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/smp_lock.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);
30 static int usb_open(struct inode * inode, struct file * file)
32 int minor = iminor(inode);
33 const struct file_operations *c;
35 const struct file_operations *old_fops, *new_fops = NULL;
37 down_read(&minor_rwsem);
38 c = usb_minors[minor];
40 if (!c || !(new_fops = fops_get(c)))
43 old_fops = file->f_op;
44 file->f_op = new_fops;
45 /* Curiouser and curiouser... NULL ->open() as "no device" ? */
47 err = file->f_op->open(inode,file);
50 file->f_op = fops_get(old_fops);
54 up_read(&minor_rwsem);
58 static const struct file_operations usb_fops = {
63 static struct usb_class {
68 static char *usb_devnode(struct device *dev, mode_t *mode)
70 struct usb_class_driver *drv;
72 drv = dev_get_drvdata(dev);
73 if (!drv || !drv->devnode)
75 return drv->devnode(dev, mode);
78 static int init_usb_class(void)
82 if (usb_class != NULL) {
83 kref_get(&usb_class->kref);
87 usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
93 kref_init(&usb_class->kref);
94 usb_class->class = class_create(THIS_MODULE, "usb");
95 if (IS_ERR(usb_class->class)) {
96 result = IS_ERR(usb_class->class);
97 printk(KERN_ERR "class_create failed for usb devices\n");
102 usb_class->class->devnode = usb_devnode;
108 static void release_usb_class(struct kref *kref)
110 /* Ok, we cheat as we know we only have one usb_class */
111 class_destroy(usb_class->class);
116 static void destroy_usb_class(void)
119 kref_put(&usb_class->kref, release_usb_class);
122 int usb_major_init(void)
126 error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
128 printk(KERN_ERR "Unable to get major %d for usb devices\n",
134 void usb_major_cleanup(void)
136 unregister_chrdev(USB_MAJOR, "usb");
140 * usb_register_dev - register a USB device, and ask for a minor number
141 * @intf: pointer to the usb_interface that is being registered
142 * @class_driver: pointer to the usb_class_driver for this device
144 * This should be called by all USB drivers that use the USB major number.
145 * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
146 * dynamically allocated out of the list of available ones. If it is not
147 * enabled, the minor number will be based on the next available free minor,
148 * starting at the class_driver->minor_base.
150 * This function also creates a usb class device in the sysfs tree.
152 * usb_deregister_dev() must be called when the driver is done with
153 * the minor numbers given out by this function.
155 * Returns -EINVAL if something bad happens with trying to register a
156 * device, and 0 on success.
158 int usb_register_dev(struct usb_interface *intf,
159 struct usb_class_driver *class_driver)
161 int retval = -EINVAL;
162 int minor_base = class_driver->minor_base;
167 #ifdef CONFIG_USB_DYNAMIC_MINORS
169 * We don't care what the device tries to start at, we want to start
170 * at zero to pack the devices into the smallest available space with
171 * no holes in the minor range.
177 dbg ("looking for a minor, starting at %d", minor_base);
179 if (class_driver->fops == NULL)
182 down_write(&minor_rwsem);
183 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
184 if (usb_minors[minor])
187 usb_minors[minor] = class_driver->fops;
192 up_write(&minor_rwsem);
197 retval = init_usb_class();
203 /* create a usb class device for this usb interface */
204 snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
205 temp = strrchr(name, '/');
206 if (temp && (temp[1] != '\0'))
210 intf->usb_dev = device_create(usb_class->class, &intf->dev,
211 MKDEV(USB_MAJOR, minor), class_driver,
213 if (IS_ERR(intf->usb_dev)) {
214 down_write(&minor_rwsem);
215 usb_minors[intf->minor] = NULL;
216 up_write(&minor_rwsem);
217 retval = PTR_ERR(intf->usb_dev);
222 EXPORT_SYMBOL_GPL(usb_register_dev);
225 * usb_deregister_dev - deregister a USB device's dynamic minor.
226 * @intf: pointer to the usb_interface that is being deregistered
227 * @class_driver: pointer to the usb_class_driver for this device
229 * Used in conjunction with usb_register_dev(). This function is called
230 * when the USB driver is finished with the minor numbers gotten from a
231 * call to usb_register_dev() (usually when the device is disconnected
234 * This function also removes the usb class device from the sysfs tree.
236 * This should be called by all drivers that use the USB major number.
238 void usb_deregister_dev(struct usb_interface *intf,
239 struct usb_class_driver *class_driver)
241 int minor_base = class_driver->minor_base;
244 #ifdef CONFIG_USB_DYNAMIC_MINORS
248 if (intf->minor == -1)
251 dbg ("removing %d minor", intf->minor);
253 down_write(&minor_rwsem);
254 usb_minors[intf->minor] = NULL;
255 up_write(&minor_rwsem);
257 snprintf(name, sizeof(name), class_driver->name, intf->minor - minor_base);
258 device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
259 intf->usb_dev = NULL;
263 EXPORT_SYMBOL_GPL(usb_deregister_dev);