[patch update] PM: Introduce core framework for run-time PM of I/O devices (rev. 4)

Rafael J. Wysocki
2009-06-24T00:36:23Z

On Wednesday 24 June 2009, Rafael J. Wysocki wrote:
> On Tuesday 23 June 2009, Alan Stern wrote:
> > On Tue, 23 Jun 2009, Rafael J. Wysocki wrote:
> >
> > > Hi,
> > >
> > > Below is a new revision of the patch introducing the run-time PM framework.
> > >
> > > The most visible changes from the last version:
> > >
> > > * I realized that if child_count is atomic, we can drop the parent locking from
> > > all of the functions, so I did that.
> > >
> > > * Introduced pm_runtime_put() that decrements the resume counter and queues
> > > up an idle notification if the counter went down to 0 (and wasn't 0 previously).
> > > Using asynchronous notification makes it possible to call pm_runtime_put()
> > > from interrupt context, if necessary.
> > >
> > > * Changed the meaning of the RPM_WAKE bit slightly (it is now also used for
> > > disabling run-time PM for a device along with the resume counter).
> > >
> > > Please let me know if I've overlooked anything. :-)
> >
> > This first thing to strike me was that you moved the idle notifications
> > into the workqueue.
>
> Yes, I did.
>
> > Is that really needed? Would we be better off just make the idle
> > callbacks directly from pm_runtime_put? They would run in whatever
> > context the driver happened to be in at the time.
> >
> > It's not clear exactly how much work the idle callbacks will need to
> > do, but it seems likely that they won't have to do too much more than
> > call pm_request_suspend. And of course, that can be done in_interrupt.
>
> I just don't want to put any constraints on the implementation of
> ->runtime_idle(). The requirement that it be suitable for calling from
> interrupt context may be quite inconvenient for some drivers and I'm afraid
> they may have problems with meeting it.

BTW, appended is a new update. Hopefully, the majority of bugs were found
and fixed this time.

I dropped the documentation for now, until the code settles down.

Also, I removed the automatic incrementing and decrementing of resume_count
in __pm_runtime_resume() and pm_request_resume().

Description of RPM_NOTIFY is missing (sorry for that). It's set when idle
notification has been scheduled for the device and reset before running
pm_runtime_idle() by the work function.

Comments welcome.

Best,
Rafael

---
From: Rafael J. Wysocki <rjw@sisk.pl>
Subject: PM: Introduce core framework for run-time PM of I/O devices (rev. 4)

Introduce a core framework for run-time power management of I/O
devices. Add device run-time PM fields to 'struct dev_pm_info'
and device run-time PM callbacks to 'struct dev_pm_ops'. Introduce
a run-time PM workqueue and define some device run-time PM helper
functions at the core level. Document all these things.

Not-yet-signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/base/dd.c | 9
drivers/base/power/Makefile | 1
drivers/base/power/main.c | 16
drivers/base/power/power.h | 11
drivers/base/power/runtime.c | 709 +++++++++++++++++++++++++++++++++++++++++++
include/linux/pm.h | 98 +++++
include/linux/pm_runtime.h | 136 ++++++++
kernel/power/Kconfig | 14
kernel/power/main.c | 17 +
9 files changed, 1001 insertions(+), 10 deletions(-)

Index: linux-2.6/kernel/power/Kconfig
===================================================================
--- linux-2.6.orig/kernel/power/Kconfig
+++ linux-2.6/kernel/power/Kconfig
@@ -208,3 +208,17 @@ config APM_EMULATION
random kernel OOPSes or reboots that don't seem to be related to
anything, try disabling/enabling this option (or disabling/enabling
APM in your BIOS).
+
+config PM_RUNTIME
+ bool "Run-time PM core functionality"
+ depends on PM
+ ---help---
+ Enable functionality allowing I/O devices to be put into energy-saving
+ (low power) states at run time (or autosuspended) after a specified
+ period of inactivity and woken up in response to a hardware-generated
+ wake-up event or a driver's request.
+
+ Hardware support is generally required for this functionality to work
+ and the bus type drivers of the buses the devices are on are
+ responsibile for the actual handling of the autosuspend requests and
+ wake-up events.
Index: linux-2.6/kernel/power/main.c
===================================================================
--- linux-2.6.orig/kernel/power/main.c
+++ linux-2.6/kernel/power/main.c
@@ -11,6 +11,7 @@
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/resume-trace.h>
+#include <linux/workqueue.h>

#include "power.h"

@@ -217,8 +218,24 @@ static struct attribute_group attr_group
.attrs = g,
};

+#ifdef CONFIG_PM_RUNTIME
+struct workqueue_struct *pm_wq;
+
+static int __init pm_start_workqueue(void)
+{
+ pm_wq = create_freezeable_workqueue("pm");
+
+ return pm_wq ? 0 : -ENOMEM;
+}
+#else
+static inline int pm_start_workqueue(void) { return 0; }
+#endif
+
static int __init pm_init(void)
{
+ int error = pm_start_workqueue();
+ if (error)
+ return error;
power_kobj = kobject_create_and_add("power", NULL);
if (!power_kobj)
return -ENOMEM;
Index: linux-2.6/include/linux/pm.h
===================================================================
--- linux-2.6.orig/include/linux/pm.h
+++ linux-2.6/include/linux/pm.h
@@ -22,6 +22,9 @@
#define _LINUX_PM_H

