/*
* drivers/base/dd.c - The core device/driver interactions.
*
* This file contains the (sometimes tricky) code that controls the
* interactions between devices and drivers, which primarily includes
* driver binding and unbinding.
*
* All of this code used to exist in drivers/base/bus.c, but was
* relocated to here in the name of compartmentalization (since it wasn't
* strictly code just for the 'struct bus_type'.
*
* Copyright (c) 2002-5 Patrick Mochel
* Copyright (c) 2002-3 Open Source Development Labs
*
* This file is released under the GPLv2
*/
#include <linux/device.h>
#include <linux/module.h>
#include "base.h"
#include "power/power.h"
#define to_drv(node) container_of(node, struct device_driver, kobj.entry)
/**
* device_bind_driver - bind a driver to one device.
* @dev: device.
*
* Allow manual attachment of a driver to a device.
* Caller must have already set @dev->driver.
*
* Note that this does not modify the bus reference count
* nor take the bus's rwsem. Please verify those are accounted
* for before calling this. (It is ok to call with no other effort
* from a driver's probe() method.)
*
* This function must be called with @dev->sem held.
*/
void device_bind_driver(struct device * dev)
{
if (klist_node_attached(&dev->knode_driver))
return;
pr_debug("bound device '%s' to driver '%s'\n",
dev->bus_id, dev->driver->name);
klist_add_tail(&dev->knode_driver, &dev->driver->klist_devices);
sysfs_create_link(&dev->driver->kobj, &dev->kobj,
kobject_name(&dev->kobj));
sysfs_create_link(&dev->kobj, &dev->driver->kobj, "driver");
}
/**
* driver_probe_device - attempt to bind device & driver.
* @drv: driver.
* @dev: device.
*
* First, we call the bus's match function, if one present, which
* should compare the device IDs the driver supports with the
* device IDs of the device. Note we don't do this ourselves
* because we don't know the format of the ID structures, nor what
* is to be considered a match and what is not.
*
*
* This function returns 1 if a match is found, an error if one
* occurs (that is not -ENODEV or -ENXIO), and 0 otherwise.
*
* This function must be called with @dev->sem held.
*/
int driver_probe_device(struct device_driver * drv, struct device * dev)
{
int ret = 0;
if (drv->bus->match && !drv->bus->match(dev, drv))
goto Done;
pr_debug("%s: Matched Device %s with Driver %s\n",
drv->bus->name, dev->bus_id, drv->name);
dev->driver = drv;
if (drv->probe) {
ret = drv->probe(dev);
if (ret) {
dev->driver = NULL;
goto ProbeFailed;
}
}
device_bind_driver(dev);
ret = 1;
pr_debug("%s: Bound Device %s to Driver %s\n",
drv->bus->name, dev->bus_id, drv->name);
goto Done;
ProbeFailed:
if (ret == -ENODEV || ret == -ENXIO) {
/* Driver matched, but didn't support device
* or device not found.
* Not an error; keep going.
*/
ret = 0;
} else {
/* driver matched but the probe failed */
printk(KERN_WARNING
"%s: probe of %s failed with error %d\n",
drv->name, dev->bus_id, ret);
}
Done:
return ret;
}
static int __device_attach(struct device_driver * drv, void * data)
{
struct device * dev = data;
return driver_probe_device(drv, dev);
}
/**
* device_attach - try to attach device to a driver.
* @dev: device.
*
* Walk the list of drivers that the bus has and call
* driver_probe_device() for each pair. If a compatible
* pair is found, break out and return.
*
* Returns 1 if the device was bound to a driver;
* 0 if no matching device was found; error code otherwise.
*/
int device_attach(struct device * dev)
{
int ret = 0;
down(&dev->sem);
if (dev->driver) {
device_bind_driver(dev);
ret = 1;
} else
ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
up(&dev->sem);
return ret;
}
static int __driver_attach(struct device * dev, void * data)
{
struct device_driver * drv = data;
/*
* Lock device and try to bind to it. We drop the error
* here and always return 0, because we need to keep trying
* to bind to devices and some drivers will return an error
* simply if it didn't support the device.
*
* driver_probe_device() will spit a warning if there
* is an error.
*/
down(&dev->sem);
if (!dev->driver)
driver_probe_device(drv, dev);
up(&dev->sem);
return 0;
}
/**
* driver_attach - try to bind driver to devices.
* @drv: driver.
*
* Walk the list of devices that the bus has on it and try to
* match the driver with each one. If driver_probe_device()
* returns 0 and the @dev->driver is set, we've found a
* compatible pair.
*/
void driver_attach(struct device_driver * drv)
{
bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
}
/**
* device_release_driver - manually detach device from driver.
* @dev: device.
*
* Manually detach device from driver.
*
* __device_release_driver() must be called with @dev->sem held.
*/
static void __device_release_driver(struct device * dev)
{
struct device_driver * drv;
drv = dev->driver;
if (drv) {
get_driver(drv);
sysfs_remove_link(&drv->kobj, kobject_name(&dev->kobj));
sysfs_remove_link(&dev->kobj, "driver");
klist_remove(&dev->knode_driver);
if (drv->remove)
drv->remove(dev);
dev->driver = NULL;
put_driver(drv);
}
}
void device_release_driver(struct device * dev)
{
/*
* If anyone calls device_release_driver() recursively from
* within their ->remove callback for the same device, they
* will deadlock right here.
*/
down(&dev->sem);
__device_release_driver(dev);
up(&dev->sem);
}
/**
* driver_detach - detach driver from all devices it controls.
* @drv: driver.
*/
void driver_detach(struct device_driver * drv)
{
struct device * dev;
for (;;) {
spin_lock_irq(&drv->klist_devices.k_lock);
if (list_empty(&drv->klist_devices.k_list)) {
spin_unlock_irq(&drv->klist_devices.k_lock);
break;
}
dev = list_entry(drv->klist_devices.k_list.prev,
struct device, knode_driver.n_node);
get_device(dev);
spin_unlock_irq(&drv->klist_devices.k_lock);
down(&dev->sem);
if (dev->driver == drv)
__device_release_driver(dev);
up(&dev->sem);
put_device(dev);
}
}
EXPORT_SYMBOL_GPL(device_bind_driver);
EXPORT_SYMBOL_GPL(device_release_driver);
EXPORT_SYMBOL_GPL(device_attach);
EXPORT_SYMBOL_GPL(driver_attach);
