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