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