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/devfs_fs_kernel.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/errno.h>
  23
  24 #ifdef CONFIG_USB_DEBUG
  25         #define DEBUG
  26 #else
  27         #undef DEBUG
  28 #endif
  29 #include <linux/usb.h>
  30
  31 #include "usb.h"
  32
  33 #define MAX_USB_MINORS  256
  34 static struct file_operations *usb_minors[MAX_USB_MINORS];
  35 static DEFINE_SPINLOCK(minor_lock);
  36
  37 static int usb_open(struct inode * inode, struct file * file)
  38 {
  39         int minor = iminor(inode);
  40         struct file_operations *c;
  41         int err = -ENODEV;
  42         struct file_operations *old_fops, *new_fops = NULL;
  43
  44         spin_lock (&minor_lock);
  45         c = usb_minors[minor];
  46
  47         if (!c || !(new_fops = fops_get(c))) {
  48                 spin_unlock(&minor_lock);
  49                 return err;
  50         }
  51         spin_unlock(&minor_lock);
  52
  53         old_fops = file->f_op;
  54         file->f_op = new_fops;
  55         /* Curiouser and curiouser... NULL ->open() as "no device" ? */
  56         if (file->f_op->open)
  57                 err = file->f_op->open(inode,file);
  58         if (err) {
  59                 fops_put(file->f_op);
  60                 file->f_op = fops_get(old_fops);
  61         }
  62         fops_put(old_fops);
  63         return err;
  64 }
  65
  66 static struct file_operations usb_fops = {
  67         .owner =        THIS_MODULE,
  68         .open =         usb_open,
  69 };
  70
  71 static struct class_simple *usb_class;
  72
  73 int usb_major_init(void)
  74 {
  75         int error;
  76
  77         error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
  78         if (error) {
  79                 err("unable to get major %d for usb devices", USB_MAJOR);
  80                 goto out;
  81         }
  82
  83         usb_class = class_simple_create(THIS_MODULE, "usb");
  84         if (IS_ERR(usb_class)) {
  85                 err("class_simple_create failed for usb devices");
  86                 unregister_chrdev(USB_MAJOR, "usb");
  87                 goto out;
  88         }
  89
  90         devfs_mk_dir("usb");
  91
  92 out:
  93         return error;
  94 }
  95
  96 void usb_major_cleanup(void)
  97 {
  98         class_simple_destroy(usb_class);
  99         devfs_remove("usb");
 100         unregister_chrdev(USB_MAJOR, "usb");
 101 }
 102
 103 /**
 104  * usb_register_dev - register a USB device, and ask for a minor number
 105  * @intf: pointer to the usb_interface that is being registered
 106  * @class_driver: pointer to the usb_class_driver for this device
 107  *
 108  * This should be called by all USB drivers that use the USB major number.
 109  * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
 110  * dynamically allocated out of the list of available ones.  If it is not
 111  * enabled, the minor number will be based on the next available free minor,
 112  * starting at the class_driver->minor_base.
 113  *
 114  * This function also creates the devfs file for the usb device, if devfs
 115  * is enabled, and creates a usb class device in the sysfs tree.
 116  *
 117  * usb_deregister_dev() must be called when the driver is done with
 118  * the minor numbers given out by this function.
 119  *
 120  * Returns -EINVAL if something bad happens with trying to register a
 121  * device, and 0 on success.
 122  */
 123 int usb_register_dev(struct usb_interface *intf,
 124                      struct usb_class_driver *class_driver)
 125 {
 126         int retval = -EINVAL;
 127         int minor_base = class_driver->minor_base;
 128         int minor = 0;
 129         char name[BUS_ID_SIZE];
 130         char *temp;
 131
 132 #ifdef CONFIG_USB_DYNAMIC_MINORS
 133         /*
 134          * We don't care what the device tries to start at, we want to start
 135          * at zero to pack the devices into the smallest available space with
 136          * no holes in the minor range.
 137          */
 138         minor_base = 0;
 139 #endif
 140         intf->minor = -1;
 141
 142         dbg ("looking for a minor, starting at %d", minor_base);
 143
 144         if (class_driver->fops == NULL)
 145                 goto exit;
 146
 147         spin_lock (&minor_lock);
 148         for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
 149                 if (usb_minors[minor])
 150                         continue;
 151
 152                 usb_minors[minor] = class_driver->fops;
 153
 154                 retval = 0;
 155                 break;
 156         }
 157         spin_unlock (&minor_lock);
 158
 159         if (retval)
 160                 goto exit;
 161
 162         intf->minor = minor;
 163
 164         /* handle the devfs registration */
 165         snprintf(name, BUS_ID_SIZE, class_driver->name, minor - minor_base);
 166         devfs_mk_cdev(MKDEV(USB_MAJOR, minor), class_driver->mode, name);
 167
 168         /* create a usb class device for this usb interface */
 169         temp = strrchr(name, '/');
 170         if (temp && (temp[1] != 0x00))
 171                 ++temp;
 172         else
 173                 temp = name;
 174         intf->class_dev = class_simple_device_add(usb_class, MKDEV(USB_MAJOR, minor), &intf->dev, "%s", temp);
 175         if (IS_ERR(intf->class_dev)) {
 176                 spin_lock (&minor_lock);
 177                 usb_minors[intf->minor] = NULL;
 178                 spin_unlock (&minor_lock);
 179                 devfs_remove (name);
 180                 retval = PTR_ERR(intf->class_dev);
 181         }
 182 exit:
 183         return retval;
 184 }
 185 EXPORT_SYMBOL(usb_register_dev);
 186
 187 /**
 188  * usb_deregister_dev - deregister a USB device's dynamic minor.
 189  * @intf: pointer to the usb_interface that is being deregistered
 190  * @class_driver: pointer to the usb_class_driver for this device
 191  *
 192  * Used in conjunction with usb_register_dev().  This function is called
 193  * when the USB driver is finished with the minor numbers gotten from a
 194  * call to usb_register_dev() (usually when the device is disconnected
 195  * from the system.)
 196  *
 197  * This function also cleans up the devfs file for the usb device, if devfs
 198  * is enabled, and removes the usb class device from the sysfs tree.
 199  *
 200  * This should be called by all drivers that use the USB major number.
 201  */
 202 void usb_deregister_dev(struct usb_interface *intf,
 203                         struct usb_class_driver *class_driver)
 204 {
 205         int minor_base = class_driver->minor_base;
 206         char name[BUS_ID_SIZE];
 207
 208 #ifdef CONFIG_USB_DYNAMIC_MINORS
 209         minor_base = 0;
 210 #endif
 211
 212         if (intf->minor == -1)
 213                 return;
 214
 215         dbg ("removing %d minor", intf->minor);
 216
 217         spin_lock (&minor_lock);
 218         usb_minors[intf->minor] = NULL;
 219         spin_unlock (&minor_lock);
 220
 221         snprintf(name, BUS_ID_SIZE, class_driver->name, intf->minor - minor_base);
 222         devfs_remove (name);
 223         class_simple_device_remove(MKDEV(USB_MAJOR, intf->minor));
 224         intf->class_dev = NULL;
 225         intf->minor = -1;
 226 }
 227 EXPORT_SYMBOL(usb_deregister_dev);
 228
 229