/drivers/usb/core/File.c

/* * 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_MINORS256static 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 minor = iminor(inode);const struct file_operations *c;int err = -ENODEV;const struct file_operations *old_fops, *new_fops = NULL;down_read(&minor_rwsem);c = usb_minors[minor];if (!c || !(new_fops = fops_get(c)))goto done;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); done:up_read(&minor_rwsem);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, mode_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) {kref_get(&usb_class->kref);goto exit;}usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);if (!usb_class) {result = -ENOMEM;goto exit;}kref_init(&usb_class->kref);usb_class->class = class_create(THIS_MODULE, "usb");if (IS_ERR(usb_class->class)) {result = IS_ERR(usb_class->class);printk(KERN_ERR "class_create failed for usb devices\n");kfree(usb_class);usb_class = NULL;goto exit;}usb_class->class->devnode = usb_devnode;exit:return result;}static void release_usb_class(struct kref *kref){/* Ok, we cheat as we know we only have one usb_class */class_destroy(usb_class->class);kfree(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",       USB_MAJOR);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. * * Returns -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;#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_base = 0;#endifif (class_driver->fops == NULL)return -EINVAL;if (intf->minor >= 0)return -EADDRINUSE;retval = init_usb_class();if (retval)return retval;dev_dbg(&intf->dev, "looking for a minor, starting at %d", minor_base);down_write(&minor_rwsem);for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {if (usb_minors[minor])continue;usb_minors[minor] = class_driver->fops;intf->minor = minor;break;}up_write(&minor_rwsem);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;elsetemp = 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)) {down_write(&minor_rwsem);usb_minors[minor] = NULL;intf->minor = -1;up_write(&minor_rwsem);retval = PTR_ERR(intf->usb_dev);}return retval;}EXPORT_SYMBOL_GPL(usb_register_dev);/** * 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){int minor_base = class_driver->minor_base;char name[20];#ifdef CONFIG_USB_DYNAMIC_MINORSminor_base = 0;#endifif (intf->minor == -1)return;dbg ("removing %d minor", intf->minor);down_write(&minor_rwsem);usb_minors[intf->minor] = NULL;up_write(&minor_rwsem);snprintf(name, sizeof(name), class_driver->name, intf->minor - minor_base);device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));intf->usb_dev = NULL;intf->minor = -1;destroy_usb_class();}EXPORT_SYMBOL_GPL(usb_deregister_dev);