#include <linux/list.h>
+#include <linux/workqueue.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>

/*
* Callbacks for platform drivers to implement.
@@ -165,6 +168,28 @@ typedef struct pm_message {
* It is allowed to unregister devices while the above callbacks are being
* executed. However, it is not allowed to unregister a device from within any
* of its own callbacks.
+ *
+ * There also are the following callbacks related to run-time power management
+ * of devices:
+ *
+ * @runtime_suspend: Prepare the device for a condition in which it won't be
+ * able to communicate with the CPU(s) and RAM due to power management.
+ * This need not mean that the device should be put into a low power state.
+ * For example, if the device is behind a link which is about to be turned
+ * off, the device may remain at full power. Still, if the device does go
+ * to low power and if device_may_wakeup(dev) is true, remote wake-up
+ * (i.e. hardware mechanism allowing the device to request a change of its
+ * power state, such as PCI PME) should be enabled for it.
+ *
+ * @runtime_resume: Put the device into the fully active state in response to a
+ * wake-up event generated by hardware or at a request of software. If
+ * necessary, put the device into the full power state and restore its
+ * registers, so that it is fully operational.
+ *
+ * @runtime_idle: Device appears to be inactive and it might be put into a low
+ * power state if all of the necessary conditions are satisfied. Check
+ * these conditions and handle the device as appropriate, possibly queueing
+ * a suspend request for it.
*/

struct dev_pm_ops {
@@ -182,6 +207,9 @@ struct dev_pm_ops {
int (*thaw_noirq)(struct device *dev);
int (*poweroff_noirq)(struct device *dev);
int (*restore_noirq)(struct device *dev);
+ int (*runtime_suspend)(struct device *dev);
+ int (*runtime_resume)(struct device *dev);
+ void (*runtime_idle)(struct device *dev);
};

/**
@@ -315,14 +343,78 @@ enum dpm_state {
DPM_OFF_IRQ,
};

+/**
+ * Device run-time power management state.
+ *
+ * These state labels are used internally by the PM core to indicate the current
+ * status of a device with respect to the PM core operations. They do not
+ * reflect the actual power state of the device or its status as seen by the
+ * driver.
+ *
+ * RPM_ACTIVE Device is fully operational, no run-time PM requests are
+ * pending for it.
+ *
+ * RPM_IDLE It has been requested that the device be suspended.
+ * Suspend request has been put into the run-time PM
+ * workqueue and it's pending execution.
+ *
+ * RPM_SUSPENDING Device bus type's ->runtime_suspend() callback is being
+ * executed.
+ *
+ * RPM_SUSPENDED Device bus type's ->runtime_suspend() callback has
+ * completed successfully. The device is regarded as
+ * suspended.
+ *
+ * RPM_WAKE It has been requested that the device be woken up.
+ * Resume request has been put into the run-time PM
+ * workqueue and it's pending execution.
+ *
+ * RPM_RESUMING Device bus type's ->runtime_resume() callback is being
+ * executed.
+ *
+ * RPM_ERROR Represents a condition from which the PM core cannot
+ * recover by itself. If the device's run-time PM status
+ * field has this value, all of the run-time PM operations
+ * carried out for the device by the core will fail, until
+ * the status field is changed to either RPM_ACTIVE or
+ * RPM_SUSPENDED (it is not valid to use the other values
+ * in such a situation) by the device's driver or bus type.
+ * This happens when the device bus type's
+ * ->runtime_suspend() or ->runtime_resume() callback
+ * returns error code different from -EAGAIN or -EBUSY.
+ */
+
+#define RPM_ACTIVE 0
+#define RPM_IDLE 0x01
+#define RPM_SUSPENDING 0x02
+#define RPM_SUSPENDED 0x04
+#define RPM_WAKE 0x08
+#define RPM_RESUMING 0x10
+#define RPM_NOTIFY 0x20
+#define RPM_ERROR 0x3F
+
struct dev_pm_info {
pm_message_t power_state;
- unsigned can_wakeup:1;
- unsigned should_wakeup:1;
+ unsigned int can_wakeup:1;
+ unsigned int should_wakeup:1;
enum dpm_state status; /* Owned by the PM core */
-#ifdef CONFIG_PM_SLEEP
+#ifdef CONFIG_PM_SLEEP
struct list_head entry;
#endif
+#ifdef CONFIG_PM_RUNTIME
+ struct delayed_work suspend_work;
+ struct work_struct work;
+ struct completion work_done;
+ unsigned int ignore_children:1;
+ unsigned int runtime_break:1;
+ unsigned int runtime_busy:1;
+ unsigned int runtime_disabled:1;
+ unsigned int runtime_status:6;
+ int runtime_error;
+ atomic_t resume_count;
+ atomic_t child_count;
+ spinlock_t lock;
+#endif
};

