drivers/base/dd.c - linux - Git at Google

 /*
  * 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
  * Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
  * Copyright (c) 2007 Novell Inc.
  *
  * This file is released under the GPLv2
  */

 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/kthread.h>
 #include <linux/wait.h>

 #include "base.h"
 #include "power/power.h"


 static void driver_bound(struct device *dev)
 {
 	if (klist_node_attached(&dev->knode_driver)) {
 		printk(KERN_WARNING "%s: device %s already bound\n",
 			__FUNCTION__, kobject_name(&dev->kobj));
 		return;
 	}

 	pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->bus_id,
 		 __FUNCTION__, dev->driver->name);

 	if (dev->bus)
 		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 					     BUS_NOTIFY_BOUND_DRIVER, dev);

 	klist_add_tail(&dev->knode_driver, &dev->driver->p->klist_devices);
 }

 static int driver_sysfs_add(struct device *dev)
 {
 	int ret;

 	ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
 			  kobject_name(&dev->kobj));
 	if (ret == 0) {
 		ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
 					"driver");
 		if (ret)
 			sysfs_remove_link(&dev->driver->p->kobj,
 					kobject_name(&dev->kobj));
 	}
 	return ret;
 }

 static void driver_sysfs_remove(struct device *dev)
 {
 	struct device_driver *drv = dev->driver;

 	if (drv) {
 		sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
 		sysfs_remove_link(&dev->kobj, "driver");
 	}
 }

 /**
  * 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.
  */
 int device_bind_driver(struct device *dev)
 {
 	int ret;

 	ret = driver_sysfs_add(dev);
 	if (!ret)
 		driver_bound(dev);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(device_bind_driver);

 static atomic_t probe_count = ATOMIC_INIT(0);
 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);

 static int really_probe(struct device *dev, struct device_driver *drv)
 {
 	int ret = 0;

 	atomic_inc(&probe_count);
 	pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
 		 drv->bus->name, __FUNCTION__, drv->name, dev->bus_id);
 	WARN_ON(!list_empty(&dev->devres_head));

 	dev->driver = drv;
 	if (driver_sysfs_add(dev)) {
 		printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
 			__FUNCTION__, dev->bus_id);
 		goto probe_failed;
 	}

 	if (dev->bus->probe) {
 		ret = dev->bus->probe(dev);
 		if (ret)
 			goto probe_failed;
 	} else if (drv->probe) {
 		ret = drv->probe(dev);
 		if (ret)
 			goto probe_failed;
 	}

 	driver_bound(dev);
 	ret = 1;
 	pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
 		 drv->bus->name, __FUNCTION__, dev->bus_id, drv->name);
 	goto done;

 probe_failed:
 	devres_release_all(dev);
 	driver_sysfs_remove(dev);
 	dev->driver = NULL;

 	if (ret != -ENODEV && ret != -ENXIO) {
 		/* driver matched but the probe failed */
 		printk(KERN_WARNING
 		       "%s: probe of %s failed with error %d\n",
 		       drv->name, dev->bus_id, ret);
 	}
 	/*
 	 * Ignore errors returned by ->probe so that the next driver can try
 	 * its luck.
 	 */
 	ret = 0;
 done:
 	atomic_dec(&probe_count);
 	wake_up(&probe_waitqueue);
 	return ret;
 }

 /**
  * driver_probe_done
  * Determine if the probe sequence is finished or not.
  *
  * Should somehow figure out how to use a semaphore, not an atomic variable...
  */
 int driver_probe_done(void)
 {
 	pr_debug("%s: probe_count = %d\n", __FUNCTION__,
 		 atomic_read(&probe_count));
 	if (atomic_read(&probe_count))
 		return -EBUSY;
 	return 0;
 }

 /**
  * driver_probe_device - attempt to bind device & driver together
  * @drv: driver to bind a device to
  * @dev: device to try to bind to the driver
  *
  * 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, -ENODEV if the device is
  * not registered, and 0 otherwise.
  *
  * This function must be called with @dev->sem held.  When called for a
  * USB interface, @dev->parent->sem must be held as well.
  */
 int driver_probe_device(struct device_driver *drv, struct device *dev)
 {
 	int ret = 0;

 	if (!device_is_registered(dev))
 		return -ENODEV;
 	if (drv->bus->match && !drv->bus->match(dev, drv))
 		goto done;

 	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
 		 drv->bus->name, __FUNCTION__, dev->bus_id, drv->name);

 	ret = really_probe(dev, drv);

 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;
  * -ENODEV if the device is not registered.
  *
  * When called for a USB interface, @dev->parent->sem must be held.
  */
 int device_attach(struct device *dev)
 {
 	int ret = 0;

 	down(&dev->sem);
 	if (dev->driver) {
 		ret = device_bind_driver(dev);
 		if (ret == 0)
 			ret = 1;
 		else {
 			dev->driver = NULL;
 			ret = 0;
 		}
 	} else {
 		ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
 	}
 	up(&dev->sem);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(device_attach);

