linux/drivers/usb/core/file.c
Greg Kroah-Hartman aa1f3bb567 USB: core: move existing SPDX tags to top of the file
To match the rest of the kernel, the SPDX tags for the drivers/usb/core/
files are moved to the first line of the file.  This makes it more
obvious the tag is present as well as making it match the other 12k
files in the tree with this location.

It also uses // to match the "expected style" as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-03 10:12:26 +01:00

248 lines
6.2 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* drivers/usb/core/file.c
*
* (C) Copyright Linus Torvalds 1999
* (C) Copyright Johannes Erdfelt 1999-2001
* (C) Copyright Andreas Gal 1999
* (C) Copyright Gregory P. Smith 1999
* (C) Copyright Deti Fliegl 1999 (new USB architecture)
* (C) Copyright Randy Dunlap 2000
* (C) Copyright David Brownell 2000-2001 (kernel hotplug, usb_device_id,
* more docs, etc)
* (C) Copyright Yggdrasil Computing, Inc. 2000
* (usb_device_id matching changes by Adam J. Richter)
* (C) Copyright Greg Kroah-Hartman 2002-2003
*
* Released under the GPLv2 only.
*/
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/rwsem.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/usb.h>
#include "usb.h"
#define MAX_USB_MINORS 256
static const struct file_operations *usb_minors[MAX_USB_MINORS];
static DECLARE_RWSEM(minor_rwsem);
static DEFINE_MUTEX(init_usb_class_mutex);
static int usb_open(struct inode *inode, struct file *file)
{
int err = -ENODEV;
const struct file_operations *new_fops;
down_read(&minor_rwsem);
new_fops = fops_get(usb_minors[iminor(inode)]);
if (!new_fops)
goto done;
replace_fops(file, new_fops);
/* Curiouser and curiouser... NULL ->open() as "no device" ? */
if (file->f_op->open)
err = file->f_op->open(inode, file);
done:
up_read(&minor_rwsem);
return err;
}
static const struct file_operations usb_fops = {
.owner = THIS_MODULE,
.open = usb_open,
.llseek = noop_llseek,
};
static struct usb_class {
struct kref kref;
struct class *class;
} *usb_class;
static char *usb_devnode(struct device *dev, umode_t *mode)
{
struct usb_class_driver *drv;
drv = dev_get_drvdata(dev);
if (!drv || !drv->devnode)
return NULL;
return drv->devnode(dev, mode);
}
static int init_usb_class(void)
{
int result = 0;
if (usb_class != NULL) {
kref_get(&usb_class->kref);
goto exit;
}
usb_class = kmalloc(sizeof(*usb_class), GFP_KERNEL);
if (!usb_class) {
result = -ENOMEM;
goto exit;
}
kref_init(&usb_class->kref);
usb_class->class = class_create(THIS_MODULE, "usbmisc");
if (IS_ERR(usb_class->class)) {
result = PTR_ERR(usb_class->class);
printk(KERN_ERR "class_create failed for usb devices\n");
kfree(usb_class);
usb_class = NULL;
goto exit;
}
usb_class->class->devnode = usb_devnode;
exit:
return result;
}
static void release_usb_class(struct kref *kref)
{
/* Ok, we cheat as we know we only have one usb_class */
class_destroy(usb_class->class);
kfree(usb_class);
usb_class = NULL;
}
static void destroy_usb_class(void)
{
mutex_lock(&init_usb_class_mutex);
kref_put(&usb_class->kref, release_usb_class);
mutex_unlock(&init_usb_class_mutex);
}
int usb_major_init(void)
{
int error;
error = register_chrdev(USB_MAJOR, "usb", &usb_fops);
if (error)
printk(KERN_ERR "Unable to get major %d for usb devices\n",
USB_MAJOR);
return error;
}
void usb_major_cleanup(void)
{
unregister_chrdev(USB_MAJOR, "usb");
}
/**
* usb_register_dev - register a USB device, and ask for a minor number
* @intf: pointer to the usb_interface that is being registered
* @class_driver: pointer to the usb_class_driver for this device
*
* This should be called by all USB drivers that use the USB major number.
* If CONFIG_USB_DYNAMIC_MINORS is enabled, the minor number will be
* dynamically allocated out of the list of available ones. If it is not
* enabled, the minor number will be based on the next available free minor,
* starting at the class_driver->minor_base.
*
* This function also creates a usb class device in the sysfs tree.
*
* usb_deregister_dev() must be called when the driver is done with
* the minor numbers given out by this function.
*
* Return: -EINVAL if something bad happens with trying to register a
* device, and 0 on success.
*/
int usb_register_dev(struct usb_interface *intf,
struct usb_class_driver *class_driver)
{
int retval;
int minor_base = class_driver->minor_base;
int minor;
char name[20];
#ifdef CONFIG_USB_DYNAMIC_MINORS
/*
* We don't care what the device tries to start at, we want to start
* at zero to pack the devices into the smallest available space with
* no holes in the minor range.
*/
minor_base = 0;
#endif
if (class_driver->fops == NULL)
return -EINVAL;
if (intf->minor >= 0)
return -EADDRINUSE;
mutex_lock(&init_usb_class_mutex);
retval = init_usb_class();
mutex_unlock(&init_usb_class_mutex);
if (retval)
return retval;
dev_dbg(&intf->dev, "looking for a minor, starting at %d\n", minor_base);
down_write(&minor_rwsem);
for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) {
if (usb_minors[minor])
continue;
usb_minors[minor] = class_driver->fops;
intf->minor = minor;
break;
}
up_write(&minor_rwsem);
if (intf->minor < 0)
return -EXFULL;
/* create a usb class device for this usb interface */
snprintf(name, sizeof(name), class_driver->name, minor - minor_base);
intf->usb_dev = device_create(usb_class->class, &intf->dev,
MKDEV(USB_MAJOR, minor), class_driver,
"%s", kbasename(name));
if (IS_ERR(intf->usb_dev)) {
down_write(&minor_rwsem);
usb_minors[minor] = NULL;
intf->minor = -1;
up_write(&minor_rwsem);
retval = PTR_ERR(intf->usb_dev);
}
return retval;
}
EXPORT_SYMBOL_GPL(usb_register_dev);
/**
* usb_deregister_dev - deregister a USB device's dynamic minor.
* @intf: pointer to the usb_interface that is being deregistered
* @class_driver: pointer to the usb_class_driver for this device
*
* Used in conjunction with usb_register_dev(). This function is called
* when the USB driver is finished with the minor numbers gotten from a
* call to usb_register_dev() (usually when the device is disconnected
* from the system.)
*
* This function also removes the usb class device from the sysfs tree.
*
* This should be called by all drivers that use the USB major number.
*/
void usb_deregister_dev(struct usb_interface *intf,
struct usb_class_driver *class_driver)
{
if (intf->minor == -1)
return;
dev_dbg(&intf->dev, "removing %d minor\n", intf->minor);
down_write(&minor_rwsem);
usb_minors[intf->minor] = NULL;
up_write(&minor_rwsem);
device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));
intf->usb_dev = NULL;
intf->minor = -1;
destroy_usb_class();
}
EXPORT_SYMBOL_GPL(usb_deregister_dev);