/*
Index: linux-2.6/drivers/base/power/Makefile
===================================================================
--- linux-2.6.orig/drivers/base/power/Makefile
+++ linux-2.6/drivers/base/power/Makefile
@@ -1,5 +1,6 @@
obj-$(CONFIG_PM) += sysfs.o
obj-$(CONFIG_PM_SLEEP) += main.o
+obj-$(CONFIG_PM_RUNTIME) += runtime.o
obj-$(CONFIG_PM_TRACE_RTC) += trace.o

ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
Index: linux-2.6/drivers/base/power/runtime.c
===================================================================
--- /dev/null
+++ linux-2.6/drivers/base/power/runtime.c
@@ -0,0 +1,709 @@
+/*
+ * drivers/base/power/runtime.c - Helper functions for device run-time PM
+ *
+ * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/pm_runtime.h>
+#include <linux/jiffies.h>
+
+/**
+ * pm_runtime_idle - Check if device can be suspended and notify its bus type.
+ * @dev: Device to notify.
+ */
+void pm_runtime_idle(struct device *dev)
+{
+ if (!pm_suspend_possible(dev))
+ return;
+
+ if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_idle)
+ dev->bus->pm->runtime_idle(dev);
+}
+EXPORT_SYMBOL_GPL(pm_runtime_idle);
+
+/**
+ * __pm_get_child - Increment the counter of unsuspended children of a device.
+ * @dev: Device to handle;
+ */
+static void __pm_get_child(struct device *dev)
+{
+ atomic_inc(&dev->power.child_count);
+}
+
+/**
+ * __pm_put_child - Decrement the counter of unsuspended children of a device.
+ * @dev: Device to handle;
+ */
+static void __pm_put_child(struct device *dev)
+{
+ if (!atomic_add_unless(&dev->power.child_count, -1, 0))
+ dev_WARN(dev, "Unbalanced counter decrementation");
+}
+
+/**
+ * __pm_runtime_suspend - Run a device bus type's runtime_suspend() callback.
+ * @dev: Device to suspend.
+ * @sync: If unset, the funtion has been called via pm_wq.
+ *
+ * Check if the run-time PM status of the device is appropriate and run the
+ * ->runtime_suspend() callback provided by the device's bus type. Update the
+ * run-time PM flags in the device object to reflect the current status of the
+ * device.
+ */
+int __pm_runtime_suspend(struct device *dev, bool sync)
+{
+ struct device *parent = NULL;
+ unsigned long flags;
+ int error = -EINVAL;
+
+ might_sleep();
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ repeat:
+ if (dev->power.runtime_status == RPM_ERROR) {
+ goto out;
+ } else if (dev->power.runtime_status & RPM_SUSPENDED) {
+ error = 0;
+ goto out;
+ } else if (atomic_read(&dev->power.resume_count) > 0
+ || dev->power.runtime_disabled
+ || (dev->power.runtime_status & (RPM_WAKE|RPM_RESUMING))
+ || (!sync && dev->power.runtime_status == RPM_IDLE
+ && dev->power.runtime_break)) {
+ /*
+ * We're forbidden to suspend the device, it is resuming or has
+ * a resume request pending, or a pending suspend request has
+ * just been cancelled and we're running as a result of that
+ * request.
+ */
+ error = -EAGAIN;
+ goto out;
+ } else if (dev->power.runtime_status & RPM_SUSPENDING) {
+ /* Another suspend is running in parallel with us. */
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ wait_for_completion(&dev->power.work_done);
+
+ return dev->power.runtime_error;
+ } else if (dev->power.runtime_status & RPM_NOTIFY) {
+ /*
+ * Idle notification is pending for the device, so preempt it.
+ * There also may be a suspend request pending, but the idle
+ * notification work function will run earlier, so make it
+ * cancel that request for us.
+ */
+ if (dev->power.runtime_status & RPM_IDLE)
+ dev->power.runtime_status |= RPM_WAKE;
+ dev->power.runtime_break = true;
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ flush_work(&dev->power.work);
+
+ goto repeat;
+ } else if (sync && dev->power.runtime_status == RPM_IDLE
+ && !dev->power.runtime_break) {
+ /*
+ * Suspend request is pending, but we're not running as a result
+ * of that request, so cancel it. Since we're not clearing the
+ * RPM_IDLE bit now, no new suspend requests will be queued up
+ * while the cancelled pending one is waited for.
+ */
+ dev->power.runtime_break = true;
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ cancel_delayed_work_sync(&dev->power.suspend_work);
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ /* Repeat if anyone else has already cleared the status. */
+ if (dev->power.runtime_status != RPM_IDLE
+ || !dev->power.runtime_break)
+ goto repeat;
+
+ dev->power.runtime_break = false;
+ }
+
+ if (!pm_children_suspended(dev)) {
+ /*
+ * We can only suspend the device if all of its children have
+ * been suspended.
+ */
+ dev->power.runtime_status = RPM_ACTIVE;
+ error = -EBUSY;
+ goto out;
+ }
+
+ dev->power.runtime_status = RPM_SUSPENDING;
+ init_completion(&dev->power.work_done);
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_suspend)
+ error = dev->bus->pm->runtime_suspend(dev);
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ switch (error) {
+ case 0:
+ /*
+ * Resume request might have been queued up in the meantime, in
+ * which case the RPM_WAKE bit is also set in runtime_status.
+ */
