--- /dev/null
+/*
+ * 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/slab.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 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)
+{
+ 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)
+ 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];
+ 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
+
+ if (class_driver->fops == NULL)
+ return -EINVAL;
+ if (intf->minor >= 0)
+ return -EADDRINUSE;
+
+ retval = init_usb_class();
+ 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);
+ temp = strrchr(name, '/');
+ if (temp && (temp[1] != '\0'))
+ ++temp;
+ else
+ temp = name;
+ intf->usb_dev = device_create(usb_class->class, &intf->dev,
+ MKDEV(USB_MAJOR, minor), class_driver,
+ "%s", temp);
+ 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);
Code Review / kvmfornfv.git / blobdiff