[PATCH] driver core: Add the ability to unbind drivers to devices from userspace

[Greg KH <greg@kroah.com>]

This adds a single file, "unbind", to the sysfs directory of every
device that is currently bound to a driver.  To unbind the driver from
the device, write anything to this file and they will be disconnected
from each other.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 drivers/base/dd.c |   11 +++++++++++
 1 files changed, 11 insertions(+)

--- gregkh-2.6.orig/drivers/base/dd.c	2005-06-22 17:56:48.000000000 -0700
+++ gregkh-2.6/drivers/base/dd.c	2005-06-22 17:56:59.000000000 -0700
@@ -23,6 +23,15 @@
 
 #define to_drv(node) container_of(node, struct device_driver, kobj.entry)
 
+/* manually detach a device from it's associated driver. */
+/* Any write will cause it to happen. */
+static ssize_t device_unbind(struct device *dev, struct device_attribute *attr,
+			     const char *buf, size_t count)
+{
+	device_release_driver(dev);
+	return count;
+}
+static DEVICE_ATTR(unbind, S_IWUSR, NULL, device_unbind);
 
 /**
  *	device_bind_driver - bind a driver to one device.
@@ -46,6 +55,7 @@
 	sysfs_create_link(&dev->driver->kobj, &dev->kobj,
 			  kobject_name(&dev->kobj));
 	sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver");
+	device_create_file(dev, &dev_attr_unbind);
 }
 
 /**
@@ -191,6 +201,7 @@
 		get_driver(drv);
 		sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
 		sysfs_remove_link(&dev->kobj, "driver");
+		device_remove_file(dev, &dev_attr_unbind);
 		klist_remove(&dev->knode_driver);
 
 		if (drv->remove)