+ dev->power.runtime_status &= ~RPM_SUSPENDING;
+ dev->power.runtime_status |= RPM_SUSPENDED;
+ break;
+ case -EAGAIN:
+ case -EBUSY:
+ dev->power.runtime_status = RPM_ACTIVE;
+ break;
+ default:
+ dev->power.runtime_status = RPM_ERROR;
+ }
+ dev->power.runtime_error = error;
+ complete_all(&dev->power.work_done);
+
+ if (!error && !(dev->power.runtime_status & RPM_WAKE) && dev->parent)
+ parent = dev->parent;
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ if (parent) {
+ __pm_put_child(parent);
+
+ if (!parent->power.ignore_children)
+ pm_runtime_idle(parent);
+ }
+
+ return error;
+}
+EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
+
+/**
+ * pm_runtime_suspend_work - Run pm_runtime_suspend() for a device.
+ * @work: Work structure used for scheduling the execution of this function.
+ *
+ * Use @work to get the device object the suspend has been scheduled for and
+ * run pm_runtime_suspend() for it.
+ */
+static void pm_runtime_suspend_work(struct work_struct *work)
+{
+ __pm_runtime_suspend(suspend_work_to_device(work), false);
+}
+
+/**
+ * pm_request_suspend - Schedule run-time suspend of given device.
+ * @dev: Device to suspend.
+ * @msec: Time to wait before attempting to suspend the device, in milliseconds.
+ */
+void pm_request_suspend(struct device *dev, unsigned int msec)
+{
+ unsigned long flags;
+ unsigned long delay = msecs_to_jiffies(msec);
+
+ if (atomic_read(&dev->power.resume_count) > 0)
+ return;
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ /* There may be an idle notification in progress, so be careful. */
+ if (!(dev->power.runtime_status & ~RPM_NOTIFY)
+ || dev->power.runtime_disabled)
+ goto out;
+
+ dev->power.runtime_status |= RPM_IDLE;
+ dev->power.runtime_break = false;
+ queue_delayed_work(pm_wq, &dev->power.suspend_work, delay);
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+}
+EXPORT_SYMBOL_GPL(pm_request_suspend);
+
+/**
+ * __pm_runtime_resume - Run a device bus type's runtime_resume() callback.
+ * @dev: Device to resume.
+ * @sync: If unset, the funtion has been called via pm_wq.
+ *
+ * Check if the device is really suspended and run the ->runtime_resume()
+ * callback provided by the device's bus type driver. Update the run-time PM
+ * flags in the device object to reflect the current status of the device. If
+ * runtime suspend is in progress while this function is being run, wait for it
+ * to finish before resuming the device. If runtime suspend is scheduled, but
+ * it hasn't started yet, cancel it and we're done.
+ */
+int __pm_runtime_resume(struct device *dev, bool sync)
+{
+ struct device *parent = dev->parent;
+ unsigned long flags;
+ bool put_parent = false;
+ int error = -EINVAL;
+
+ might_sleep();
+
+ repeat:
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ repeat_locked:
+ if (dev->power.runtime_status == RPM_ERROR) {
+ goto out;
+ } else if (dev->power.runtime_disabled) {
+ error = -EAGAIN;
+ goto out;
+ } else if (dev->power.runtime_status == RPM_ACTIVE) {
+ error = 0;
+ goto out;
+ } else if (dev->power.runtime_status & RPM_NOTIFY) {
+ /*
+ * Device has an idle notification pending, preempt it.
+ * There also may be a suspend request pending, but the idle
+ * notification function will run earlier, so make it cancel
+ * that request for us.
+ */
+ if (dev->power.runtime_status & RPM_IDLE)
+ dev->power.runtime_status |= RPM_WAKE;
+ dev->power.runtime_break = true;
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ flush_work(&dev->power.work);
+ goto repeat;
+ } else if (dev->power.runtime_status == RPM_IDLE
+ && !dev->power.runtime_break) {
+ /* Suspend request is pending, not yet aborted, so cancel it. */
+ dev->power.runtime_break = true;
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ cancel_delayed_work_sync(&dev->power.suspend_work);
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ /* Repeat if anyone else has already changed the status. */
+ if (dev->power.runtime_status != RPM_IDLE
+ || !dev->power.runtime_break)
+ goto repeat_locked;
+
+ /* The RPM_IDLE bit is still set, so clear it and return. */
+ dev->power.runtime_status = RPM_ACTIVE;
+ error = 0;
+ goto out;
+ } else if (sync && (dev->power.runtime_status & RPM_WAKE)) {
+ /* Resume request is pending, so let it run. */
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ flush_work(&dev->power.work);
+ goto repeat;
+ } else if (dev->power.runtime_status & RPM_SUSPENDING) {
+ /*
+ * Suspend is running in parallel with us. Wait for it to
+ * complete and repeat.
+ */
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ wait_for_completion(&dev->power.work_done);
+ goto repeat;
+ } else if (!put_parent && parent
+ && dev->power.runtime_status == RPM_SUSPENDED) {
+ /*
+ * Increase the parent's resume counter and request that it be
+ * woken up if necessary.
+ */
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ __pm_runtime_get(parent);
+ error = pm_runtime_resume(parent);
+ if (error) {
+ __pm_runtime_put(parent);
+ return error;
+ }
+
+ put_parent = true;
+ error = -EINVAL;
+ goto repeat;
