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

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>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 2c64b792d074..fa41ee90a53a 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -133,6 +133,34 @@ static struct kobj_type ktype_bus = {
 decl_subsys(bus, &ktype_bus, NULL);
 
 
+/* Manually detach a device from it's associated driver. */
+static int driver_helper(struct device *dev, void *data)
+{
+        const char *name = data;
+
+        if (strcmp(name, dev->bus_id) == 0)
+                return 1;
+        return 0;
+}
+
+static ssize_t driver_unbind(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 == drv)) {
+                device_release_driver(dev);
+                err = count;
+        }
+        return err;
+}
+static DRIVER_ATTR(unbind, S_IWUSR, NULL, driver_unbind);
+
+
 static struct device * next_device(struct klist_iter * i)
 {
         struct klist_node * n = klist_next(i);
@@ -396,6 +424,7 @@ int bus_add_driver(struct device_driver * drv)
                 module_add_driver(drv->owner, drv);
 
                 driver_add_attrs(bus, drv);
+                driver_create_file(drv, &driver_attr_unbind);
         }
         return error;
 }
@@ -413,6 +442,7 @@ 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_unbind);
                 driver_remove_attrs(drv->bus, drv);
                 klist_remove(&drv->knode_bus);
                 pr_debug("bus %s: remove driver %s\n", drv->bus->name, drv->name);