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