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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * drivers/usb/core/file.c
4 *
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,
12 * more docs, etc)
13 * (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 *
17 * Released under the GPLv2 only.
18 */
19
20#include <linux/module.h>
21#include <linux/errno.h>
22#include <linux/rwsem.h>
23#include <linux/slab.h>
24#include <linux/string.h>
25#include <linux/usb.h>
26
27#include "usb.h"
28
29#define MAX_USB_MINORS 256
30static const struct file_operations *usb_minors[MAX_USB_MINORS];
31static DECLARE_RWSEM(minor_rwsem);
32
33static int usb_open(struct inode *inode, struct file *file)
34{
35 int err = -ENODEV;
36 const struct file_operations *new_fops;
37
38 down_read(&minor_rwsem);
39 new_fops = fops_get(usb_minors[iminor(inode)]);
40
41 if (!new_fops)
42 goto done;
43
44 replace_fops(file, new_fops);
45 /* Curiouser and curiouser... NULL ->open() as "no device" ? */
46 if (file->f_op->open)
47 err = file->f_op->open(inode, file);
48 done:
49 up_read(&minor_rwsem);
50 return err;
51}
52
53static const struct file_operations usb_fops = {
54 .owner = THIS_MODULE,
55 .open = usb_open,
56 .llseek = noop_llseek,
57};
58
59static char *usb_devnode(const struct device *dev, umode_t *mode)
60{
61 struct usb_class_driver *drv;
62
63 drv = dev_get_drvdata(dev);
64 if (!drv || !drv->devnode)
65 return NULL;
66 return drv->devnode(dev, mode);
67}
68
69const struct class usbmisc_class = {
70 .name = "usbmisc",
71 .devnode = usb_devnode,
72};
73
74int usb_major_init(void)
75{
76 int error;
77
78 error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
79 if (error)
80 printk(KERN_ERR "Unable to get major %d for usb devices\n",
81 USB_MAJOR);
82
83 return error;
84}
85
86void usb_major_cleanup(void)
87{
88 unregister_chrdev(USB_MAJOR, "usb");
89}
90
91/**
92 * usb_register_dev - register a USB device, and ask for a minor number
93 * @intf: pointer to the usb_interface that is being registered
94 * @class_driver: pointer to the usb_class_driver for this device
95 *
96 * This should be called by all USB drivers that use the USB major number.
97 * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
98 * dynamically allocated out of the list of available ones. If it is not
99 * enabled, the minor number will be based on the next available free minor,
100 * starting at the class_driver->minor_base.
101 *
102 * This function also creates a usb class device in the sysfs tree.
103 *
104 * usb_deregister_dev() must be called when the driver is done with
105 * the minor numbers given out by this function.
106 *
107 * Return: -EINVAL if something bad happens with trying to register a
108 * device, and 0 on success.
109 */
110int usb_register_dev(struct usb_interface *intf,
111 struct usb_class_driver *class_driver)
112{
113 int retval = 0;
114 int minor_base = class_driver->minor_base;
115 int minor;
116 char name[20];
117
118#ifdef CONFIG_USB_DYNAMIC_MINORS
119 /*
120 * We don't care what the device tries to start at, we want to start
121 * at zero to pack the devices into the smallest available space with
122 * no holes in the minor range.
123 */
124 minor_base = 0;
125#endif
126
127 if (class_driver->fops == NULL)
128 return -EINVAL;
129 if (intf->minor >= 0)
130 return -EADDRINUSE;
131
132 dev_dbg(&intf->dev, "looking for a minor, starting at %d\n", minor_base);
133
134 down_write(&minor_rwsem);
135 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
136 if (usb_minors[minor])
137 continue;
138
139 usb_minors[minor] = class_driver->fops;
140 intf->minor = minor;
141 break;
142 }
143 if (intf->minor < 0) {
144 up_write(&minor_rwsem);
145 return -EXFULL;
146 }
147
148 /* create a usb class device for this usb interface */
149 snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
150 intf->usb_dev = device_create(&usbmisc_class, &intf->dev,
151 MKDEV(USB_MAJOR, minor), class_driver,
152 "%s", kbasename(name));
153 if (IS_ERR(intf->usb_dev)) {
154 usb_minors[minor] = NULL;
155 intf->minor = -1;
156 retval = PTR_ERR(intf->usb_dev);
157 }
158 up_write(&minor_rwsem);
159 return retval;
160}
161EXPORT_SYMBOL_GPL(usb_register_dev);
162
163/**
164 * usb_deregister_dev - deregister a USB device's dynamic minor.
