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/smp_lock.h>
22 #include <linux/usb.h>
23
24 #include "usb.h"
25
26 #define MAX_USB_MINORS 256
27 static const struct file_operations *usb_minors[MAX_USB_MINORS];
28 static DECLARE_RWSEM(minor_rwsem);
29
30 static 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 lock_kernel();
38 down_read(&minor_rwsem);
39 c = usb_minors[minor];
40
41 if (!c || !(new_fops = fops_get(c)))
42 goto done;
43
44 old_fops = file->f_op;
45 file->f_op = new_fops;
46 /* Curiouser and curiouser... NULL ->open() as "no device" ? */
47 if (file->f_op->open)
48 err = file->f_op->open(inode,file);
49 if (err) {
50 fops_put(file->f_op);
51 file->f_op = fops_get(old_fops);
52 }
53 fops_put(old_fops);
54 done:
55 up_read(&minor_rwsem);
56 unlock_kernel();
57 return err;
58 }
59
60 static const struct file_operations usb_fops = {
61 .owner = THIS_MODULE,
62 .open = usb_open,
63 };
64
65 static struct usb_class {
66 struct kref kref;
67 struct class *class;
68 } *usb_class;
69
70 static char *usb_nodename(struct device *dev)
71 {
72 struct usb_class_driver *drv;
73
74 drv = dev_get_drvdata(dev);
75 if (!drv || !drv->nodename)
76 return NULL;
77 return drv->nodename(dev);
78 }
79
80 static int init_usb_class(void)
81 {
82 int result = 0;
83
84 if (usb_class != NULL) {
85 kref_get(&usb_class->kref);
86 goto exit;
87 }
88
89 usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
90 if (!usb_class) {
91 result = -ENOMEM;
92 goto exit;
93 }
94
95 kref_init(&usb_class->kref);
96 usb_class->class = class_create(THIS_MODULE, "usb");
97 if (IS_ERR(usb_class->class)) {
98 result = IS_ERR(usb_class->class);
99 printk(KERN_ERR "class_create failed for usb devices\n");
100 kfree(usb_class);
101 usb_class = NULL;
102 }
103 usb_class->class->nodename = usb_nodename;
104
105 exit:
106 return result;
107 }
108
109 static 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
117 static void destroy_usb_class(void)
118 {
119 if (usb_class)
120 kref_put(&usb_class->kref, release_usb_class);
121 }
122
123 int 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
135 void 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 */
159 int usb_register_dev(struct usb_interface *intf,
160 struct usb_class_driver *class_driver)
161 {
162 int retval = -EINVAL;
163 int minor_base = class_driver->minor_base;
164 int minor = 0;
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 intf->minor = -1;
177
178 dbg ("looking for a minor, starting at %d", minor_base);
179
180 if (class_driver->fops == NULL)
181 goto exit;
182
183 down_write(&minor_rwsem);
184 for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
185 if (usb_minors[minor])
186 continue;
187
188 usb_minors[minor] = class_driver->fops;
189
190 retval = 0;
191 break;
192 }
193 up_write(&minor_rwsem);
194
195 if (retval)
196 goto exit;
197
198 retval = init_usb_class();
199 if (retval)
200 goto exit;
201
202 intf->minor = minor;
203
204 /* create a usb class device for this usb interface */
205 snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
206 temp = strrchr(name, '/');
207 if (temp && (temp[1] != '\0'))
208 ++temp;
209 else
210 temp = name;
211 intf->usb_dev = device_create(usb_class->class, &intf->dev,
212 MKDEV(USB_MAJOR, minor), class_driver,
213 "%s", temp);
214 if (IS_ERR(intf->usb_dev)) {
215 down_write(&minor_rwsem);
216 usb_minors[intf->minor] = NULL;
217 up_write(&minor_rwsem);
218 retval = PTR_ERR(intf->usb_dev);
219 }
220 exit:
221 return retval;
222 }
223 EXPORT_SYMBOL_GPL(usb_register_dev);
224
225 /**
226 * usb_deregister_dev - deregister a USB device's dynamic minor.
227 * @intf: pointer to the usb_interface that is being deregistered
228 * @class_driver: pointer to the usb_class_driver for this device
229 *
230 * Used in conjunction with usb_register_dev(). This function is called
231 * when the USB driver is finished with the minor numbers gotten from a
232 * call to usb_register_dev() (usually when the device is disconnected
233 * from the system.)
234 *
235 * This function also removes the usb class device from the sysfs tree.
236 *
237 * This should be called by all drivers that use the USB major number.
238 */
239 void usb_deregister_dev(struct usb_interface *intf,
240 struct usb_class_driver *class_driver)
241 {
242 int minor_base = class_driver->minor_base;
243 char name[20];
244
245 #ifdef CONFIG_USB_DYNAMIC_MINORS
246 minor_base = 0;
247 #endif
248
249 if (intf->minor == -1)
250 return;
251
252 dbg ("removing %d minor", intf->minor);
253
254 down_write(&minor_rwsem);
255 usb_minors[intf->minor] = NULL;
256 up_write(&minor_rwsem);
257
258 snprintf(name, sizeof(name), class_driver->name, intf->minor - minor_base);
259 device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
260 intf->usb_dev = NULL;
261 intf->minor = -1;
262 destroy_usb_class();
263 }
264 EXPORT_SYMBOL_GPL(usb_deregister_dev);
265
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