diff options
Diffstat (limited to 'drivers/base/dd.c')
| -rw-r--r-- | drivers/base/dd.c | 367 |
1 files changed, 367 insertions, 0 deletions
diff --git a/drivers/base/dd.c b/drivers/base/dd.c new file mode 100644 index 0000000..20febc0 --- /dev/null +++ b/drivers/base/dd.c @@ -0,0 +1,367 @@ +/* + * 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", + __func__, kobject_name(&dev->kobj)); + return; + } + + pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->bus_id, + __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->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->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", + __func__, 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, __func__, 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", __func__, + 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, __func__, 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 (drv->bus->match && !drv->bus->match(dev, drv)) + 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); + 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); + } +} |