165 * @intf: pointer to the usb_interface that is being deregistered
166 * @class_driver: pointer to the usb_class_driver for this device
167 *
168 * Used in conjunction with usb_register_dev(). This function is called
169 * when the USB driver is finished with the minor numbers gotten from a
170 * call to usb_register_dev() (usually when the device is disconnected
171 * from the system.)
172 *
173 * This function also removes the usb class device from the sysfs tree.
174 *
175 * This should be called by all drivers that use the USB major number.
176 */
177void usb_deregister_dev(struct usb_interface *intf,
178 struct usb_class_driver *class_driver)
179{
180 if (intf->minor == -1)
181 return;
182
183 dev_dbg(&intf->dev, "removing %d minor\n", intf->minor);
184 device_destroy(&usbmisc_class, MKDEV(USB_MAJOR, intf->minor));
185
186 down_write(&minor_rwsem);
187 usb_minors[intf->minor] = NULL;
188 up_write(&minor_rwsem);
189
190 intf->usb_dev = NULL;
191 intf->minor = -1;
192}
193EXPORT_SYMBOL_GPL(usb_deregister_dev);
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
27static const struct file_operations *usb_minors[MAX_USB_MINORS];
28static DECLARE_RWSEM(minor_rwsem);
29
30static int usb_open(struct inode * inode, struct file * file)
31{
32 int minor = iminor(inode);
33 const struct file_operations *c;
34 int err = -ENODEV;
35 const struct file_operations *old_fops, *new_fops = NULL;
36
37 down_read(&minor_rwsem);
38 c = usb_minors[minor];
39
40 if (!c || !(new_fops = fops_get(c)))
41 goto done;
42
43 old_fops = file->f_op;
44 file->f_op = new_fops;
45 /* Curiouser and curiouser... NULL ->open() as "no device" ? */
46 if (file->f_op->open)
47 err = file->f_op->open(inode,file);
48 if (err) {
49 fops_put(file->f_op);
50 file->f_op = fops_get(old_fops);
51 }
52 fops_put(old_fops);
53 done:
54 up_read(&minor_rwsem);
55 return err;
56}
57
58static const struct file_operations usb_fops = {
59 .owner = THIS_MODULE,
60 .open = usb_open,
61 .llseek = noop_llseek,
62};
63
64static struct usb_class {
65 struct kref kref;
66 struct class *class;
67} *usb_class;
68
69static char *usb_devnode(struct device *dev, mode_t *mode)
70{
71 struct usb_class_driver *drv;
72
73 drv = dev_get_drvdata(dev);
74 if (!drv || !drv->devnode)
75 return NULL;
76 return drv->devnode(dev, mode);
77}
78
79static int init_usb_class(void)
80{
81 int result = 0;
82
83 if (usb_class != NULL) {
84 kref_get(&usb_class->kref);
85 goto exit;
86 }
87
88 usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
89 if (!usb_class) {
90 result = -ENOMEM;
91 goto exit;
92 }
93
94 kref_init(&usb_class->kref);
95 usb_class->class = class_create(THIS_MODULE, "usb");
96 if (IS_ERR(usb_class->class)) {
97 result = IS_ERR(usb_class->class);
98 printk(KERN_ERR "class_create failed for usb devices\n");
99 kfree(usb_class);
100 usb_class = NULL;
101 goto exit;
102 }
103 usb_class->class->devnode = usb_devnode;
104
105exit:
106 return result;
107}
108
109static void release_usb_class(struct kref *kref)
110{
111 /* Ok, we cheat as we know we only have one usb_class */
112 class_destroy(usb_class->class);
113 kfree(usb_class);
114 usb_class = NULL;
115}
116
117static void destroy_usb_class(void)
118{
119 if (usb_class)
120 kref_put(&usb_class->kref, release_usb_class);
121}
122
123int usb_major_init(void)
124{
125 int error;
126
127 error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
128 if (error)
129 printk(KERN_ERR "Unable to get major %d for usb devices\n",
130 USB_MAJOR);
131
132 return error;
133}
134
135void usb_major_cleanup(void)
136{
137 unregister_chrdev(USB_MAJOR, "usb");
138}
139
140/**
141 * usb_register_dev - register a USB device, and ask for a minor number
142 * @intf: pointer to the usb_interface that is being registered
143 * @class_driver: pointer to the usb_class_driver for this device
144 *
145 * This should be called by all USB drivers that use the USB major number.
