diff options
Diffstat (limited to 'drivers/usb/core/file.c')
| -rw-r--r-- | drivers/usb/core/file.c | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/drivers/usb/core/file.c b/drivers/usb/core/file.c new file mode 100644 index 000000000..558890ada --- /dev/null +++ b/drivers/usb/core/file.c @@ -0,0 +1,247 @@ +// 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); |