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 |
30 | static const struct file_operations *usb_minors[MAX_USB_MINORS]; |
31 | static DECLARE_RWSEM(minor_rwsem); |
32 | |
33 | static 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(sem: &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(sem: &minor_rwsem); |
50 | return err; |
51 | } |
52 | |
53 | static const struct file_operations usb_fops = { |
54 | .owner = THIS_MODULE, |
55 | .open = usb_open, |
56 | .llseek = noop_llseek, |
57 | }; |
58 | |
59 | static 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 | |
69 | const struct class usbmisc_class = { |
70 | .name = "usbmisc" , |
71 | .devnode = usb_devnode, |
72 | }; |
73 | |
74 | int usb_major_init(void) |
75 | { |
76 | int error; |
77 | |
78 | error = register_chrdev(USB_MAJOR, name: "usb" , fops: &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 | |
86 | void usb_major_cleanup(void) |
87 | { |
88 | unregister_chrdev(USB_MAJOR, name: "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 | */ |
110 | int 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(sem: &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(sem: &minor_rwsem); |
145 | return -EXFULL; |
146 | } |
147 | |
148 | /* create a usb class device for this usb interface */ |
149 | snprintf(buf: name, size: sizeof(name), fmt: class_driver->name, minor - minor_base); |
150 | intf->usb_dev = device_create(cls: &usbmisc_class, parent: &intf->dev, |
151 | MKDEV(USB_MAJOR, minor), drvdata: class_driver, |
152 | fmt: "%s" , kbasename(path: name)); |
153 | if (IS_ERR(ptr: intf->usb_dev)) { |
154 | usb_minors[minor] = NULL; |
155 | intf->minor = -1; |
156 | retval = PTR_ERR(ptr: intf->usb_dev); |
157 | } |
158 | up_write(sem: &minor_rwsem); |
159 | return retval; |
160 | } |
161 | EXPORT_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 | */ |
177 | void 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(cls: &usbmisc_class, MKDEV(USB_MAJOR, intf->minor)); |
185 | |
186 | down_write(sem: &minor_rwsem); |
187 | usb_minors[intf->minor] = NULL; |
188 | up_write(sem: &minor_rwsem); |
189 | |
190 | intf->usb_dev = NULL; |
191 | intf->minor = -1; |
192 | } |
193 | EXPORT_SYMBOL_GPL(usb_deregister_dev); |
194 | |