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Greg Kroah-Hartmanaa1f3bb2017-11-03 09:18:41 +01001// SPDX-License-Identifier: GPL-2.0
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
Uwe Zeisbergerf30c2262006-10-03 23:01:26 +02003 * drivers/usb/core/file.c
Linus Torvalds1da177e2005-04-16 15:20:36 -07004 *
5 * (C) Copyright Linus Torvalds 1999
6 * (C) Copyright Johannes Erdfelt 1999-2001
7 * (C) Copyright Andreas Gal 1999
8 * (C) Copyright Gregory P. Smith 1999
9 * (C) Copyright Deti Fliegl 1999 (new USB architecture)
10 * (C) Copyright Randy Dunlap 2000
11 * (C) Copyright David Brownell 2000-2001 (kernel hotplug, usb_device_id,
Matthias Beyer469271f2013-10-10 23:41:27 +020012 * more docs, etc)
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 * (C) Copyright Yggdrasil Computing, Inc. 2000
14 * (usb_device_id matching changes by Adam J. Richter)
15 * (C) Copyright Greg Kroah-Hartman 2002-2003
16 *
Greg Kroah-Hartmanb65fba32016-10-28 17:16:36 -040017 * Released under the GPLv2 only.
Linus Torvalds1da177e2005-04-16 15:20:36 -070018 */
19
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/module.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/errno.h>
Alan Sternd4ead162007-05-22 11:46:41 -040022#include <linux/rwsem.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090023#include <linux/slab.h>
Andy Shevchenkof8868ed2015-12-10 16:49:14 +020024#include <linux/string.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/usb.h>
26
Greg KH6d5e8252005-04-18 17:39:24 -070027#include "usb.h"
28
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#define MAX_USB_MINORS 256
Arjan van de Ven99ac48f2006-03-28 01:56:41 -080030static const struct file_operations *usb_minors[MAX_USB_MINORS];
Alan Sternd4ead162007-05-22 11:46:41 -040031static DECLARE_RWSEM(minor_rwsem);
Ajay Kaher2f86a962017-03-28 08:09:32 -040032static DEFINE_MUTEX(init_usb_class_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
Matthias Beyer1335f2d2013-10-10 23:41:28 +020034static int usb_open(struct inode *inode, struct file *file)
Linus Torvalds1da177e2005-04-16 15:20:36 -070035{
Linus Torvalds1da177e2005-04-16 15:20:36 -070036 int err = -ENODEV;
Al Viroe84f9e52013-09-22 14:17:15 -040037 const struct file_operations *new_fops;
Linus Torvalds1da177e2005-04-16 15:20:36 -070038
Alan Sternd4ead162007-05-22 11:46:41 -040039 down_read(&minor_rwsem);
Al Viroe84f9e52013-09-22 14:17:15 -040040 new_fops = fops_get(usb_minors[iminor(inode)]);
Linus Torvalds1da177e2005-04-16 15:20:36 -070041
Al Viroe84f9e52013-09-22 14:17:15 -040042 if (!new_fops)
Alan Sternd4ead162007-05-22 11:46:41 -040043 goto done;
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
Al Viroe84f9e52013-09-22 14:17:15 -040045 replace_fops(file, new_fops);
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 /* Curiouser and curiouser... NULL ->open() as "no device" ? */
47 if (file->f_op->open)
Matthias Beyer469271f2013-10-10 23:41:27 +020048 err = file->f_op->open(inode, file);
Alan Sternd4ead162007-05-22 11:46:41 -040049 done:
50 up_read(&minor_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 return err;
52}
53
Luiz Fernando N. Capitulino066202d2006-08-05 20:37:11 -030054static const struct file_operations usb_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 .owner = THIS_MODULE,
56 .open = usb_open,
Arnd Bergmann6038f372010-08-15 18:52:59 +020057 .llseek = noop_llseek,
Linus Torvalds1da177e2005-04-16 15:20:36 -070058};
59
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -070060static struct usb_class {
61 struct kref kref;
62 struct class *class;
63} *usb_class;
64
Al Viro2c9ede52011-07-23 20:24:48 -040065static char *usb_devnode(struct device *dev, umode_t *mode)
Kay Sieversf7a386c2009-04-30 15:23:42 +020066{
67 struct usb_class_driver *drv;
68
69 drv = dev_get_drvdata(dev);
Kay Sieverse454cea2009-09-18 23:01:12 +020070 if (!drv || !drv->devnode)
Kay Sieversf7a386c2009-04-30 15:23:42 +020071 return NULL;
Kay Sieverse454cea2009-09-18 23:01:12 +020072 return drv->devnode(dev, mode);
