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/module.h> 19 #include <linux/spinlock.h> 20 #include <linux/errno.h> 21 #include <linux/usb.h> 22 23 #include "usb.h" 24 25 #define MAX_USB_MINORS 256 26 static const struct file_operations *usb_minors[MAX_USB_MINORS]; 27 static DEFINE_SPINLOCK(minor_lock); 28 29 static int usb_open(struct inode * inode, struct file * file) 30 { 31 int minor = iminor(inode); 32 const struct file_operations *c; 33 int err = -ENODEV; 34 const struct file_operations *old_fops, *new_fops = NULL; 35 36 spin_lock (&minor_lock); 37 c = usb_minors[minor]; 38 39 if (!c || !(new_fops = fops_get(c))) { 40 spin_unlock(&minor_lock); 41 return err; 42 } 43 spin_unlock(&minor_lock); 44 45 old_fops = file->f_op; 46 file->f_op = new_fops; 47 /* Curiouser and curiouser... NULL ->open() as "no device" ? */ 48 if (file->f_op->open) 49 err = file->f_op->open(inode,file); 50 if (err) { 51 fops_put(file->f_op); 52 file->f_op = fops_get(old_fops); 53 } 54 fops_put(old_fops); 55 return err; 56 } 57 58 static struct file_operations usb_fops = { 59 .owner = THIS_MODULE, 60 .open = usb_open, 61 }; 62 63 static struct usb_class { 64 struct kref kref; 65 struct class *class; 66 } *usb_class; 67 68 static int init_usb_class(void) 69 { 70 int result = 0; 71 72 if (usb_class != NULL) { 73 kref_get(&usb_class->kref); 74 goto exit; 75 } 76 77 usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL); 78 if (!usb_class) { 79 result = -ENOMEM; 80 goto exit; 81 } 82 83 kref_init(&usb_class->kref); 84 usb_class->class = class_create(THIS_MODULE, "usb"); 85 if (IS_ERR(usb_class->class)) { 86 result = IS_ERR(usb_class->class); 87 err("class_create failed for usb devices"); 88 kfree(usb_class); 89 usb_class = NULL; 90 } 91 92 exit: 93 return result; 94 } 95 96 static void release_usb_class(struct kref *kref) 97 { 98 /* Ok, we cheat as we know we only have one usb_class */ 99 class_destroy(usb_class->class); 100 kfree(usb_class); 101 usb_class = NULL; 102 } 103 104 static void destroy_usb_class(void) 105 { 106 if (usb_class) 107 kref_put(&usb_class->kref, release_usb_class); 108 } 109 110 int usb_major_init(void) 111 { 112 int error; 113 114 error = register_chrdev(USB_MAJOR, "usb", &usb_fops); 115 if (error) 116 err("unable to get major %d for usb devices", USB_MAJOR); 117 118 return error; 119 } 120 121 void usb_major_cleanup(void) 122 { 123 unregister_chrdev(USB_MAJOR, "usb"); 124 } 125 126 /** 127 * usb_register_dev - register a USB device, and ask for a minor number 128 * @intf: pointer to the usb_interface that is being registered 129 * @class_driver: pointer to the usb_class_driver for this device 130 * 131 * This should be called by all USB drivers that use the USB major number. 132 * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be 133 * dynamically allocated out of the list of available ones. If it is not 134 * enabled, the minor number will be based on the next available free minor, 135 * starting at the class_driver->minor_base. 136 * 137 * This function also creates a usb class device in the sysfs tree. 138 * 139 * usb_deregister_dev() must be called when the driver is done with 140 * the minor numbers given out by this function. 141 * 142 * Returns -EINVAL if something bad happens with trying to register a 143 * device, and 0 on success. 144 */ 145 int usb_register_dev(struct usb_interface *intf, 146 struct usb_class_driver *class_driver) 147 { 148 int retval = -EINVAL; 149 int minor_base = class_driver->minor_base; 150 int minor = 0; 151 char name[BUS_ID_SIZE]; 152 char *temp; 153 154 #ifdef CONFIG_USB_DYNAMIC_MINORS 155 /* 156 * We don't care what the device tries to start at, we want to start 157 * at zero to pack the devices into the smallest available space with 158 * no holes in the minor range. 159 */ 160 minor_base = 0; 161 #endif 162 intf->minor = -1; 163 164 dbg ("looking for a minor, starting at %d", minor_base); 165 166 if (class_driver->fops == NULL) 167 goto exit; 168 169 spin_lock (&minor_lock); 170 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) { 171 if (usb_minors[minor]) 172 continue; 173 174 usb_minors[minor] = class_driver->fops; 175 176 retval = 0; 177 break; 178 } 179 spin_unlock (&minor_lock); 180 181 if (retval) 182 goto exit; 183 184 retval = init_usb_class(); 185 if (retval) 186 goto exit; 187 188 intf->minor = minor; 189 190 /* create a usb class device for this usb interface */ 191 snprintf(name, BUS_ID_SIZE, class_driver->name, minor - minor_base); 192 temp = strrchr(name, '/'); 193 if (temp && (temp[1] != 0x00)) 194 ++temp; 195 else 196 temp = name; 197 intf->class_dev = class_device_create(usb_class->class, NULL, 198 MKDEV(USB_MAJOR, minor), 199 &intf->dev, "%s", temp); 200 if (IS_ERR(intf->class_dev)) { 201 spin_lock (&minor_lock); 202 usb_minors[intf->minor] = NULL; 203 spin_unlock (&minor_lock); 204 retval = PTR_ERR(intf->class_dev); 205 } 206 exit: 207 return retval; 208 } 209 EXPORT_SYMBOL(usb_register_dev); 210 211 /** 212 * usb_deregister_dev - deregister a USB device's dynamic minor. 213 * @intf: pointer to the usb_interface that is being deregistered 214 * @class_driver: pointer to the usb_class_driver for this device 215 * 216 * Used in conjunction with usb_register_dev(). This function is called 217 * when the USB driver is finished with the minor numbers gotten from a 218 * call to usb_register_dev() (usually when the device is disconnected 219 * from the system.) 220 * 221 * This function also removes the usb class device from the sysfs tree. 222 * 223 * This should be called by all drivers that use the USB major number. 224 */ 225 void usb_deregister_dev(struct usb_interface *intf, 226 struct usb_class_driver *class_driver) 227 { 228 int minor_base = class_driver->minor_base; 229 char name[BUS_ID_SIZE]; 230 231 #ifdef CONFIG_USB_DYNAMIC_MINORS 232 minor_base = 0; 233 #endif 234 235 if (intf->minor == -1) 236 return; 237 238 dbg ("removing %d minor", intf->minor); 239 240 spin_lock (&minor_lock); 241 usb_minors[intf->minor] = NULL; 242 spin_unlock (&minor_lock); 243 244 snprintf(name, BUS_ID_SIZE, class_driver->name, intf->minor - minor_base); 245 class_device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor)); 246 intf->class_dev = NULL; 247 intf->minor = -1; 248 destroy_usb_class(); 249 } 250 EXPORT_SYMBOL(usb_deregister_dev); 251 252 253