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linux
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drivers
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usb
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core
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file.c
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252 lines (215 loc) · 6.09 KB
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linux
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drivers
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usb
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file.c
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/* * 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 * */ #include <linux/module.h> #include <linux/errno.h> #include <linux/rwsem.h> #include <linux/smp_lock.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 int usb_open(struct inode * inode, struct file * file) { int minor = iminor(inode); const struct file_operations *c; int err = -ENODEV; const struct file_operations *old_fops, *new_fops = NULL; lock_kernel(); down_read(&minor_rwsem); c = usb_minors[minor]; if (!c || !(new_fops = fops_get(c))) goto done; old_fops = file->f_op; file->f_op = new_fops; /* Curiouser and curiouser... NULL ->open() as "no device" ? */ if (file->f_op->open) err = file->f_op->open(inode,file); if (err) { fops_put(file->f_op); file->f_op = fops_get(old_fops); } fops_put(old_fops); done: up_read(&minor_rwsem); unlock_kernel(); return err; } static const struct file_operations usb_fops = { .owner = THIS_MODULE, .open = usb_open, }; static struct usb_class { struct kref kref; struct class *class; } *usb_class; 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, "usb"); if (IS_ERR(usb_class->class)) { result = IS_ERR(usb_class->class); err("class_create failed for usb devices"); kfree(usb_class); usb_class = NULL; } 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) { if (usb_class) kref_put(&usb_class->kref, release_usb_class); } int usb_major_init(void) { int error; error = register_chrdev(USB_MAJOR, "usb", &usb_fops); if (error) err("unable to get major %d for usb devices", 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. * * Returns -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 = -EINVAL; int minor_base = class_driver->minor_base; int minor = 0; char name[20]; char *temp; #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 intf->minor = -1; dbg ("looking for a minor, starting at %d", minor_base); if (class_driver->fops == NULL) goto exit; down_write(&minor_rwsem); for (minor = minor_base; minor < MAX_USB_MINORS; ++minor) { if (usb_minors[minor]) continue; usb_minors[minor] = class_driver->fops; retval = 0; break; } up_write(&minor_rwsem); if (retval) goto exit; retval = init_usb_class(); if (retval) goto exit; intf->minor = minor; /* create a usb class device for this usb interface */ snprintf(name, sizeof(name), class_driver->name, minor - minor_base); temp = strrchr(name, '/'); if (temp && (temp[1] != '\0')) ++temp; else temp = name; intf->usb_dev = device_create_drvdata(usb_class->class, &intf->dev, MKDEV(USB_MAJOR, minor), NULL, "%s", temp); if (IS_ERR(intf->usb_dev)) { down_write(&minor_rwsem); usb_minors[intf->minor] = NULL; up_write(&minor_rwsem); retval = PTR_ERR(intf->usb_dev); } exit: 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) { int minor_base = class_driver->minor_base; char name[20]; #ifdef CONFIG_USB_DYNAMIC_MINORS minor_base = 0; #endif if (intf->minor == -1) return; dbg ("removing %d minor", intf->minor); down_write(&minor_rwsem); usb_minors[intf->minor] = NULL; up_write(&minor_rwsem); snprintf(name, sizeof(name), class_driver->name, intf->minor - minor_base); 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);
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