/* * 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/delay.h> #include <linux/module.h> #include <linux/kthread.h> #include <linux/wait.h> #include <linux/async.h> #include "base.h" #include "power/power.h" static void driver_bound(struct device *dev) { if (klist_node_attached(&dev->p->knode_driver)) { printk(KERN_WARNING "%s: device %s already bound\n", __func__, kobject_name(&dev->kobj)); return; } pr_debug("driver: '%s': %s: bound to device '%s'\n", dev_name(dev), __func__, dev->driver->name); if (dev->bus) blocking_notifier_call_chain(&dev->bus->p->bus_notifier, BUS_NOTIFY_BOUND_DRIVER, dev); klist_add_tail(&dev->p->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, __func__, drv->name, dev_name(dev)); 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", __func__, dev_name(dev)); 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, __func__, dev_name(dev), 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_name(dev), 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", __func__, atomic_read(&probe_count)); if (atomic_read(&probe_count)) return -EBUSY; return 0; } /** * wait_for_device_probe * Wait for device probing to be completed. */ void wait_for_device_probe(void) { /* wait for the known devices to complete their probing */ wait_event(probe_waitqueue, atomic_read(&probe_count) == 0); async_synchronize_full(); } /** * 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 * * This function returns -ENODEV if the device is not registered, * 1 if the device is bound sucessfully 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; pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); ret = really_probe(dev, drv); return ret; } static int __device_attach(struct device_driver *drv, void *data) { struct device *dev = data; if (!driver_match_device(drv, dev)) return 0; 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 (!driver_match_device(drv, dev)) return 0; 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); 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->p->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_private *dev_prv; 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_prv = list_entry(drv->p->klist_devices.k_list.prev, struct device_private, knode_driver.n_node); dev = dev_prv->device; 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); } }