+ } else if (dev->power.runtime_status == RPM_RESUMING) {
+ /*
+ * There's another resume running in parallel with us. Wait for
+ * it to complete and return.
+ */
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ wait_for_completion(&dev->power.work_done);
+ error = dev->power.runtime_error;
+ goto out_parent;
+ }
+
+ if (dev->power.runtime_status == RPM_SUSPENDED && parent)
+ __pm_get_child(parent);
+
+ dev->power.runtime_status = RPM_RESUMING;
+ init_completion(&dev->power.work_done);
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ /*
+ * We can decrement the parent's resume counter right now, because it
+ * can't be suspended anyway after the __pm_get_child() above.
+ */
+ if (put_parent) {
+ __pm_runtime_put(parent);
+ put_parent = false;
+ }
+
+ if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_resume)
+ error = dev->bus->pm->runtime_resume(dev);
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ dev->power.runtime_status = error ? RPM_ERROR : RPM_ACTIVE;
+ dev->power.runtime_error = error;
+ complete_all(&dev->power.work_done);
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ out_parent:
+ if (put_parent)
+ __pm_runtime_put(parent);
+
+ if (!sync && !error)
+ pm_runtime_idle(dev);
+
+ return error;
+}
+EXPORT_SYMBOL_GPL(pm_runtime_resume);
+
+/**
+ * pm_runtime_work - Run __pm_runtime_resume() for a device.
+ * @work: Work structure used for scheduling the execution of this function.
+ *
+ * Use @work to get the device object the resume has been scheduled for and run
+ * __pm_runtime_resume() for it.
+ */
+static void pm_runtime_work(struct work_struct *work)
+{
+ __pm_runtime_resume(work_to_device(work), false);
+}
+
+/**
+ * pm_notify_or_cancel_work - Run pm_runtime_idle() or cancel a suspend request.
+ * @work: Work structure used for scheduling the execution of this function.
+ *
+ * Use @work to find a device and either execute pm_runtime_idle() for that
+ * device, or cancel a pending suspend request for it depending on the device's
+ * run-time PM status.
+ */
+static void pm_notify_or_cancel_work(struct work_struct *work)
+{
+ struct device *dev = work_to_device(work);
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ /*
+ * There are three situations in which this function is run. First, if
+ * there's a request to notify the device's bus type that the device is
+ * idle. Second, if there's a request to cancel a pending suspend
+ * request. Finally, if the previous two happen at the same time.
+ * However, we only need to run pm_runtime_idle() in the first
+ * situation, because in the last one the request to suspend being
+ * cancelled must have happened after the request to run idle
+ * notification, which means that runtime_break is set. In addition to
+ * that, runtime_break will be set if synchronous suspend or resume has
+ * run before us.
+ */
+ dev->power.runtime_status &= ~RPM_NOTIFY;
+ if (!dev->power.runtime_break)
+ goto notify;
+
+ if (dev->power.runtime_status == (RPM_IDLE|RPM_WAKE)) {
+ /* We have a suspend request to cancel. */
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ cancel_delayed_work_sync(&dev->power.suspend_work);
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ /* Clear the status if someone else hasn't done it yet. */
+ if (dev->power.runtime_status != (RPM_IDLE|RPM_WAKE)
+ || !dev->power.runtime_break)
+ goto out;
+ }
+
+ dev->power.runtime_status = RPM_ACTIVE;
+ dev->power.runtime_break = false;
+ goto out;
+
+ notify:
+ dev->power.runtime_busy = true;
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ pm_runtime_idle(dev);
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ dev->power.runtime_busy = false;
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+}
+
+/**
+ * pm_request_resume - Schedule run-time resume of given device.
+ * @dev: Device to resume.
+ */
+int pm_request_resume(struct device *dev)
+{
+ struct device *parent = dev->parent;
+ unsigned long flags;
+ int error = 0;
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ if (dev->power.runtime_status == RPM_ERROR) {
+ error = -EINVAL;
+ } else if (dev->power.runtime_disabled) {
+ error = -EAGAIN;
+ } else if (dev->power.runtime_status == RPM_ACTIVE) {
+ error = -EBUSY;
+ } else if (dev->power.runtime_status & RPM_NOTIFY) {
+ /*
+ * Device has an idle notification pending, so make it fail.
+ * It may also have a suspend request pending, but the idle
+ * notification work function will run before it and can cancel
+ * it for us just fine.
+ */
+ dev->power.runtime_status |= RPM_WAKE;
+ dev->power.runtime_break = true;
+ error = -EBUSY;
+ } else if (dev->power.runtime_status & (RPM_WAKE|RPM_RESUMING)) {
+ error = -EINPROGRESS;
+ }
+ if (error)
+ goto out;
+
+ if (dev->power.runtime_status == RPM_IDLE) {
+ error = -EBUSY;
+
+ /* Check if the suspend is being cancelled already. */
+ if (dev->power.runtime_break)
+ goto out;
+
+ /* Suspend request is pending. Queue a request to cancel it. */
+ dev->power.runtime_break = true;
+ INIT_WORK(&dev->power.work, pm_notify_or_cancel_work);
