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); 226 227 228