAX_USB_MINORS];
static DECLARE_RWSEM(minor_rwsem);
static int usb_open(struct inode *inode, struct file *file)
int err = -ENODEV;
const struct file_operations *new_fops;
new_fops = fops_get(usb_minors[iminor(inode)]);
if (!new_fops)
goto done;
replace_fops(file, new_fops);
/* Curiouser and curiouser... NULL ->open() as "no device" ? */
if (file->f_op->open)
err = file->f_op->open(inode, file);
return err;
static const struct file_operations usb_fops = {
.owner = THIS_MODULE,
.open = usb_open,
.llseek = noop_llseek,
static struct usb_class {
struct kref kref;
struct class *class;
} *usb_class;
static char *usb_devnode(struct device *dev, umode_t *mode)
struct usb_class_driver *drv;
drv = dev_get_drvdata(dev);
if (!drv || !drv->devnode)
return NULL;
return drv->devnode(dev, mode);
static int init_usb_class(void)
int result = 0;
if (usb_class != NULL) {
goto exit;
usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
if (!usb_class) {
result = -ENOMEM;
goto exit;
usb_class->class = class_create(THIS_MODULE, "usbmisc");
if (IS_ERR(usb_class->class)) {
result = PTR_ERR(usb_class->class);
printk(KERN_ERR "class_create failed for usb devices\n");
usb_class = NULL;
goto exit;
usb_class->class->devnode = usb_devnode;
return result;
static void release_usb_class(struct kref *kref)
/* Ok, we cheat as we know we only have one usb_class */
usb_class = NULL;
static void destroy_usb_class(void)
if (usb_class)
kref_put(&usb_class->kref, release_usb_class);
int usb_major_init(void)
int error;
error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
if (error)
printk(KERN_ERR "Unable to get major %d for usb devices\n",
return error;
void usb_major_cleanup(void)
unregister_chrdev(USB_MAJOR, "usb");
* usb_register_dev - register a USB device, and ask for a minor number
* @intf: pointer to the usb_interface that is being registered
* @class_driver: pointer to the usb_class_driver for this device
* 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 class_driver->minor_base.
* This function also creates a usb class device in the sysfs tree.
* usb_deregister_dev() must be called when the driver is done with
* the minor numbers given out by this function.
* Return: -EINVAL if something bad happens with trying to register a
* device, and 0 on success.
int usb_register_dev(struct usb_interface *intf,
struct usb_class_driver *class_driver)
int retval;
int minor_base = class_driver->minor_base;
int minor;
char name[20];
char *temp;
* 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_base = 0;
if (class_driver->fops == NULL)
return -EINVAL;
if (intf->minor >= 0)
retval = init_usb_class();
if (retval)
return retval;
dev_dbg(&intf->dev, "looking for a minor, starting at %d\n", minor_base);
for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
if (usb_minors[minor])
usb_minors[minor] = class_driver->fops;
intf->minor = minor;
if (intf->minor < 0)
return -EXFULL;
/* create a usb class device for this usb interface */
snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
temp = strrchr(name, '/');
if (temp && (temp[1] != '\0'))
temp = name;
intf->usb_dev = device_create(usb_class->class, &intf->dev,
MKDEV(USB_MAJOR, minor), class_driver,
"%s", temp);
if (IS_ERR(intf->usb_dev)) {
usb_minors[minor] = NULL;
intf->minor = -1;
retval = PTR_ERR(intf->usb_dev);
return retval;
* usb_deregister_dev - deregister a USB device's dynamic minor.
* @intf: pointer to the usb_interface that is being deregistered
* @class_driver: pointer to the usb_class_driver for this device
* 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 function also removes the usb class device from the sysfs tree.
* This should be called by all drivers that use the USB major number.
void usb_deregister_dev(struct usb_interface *intf,
struct usb_class_driver *class_driver)
if (intf->minor == -1)
dev_dbg(&intf->dev, "removing %d minor\n", intf->minor);
usb_minors[intf->minor] = NULL;
device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
intf->usb_dev = NULL;
intf->minor = -1;