+ goto queue;
+ }
+
+ if (dev->power.runtime_status == RPM_SUSPENDED && parent)
+ __pm_get_child(parent);
+
+ INIT_WORK(&dev->power.work, pm_runtime_work);
+
+ queue:
+ /*
+ * The device may be suspending at the moment or there may be a resume
+ * request pending for it and we can't clear the RPM_SUSPENDING and
+ * RPM_IDLE bits in its runtime_status just yet.
+ */
+ dev->power.runtime_status |= RPM_WAKE;
+ queue_work(pm_wq, &dev->power.work);
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ return error;
+}
+EXPORT_SYMBOL_GPL(pm_request_resume);
+
+/**
+ * pm_runtime_put - Decrement the resume counter and run idle notification.
+ * @dev: Device to handle.
+ *
+ * Decrement the device's resume counter, check if it is possible to suspend the
+ * device and notify its bus type in that case.
+ */
+void pm_runtime_put(struct device *dev)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ if (!__pm_runtime_put(dev)) {
+ dev_WARN(dev, "Unbalanced counter decrementation");
+ goto out;
+ }
+
+ if (!pm_suspend_possible(dev))
+ goto out;
+
+ /* Do not queue up a notification if one is already in progress. */
+ if ((dev->power.runtime_status & RPM_NOTIFY) || dev->power.runtime_busy)
+ goto out;
+
+ /*
+ * The notification is asynchronous so that this function can be called
+ * from interrupt context.
+ */
+ dev->power.runtime_status = RPM_NOTIFY;
+ dev->power.runtime_break = false;
+ INIT_WORK(&dev->power.work, pm_notify_or_cancel_work);
+ queue_work(pm_wq, &dev->power.work);
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+}
+EXPORT_SYMBOL_GPL(pm_runtime_put);
+
+/**
+ * __pm_runtime_clear_status - Change the run-time PM status of a device.
+ * @dev: Device to handle.
+ * @status: New value of the device's run-time PM status.
+ *
+ * Change the run-time PM status of the device to @status, which must be
+ * either RPM_ACTIVE or RPM_SUSPENDED, if its current value is equal to
+ * RPM_ERROR.
+ */
+void __pm_runtime_clear_status(struct device *dev, unsigned int status)
+{
+ struct device *parent = dev->parent;
+ unsigned long flags;
+
+ if (status & ~RPM_SUSPENDED)
+ return;
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ if (dev->power.runtime_status != RPM_ERROR)
+ goto out;
+
+ dev->power.runtime_status = status;
+ if (status == RPM_SUSPENDED && parent)
+ __pm_put_child(parent);
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+}
+EXPORT_SYMBOL_GPL(__pm_runtime_clear_status);
+
+/**
+ * pm_runtime_enable - Enable run-time PM of a device.
+ * @dev: Device to handle.
+ */
+void pm_runtime_enable(struct device *dev)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ if (!dev->power.runtime_disabled)
+ goto out;
+
+ if (!__pm_runtime_put(dev))
+ dev_WARN(dev, "Unbalanced counter decrementation");
+
+ if (!atomic_read(&dev->power.resume_count))
+ dev->power.runtime_disabled = false;
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+}
+EXPORT_SYMBOL_GPL(pm_runtime_enable);
+
+/**
+ * pm_runtime_disable - Disable run-time PM of a device.
+ * @dev: Device to handle.
+ *
+ * Set the power.runtime_disabled flag for the device, cancel all pending
+ * run-time PM requests for it and wait for operations in progress to complete.
+ * The device can be either active or suspended after its run-time PM has been
+ * disabled.
+ */
+void pm_runtime_disable(struct device *dev)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ __pm_runtime_get(dev);
+
+ if (dev->power.runtime_disabled)
+ goto out;
+
+ dev->power.runtime_disabled = true;
+
+ if ((dev->power.runtime_status & (RPM_WAKE|RPM_NOTIFY))
+ || dev->power.runtime_busy) {
+ /* Resume request or idle notification pending. */
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ cancel_work_sync(&dev->power.work);
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ dev->power.runtime_status &= ~(RPM_WAKE|RPM_NOTIFY);
+ dev->power.runtime_busy = false;
+ }
+
+ if (dev->power.runtime_status & RPM_IDLE) {
+ /* Suspend request pending. */
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ cancel_delayed_work_sync(&dev->power.suspend_work);
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ dev->power.runtime_status &= ~RPM_IDLE;
+ } else if (dev->power.runtime_status & (RPM_SUSPENDING|RPM_RESUMING)) {
+ /* Suspend or wake-up in progress. */
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ wait_for_completion(&dev->power.work_done);
+ return;
+ }
+
+ out:
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+}
+EXPORT_SYMBOL_GPL(pm_runtime_disable);
+
+/**
+ * pm_runtime_init - Initialize run-time PM fields in given device object.
+ * @dev: Device object to initialize.
+ */
+void pm_runtime_init(struct device *dev)
+{
+ spin_lock_init(&dev->power.lock);
+
+ dev->power.runtime_status = RPM_ACTIVE;
+ dev->power.runtime_disabled = true;
+ atomic_set(&dev->power.resume_count, 1);
+
+ atomic_set(&dev->power.child_count, 0);
+ pm_suspend_ignore_children(dev, false);
+}
+
+/**
+ * pm_runtime_add - Update run-time PM fields of a device while adding it.
+ * @dev: Device object being added to device hierarchy.
