2 * drivers/base/dd.c - The core device/driver interactions.
4 * This file contains the (sometimes tricky) code that controls the
5 * interactions between devices and drivers, which primarily includes
6 * driver binding and unbinding.
8 * All of this code used to exist in drivers/base/bus.c, but was
9 * relocated to here in the name of compartmentalization (since it wasn't
10 * strictly code just for the 'struct bus_type'.
12 * Copyright (c) 2002-5 Patrick Mochel
13 * Copyright (c) 2002-3 Open Source Development Labs
15 * This file is released under the GPLv2
18 #include <linux/device.h>
19 #include <linux/module.h>
22 #include "power/power.h"
24 #define to_drv(node) container_of(node, struct device_driver, kobj.entry)
28 * device_bind_driver - bind a driver to one device.
31 * Allow manual attachment of a driver to a device.
32 * Caller must have already set @dev->driver.
34 * Note that this does not modify the bus reference count
35 * nor take the bus's rwsem. Please verify those are accounted
36 * for before calling this. (It is ok to call with no other effort
37 * from a driver's probe() method.)
39 * This function must be called with @dev->sem held.
41 void device_bind_driver(struct device * dev)
43 if (klist_node_attached(&dev->knode_driver))
46 pr_debug("bound device '%s' to driver '%s'\n",
47 dev->bus_id, dev->driver->name);
48 klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
49 sysfs_create_link(&dev->driver->kobj, &dev->kobj,
50 kobject_name(&dev->kobj));
51 sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver");
55 * driver_probe_device - attempt to bind device & driver.
59 * First, we call the bus's match function, if one present, which
60 * should compare the device IDs the driver supports with the
61 * device IDs of the device. Note we don't do this ourselves
62 * because we don't know the format of the ID structures, nor what
63 * is to be considered a match and what is not.
65 * This function returns 1 if a match is found, an error if one
66 * occurs (that is not -ENODEV or -ENXIO), and 0 otherwise.
68 * This function must be called with @dev->sem held. When called
69 * for a USB interface, @dev->parent->sem must be held as well.
71 int driver_probe_device(struct device_driver * drv, struct device * dev)
75 if (drv->bus->match && !drv->bus->match(dev, drv))
78 pr_debug("%s: Matched Device %s with Driver %s\n",
79 drv->bus->name, dev->bus_id, drv->name);
82 ret = drv->probe(dev);
88 device_bind_driver(dev);
90 pr_debug("%s: Bound Device %s to Driver %s\n",
91 drv->bus->name, dev->bus_id, drv->name);
95 if (ret == -ENODEV || ret == -ENXIO) {
96 /* Driver matched, but didn't support device
97 * or device not found.
98 * Not an error; keep going.
102 /* driver matched but the probe failed */
104 "%s: probe of %s failed with error %d\n",
105 drv->name, dev->bus_id, ret);
111 static int __device_attach(struct device_driver * drv, void * data)
113 struct device * dev = data;
114 return driver_probe_device(drv, dev);
118 * device_attach - try to attach device to a driver.
121 * Walk the list of drivers that the bus has and call
122 * driver_probe_device() for each pair. If a compatible
123 * pair is found, break out and return.
125 * Returns 1 if the device was bound to a driver;
126 * 0 if no matching device was found; error code otherwise.
128 * When called for a USB interface, @dev->parent->sem must be held.
130 int device_attach(struct device * dev)
136 device_bind_driver(dev);
139 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
144 static int __driver_attach(struct device * dev, void * data)
146 struct device_driver * drv = data;
149 * Lock device and try to bind to it. We drop the error
150 * here and always return 0, because we need to keep trying
151 * to bind to devices and some drivers will return an error
152 * simply if it didn't support the device.
154 * driver_probe_device() will spit a warning if there
158 if (dev->parent) /* Needed for USB */
159 down(&dev->parent->sem);
162 driver_probe_device(drv, dev);
165 up(&dev->parent->sem);
171 * driver_attach - try to bind driver to devices.
174 * Walk the list of devices that the bus has on it and try to
175 * match the driver with each one. If driver_probe_device()
176 * returns 0 and the @dev->driver is set, we've found a
179 void driver_attach(struct device_driver * drv)
181 bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
185 * device_release_driver - manually detach device from driver.
188 * Manually detach device from driver.
190 * __device_release_driver() must be called with @dev->sem held.
191 * When called for a USB interface, @dev->parent->sem must be held
195 static void __device_release_driver(struct device * dev)
197 struct device_driver * drv;
202 sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
203 sysfs_remove_link(&dev->kobj, "driver");
204 klist_remove(&dev->knode_driver);
213 void device_release_driver(struct device * dev)
216 * If anyone calls device_release_driver() recursively from
217 * within their ->remove callback for the same device, they
218 * will deadlock right here.
221 __device_release_driver(dev);
227 * driver_detach - detach driver from all devices it controls.
230 void driver_detach(struct device_driver * drv)
235 spin_lock(&drv->klist_devices.k_lock);
236 if (list_empty(&drv->klist_devices.k_list)) {
237 spin_unlock(&drv->klist_devices.k_lock);
240 dev = list_entry(drv->klist_devices.k_list.prev,
241 struct device, knode_driver.n_node);
243 spin_unlock(&drv->klist_devices.k_lock);
245 if (dev->parent) /* Needed for USB */
246 down(&dev->parent->sem);
248 if (dev->driver == drv)
249 __device_release_driver(dev);
252 up(&dev->parent->sem);
258 EXPORT_SYMBOL_GPL(device_bind_driver);
259 EXPORT_SYMBOL_GPL(device_release_driver);
260 EXPORT_SYMBOL_GPL(device_attach);
261 EXPORT_SYMBOL_GPL(driver_attach);