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, umode_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);
254