+ */
+void pm_runtime_add(struct device *dev)
+{
+ dev->power.runtime_busy = false;
+ INIT_DELAYED_WORK(&dev->power.suspend_work, pm_runtime_suspend_work);
+
+ if (dev->parent)
+ __pm_get_child(dev->parent);
+}
Index: linux-2.6/include/linux/pm_runtime.h
===================================================================
--- /dev/null
+++ linux-2.6/include/linux/pm_runtime.h
@@ -0,0 +1,136 @@
+/*
+ * pm_runtime.h - Device run-time power management helper functions.
+ *
+ * Copyright (C) 2009 Rafael J. Wysocki <rjw@sisk.pl>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#ifndef _LINUX_PM_RUNTIME_H
+#define _LINUX_PM_RUNTIME_H
+
+#include <linux/device.h>
+#include <linux/pm.h>
+
+#ifdef CONFIG_PM_RUNTIME
+
+extern struct workqueue_struct *pm_wq;
+
+extern void pm_runtime_init(struct device *dev);
+extern void pm_runtime_add(struct device *dev);
+extern void pm_runtime_put(struct device *dev);
+extern void pm_runtime_idle(struct device *dev);
+extern int __pm_runtime_suspend(struct device *dev, bool sync);
+extern void pm_request_suspend(struct device *dev, unsigned int msec);
+extern int __pm_runtime_resume(struct device *dev, bool sync);
+extern int pm_request_resume(struct device *dev);
+extern void __pm_runtime_clear_status(struct device *dev, unsigned int status);
+extern void pm_runtime_enable(struct device *dev);
+extern void pm_runtime_disable(struct device *dev);
+
+static inline struct device *suspend_work_to_device(struct work_struct *work)
+{
+ struct delayed_work *dw = to_delayed_work(work);
+ struct dev_pm_info *dpi;
+
+ dpi = container_of(dw, struct dev_pm_info, suspend_work);
+ return container_of(dpi, struct device, power);
+}
+
+static inline struct device *work_to_device(struct work_struct *work)
+{
+ struct dev_pm_info *dpi;
+
+ dpi = container_of(work, struct dev_pm_info, work);
+ return container_of(dpi, struct device, power);
+}
+
+static inline void __pm_runtime_get(struct device *dev)
+{
+ atomic_inc(&dev->power.resume_count);
+}
+
+static inline bool __pm_runtime_put(struct device *dev)
+{
+ return !!atomic_add_unless(&dev->power.resume_count, -1, 0);
+}
+
+static inline bool pm_children_suspended(struct device *dev)
+{
+ return dev->power.ignore_children
+ || !atomic_read(&dev->power.child_count);
+}
+
+static inline bool pm_suspend_possible(struct device *dev)
+{
+ return pm_children_suspended(dev)
+ && !atomic_read(&dev->power.resume_count)
+ && !(dev->power.runtime_status & ~RPM_NOTIFY)
+ && !dev->power.runtime_disabled;
+}
+
+static inline void pm_suspend_ignore_children(struct device *dev, bool enable)
+{
+ dev->power.ignore_children = enable;
+}
+
+#else /* !CONFIG_PM_RUNTIME */
+
+static inline void pm_runtime_init(struct device *dev) {}
+static inline void pm_runtime_add(struct device *dev) {}
+static inline void pm_runtime_put(struct device *dev) {}
+static inline void pm_runtime_idle(struct device *dev) {}
+static inline int __pm_runtime_suspend(struct device *dev, bool sync)
+{
+ return -ENOSYS;
+}
+static inline void pm_request_suspend(struct device *dev, unsigned int msec) {}
+static inline int __pm_runtime_resume(struct device *dev, bool sync)
+{
+ return -ENOSYS;
+}
+static inline int pm_request_resume(struct device *dev) { return -ENOSYS; }
+static inline void __pm_runtime_clear_status(struct device *dev,
+ unsigned int status) {}
+static inline void pm_runtime_enable(struct device *dev) {}
+static inline void pm_runtime_disable(struct device *dev) {}
+
+static inline void __pm_runtime_get(struct device *dev) {}
+static inline bool __pm_runtime_put(struct device *dev) { return true; }
+static inline bool pm_children_suspended(struct device *dev) { return false; }
+static inline bool pm_suspend_possible(struct device *dev) { return false; }
+static inline void pm_suspend_ignore_children(struct device *dev, bool en) {}
+
+#endif /* !CONFIG_PM_RUNTIME */
+
+static inline void pm_runtime_get(struct device *dev)
+{
+ __pm_runtime_get(dev);
+}
+
+static inline int pm_runtime_suspend(struct device *dev)
+{
+ return __pm_runtime_suspend(dev, true);
+}
+
+static inline int pm_runtime_resume(struct device *dev)
+{
+ return __pm_runtime_resume(dev, true);
+}
+
+static inline void pm_runtime_clear_active(struct device *dev)
+{
+ __pm_runtime_clear_status(dev, RPM_ACTIVE);
+}
+
+static inline void pm_runtime_clear_suspended(struct device *dev)
+{
+ __pm_runtime_clear_status(dev, RPM_SUSPENDED);
+}
+
+static inline void pm_runtime_remove(struct device *dev)
+{
+ pm_runtime_disable(dev);
+}
+
+#endif
Index: linux-2.6/drivers/base/power/main.c
===================================================================
--- linux-2.6.orig/drivers/base/power/main.c
+++ linux-2.6/drivers/base/power/main.c
@@ -21,6 +21,7 @@
#include <linux/kallsyms.h>
#include <linux/mutex.h>
#include <linux/pm.h>
+#include <linux/pm_runtime.h>
#include <linux/resume-trace.h>
#include <linux/rwsem.h>
#include <linux/interrupt.h>
@@ -49,6 +50,16 @@ static DEFINE_MUTEX(dpm_list_mtx);
static bool transition_started;

