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

This adds a single file, "bind", to the sysfs directory of every driver
registered with the driver core.  To bind a device to a driver, write
the bus id of the device you wish to bind to that specific driver to the
"bind" file (remember to not add a trailing \n).  If that bus id matches
a device on that bus, and it does not currently have a driver bound to
it, the probe sequence will be initiated with that driver and device.

Note, this requires that the driver itself be willing and able to accept
that device (usually through a device id type table).  This patch does
not make it possible to override the driver's id table.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/base.h

@@ -5,6 +5,7 @@ extern int bus_add_driver(struct device_driver *);
 extern void bus_remove_driver(struct device_driver *);
 
 extern void driver_detach(struct device_driver * drv);
+extern int driver_probe_device(struct device_driver *, struct device *);
 
 static inline struct class_device *to_class_dev(struct kobject *obj)
 {

drivers/base/bus.c

@@ -160,6 +160,30 @@ static ssize_t driver_unbind(struct device_driver *drv,
 }
 static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
 
+/*
+ * Manually attach a device to a driver.
+ * Note: the driver must want to bind to the device,
+ * it is not possible to override the driver's id table.
+ */
+static ssize_t driver_bind(struct device_driver *drv,
+			   const char *buf, size_t count)
+{
+	struct bus_type *bus = get_bus(drv->bus);
+	struct device *dev;
+	int err = -ENODEV;
+
+	dev = bus_find_device(bus, NULL, (void *)buf, driver_helper);
+	if ((dev) &&
+	    (dev->driver == NULL)) {
+		down(&dev->sem);
+		err = driver_probe_device(drv, dev);
+		up(&dev->sem);
+		put_device(dev);
+	}
+	return err;
+}
+static DRIVER_ATTR(bind, S_IWUSR, NULL, driver_bind);
+
 
 static struct device * next_device(struct klist_iter * i)
 {
@@ -425,6 +449,7 @@ int bus_add_driver(struct device_driver * drv)
 
 		driver_add_attrs(bus, drv);
 		driver_create_file(drv, &driver_attr_unbind);
+		driver_create_file(drv, &driver_attr_bind);
 	}
 	return error;
 }
@@ -442,6 +467,7 @@ int bus_add_driver(struct device_driver * drv)
 void bus_remove_driver(struct device_driver * drv)
 {
 	if (drv->bus) {
+		driver_remove_file(drv, &driver_attr_bind);
 		driver_remove_file(drv, &driver_attr_unbind);
 		driver_remove_attrs(drv->bus, drv);
 		klist_remove(&drv->knode_bus);

drivers/base/dd.c

@@ -65,7 +65,7 @@ void device_bind_driver(struct device * dev)
  *
  *	This function must be called with @dev->sem held.
  */
-static int driver_probe_device(struct device_driver * drv, struct device * dev)
+int driver_probe_device(struct device_driver * drv, struct device * dev)
 {
 	int ret = 0;