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