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