drivers/usb/core/file.c - third_party/kernel - Git at Google

 // 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;
 	}
 	if (intf->minor < 0) {
 		up_write(&minor_rwsem);
 		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)) {
 		usb_minors[minor] = NULL;
 		intf->minor = -1;
 		retval = PTR_ERR(intf->usb_dev);
 	}
 	up_write(&minor_rwsem);
 	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);
 	device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));

 	down_write(&minor_rwsem);
 	usb_minors[intf->minor] = NULL;
 	up_write(&minor_rwsem);

 	intf->usb_dev = NULL;
 	intf->minor = -1;
 	destroy_usb_class();
 }
 EXPORT_SYMBOL_GPL(usb_deregister_dev);
	// 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;
	}
	if (intf->minor < 0) {
	up_write(&minor_rwsem);
	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)) {
	usb_minors[minor] = NULL;
	intf->minor = -1;
	retval = PTR_ERR(intf->usb_dev);
	}
	up_write(&minor_rwsem);
	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);
	device_destroy(usb_class->class, MKDEV(USB_MAJOR, intf->minor));

	down_write(&minor_rwsem);
	usb_minors[intf->minor] = NULL;
	up_write(&minor_rwsem);

	intf->usb_dev = NULL;
	intf->minor = -1;
	destroy_usb_class();
	}
	EXPORT_SYMBOL_GPL(usb_deregister_dev);