Kay Sieversf7a386c2009-04-30 15:23:42 +020073}
74
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -070075static int init_usb_class(void)
76{
77 int result = 0;
78
79 if (usb_class != NULL) {
80 kref_get(&usb_class->kref);
81 goto exit;
82 }
83
84 usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
85 if (!usb_class) {
86 result = -ENOMEM;
87 goto exit;
88 }
89
90 kref_init(&usb_class->kref);
Greg Kroah-Hartman7e972432012-04-25 17:22:37 -070091 usb_class->class = class_create(THIS_MODULE, "usbmisc");
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -070092 if (IS_ERR(usb_class->class)) {
Alexey Khoroshilovde5535f2013-06-06 01:27:15 +040093 result = PTR_ERR(usb_class->class);
Greg Kroah-Hartman69a85942008-08-14 09:37:34 -070094 printk(KERN_ERR "class_create failed for usb devices\n");
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -070095 kfree(usb_class);
96 usb_class = NULL;
Dan Carpentered7487c2009-11-10 11:02:08 +020097 goto exit;
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -070098 }
Kay Sieverse454cea2009-09-18 23:01:12 +020099 usb_class->class->devnode = usb_devnode;
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -0700100
101exit:
102 return result;
103}
104
105static void release_usb_class(struct kref *kref)
106{
107 /* Ok, we cheat as we know we only have one usb_class */
108 class_destroy(usb_class->class);
109 kfree(usb_class);
110 usb_class = NULL;
111}
112
113static void destroy_usb_class(void)
114{
Ajay Kaher2f86a962017-03-28 08:09:32 -0400115 mutex_lock(&init_usb_class_mutex);
116 kref_put(&usb_class->kref, release_usb_class);
117 mutex_unlock(&init_usb_class_mutex);
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -0700118}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
120int usb_major_init(void)
121{
122 int error;
123
124 error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -0700125 if (error)
Greg Kroah-Hartman69a85942008-08-14 09:37:34 -0700126 printk(KERN_ERR "Unable to get major %d for usb devices\n",
127 USB_MAJOR);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 return error;
130}
131
132void usb_major_cleanup(void)
133{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 unregister_chrdev(USB_MAJOR, "usb");
135}
136
137/**
138 * usb_register_dev - register a USB device, and ask for a minor number
139 * @intf: pointer to the usb_interface that is being registered
140 * @class_driver: pointer to the usb_class_driver for this device
141 *
142 * This should be called by all USB drivers that use the USB major number.
143 * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
144 * dynamically allocated out of the list of available ones. If it is not
145 * enabled, the minor number will be based on the next available free minor,
146 * starting at the class_driver->minor_base.
147 *
Greg Kroah-Hartmand6e5bcf2005-06-20 21:15:16 -0700148 * This function also creates a usb class device in the sysfs tree.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 *
150 * usb_deregister_dev() must be called when the driver is done with
151 * the minor numbers given out by this function.
152 *
Yacine Belkadi626f0902013-08-02 20:10:04 +0200153 * Return: -EINVAL if something bad happens with trying to register a
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 * device, and 0 on success.
155 */
156int usb_register_dev(struct usb_interface *intf,
157 struct usb_class_driver *class_driver)
158{
Alan Stern0026e002010-09-21 15:01:53 -0400159 int retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 int minor_base = class_driver->minor_base;
Alan Stern0026e002010-09-21 15:01:53 -0400161 int minor;
Kay Sievers7071a3c2008-05-02 06:02:41 +0200162 char name[20];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163
164#ifdef CONFIG_USB_DYNAMIC_MINORS
Matthias Beyer469271f2013-10-10 23:41:27 +0200165 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 * We don't care what the device tries to start at, we want to start
167 * at zero to pack the devices into the smallest available space with
168 * no holes in the minor range.
