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