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