1 /* 2 * drivers/usb/core/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/errno.h> 20 #include <linux/rwsem.h> 21 #include <linux/slab.h> 22 #include <linux/smp_lock.h> 23 #include <linux/usb.h> 24 25 #include "usb.h" 26 27 #define MAX_USB_MINORS 256 28 static const struct file_operations *usb_minors[MAX_USB_MINORS]; 29 static DECLARE_RWSEM(minor_rwsem); 30 31 static int usb_open(struct inode * inode, struct file * file) 32 { 33 int minor = iminor(inode); 34 const struct file_operations *c; 35 int err = -ENODEV; 36 const struct file_operations *old_fops, *new_fops = NULL; 37 38 down_read(&minor_rwsem); 39 c = usb_minors[minor]; 40 41 if (!c || !(new_fops = fops_get(c))) 42 goto done; 43 44 old_fops = file->f_op; 45 file->f_op = new_fops; 46 /* Curiouser and curiouser... NULL ->open() as "no device" ? */ 47 if (file->f_op->open) 48 err = file->f_op->open(inode,file); 49 if (err) { 50 fops_put(file->f_op); 51 file->f_op = fops_get(old_fops); 52 } 53 fops_put(old_fops); 54 done: 55 up_read(&minor_rwsem); 56 return err; 57 } 58 59 static const struct file_operations usb_fops = { 60 .owner = THIS_MODULE, 61 .open = usb_open, 62 .llseek = noop_llseek, 63 }; 64 65 static struct usb_class { 66 struct kref kref; 67 struct class *class; 68 } *usb_class; 69 70 static char *usb_devnode(struct device *dev, mode_t *mode) 71 { 72 struct usb_class_driver *drv; 73 74 drv = dev_get_drvdata(dev); 75 if (!drv || !drv->devnode) 76 return NULL; 77 return drv->devnode(dev, mode); 78 } 79 80 static int init_usb_class(void) 81 { 82 int result = 0; 83 84 if (usb_class != NULL) { 85 kref_get(&usb_class->kref); 86 goto exit; 87 } 88 89 usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL); 90 if (!usb_class) { 91 result = -ENOMEM; 92 goto exit; 93 } 94 95 kref_init(&usb_class->kref); 96 usb_class->class = class_create(THIS_MODULE, "usb"); 97 if (IS_ERR(usb_class->class)) { 98 result = IS_ERR(usb_class->class); 99 printk(KERN_ERR "class_create failed for usb devices\n"); 100 kfree(usb_class); 101 usb_class = NULL; 102 goto exit; 103 } 104 usb_class->class->devnode = usb_devnode; 105 106 exit: 107 return result; 108 } 109 110 static void release_usb_class(struct kref *kref) 111 { 112 /* Ok, we cheat as we know we only have one usb_class */ 113 class_destroy(usb_class->class); 114 kfree(usb_class); 115 usb_class = NULL; 116 } 117 118 static void destroy_usb_class(void) 119 { 120 if (usb_class) 121 kref_put(&usb_class->kref, release_usb_class); 122 } 123 124 int usb_major_init(void) 125 { 126 int error; 127 128 error = register_chrdev(USB_MAJOR, "usb", &usb_fops); 129 if (error) 130 printk(KERN_ERR "Unable to get major %d for usb devices\n", 131 USB_MAJOR); 132 133 return error; 134 } 135 136 void usb_major_cleanup(void) 137 { 138 unregister_chrdev(USB_MAJOR, "usb"); 139 } 140 141 /** 142 * usb_register_dev - register a USB device, and ask for a minor number 143 * @intf: pointer to the usb_interface that is being registered 144 * @class_driver: pointer to the usb_class_driver for this device 145 * 146 * This should be called by all USB drivers that use the USB major number. 147 * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be 148 * dynamically allocated out of the list of available ones. If it is not 149 * enabled, the minor number will be based on the next available free minor, 150 * starting at the class_driver->minor_base. 151 * 152 * This function also creates a usb class device in the sysfs tree. 153 * 154 * usb_deregister_dev() must be called when the driver is done with 155 * the minor numbers given out by this function. 156 * 157 * Returns -EINVAL if something bad happens with trying to register a 158 * device, and 0 on success. 159 */ 160 int usb_register_dev(struct usb_interface *intf, 161 struct usb_class_driver *class_driver) 162 { 163 int retval; 164 int minor_base = class_driver->minor_base; 165 int minor; 166 char name[20]; 167 char *temp; 168 169 #ifdef CONFIG_USB_DYNAMIC_MINORS 170 /* 171 * We don't care what the device tries to start at, we want to start 172 * at zero to pack the devices into the smallest available space with 173 * no holes in the minor range. 174 */ 175 minor_base = 0; 176 #endif 177 178 if (class_driver->fops == NULL) 179 return -EINVAL; 180 if (intf->minor >= 0) 181 return -EADDRINUSE; 182 183 retval = init_usb_class(); 184 if (retval) 185 return retval; 186 187 dev_dbg(&intf->dev, "looking for a minor, starting at %d", minor_base); 188 189 down_write(&minor_rwsem); 190 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) { 191 if (usb_minors[minor]) 192 continue; 193 194 usb_minors[minor] = class_driver->fops; 195 intf->minor = minor; 196 break; 197 } 198 up_write(&minor_rwsem); 199 if (intf->minor < 0) 200 return -EXFULL; 201 202 /* create a usb class device for this usb interface */ 203 snprintf(name, sizeof(name), class_driver->name, minor - minor_base); 204 temp = strrchr(name, '/'); 205 if (temp && (temp[1] != '\0')) 206 ++temp; 207 else 208 temp = name; 209 intf->usb_dev = device_create(usb_class->class, &intf->dev, 210 MKDEV(USB_MAJOR, minor), class_driver, 211 "%s", temp); 212 if (IS_ERR(intf->usb_dev)) { 213 down_write(&minor_rwsem); 214 usb_minors[minor] = NULL; 215 intf->minor = -1; 216 up_write(&minor_rwsem); 217 retval = PTR_ERR(intf->usb_dev); 218 } 219 return retval; 220 } 221 EXPORT_SYMBOL_GPL(usb_register_dev); 222 223 /** 224 * usb_deregister_dev - deregister a USB device's dynamic minor. 225 * @intf: pointer to the usb_interface that is being deregistered 226 * @class_driver: pointer to the usb_class_driver for this device 227 * 228 * Used in conjunction with usb_register_dev(). This function is called 229 * when the USB driver is finished with the minor numbers gotten from a 230 * call to usb_register_dev() (usually when the device is disconnected 231 * from the system.) 232 * 233 * This function also removes the usb class device from the sysfs tree. 234 * 235 * This should be called by all drivers that use the USB major number. 236 */ 237 void usb_deregister_dev(struct usb_interface *intf, 238 struct usb_class_driver *class_driver) 239 { 240 int minor_base = class_driver->minor_base; 241 char name[20]; 242 243 #ifdef CONFIG_USB_DYNAMIC_MINORS 244 minor_base = 0; 245 #endif 246 247 if (intf->minor == -1) 248 return; 249 250 dbg ("removing %d minor", intf->minor); 251 252 down_write(&minor_rwsem); 253 usb_minors[intf->minor] = NULL; 254 up_write(&minor_rwsem); 255 256 snprintf(name, sizeof(name), class_driver->name, intf->minor - minor_base); 257 device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor)); 258 intf->usb_dev = NULL; 259 intf->minor = -1; 260 destroy_usb_class(); 261 } 262 EXPORT_SYMBOL_GPL(usb_deregister_dev); 263