608 lines
16 KiB
C
608 lines
16 KiB
C
/*
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* drivers/base/dd.c - The core device/driver interactions.
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*
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* This file contains the (sometimes tricky) code that controls the
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* interactions between devices and drivers, which primarily includes
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* driver binding and unbinding.
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*
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* All of this code used to exist in drivers/base/bus.c, but was
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* relocated to here in the name of compartmentalization (since it wasn't
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* strictly code just for the 'struct bus_type'.
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*
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* Copyright (c) 2002-5 Patrick Mochel
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* Copyright (c) 2002-3 Open Source Development Labs
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* Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
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* Copyright (c) 2007-2009 Novell Inc.
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*
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* This file is released under the GPLv2
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*/
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#include <linux/device.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/kthread.h>
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#include <linux/wait.h>
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#include <linux/async.h>
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#include <linux/pm_runtime.h>
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#include <linux/pinctrl/devinfo.h>
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#include "base.h"
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#include "power/power.h"
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/*
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* Deferred Probe infrastructure.
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*
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* Sometimes driver probe order matters, but the kernel doesn't always have
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* dependency information which means some drivers will get probed before a
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* resource it depends on is available. For example, an SDHCI driver may
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* first need a GPIO line from an i2c GPIO controller before it can be
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* initialized. If a required resource is not available yet, a driver can
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* request probing to be deferred by returning -EPROBE_DEFER from its probe hook
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*
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* Deferred probe maintains two lists of devices, a pending list and an active
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* list. A driver returning -EPROBE_DEFER causes the device to be added to the
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* pending list. A successful driver probe will trigger moving all devices
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* from the pending to the active list so that the workqueue will eventually
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* retry them.
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*
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* The deferred_probe_mutex must be held any time the deferred_probe_*_list
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* of the (struct device*)->p->deferred_probe pointers are manipulated
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*/
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static DEFINE_MUTEX(deferred_probe_mutex);
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static LIST_HEAD(deferred_probe_pending_list);
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static LIST_HEAD(deferred_probe_active_list);
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static struct workqueue_struct *deferred_wq;
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static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
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/*
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* deferred_probe_work_func() - Retry probing devices in the active list.
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*/
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static void deferred_probe_work_func(struct work_struct *work)
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{
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struct device *dev;
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struct device_private *private;
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/*
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* This block processes every device in the deferred 'active' list.
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* Each device is removed from the active list and passed to
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* bus_probe_device() to re-attempt the probe. The loop continues
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* until every device in the active list is removed and retried.
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*
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* Note: Once the device is removed from the list and the mutex is
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* released, it is possible for the device get freed by another thread
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* and cause a illegal pointer dereference. This code uses
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* get/put_device() to ensure the device structure cannot disappear
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* from under our feet.
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*/
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mutex_lock(&deferred_probe_mutex);
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while (!list_empty(&deferred_probe_active_list)) {
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private = list_first_entry(&deferred_probe_active_list,
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typeof(*dev->p), deferred_probe);
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dev = private->device;
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list_del_init(&private->deferred_probe);
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get_device(dev);
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/*
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* Drop the mutex while probing each device; the probe path may
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* manipulate the deferred list
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*/
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mutex_unlock(&deferred_probe_mutex);
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/*
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* Force the device to the end of the dpm_list since
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* the PM code assumes that the order we add things to
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* the list is a good order for suspend but deferred
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* probe makes that very unsafe.
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*/
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device_pm_lock();
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device_pm_move_last(dev);
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device_pm_unlock();
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dev_dbg(dev, "Retrying from deferred list\n");
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bus_probe_device(dev);
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mutex_lock(&deferred_probe_mutex);
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put_device(dev);
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}
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mutex_unlock(&deferred_probe_mutex);
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}
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static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
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static void driver_deferred_probe_add(struct device *dev)
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{
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mutex_lock(&deferred_probe_mutex);
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if (list_empty(&dev->p->deferred_probe)) {
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dev_dbg(dev, "Added to deferred list\n");
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list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
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}
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mutex_unlock(&deferred_probe_mutex);
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}
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void driver_deferred_probe_del(struct device *dev)
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{
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mutex_lock(&deferred_probe_mutex);
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if (!list_empty(&dev->p->deferred_probe)) {
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dev_dbg(dev, "Removed from deferred list\n");
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list_del_init(&dev->p->deferred_probe);
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}
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mutex_unlock(&deferred_probe_mutex);
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}
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static bool driver_deferred_probe_enable = false;
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/**
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* driver_deferred_probe_trigger() - Kick off re-probing deferred devices
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*
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* This functions moves all devices from the pending list to the active
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* list and schedules the deferred probe workqueue to process them. It
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* should be called anytime a driver is successfully bound to a device.
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*
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* Note, there is a race condition in multi-threaded probe. In the case where
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* more than one device is probing at the same time, it is possible for one
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* probe to complete successfully while another is about to defer. If the second
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* depends on the first, then it will get put on the pending list after the
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* trigger event has already occured and will be stuck there.