 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.
 	 */

 	if (dev->parent)	/* Needed for USB */
 		down(&dev->parent->sem);
 	down(&dev->sem);
 	if (!dev->driver)
 		driver_probe_device(drv, dev);
 	up(&dev->sem);
 	if (dev->parent)
 		up(&dev->parent->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.
  */
 int driver_attach(struct device_driver *drv)
 {
 	return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
 }
 EXPORT_SYMBOL_GPL(driver_attach);

 /*
  * __device_release_driver() must be called with @dev->sem held.
  * When called for a USB interface, @dev->parent->sem must be held as well.
  */
 static void __device_release_driver(struct device *dev)
 {
 	struct device_driver *drv;

 	drv = dev->driver;
 	if (drv) {
 		driver_sysfs_remove(dev);
 		sysfs_remove_link(&dev->kobj, "driver");

 		if (dev->bus)
 			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
 						     BUS_NOTIFY_UNBIND_DRIVER,
 						     dev);

 		if (dev->bus && dev->bus->remove)
 			dev->bus->remove(dev);
 		else if (drv->remove)
 			drv->remove(dev);
 		devres_release_all(dev);
 		dev->driver = NULL;
 		klist_remove(&dev->knode_driver);
 	}
 }

 /**
  * device_release_driver - manually detach device from driver.
  * @dev: device.
  *
  * Manually detach device from driver.
  * When called for a USB interface, @dev->parent->sem must be held.
  */
 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);
 }
 EXPORT_SYMBOL_GPL(device_release_driver);

 /**
  * driver_detach - detach driver from all devices it controls.
  * @drv: driver.
  */
 void driver_detach(struct device_driver *drv)
 {
 	struct device *dev;

 	for (;;) {
 		spin_lock(&drv->p->klist_devices.k_lock);
 		if (list_empty(&drv->p->klist_devices.k_list)) {
 			spin_unlock(&drv->p->klist_devices.k_lock);
 			break;
 		}
 		dev = list_entry(drv->p->klist_devices.k_list.prev,
 				struct device, knode_driver.n_node);
 		get_device(dev);
 		spin_unlock(&drv->p->klist_devices.k_lock);

 		if (dev->parent)	/* Needed for USB */
 			down(&dev->parent->sem);
 		down(&dev->sem);
 		if (dev->driver == drv)
 			__device_release_driver(dev);
 		up(&dev->sem);
 		if (dev->parent)
 			up(&dev->parent->sem);
 		put_device(dev);
 	}
 }
	/*
	* 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
	* Copyright (c) 2007 Greg Kroah-Hartman <gregkh@suse.de>
	* Copyright (c) 2007 Novell Inc.
	*
	* This file is released under the GPLv2
	*/

	#include <linux/device.h>
	#include <linux/module.h>
	#include <linux/kthread.h>
	#include <linux/wait.h>

	#include "base.h"
	#include "power/power.h"


	static void driver_bound(struct device *dev)
	{
	if (klist_node_attached(&dev->knode_driver)) {
	printk(KERN_WARNING "%s: device %s already bound\n",
	__FUNCTION__, kobject_name(&dev->kobj));
	return;
	}

	pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->bus_id,
	__FUNCTION__, dev->driver->name);

	if (dev->bus)
	blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
	BUS_NOTIFY_BOUND_DRIVER, dev);

	klist_add_tail(&dev->knode_driver, &dev->driver->p->klist_devices);
	}

	static int driver_sysfs_add(struct device *dev)
	{
	int ret;

	ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
	kobject_name(&dev->kobj));
	if (ret == 0) {
	ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
	"driver");
	if (ret)
	sysfs_remove_link(&dev->driver->p->kobj,
	kobject_name(&dev->kobj));
	}
	return ret;
	}

	static void driver_sysfs_remove(struct device *dev)
	{
	struct device_driver *drv = dev->driver;

	if (drv) {
	sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
	sysfs_remove_link(&dev->kobj, "driver");
	}
	}

	/**
	* 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.
	*/
	int device_bind_driver(struct device *dev)
	{
	int ret;

	ret = driver_sysfs_add(dev);
	if (!ret)
	driver_bound(dev);
	return ret;
	}
	EXPORT_SYMBOL_GPL(device_bind_driver);

	static atomic_t probe_count = ATOMIC_INIT(0);
	static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);

	static int really_probe(struct device dev, struct device_driver drv)
	{
	int ret = 0;

	atomic_inc(&probe_count);
	pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
	drv->bus->name, __FUNCTION__, drv->name, dev->bus_id);
	WARN_ON(!list_empty(&dev->devres_head));

	dev->driver = drv;
	if (driver_sysfs_add(dev)) {
	printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
	__FUNCTION__, dev->bus_id);
	goto probe_failed;
	}