146 * If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
147 * dynamically allocated out of the list of available ones. If it is not
148 * enabled, the minor number will be based on the next available free minor,
149 * starting at the class_driver->minor_base.
150 *
151 * This function also creates a usb class device in the sysfs tree.
152 *
153 * usb_deregister_dev() must be called when the driver is done with
154 * the minor numbers given out by this function.
155 *
156 * Returns -EINVAL if something bad happens with trying to register a
157 * device, and 0 on success.
158 */
159int usb_register_dev(struct usb_interface *intf,
160 struct usb_class_driver *class_driver)
161{
162 int retval;
163 int minor_base = class_driver->minor_base;
164 int minor;
165 char name[20];
166 char *temp;
167
168#ifdef CONFIG_USB_DYNAMIC_MINORS
169 /*
170 * We don't care what the device tries to start at, we want to start
171 * at zero to pack the devices into the smallest available space with
172 * no holes in the minor range.
173 */
174 minor_base = 0;
175#endif
176
177 if (class_driver->fops == NULL)
178 return -EINVAL;
179 if (intf->minor >= 0)
180 return -EADDRINUSE;
181
182 retval = init_usb_class();
183 if (retval)
184 return retval;
185
186 dev_dbg(&intf->dev, "looking for a minor, starting at %d", minor_base);
187
188 down_write(&minor_rwsem);
189 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
190 if (usb_minors[minor])
191 continue;
192
193 usb_minors[minor] = class_driver->fops;
194 intf->minor = minor;
195 break;
196 }
197 up_write(&minor_rwsem);
198 if (intf->minor < 0)
199 return -EXFULL;
200
201 /* create a usb class device for this usb interface */
202 snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
203 temp = strrchr(name, '/');
204 if (temp && (temp[1] != '\0'))
205 ++temp;
206 else
207 temp = name;
208 intf->usb_dev = device_create(usb_class->class, &intf->dev,
209 MKDEV(USB_MAJOR, minor), class_driver,
210 "%s", temp);
211 if (IS_ERR(intf->usb_dev)) {
212 down_write(&minor_rwsem);
213 usb_minors[minor] = NULL;
214 intf->minor = -1;
215 up_write(&minor_rwsem);
216 retval = PTR_ERR(intf->usb_dev);
217 }
218 return retval;
219}
220EXPORT_SYMBOL_GPL(usb_register_dev);
221
222/**
223 * usb_deregister_dev - deregister a USB device's dynamic minor.
224 * @intf: pointer to the usb_interface that is being deregistered
225 * @class_driver: pointer to the usb_class_driver for this device
226 *
227 * Used in conjunction with usb_register_dev(). This function is called
228 * when the USB driver is finished with the minor numbers gotten from a
229 * call to usb_register_dev() (usually when the device is disconnected
230 * from the system.)
231 *
232 * This function also removes the usb class device from the sysfs tree.
233 *
234 * This should be called by all drivers that use the USB major number.
235 */
236void usb_deregister_dev(struct usb_interface *intf,
237 struct usb_class_driver *class_driver)
238{
239 if (intf->minor == -1)
240 return;
241
242 dbg ("removing %d minor", intf->minor);
243
244 down_write(&minor_rwsem);
245 usb_minors[intf->minor] = NULL;
246 up_write(&minor_rwsem);
247
248 device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
249 intf->usb_dev = NULL;
250 intf->minor = -1;
251 destroy_usb_class();
252}
253EXPORT_SYMBOL_GPL(usb_deregister_dev);