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*
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* The atomic 'deferred_trigger_count' is used to determine if a successful
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* trigger has occurred in the midst of probing a driver. If the trigger count
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* changes in the midst of a probe, then deferred processing should be triggered
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* again.
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*/
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static void driver_deferred_probe_trigger(void)
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{
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if (!driver_deferred_probe_enable)
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return;
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/*
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* A successful probe means that all the devices in the pending list
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* should be triggered to be reprobed. Move all the deferred devices
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* into the active list so they can be retried by the workqueue
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*/
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mutex_lock(&deferred_probe_mutex);
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atomic_inc(&deferred_trigger_count);
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list_splice_tail_init(&deferred_probe_pending_list,
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&deferred_probe_active_list);
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mutex_unlock(&deferred_probe_mutex);
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/*
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* Kick the re-probe thread. It may already be scheduled, but it is
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* safe to kick it again.
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*/
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queue_work(deferred_wq, &deferred_probe_work);
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}
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/**
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* deferred_probe_initcall() - Enable probing of deferred devices
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*
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* We don't want to get in the way when the bulk of drivers are getting probed.
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* Instead, this initcall makes sure that deferred probing is delayed until
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* late_initcall time.
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*/
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static int deferred_probe_initcall(void)
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{
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deferred_wq = create_singlethread_workqueue("deferwq");
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if (WARN_ON(!deferred_wq))
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return -ENOMEM;
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driver_deferred_probe_enable = true;
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driver_deferred_probe_trigger();
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/* Sort as many dependencies as possible before exiting initcalls */
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flush_workqueue(deferred_wq);
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return 0;
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}
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late_initcall(deferred_probe_initcall);
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static void driver_bound(struct device *dev)
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{
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if (klist_node_attached(&dev->p->knode_driver)) {
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printk(KERN_WARNING "%s: device %s already bound\n",
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__func__, kobject_name(&dev->kobj));
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return;
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}
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pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
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__func__, dev_name(dev));
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klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
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/*
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* Make sure the device is no longer in one of the deferred lists and
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* kick off retrying all pending devices
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*/
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driver_deferred_probe_del(dev);
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driver_deferred_probe_trigger();
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if (dev->bus)
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blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
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BUS_NOTIFY_BOUND_DRIVER, dev);
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}
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static int driver_sysfs_add(struct device *dev)
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{
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int ret;
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if (dev->bus)
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blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
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BUS_NOTIFY_BIND_DRIVER, dev);
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ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
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kobject_name(&dev->kobj));
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if (ret == 0) {
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ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
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"driver");
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if (ret)
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sysfs_remove_link(&dev->driver->p->kobj,
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kobject_name(&dev->kobj));
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}
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return ret;
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}
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static void driver_sysfs_remove(struct device *dev)
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{
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struct device_driver *drv = dev->driver;
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if (drv) {
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sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
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sysfs_remove_link(&dev->kobj, "driver");
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}
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}
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/**
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* device_bind_driver - bind a driver to one device.
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* @dev: device.
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*
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* Allow manual attachment of a driver to a device.
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* Caller must have already set @dev->driver.
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*
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* Note that this does not modify the bus reference count
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* nor take the bus's rwsem. Please verify those are accounted
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* for before calling this. (It is ok to call with no other effort
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* from a driver's probe() method.)
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*
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* This function must be called with the device lock held.
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*/
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int device_bind_driver(struct device *dev)
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{
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int ret;
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ret = driver_sysfs_add(dev);
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if (!ret)
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driver_bound(dev);
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return ret;
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}
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EXPORT_SYMBOL_GPL(device_bind_driver);
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static atomic_t probe_count = ATOMIC_INIT(0);
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static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
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static int really_probe(struct device *dev, struct device_driver *drv)
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{
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int ret = 0;
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int local_trigger_count = atomic_read(&deferred_trigger_count);
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atomic_inc(&probe_count);
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pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
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drv->bus->name, __func__, drv->name, dev_name(dev));
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WARN_ON(!list_empty(&dev->devres_head));
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dev->driver = drv;
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/* If using pinctrl, bind pins now before probing */
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ret = pinctrl_bind_pins(dev);
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if (ret)
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goto probe_failed;
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if (driver_sysfs_add(dev)) {
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printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
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__func__, dev_name(dev));
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goto probe_failed;
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}
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if (dev->pm_domain && dev->pm_domain->activate) {
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ret = dev->pm_domain->activate(dev);
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if (ret)
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goto probe_failed;
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}
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if (dev->bus->probe) {
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ret = dev->bus->probe(dev);
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if (ret)
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goto probe_failed;
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} else if (drv->probe) {
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ret = drv->probe(dev);
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if (ret)
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goto probe_failed;
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}
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if (dev->pm_domain && dev->pm_domain->sync)
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dev->pm_domain->sync(dev);
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driver_bound(dev);
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ret = 1;
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pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
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drv->bus->name, __func__, dev_name(dev), drv->name);
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goto done;
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probe_failed:
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devres_release_all(dev);
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driver_sysfs_remove(dev);
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dev->driver = NULL;
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dev_set_drvdata(dev, NULL);
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if (dev->pm_domain && dev->pm_domain->dismiss)
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dev->pm_domain->dismiss(dev);
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switch (ret) {
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case -EPROBE_DEFER:
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/* Driver requested deferred probing */
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dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
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driver_deferred_probe_add(dev);
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/* Did a trigger occur while probing? Need to re-trigger if yes */
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if (local_trigger_count != atomic_read(&deferred_trigger_count))
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driver_deferred_probe_trigger();
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break;
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case -ENODEV:
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case -ENXIO:
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pr_debug("%s: probe of %s rejects match %d\n",
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drv->name, dev_name(dev), ret);
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break;
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default:
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/* driver matched but the probe failed */
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printk(KERN_WARNING
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"%s: probe of %s failed with error %d\n",
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drv->name, dev_name(dev), ret);
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}
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/*
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* Ignore errors returned by ->probe so that the next driver can try
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* its luck.