	if (dev->bus->probe) {
	ret = dev->bus->probe(dev);
	if (ret)
	goto probe_failed;
	} else if (drv->probe) {
	ret = drv->probe(dev);
	if (ret)
	goto probe_failed;
	}

	driver_bound(dev);
	ret = 1;
	pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
	drv->bus->name, __FUNCTION__, dev->bus_id, drv->name);
	goto done;

	probe_failed:
	devres_release_all(dev);
	driver_sysfs_remove(dev);
	dev->driver = NULL;

	if (ret != -ENODEV && ret != -ENXIO) {
	/* driver matched but the probe failed */
	printk(KERN_WARNING
	"%s: probe of %s failed with error %d\n",
	drv->name, dev->bus_id, ret);
	}
	/*
	* Ignore errors returned by ->probe so that the next driver can try
	* its luck.
	*/
	ret = 0;
	done:
	atomic_dec(&probe_count);
	wake_up(&probe_waitqueue);
	return ret;
	}

	/**
	* driver_probe_done
	* Determine if the probe sequence is finished or not.
	*
	* Should somehow figure out how to use a semaphore, not an atomic variable...
	*/
	int driver_probe_done(void)
	{
	pr_debug("%s: probe_count = %d\n", __FUNCTION__,
	atomic_read(&probe_count));
	if (atomic_read(&probe_count))
	return -EBUSY;
	return 0;
	}

	/**
	* driver_probe_device - attempt to bind device & driver together
	* @drv: driver to bind a device to
	* @dev: device to try to bind to the driver
	*
	* 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, -ENODEV if the device is
	* not registered, and 0 otherwise.
	*
	* This function must be called with @dev->sem held. When called for a
	* USB interface, @dev->parent->sem must be held as well.
	*/
	int driver_probe_device(struct device_driver drv, struct device dev)
	{
	int ret = 0;

	if (!device_is_registered(dev))
	return -ENODEV;
	if (drv->bus->match && !drv->bus->match(dev, drv))
	goto done;

	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
	drv->bus->name, __FUNCTION__, dev->bus_id, drv->name);

	ret = really_probe(dev, drv);

	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;
	* -ENODEV if the device is not registered.
	*
	* When called for a USB interface, @dev->parent->sem must be held.
	*/
	int device_attach(struct device *dev)
	{
	int ret = 0;

	down(&dev->sem);
	if (dev->driver) {
	ret = device_bind_driver(dev);
	if (ret == 0)
	ret = 1;
	else {
	dev->driver = NULL;
	ret = 0;
	}
	} else {
	ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
	}
	up(&dev->sem);
	return ret;
	}
	EXPORT_SYMBOL_GPL(device_attach);

	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.
	*/

	if (dev->parent) /* Needed for USB */
	down(&dev->parent->sem);
	down(&dev->sem);
	if (!dev->driver)
	driver_probe_device(drv, dev);
	up(&dev->sem);
	if (dev->parent)
	up(&dev->parent->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.
	*/
	int driver_attach(struct device_driver *drv)
	{
	return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
	}
	EXPORT_SYMBOL_GPL(driver_attach);

	/*
	* __device_release_driver() must be called with @dev->sem held.
	* When called for a USB interface, @dev->parent->sem must be held as well.
	*/
	static void __device_release_driver(struct device *dev)
	{
	struct device_driver *drv;

	drv = dev->driver;
	if (drv) {
	driver_sysfs_remove(dev);
	sysfs_remove_link(&dev->kobj, "driver");

	if (dev->bus)
	blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
	BUS_NOTIFY_UNBIND_DRIVER,
	dev);

	if (dev->bus && dev->bus->remove)
	dev->bus->remove(dev);
	else if (drv->remove)
	drv->remove(dev);
	devres_release_all(dev);
	dev->driver = NULL;
	klist_remove(&dev->knode_driver);
	}
	}

	/**
	* device_release_driver - manually detach device from driver.
	* @dev: device.
	*
	* Manually detach device from driver.
	* When called for a USB interface, @dev->parent->sem must be held.
	*/
	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);
	}
	EXPORT_SYMBOL_GPL(device_release_driver);

	/**
	* driver_detach - detach driver from all devices it controls.
	* @drv: driver.
	*/
	void driver_detach(struct device_driver *drv)
	{
	struct device *dev;

	for (;;) {
	spin_lock(&drv->p->klist_devices.k_lock);
	if (list_empty(&drv->p->klist_devices.k_list)) {
	spin_unlock(&drv->p->klist_devices.k_lock);
	break;
	}
	dev = list_entry(drv->p->klist_devices.k_list.prev,
	struct device, knode_driver.n_node);
	get_device(dev);
	spin_unlock(&drv->p->klist_devices.k_lock);

	if (dev->parent) /* Needed for USB */
	down(&dev->parent->sem);
	down(&dev->sem);
	if (dev->driver == drv)
	__device_release_driver(dev);
	up(&dev->sem);
	if (dev->parent)
	up(&dev->parent->sem);
	put_device(dev);
	}
	}