drivers/usb/core/file.c

   1 /*
   2  * drivers/usb/file.c
   3  *
   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,
  11         more docs, etc)
  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
  15  *
  16  */
  17
  18 #include <linux/config.h>
  19 #include <linux/module.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/errno.h>
  22
  23 #ifdef CONFIG_USB_DEBUG
  24         #define DEBUG
  25 #else
  26         #undef DEBUG
  27 #endif
  28 #include <linux/usb.h>
  29
  30 #include "usb.h"
  31
  32 #define MAX_USB_MINORS  256
  33 static struct file_operations *usb_minors[MAX_USB_MINORS];
  34 static DEFINE_SPINLOCK(minor_lock);
  35
  36 static int usb_open(struct inode * inode, struct file * file)
  37 {
  38         int minor = iminor(inode);
  39         struct file_operations *c;
  40         int err = -ENODEV;
  41         struct file_operations *old_fops, *new_fops = NULL;
  42
  43         spin_lock (&minor_lock);
  44         c = usb_minors[minor];
  45
  46         if (!c || !(new_fops = fops_get(c))) {
  47                 spin_unlock(&minor_lock);
  48                 return err;
  49         }
  50         spin_unlock(&minor_lock);
  51
  52         old_fops = file->f_op;
  53         file->f_op = new_fops;
  54         /* Curiouser and curiouser... NULL ->open() as "no device" ? */
  55         if (file->f_op->open)
  56                 err = file->f_op->open(inode,file);
  57         if (err) {
  58                 fops_put(file->f_op);
  59                 file->f_op = fops_get(old_fops);
  60         }
  61         fops_put(old_fops);
  62         return err;
  63 }
  64
  65 static struct file_operations usb_fops = {
  66         .owner =        THIS_MODULE,
  67         .open =         usb_open,
  68 };
  69
  70 static struct class *usb_class;
  71
  72 int usb_major_init(void)
  73 {
  74         int error;
  75
  76         error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
  77         if (error) {
  78                 err("unable to get major %d for usb devices", USB_MAJOR);
  79                 goto out;
  80         }
  81
  82         usb_class = class_create(THIS_MODULE, "usb");
  83         if (IS_ERR(usb_class)) {
  84                 error = PTR_ERR(usb_class);
  85                 err("class_create failed for usb devices");
  86                 unregister_chrdev(USB_MAJOR, "usb");
  87                 goto out;
  88         }
  89
  90 out:
  91         return error;
  92 }
  93
  94 void usb_major_cleanup(void)
  95 {
  96         class_destroy(usb_class);
  97         unregister_chrdev(USB_MAJOR, "usb");
  98 }
  99
 100 /**
 101  * usb_register_dev - register a USB device, and ask for a minor number
 102  * @intf: pointer to the usb_interface that is being registered
 103  * @class_driver: pointer to the usb_class_driver for this device
 104  *
 105  * This should be called by all USB drivers that use the USB major number.
 106  * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
 107  * dynamically allocated out of the list of available ones.  If it is not
 108  * enabled, the minor number will be based on the next available free minor,
 109  * starting at the class_driver->minor_base.
 110  *
 111  * This function also creates a usb class device in the sysfs tree.
 112  *
 113  * usb_deregister_dev() must be called when the driver is done with
 114  * the minor numbers given out by this function.
 115  *
 116  * Returns -EINVAL if something bad happens with trying to register a
 117  * device, and 0 on success.
 118  */
 119 int usb_register_dev(struct usb_interface *intf,
 120                      struct usb_class_driver *class_driver)
 121 {
 122         int retval = -EINVAL;
 123         int minor_base = class_driver->minor_base;
 124         int minor = 0;
 125         char name[BUS_ID_SIZE];
 126         char *temp;
 127
 128 #ifdef CONFIG_USB_DYNAMIC_MINORS
 129         /*
 130          * We don't care what the device tries to start at, we want to start
 131          * at zero to pack the devices into the smallest available space with
 132          * no holes in the minor range.
 133          */
 134         minor_base = 0;
 135 #endif
 136         intf->minor = -1;
 137
 138         dbg ("looking for a minor, starting at %d", minor_base);
 139
 140         if (class_driver->fops == NULL)
 141                 goto exit;
 142
 143         spin_lock (&minor_lock);
 144         for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
 145                 if (usb_minors[minor])
 146                         continue;
 147
 148                 usb_minors[minor] = class_driver->fops;
 149
 150                 retval = 0;
 151                 break;
 152         }
 153         spin_unlock (&minor_lock);
 154
 155         if (retval)
 156                 goto exit;
 157
 158         intf->minor = minor;
 159
 160         /* create a usb class device for this usb interface */
 161         snprintf(name, BUS_ID_SIZE, class_driver->name, minor - minor_base);
 162         temp = strrchr(name, '/');
 163         if (temp && (temp[1] != 0x00))
 164                 ++temp;
 165         else
 166                 temp = name;
 167         intf->class_dev = class_device_create(usb_class, NULL,
 168                                               MKDEV(USB_MAJOR, minor),
 169                                               &intf->dev, "%s", temp);
 170         if (IS_ERR(intf->class_dev)) {
 171                 spin_lock (&minor_lock);
 172                 usb_minors[intf->minor] = NULL;
 173                 spin_unlock (&minor_lock);
 174                 retval = PTR_ERR(intf->class_dev);
 175         }
 176 exit:
 177         return retval;
 178 }
 179 EXPORT_SYMBOL(usb_register_dev);
 180
 181 /**
 182  * usb_deregister_dev - deregister a USB device's dynamic minor.
 183  * @intf: pointer to the usb_interface that is being deregistered
 184  * @class_driver: pointer to the usb_class_driver for this device
 185  *
 186  * Used in conjunction with usb_register_dev().  This function is called
 187  * when the USB driver is finished with the minor numbers gotten from a
 188  * call to usb_register_dev() (usually when the device is disconnected
 189  * from the system.)
 190  *
 191  * This function also removes the usb class device from the sysfs tree.
 192  *
 193  * This should be called by all drivers that use the USB major number.
 194  */
 195 void usb_deregister_dev(struct usb_interface *intf,
 196                         struct usb_class_driver *class_driver)
 197 {
 198         int minor_base = class_driver->minor_base;
 199         char name[BUS_ID_SIZE];
 200
 201 #ifdef CONFIG_USB_DYNAMIC_MINORS
 202         minor_base = 0;
 203 #endif
 204
 205         if (intf->minor == -1)
 206                 return;
 207
 208         dbg ("removing %d minor", intf->minor);
 209
 210         spin_lock (&minor_lock);
 211         usb_minors[intf->minor] = NULL;
 212         spin_unlock (&minor_lock);
 213
 214         snprintf(name, BUS_ID_SIZE, class_driver->name, intf->minor - minor_base);
 215         class_device_destroy(usb_class, MKDEV(USB_MAJOR, intf->minor));
 216         intf->class_dev = NULL;
 217         intf->minor = -1;
 218 }
 219 EXPORT_SYMBOL(usb_deregister_dev);
 220
 221