/**
+ * device_pm_init - Initialize the PM-related part of a device object
+ * @dev: Device object to initialize.
+ */
+void device_pm_init(struct device *dev)
+{
+ dev->power.status = DPM_ON;
+ pm_runtime_init(dev);
+}
+
+/**
* device_pm_lock - lock the list of active devices used by the PM core
*/
void device_pm_lock(void)
@@ -88,6 +99,7 @@ void device_pm_add(struct device *dev)
}

list_add_tail(&dev->power.entry, &dpm_list);
+ pm_runtime_add(dev);
mutex_unlock(&dpm_list_mtx);
}

@@ -104,6 +116,7 @@ void device_pm_remove(struct device *dev
kobject_name(&dev->kobj));
mutex_lock(&dpm_list_mtx);
list_del_init(&dev->power.entry);
+ pm_runtime_remove(dev);
mutex_unlock(&dpm_list_mtx);
}

@@ -507,6 +520,7 @@ static void dpm_complete(pm_message_t st
get_device(dev);
if (dev->power.status > DPM_ON) {
dev->power.status = DPM_ON;
+ pm_runtime_enable(dev);
mutex_unlock(&dpm_list_mtx);

device_complete(dev, state);
@@ -753,6 +767,7 @@ static int dpm_prepare(pm_message_t stat

get_device(dev);
dev->power.status = DPM_PREPARING;
+ pm_runtime_disable(dev);
mutex_unlock(&dpm_list_mtx);

error = device_prepare(dev, state);
@@ -760,6 +775,7 @@ static int dpm_prepare(pm_message_t stat
mutex_lock(&dpm_list_mtx);
if (error) {
dev->power.status = DPM_ON;
+ pm_runtime_enable(dev);
if (error == -EAGAIN) {
put_device(dev);
continue;
Index: linux-2.6/drivers/base/dd.c
===================================================================
--- linux-2.6.orig/drivers/base/dd.c
+++ linux-2.6/drivers/base/dd.c
@@ -23,6 +23,7 @@
#include <linux/kthread.h>
#include <linux/wait.h>
#include <linux/async.h>
+#include <linux/pm_runtime.h>

#include "base.h"
#include "power/power.h"
@@ -202,8 +203,12 @@ int driver_probe_device(struct device_dr
pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
drv->bus->name, __func__, dev_name(dev), drv->name);

+ pm_runtime_disable(dev);
+
ret = really_probe(dev, drv);

+ pm_runtime_enable(dev);
+
return ret;
}

@@ -306,6 +311,8 @@ static void __device_release_driver(stru

drv = dev->driver;
if (drv) {
+ pm_runtime_disable(dev);
+
driver_sysfs_remove(dev);

if (dev->bus)
@@ -320,6 +327,8 @@ static void __device_release_driver(stru
devres_release_all(dev);
dev->driver = NULL;
klist_remove(&dev->p->knode_driver);
+
+ pm_runtime_enable(dev);
}
}

Index: linux-2.6/drivers/base/power/power.h
===================================================================
--- linux-2.6.orig/drivers/base/power/power.h
+++ linux-2.6/drivers/base/power/power.h
@@ -1,8 +1,3 @@
-static inline void device_pm_init(struct device *dev)
-{
- dev->power.status = DPM_ON;
-}
-
#ifdef CONFIG_PM_SLEEP

/*
@@ -16,14 +11,16 @@ static inline struct device *to_device(s
return container_of(entry, struct device, power.entry);
}

+extern void device_pm_init(struct device *dev);
extern void device_pm_add(struct device *);
extern void device_pm_remove(struct device *);
extern void device_pm_move_before(struct device *, struct device *);
extern void device_pm_move_after(struct device *, struct device *);
extern void device_pm_move_last(struct device *);

-#else /* CONFIG_PM_SLEEP */
+#else /* !CONFIG_PM_SLEEP */

+static inline void device_pm_init(struct device *dev) {}
static inline void device_pm_add(struct device *dev) {}
static inline void device_pm_remove(struct device *dev) {}
static inline void device_pm_move_before(struct device *deva,
@@ -32,7 +29,7 @@ static inline void device_pm_move_after(
struct device *devb) {}
static inline void device_pm_move_last(struct device *dev) {}

-#endif
+#endif /* !CONFIG_PM_SLEEP */

#ifdef CONFIG_PM