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*/
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ret = 0;
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done:
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atomic_dec(&probe_count);
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wake_up(&probe_waitqueue);
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return ret;
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}
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/**
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* driver_probe_done
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* Determine if the probe sequence is finished or not.
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*
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* Should somehow figure out how to use a semaphore, not an atomic variable...
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*/
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int driver_probe_done(void)
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{
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pr_debug("%s: probe_count = %d\n", __func__,
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atomic_read(&probe_count));
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if (atomic_read(&probe_count))
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return -EBUSY;
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return 0;
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}
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/**
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* wait_for_device_probe
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* Wait for device probing to be completed.
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*/
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void wait_for_device_probe(void)
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{
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/* wait for the known devices to complete their probing */
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wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
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async_synchronize_full();
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}
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EXPORT_SYMBOL_GPL(wait_for_device_probe);
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/**
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* driver_probe_device - attempt to bind device & driver together
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* @drv: driver to bind a device to
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* @dev: device to try to bind to the driver
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*
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* This function returns -ENODEV if the device is not registered,
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* 1 if the device is bound successfully and 0 otherwise.
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*
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* This function must be called with @dev lock held. When called for a
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* USB interface, @dev->parent lock must be held as well.
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*/
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int driver_probe_device(struct device_driver *drv, struct device *dev)
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{
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int ret = 0;
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if (!device_is_registered(dev))
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return -ENODEV;
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pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
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drv->bus->name, __func__, dev_name(dev), drv->name);
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pm_runtime_barrier(dev);
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ret = really_probe(dev, drv);
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pm_request_idle(dev);
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return ret;
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}
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static int __device_attach(struct device_driver *drv, void *data)
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{
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struct device *dev = data;
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if (!driver_match_device(drv, dev))
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return 0;
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return driver_probe_device(drv, dev);
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}
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/**
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* device_attach - try to attach device to a driver.
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* @dev: device.
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*
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* Walk the list of drivers that the bus has and call
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* driver_probe_device() for each pair. If a compatible
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* pair is found, break out and return.
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*
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* Returns 1 if the device was bound to a driver;
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* 0 if no matching driver was found;
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* -ENODEV if the device is not registered.
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*
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* When called for a USB interface, @dev->parent lock must be held.
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*/
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int device_attach(struct device *dev)
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{
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int ret = 0;
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device_lock(dev);
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if (dev->driver) {
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if (klist_node_attached(&dev->p->knode_driver)) {
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ret = 1;
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goto out_unlock;
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}
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ret = device_bind_driver(dev);
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if (ret == 0)
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ret = 1;
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else {
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dev->driver = NULL;
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ret = 0;
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}
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} else {
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ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
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pm_request_idle(dev);
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}
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out_unlock:
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device_unlock(dev);
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return ret;
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}
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EXPORT_SYMBOL_GPL(device_attach);
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static int __driver_attach(struct device *dev, void *data)
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{
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struct device_driver *drv = data;
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/*
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* Lock device and try to bind to it. We drop the error
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* here and always return 0, because we need to keep trying
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* to bind to devices and some drivers will return an error
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* simply if it didn't support the device.
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*
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* driver_probe_device() will spit a warning if there
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* is an error.
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*/
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if (!driver_match_device(drv, dev))
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return 0;
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if (dev->parent) /* Needed for USB */
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device_lock(dev->parent);
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device_lock(dev);
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if (!dev->driver)
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driver_probe_device(drv, dev);
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device_unlock(dev);
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if (dev->parent)
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device_unlock(dev->parent);
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return 0;
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}
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/**
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* driver_attach - try to bind driver to devices.
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* @drv: driver.
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*
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* Walk the list of devices that the bus has on it and try to
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* match the driver with each one. If driver_probe_device()
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* returns 0 and the @dev->driver is set, we've found a
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* compatible pair.
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*/
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int driver_attach(struct device_driver *drv)
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{
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return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
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}
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EXPORT_SYMBOL_GPL(driver_attach);
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/*
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* __device_release_driver() must be called with @dev lock held.
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* When called for a USB interface, @dev->parent lock must be held as well.
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*/
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static void __device_release_driver(struct device *dev)
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{
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struct device_driver *drv;
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drv = dev->driver;
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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);
|
|
}
|
|
}
|