6 files changed, 473 insertions, 14 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-power b/Documentation/ABI/testing/sysfs-devices-power
index 6bb2dd3c3a71..7628cd1bc36a 100644
--- a/Documentation/ABI/testing/sysfs-devices-power
+++ b/Documentation/ABI/testing/sysfs-devices-power
@@ -147,3 +147,21 @@ Description:
                 milliseconds.  This attribute is read-only.  If the device is
                 not enabled to wake up the system from sleep states, this
                 attribute is empty.
+
+What:           /sys/devices/.../power/autosuspend_delay_ms
+Date:           September 2010
+Contact:        Alan Stern <stern@rowland.harvard.edu>
+Description:
+                The /sys/devices/.../power/autosuspend_delay_ms attribute
+                contains the autosuspend delay value (in milliseconds).  Some
+                drivers do not want their device to suspend as soon as it
+                becomes idle at run time; they want the device to remain
+                inactive for a certain minimum period of time first.  That
+                period is called the autosuspend delay.  Negative values will
+                prevent the device from being suspended at run time (similar
+                to writing "on" to the power/control attribute).  Values >=
+                1000 will cause the autosuspend timer expiration to be rounded
+                up to the nearest second.
+
+                Not all drivers support this attribute.  If it isn't supported,
+                attempts to read or write it will yield I/O errors.
diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 9ba49b21ac86..489e9bacd165 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -158,7 +158,8 @@ rules:
     to execute it, the other callbacks will not be executed for the same device.
 
   * A request to execute ->runtime_resume() will cancel any pending or
-    scheduled requests to execute the other callbacks for the same device.
+    scheduled requests to execute the other callbacks for the same device,
+    except for scheduled autosuspends.
 
 3. Run-time PM Device Fields
 
@@ -166,7 +167,7 @@ The following device run-time PM fields are present in 'struct dev_pm_info', as
 defined in include/linux/pm.h:
 
   struct timer_list suspend_timer;
-    - timer used for scheduling (delayed) suspend request
+    - timer used for scheduling (delayed) suspend and autosuspend requests
 
   unsigned long timer_expires;
     - timer expiration time, in jiffies (if this is different from zero, the
@@ -236,6 +237,23 @@ defined in include/linux/pm.h:
       Section 8); it may be modified only by the pm_runtime_no_callbacks()
       helper function
 
+  unsigned int use_autosuspend;
+    - indicates that the device's driver supports delayed autosuspend (see
+      Section 9); it may be modified only by the
+      pm_runtime{_dont}_use_autosuspend() helper functions
+
+  unsigned int timer_autosuspends;
+    - indicates that the PM core should attempt to carry out an autosuspend
+      when the timer expires rather than a normal suspend
+
+  int autosuspend_delay;
+    - the delay time (in milliseconds) to be used for autosuspend
+
+  unsigned long last_busy;
+    - the time (in jiffies) when the pm_runtime_mark_last_busy() helper
+      function was last called for this device; used in calculating inactivity
+      periods for autosuspend
+
 All of the above fields are members of the 'power' member of 'struct device'.
 
 4. Run-time PM Device Helper Functions
@@ -261,6 +279,12 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
       error code on failure, where -EAGAIN or -EBUSY means it is safe to attempt
       to suspend the device again in future
 
+  int pm_runtime_autosuspend(struct device *dev);
+    - same as pm_runtime_suspend() except that the autosuspend delay is taken
+      into account; if pm_runtime_autosuspend_expiration() says the delay has
+      not yet expired then an autosuspend is scheduled for the appropriate time
+      and 0 is returned
+
   int pm_runtime_resume(struct device *dev);
     - execute the subsystem-level resume callback for the device; returns 0 on
       success, 1 if the device's run-time PM status was already 'active' or
@@ -273,6 +297,11 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
       device (the request is represented by a work item in pm_wq); returns 0 on
       success or error code if the request has not been queued up
 
+  int pm_request_autosuspend(struct device *dev);
+    - schedule the execution of the subsystem-level suspend callback for the
+      device when the autosuspend delay has expired; if the delay has already
+      expired then the work item is queued up immediately
+
   int pm_schedule_suspend(struct device *dev, unsigned int delay);
     - schedule the execution of the subsystem-level suspend callback for the
       device in future, where 'delay' is the time to wait before queuing up a
@@ -304,12 +333,20 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
     - decrement the device's usage counter
 
   int pm_runtime_put(struct device *dev);
-    - decrement the device's usage counter, run pm_request_idle(dev) and return
-      its result
+    - decrement the device's usage counter; if the result is 0 then run
+      pm_request_idle(dev) and return its result
+
+  int pm_runtime_put_autosuspend(struct device *dev);
+    - decrement the device's usage counter; if the result is 0 then run
+      pm_request_autosuspend(dev) and return its result
 
   int pm_runtime_put_sync(struct device *dev);
-    - decrement the device's usage counter, run pm_runtime_idle(dev) and return
-      its result
+    - decrement the device's usage counter; if the result is 0 then run
+      pm_runtime_idle(dev) and return its result
+
+  int pm_runtime_put_sync_autosuspend(struct device *dev);
+    - decrement the device's usage counter; if the result is 0 then run
+      pm_runtime_autosuspend(dev) and return its result
 
   void pm_runtime_enable(struct device *dev);
     - enable the run-time PM helper functions to run the device bus type's
@@ -360,19 +397,46 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
       PM attributes from /sys/devices/.../power (or prevent them from being
       added when the device is registered)
 
