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/smp_lock.h>
23 #include <linux/usb.h>
27 #define MAX_USB_MINORS 256
28 static const struct file_operations *usb_minors[MAX_USB_MINORS];
29 static DECLARE_RWSEM(minor_rwsem);
31 static int usb_open(struct inode * inode, struct file * file)
33 int minor = iminor(inode);
34 const struct file_operations *c;
36 const struct file_operations *old_fops, *new_fops = NULL;
38 down_read(&minor_rwsem);
39 c = usb_minors[minor];
41 if (!c || !(new_fops = fops_get(c)))
44 old_fops = file->f_op;
45 file->f_op = new_fops;
46 /* Curiouser and curiouser... NULL ->open() as "no device" ? */
48 err = file->f_op->open(inode,file);
51 file->f_op = fops_get(old_fops);
55 up_read(&minor_rwsem);
59 static const struct file_operations usb_fops = {
62 .llseek = noop_llseek,
65 static struct usb_class {
70 static char *usb_devnode(struct device *dev, mode_t *mode)
72 struct usb_class_driver *drv;
74 drv = dev_get_drvdata(dev);
75 if (!drv || !drv->devnode)
77 return drv->devnode(dev, mode);
80 static int init_usb_class(void)
84 if (usb_class != NULL) {
85 kref_get(&usb_class->kref);
89 usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
95 kref_init(&usb_class->kref);
96 usb_class->class = class_create(THIS_MODULE, "usb");
97 if (IS_ERR(usb_class->class)) {
98 result = IS_ERR(usb_class->class);
99 printk(KERN_ERR "class_create failed for usb devices\n");
104 usb_class->class->devnode = usb_devnode;
110 static void release_usb_class(struct kref *kref)
112 /* Ok, we cheat as we know we only have one usb_class */
113 class_destroy(usb_class->class);
118 static void destroy_usb_class(void)
121 kref_put(&usb_class->kref, release_usb_class);
124 int usb_major_init(void)
128 error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
130 printk(KERN_ERR "Unable to get major %d for usb devices\n",
136 void usb_major_cleanup(void)
138 unregister_chrdev(USB_MAJOR, "usb");
142 * usb_register_dev - register a USB device, and ask for a minor number
143 * @intf: pointer to the usb_interface that is being registered
144 * @class_driver: pointer to the usb_class_driver for this device
146 * This should be called by all USB drivers that use the USB major number.
147 * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
148 * dynamically allocated out of the list of available ones. If it is not
149 * enabled, the minor number will be based on the next available free minor,
150 * starting at the class_driver->minor_base.
152 * This function also creates a usb class device in the sysfs tree.
154 * usb_deregister_dev() must be called when the driver is done with
155 * the minor numbers given out by this function.
157 * Returns -EINVAL if something bad happens with trying to register a
158 * device, and 0 on success.
160 int usb_register_dev(struct usb_interface *intf,
161 struct usb_class_driver *class_driver)
164 int minor_base = class_driver->minor_base;
169 #ifdef CONFIG_USB_DYNAMIC_MINORS
171 * We don't care what the device tries to start at, we want to start
172 * at zero to pack the devices into the smallest available space with
173 * no holes in the minor range.
178 if (class_driver->fops == NULL)
180 if (intf->minor >= 0)
183 retval = init_usb_class();
187 dev_dbg(&intf->dev, "looking for a minor, starting at %d", minor_base);
189 down_write(&minor_rwsem);
190 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
191 if (usb_minors[minor])
194 usb_minors[minor] = class_driver->fops;
198 up_write(&minor_rwsem);
202 /* create a usb class device for this usb interface */
203 snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
204 temp = strrchr(name, '/');
205 if (temp && (temp[1] != '\0'))
209 intf->usb_dev = device_create(usb_class->class, &intf->dev,
210 MKDEV(USB_MAJOR, minor), class_driver,
212 if (IS_ERR(intf->usb_dev)) {
213 down_write(&minor_rwsem);
214 usb_minors[minor] = NULL;
216 up_write(&minor_rwsem);
217 retval = PTR_ERR(intf->usb_dev);
221 EXPORT_SYMBOL_GPL(usb_register_dev);
224 * usb_deregister_dev - deregister a USB device's dynamic minor.
225 * @intf: pointer to the usb_interface that is being deregistered
226 * @class_driver: pointer to the usb_class_driver for this device
228 * Used in conjunction with usb_register_dev(). This function is called
229 * when the USB driver is finished with the minor numbers gotten from a
230 * call to usb_register_dev() (usually when the device is disconnected
233 * This function also removes the usb class device from the sysfs tree.
235 * This should be called by all drivers that use the USB major number.
237 void usb_deregister_dev(struct usb_interface *intf,
238 struct usb_class_driver *class_driver)
240 int minor_base = class_driver->minor_base;
243 #ifdef CONFIG_USB_DYNAMIC_MINORS
247 if (intf->minor == -1)
250 dbg ("removing %d minor", intf->minor);
252 down_write(&minor_rwsem);
253 usb_minors[intf->minor] = NULL;
254 up_write(&minor_rwsem);
256 snprintf(name, sizeof(name), class_driver->name, intf->minor - minor_base);
257 device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
258 intf->usb_dev = NULL;
262 EXPORT_SYMBOL_GPL(usb_deregister_dev);