169 */
170 minor_base = 0;
171#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172
173 if (class_driver->fops == NULL)
Alan Stern0026e002010-09-21 15:01:53 -0400174 return -EINVAL;
175 if (intf->minor >= 0)
176 return -EADDRINUSE;
177
Ajay Kaher2f86a962017-03-28 08:09:32 -0400178 mutex_lock(&init_usb_class_mutex);
Alan Stern0026e002010-09-21 15:01:53 -0400179 retval = init_usb_class();
Ajay Kaher2f86a962017-03-28 08:09:32 -0400180 mutex_unlock(&init_usb_class_mutex);
181
Alan Stern0026e002010-09-21 15:01:53 -0400182 if (retval)
183 return retval;
184
Greg Kroah-Hartman079d4402012-05-01 21:33:35 -0700185 dev_dbg(&intf->dev, "looking for a minor, starting at %d\n", minor_base);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186
Alan Sternd4ead162007-05-22 11:46:41 -0400187 down_write(&minor_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
189 if (usb_minors[minor])
190 continue;
191
192 usb_minors[minor] = class_driver->fops;
Alan Stern0026e002010-09-21 15:01:53 -0400193 intf->minor = minor;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 break;
195 }
Alan Stern303911c2019-08-12 16:11:07 -0400196 if (intf->minor < 0) {
197 up_write(&minor_rwsem);
Alan Stern0026e002010-09-21 15:01:53 -0400198 return -EXFULL;
Alan Stern303911c2019-08-12 16:11:07 -0400199 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 /* create a usb class device for this usb interface */
Kay Sievers7071a3c2008-05-02 06:02:41 +0200202 snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
Greg Kroah-Hartmanb0b090e2008-07-21 20:03:34 -0700203 intf->usb_dev = device_create(usb_class->class, &intf->dev,
Kay Sieversf7a386c2009-04-30 15:23:42 +0200204 MKDEV(USB_MAJOR, minor), class_driver,
Andy Shevchenkof8868ed2015-12-10 16:49:14 +0200205 "%s", kbasename(name));
Greg Kroah-Hartman0873c762006-06-20 13:09:50 -0700206 if (IS_ERR(intf->usb_dev)) {
Alan Stern0026e002010-09-21 15:01:53 -0400207 usb_minors[minor] = NULL;
208 intf->minor = -1;
Greg Kroah-Hartman0873c762006-06-20 13:09:50 -0700209 retval = PTR_ERR(intf->usb_dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 }
Alan Stern303911c2019-08-12 16:11:07 -0400211 up_write(&minor_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 return retval;
213}
Greg Kroah-Hartman782e70c2008-01-25 11:12:21 -0600214EXPORT_SYMBOL_GPL(usb_register_dev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
216/**
217 * usb_deregister_dev - deregister a USB device's dynamic minor.
218 * @intf: pointer to the usb_interface that is being deregistered
219 * @class_driver: pointer to the usb_class_driver for this device
220 *
221 * Used in conjunction with usb_register_dev(). This function is called
222 * when the USB driver is finished with the minor numbers gotten from a
223 * call to usb_register_dev() (usually when the device is disconnected
224 * from the system.)
225 *
Greg Kroah-Hartmand6e5bcf2005-06-20 21:15:16 -0700226 * This function also removes the usb class device from the sysfs tree.
227 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 * This should be called by all drivers that use the USB major number.
229 */
230void usb_deregister_dev(struct usb_interface *intf,
231 struct usb_class_driver *class_driver)
232{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 if (intf->minor == -1)
234 return;
235
Greg Kroah-Hartman079d4402012-05-01 21:33:35 -0700236 dev_dbg(&intf->dev, "removing %d minor\n", intf->minor);
Alan Stern303911c2019-08-12 16:11:07 -0400237 device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238
Alan Sternd4ead162007-05-22 11:46:41 -0400239 down_write(&minor_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 usb_minors[intf->minor] = NULL;
Alan Sternd4ead162007-05-22 11:46:41 -0400241 up_write(&minor_rwsem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242
Greg Kroah-Hartman0873c762006-06-20 13:09:50 -0700243 intf->usb_dev = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 intf->minor = -1;
Greg Kroah-Hartman43104f12006-06-20 15:14:07 -0700245 destroy_usb_class();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246}
Greg Kroah-Hartman782e70c2008-01-25 11:12:21 -0600247EXPORT_SYMBOL_GPL(usb_deregister_dev);