diff options
Diffstat (limited to 'drivers/base/dd.c')
| -rw-r--r-- | drivers/base/dd.c | 607 |
1 files changed, 607 insertions, 0 deletions
diff --git a/drivers/base/dd.c b/drivers/base/dd.c new file mode 100644 index 000000000..e843fdbe4 --- /dev/null +++ b/drivers/base/dd.c @@ -0,0 +1,607 @@ +/* + * 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) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de> + * Copyright (c) 2007-2009 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 <linux/pm_runtime.h> +#include <linux/pinctrl/devinfo.h> + +#include "base.h" +#include "power/power.h" + +/* + * Deferred Probe infrastructure. + * + * Sometimes driver probe order matters, but the kernel doesn't always have + * dependency information which means some drivers will get probed before a + * resource it depends on is available. For example, an SDHCI driver may + * first need a GPIO line from an i2c GPIO controller before it can be + * initialized. If a required resource is not available yet, a driver can + * request probing to be deferred by returning -EPROBE_DEFER from its probe hook + * + * Deferred probe maintains two lists of devices, a pending list and an active + * list. A driver returning -EPROBE_DEFER causes the device to be added to the + * pending list. A successful driver probe will trigger moving all devices + * from the pending to the active list so that the workqueue will eventually + * retry them. + * + * The deferred_probe_mutex must be held any time the deferred_probe_*_list + * of the (struct device*)->p->deferred_probe pointers are manipulated + */ +static DEFINE_MUTEX(deferred_probe_mutex); +static LIST_HEAD(deferred_probe_pending_list); +static LIST_HEAD(deferred_probe_active_list); +static struct workqueue_struct *deferred_wq; +static atomic_t deferred_trigger_count = ATOMIC_INIT(0); + +/* + * deferred_probe_work_func() - Retry probing devices in the active list. + */ +static void deferred_probe_work_func(struct work_struct *work) +{ + struct device *dev; + struct device_private *private; + /* + * This block processes every device in the deferred 'active' list. + * Each device is removed from the active list and passed to + * bus_probe_device() to re-attempt the probe. The loop continues + * until every device in the active list is removed and retried. + * + * Note: Once the device is removed from the list and the mutex is + * released, it is possible for the device get freed by another thread + * and cause a illegal pointer dereference. This code uses + * get/put_device() to ensure the device structure cannot disappear + * from under our feet. + */ + mutex_lock(&deferred_probe_mutex); + while (!list_empty(&deferred_probe_active_list)) { + private = list_first_entry(&deferred_probe_active_list, + typeof(*dev->p), deferred_probe); + dev = private->device; + list_del_init(&private->deferred_probe); + + get_device(dev); + + /* + * Drop the mutex while probing each device; the probe path may + * manipulate the deferred list + */ + mutex_unlock(&deferred_probe_mutex); + + /* + * Force the device to the end of the dpm_list since + * the PM code assumes that the order we add things to + * the list is a good order for suspend but deferred + * probe makes that very unsafe. + */ + device_pm_lock(); + device_pm_move_last(dev); + device_pm_unlock(); + + dev_dbg(dev, "Retrying from deferred list\n"); + bus_probe_device(dev); + + mutex_lock(&deferred_probe_mutex); + + put_device(dev); + } + mutex_unlock(&deferred_probe_mutex); +} +static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func); + +static void driver_deferred_probe_add(struct device *dev) +{ + mutex_lock(&deferred_probe_mutex); + if (list_empty(&dev->p->deferred_probe)) { + dev_dbg(dev, "Added to deferred list\n"); + list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list); + } + mutex_unlock(&deferred_probe_mutex); +} + +void driver_deferred_probe_del(struct device *dev) +{ + mutex_lock(&deferred_probe_mutex); + if (!list_empty(&dev->p->deferred_probe)) { + dev_dbg(dev, "Removed from deferred list\n"); + list_del_init(&dev->p->deferred_probe); + } + mutex_unlock(&deferred_probe_mutex); +} + +static bool driver_deferred_probe_enable = false; +/** + * driver_deferred_probe_trigger() - Kick off re-probing deferred devices + * + * This functions moves all devices from the pending list to the active + * list and schedules the deferred probe workqueue to process them. It + * should be called anytime a driver is successfully bound to a device. + * + * Note, there is a race condition in multi-threaded probe. In the case where + * more than one device is probing at the same time, it is possible for one + * probe to complete successfully while another is about to defer. If the second + * depends on the first, then it will get put on the pending list after the + * trigger event has already occured and will be stuck there. + * + * The atomic 'deferred_trigger_count' is used to determine if a successful + * trigger has occurred in the midst of probing a driver. If the trigger count + * changes in the midst of a probe, then deferred processing should be triggered + * again. + */ +static void driver_deferred_probe_trigger(void) +{ + if (!driver_deferred_probe_enable) + return; + + /* + * A successful probe means that all the devices in the pending list + * should be triggered to be reprobed. Move all the deferred devices + * into the active list so they can be retried by the workqueue + */ + mutex_lock(&deferred_probe_mutex); + atomic_inc(&deferred_trigger_count); + list_splice_tail_init(&deferred_probe_pending_list, + &deferred_probe_active_list); + mutex_unlock(&deferred_probe_mutex); + + /* + * Kick the re-probe thread. It may already be scheduled, but it is + * safe to kick it again. + */ + queue_work(deferred_wq, &deferred_probe_work); +} + +/** + * deferred_probe_initcall() - Enable probing of deferred devices + * + * We don't want to get in the way when the bulk of drivers are getting probed. + * Instead, this initcall makes sure that deferred probing is delayed until + * late_initcall time. + */ +static int deferred_probe_initcall(void) +{ + deferred_wq = create_singlethread_workqueue("deferwq"); + if (WARN_ON(!deferred_wq)) + return -ENOMEM; + + driver_deferred_probe_enable = true; + driver_deferred_probe_trigger(); + /* Sort as many dependencies as possible before exiting initcalls */ + flush_workqueue(deferred_wq); + return 0; +} +late_initcall(deferred_probe_initcall); + +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->driver->name, + __func__, dev_name(dev)); + + klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices); + + /* + * Make sure the device is no longer in one of the deferred lists and + * kick off retrying all pending devices + */ + driver_deferred_probe_del(dev); + driver_deferred_probe_trigger(); + + if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_BOUND_DRIVER, dev); +} + +static int driver_sysfs_add(struct device *dev) +{ + int ret; + + if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_BIND_DRIVER, dev); + + 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 the device lock 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; + int local_trigger_count = atomic_read(&deferred_trigger_count); + + 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 using pinctrl, bind pins now before probing */ + ret = pinctrl_bind_pins(dev); + if (ret) + goto probe_failed; + + if (driver_sysfs_add(dev)) { + printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n", + __func__, dev_name(dev)); + goto probe_failed; + } + + if (dev->pm_domain && dev->pm_domain->activate) { + ret = dev->pm_domain->activate(dev); + if (ret) + 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; + } + + if (dev->pm_domain && dev->pm_domain->sync) + dev->pm_domain->sync(dev); + + 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; + dev_set_drvdata(dev, NULL); + if (dev->pm_domain && dev->pm_domain->dismiss) + dev->pm_domain->dismiss(dev); + + switch (ret) { + case -EPROBE_DEFER: + /* Driver requested deferred probing */ + dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name); + driver_deferred_probe_add(dev); + /* Did a trigger occur while probing? Need to re-trigger if yes */ + if (local_trigger_count != atomic_read(&deferred_trigger_count)) + driver_deferred_probe_trigger(); + break; + case -ENODEV: + case -ENXIO: + pr_debug("%s: probe of %s rejects match %d\n", + drv->name, dev_name(dev), ret); + break; + default: + /* 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(); +} +EXPORT_SYMBOL_GPL(wait_for_device_probe); + +/** + * 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 successfully and 0 otherwise. + * + * This function must be called with @dev lock held. When called for a + * USB interface, @dev->parent lock 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); + + pm_runtime_barrier(dev); + ret = really_probe(dev, drv); + pm_request_idle(dev); + + 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 driver was found; + * -ENODEV if the device is not registered. + * + * When called for a USB interface, @dev->parent lock must be held. + */ +int device_attach(struct device *dev) +{ + int ret = 0; + + device_lock(dev); + if (dev->driver) { + if (klist_node_attached(&dev->p->knode_driver)) { + ret = 1; + goto out_unlock; + } + 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); + pm_request_idle(dev); + } +out_unlock: + device_unlock(dev); + 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 */ + device_lock(dev->parent); + device_lock(dev); + if (!dev->driver) + driver_probe_device(drv, dev); + device_unlock(dev); + if (dev->parent) + device_unlock(dev->parent); + + 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 lock held. + * When called for a USB interface, @dev->parent lock must be held as well. + */ +static void __device_release_driver(struct device *dev) +{ + struct device_driver *drv; + + drv = dev->driver; + if (drv) { + pm_runtime_get_sync(dev); + + driver_sysfs_remove(dev); + + if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_UNBIND_DRIVER, + dev); + + pm_runtime_put_sync(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; + dev_set_drvdata(dev, NULL); + if (dev->pm_domain && dev->pm_domain->dismiss) + dev->pm_domain->dismiss(dev); + + klist_remove(&dev->p->knode_driver); + if (dev->bus) + blocking_notifier_call_chain(&dev->bus->p->bus_notifier, + BUS_NOTIFY_UNBOUND_DRIVER, + dev); + + } +} + +/** + * device_release_driver - manually detach device from driver. + * @dev: device. + * + * Manually detach device from driver. + * When called for a USB interface, @dev->parent lock 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. + */ + device_lock(dev); + __device_release_driver(dev); + device_unlock(dev); +} +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 */ + device_lock(dev->parent); + device_lock(dev); + if (dev->driver == drv) + __device_release_driver(dev); + device_unlock(dev); + if (dev->parent) + device_unlock(dev->parent); + put_device(dev); + } +} |