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