2 * drivers/usb/core/file.c
4 * (C) Copyright Linus Torvalds 1999
5 * (C) Copyright Johannes Erdfelt 1999-2001
6 * (C) Copyright Andreas Gal 1999
7 * (C) Copyright Gregory P. Smith 1999
8 * (C) Copyright Deti Fliegl 1999 (new USB architecture)
9 * (C) Copyright Randy Dunlap 2000
10 * (C) Copyright David Brownell 2000-2001 (kernel hotplug, usb_device_id,
12 * (C) Copyright Yggdrasil Computing, Inc. 2000
13 * (usb_device_id matching changes by Adam J. Richter)
14 * (C) Copyright Greg Kroah-Hartman 2002-2003
18 #include <linux/module.h>
19 #include <linux/errno.h>
20 #include <linux/rwsem.h>
21 #include <linux/slab.h>
22 #include <linux/usb.h>
26 #define MAX_USB_MINORS 256
27 static const struct file_operations *usb_minors[MAX_USB_MINORS];
28 static DECLARE_RWSEM(minor_rwsem);
29 static DEFINE_MUTEX(init_usb_class_mutex);
31 static int usb_open(struct inode *inode, struct file *file)
34 const struct file_operations *new_fops;
36 down_read(&minor_rwsem);
37 new_fops = fops_get(usb_minors[iminor(inode)]);
42 replace_fops(file, new_fops);
43 /* Curiouser and curiouser... NULL ->open() as "no device" ? */
45 err = file->f_op->open(inode, file);
47 up_read(&minor_rwsem);
51 static const struct file_operations usb_fops = {
54 .llseek = noop_llseek,
57 static struct usb_class {
62 static char *usb_devnode(struct device *dev, umode_t *mode)
64 struct usb_class_driver *drv;
66 drv = dev_get_drvdata(dev);
67 if (!drv || !drv->devnode)
69 return drv->devnode(dev, mode);
72 static int init_usb_class(void)
76 if (usb_class != NULL) {
77 kref_get(&usb_class->kref);
81 usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
87 kref_init(&usb_class->kref);
88 usb_class->class = class_create(THIS_MODULE, "usbmisc");
89 if (IS_ERR(usb_class->class)) {
90 result = PTR_ERR(usb_class->class);
91 printk(KERN_ERR "class_create failed for usb devices\n");
96 usb_class->class->devnode = usb_devnode;
102 static void release_usb_class(struct kref *kref)
104 /* Ok, we cheat as we know we only have one usb_class */
105 class_destroy(usb_class->class);
110 static void destroy_usb_class(void)
112 mutex_lock(&init_usb_class_mutex);
113 kref_put(&usb_class->kref, release_usb_class);
114 mutex_unlock(&init_usb_class_mutex);
117 int usb_major_init(void)
121 error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
123 printk(KERN_ERR "Unable to get major %d for usb devices\n",
129 void usb_major_cleanup(void)
131 unregister_chrdev(USB_MAJOR, "usb");
135 * usb_register_dev - register a USB device, and ask for a minor number
136 * @intf: pointer to the usb_interface that is being registered
137 * @class_driver: pointer to the usb_class_driver for this device
139 * This should be called by all USB drivers that use the USB major number.
140 * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
141 * dynamically allocated out of the list of available ones. If it is not
142 * enabled, the minor number will be based on the next available free minor,
143 * starting at the class_driver->minor_base.
145 * This function also creates a usb class device in the sysfs tree.
147 * usb_deregister_dev() must be called when the driver is done with
148 * the minor numbers given out by this function.
150 * Return: -EINVAL if something bad happens with trying to register a
151 * device, and 0 on success.
153 int usb_register_dev(struct usb_interface *intf,
154 struct usb_class_driver *class_driver)
157 int minor_base = class_driver->minor_base;
162 #ifdef CONFIG_USB_DYNAMIC_MINORS
164 * We don't care what the device tries to start at, we want to start
165 * at zero to pack the devices into the smallest available space with
166 * no holes in the minor range.
171 if (class_driver->fops == NULL)
173 if (intf->minor >= 0)
176 mutex_lock(&init_usb_class_mutex);
177 retval = init_usb_class();
178 mutex_unlock(&init_usb_class_mutex);
183 dev_dbg(&intf->dev, "looking for a minor, starting at %d\n", minor_base);
185 down_write(&minor_rwsem);
186 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
187 if (usb_minors[minor])
190 usb_minors[minor] = class_driver->fops;
194 if (intf->minor < 0) {
195 up_write(&minor_rwsem);
199 /* create a usb class device for this usb interface */
200 snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
201 temp = strrchr(name, '/');
202 if (temp && (temp[1] != '\0'))
206 intf->usb_dev = device_create(usb_class->class, &intf->dev,
207 MKDEV(USB_MAJOR, minor), class_driver,
209 if (IS_ERR(intf->usb_dev)) {
210 usb_minors[minor] = NULL;
212 retval = PTR_ERR(intf->usb_dev);
214 up_write(&minor_rwsem);
217 EXPORT_SYMBOL_GPL(usb_register_dev);
220 * usb_deregister_dev - deregister a USB device's dynamic minor.
221 * @intf: pointer to the usb_interface that is being deregistered
222 * @class_driver: pointer to the usb_class_driver for this device
224 * Used in conjunction with usb_register_dev(). This function is called
225 * when the USB driver is finished with the minor numbers gotten from a
226 * call to usb_register_dev() (usually when the device is disconnected
229 * This function also removes the usb class device from the sysfs tree.
231 * This should be called by all drivers that use the USB major number.
233 void usb_deregister_dev(struct usb_interface *intf,
234 struct usb_class_driver *class_driver)
236 if (intf->minor == -1)
239 dev_dbg(&intf->dev, "removing %d minor\n", intf->minor);
240 device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
242 down_write(&minor_rwsem);
243 usb_minors[intf->minor] = NULL;
244 up_write(&minor_rwsem);
246 intf->usb_dev = NULL;
250 EXPORT_SYMBOL_GPL(usb_deregister_dev);