+  void pm_runtime_mark_last_busy(struct device *dev);
+    - set the power.last_busy field to the current time
+
+  void pm_runtime_use_autosuspend(struct device *dev);
+    - set the power.use_autosuspend flag, enabling autosuspend delays
+
+  void pm_runtime_dont_use_autosuspend(struct device *dev);
+    - clear the power.use_autosuspend flag, disabling autosuspend delays
+
+  void pm_runtime_set_autosuspend_delay(struct device *dev, int delay);
+    - set the power.autosuspend_delay value to 'delay' (expressed in
+      milliseconds); if 'delay' is negative then run-time suspends are
+      prevented
+
+  unsigned long pm_runtime_autosuspend_expiration(struct device *dev);
+    - calculate the time when the current autosuspend delay period will expire,
+      based on power.last_busy and power.autosuspend_delay; if the delay time
+      is 1000 ms or larger then the expiration time is rounded up to the
+      nearest second; returns 0 if the delay period has already expired or
+      power.use_autosuspend isn't set, otherwise returns the expiration time
+      in jiffies
+
 It is safe to execute the following helper functions from interrupt context:
 
 pm_request_idle()
+pm_request_autosuspend()
 pm_schedule_suspend()
 pm_request_resume()
 pm_runtime_get_noresume()
 pm_runtime_get()
 pm_runtime_put_noidle()
 pm_runtime_put()
+pm_runtime_put_autosuspend()
+pm_runtime_enable()
 pm_suspend_ignore_children()
 pm_runtime_set_active()
 pm_runtime_set_suspended()
-pm_runtime_enable()
+pm_runtime_suspended()
+pm_runtime_mark_last_busy()
+pm_runtime_autosuspend_expiration()
 
 5. Run-time PM Initialization, Device Probing and Removal
 
@@ -561,3 +625,115 @@ As a consequence, the PM core will never directly inform the device's subsystem
 or driver about run-time power changes.  Instead, the driver for the device's
 parent must take responsibility for telling the device's driver when the
 parent's power state changes.
+
+9. Autosuspend, or automatically-delayed suspends
+
+Changing a device's power state isn't free; it requires both time and energy.
+A device should be put in a low-power state only when there's some reason to
+think it will remain in that state for a substantial time.  A common heuristic
+says that a device which hasn't been used for a while is liable to remain
+unused; following this advice, drivers should not allow devices to be suspended
+at run-time until they have been inactive for some minimum period.  Even when
+the heuristic ends up being non-optimal, it will still prevent devices from
+"bouncing" too rapidly between low-power and full-power states.
+
+The term "autosuspend" is an historical remnant.  It doesn't mean that the
+device is automatically suspended (the subsystem or driver still has to call
+the appropriate PM routines); rather it means that run-time suspends will
+automatically be delayed until the desired period of inactivity has elapsed.
+
+Inactivity is determined based on the power.last_busy field.  Drivers should
+call pm_runtime_mark_last_busy() to update this field after carrying out I/O,
+typically just before calling pm_runtime_put_autosuspend().  The desired length
+of the inactivity period is a matter of policy.  Subsystems can set this length
+initially by calling pm_runtime_set_autosuspend_delay(), but after device
+registration the length should be controlled by user space, using the
+/sys/devices/.../power/autosuspend_delay_ms attribute.
+
+In order to use autosuspend, subsystems or drivers must call
+pm_runtime_use_autosuspend() (preferably before registering the device), and
+thereafter they should use the various *_autosuspend() helper functions instead
+of the non-autosuspend counterparts:
+
+        Instead of: pm_runtime_suspend    use: pm_runtime_autosuspend;
+        Instead of: pm_schedule_suspend   use: pm_request_autosuspend;
+        Instead of: pm_runtime_put        use: pm_runtime_put_autosuspend;
+        Instead of: pm_runtime_put_sync   use: pm_runtime_put_sync_autosuspend.
+
+Drivers may also continue to use the non-autosuspend helper functions; they
+will behave normally, not taking the autosuspend delay into account.
+Similarly, if the power.use_autosuspend field isn't set then the autosuspend
+helper functions will behave just like the non-autosuspend counterparts.
+
+The implementation is well suited for asynchronous use in interrupt contexts.
+However such use inevitably involves races, because the PM core can't
+synchronize ->runtime_suspend() callbacks with the arrival of I/O requests.
+This synchronization must be handled by the driver, using its private lock.
+Here is a schematic pseudo-code example:
+
+        foo_read_or_write(struct foo_priv *foo, void *data)
+        {
+                lock(&foo->private_lock);
+                add_request_to_io_queue(foo, data);
+                if (foo->num_pending_requests++ == 0)
+                        pm_runtime_get(&foo->dev);
+                if (!foo->is_suspended)
+                        foo_process_next_request(foo);
+                unlock(&foo->private_lock);
+        }
+
+        foo_io_completion(struct foo_priv *foo, void *req)
+        {
+                lock(&foo->private_lock);
+                if (--foo->num_pending_requests == 0) {
+                        pm_runtime_mark_last_busy(&foo->dev);
+                        pm_runtime_put_autosuspend(&foo->dev);
+                } else {
+                        foo_process_next_request(foo);
+                }
+                unlock(&foo->private_lock);
+                /* Send req result back to the user ... */
+        }
+
+        int foo_runtime_suspend(struct device *dev)
+        {
+                struct foo_priv foo = container_of(dev, ...);
+                int ret = 0;
+
+                lock(&foo->private_lock);
+                if (foo->num_pending_requests > 0) {
+                        ret = -EBUSY;
+                } else {
+                        /* ... suspend the device ... */
+                        foo->is_suspended = 1;
+                }
+                unlock(&foo->private_lock);
+                return ret;
+        }
+
+        int foo_runtime_resume(struct device *dev)
+        {
+                struct foo_priv foo = container_of(dev, ...);
+
+                lock(&foo->private_lock);
+                /* ... resume the device ... */
+                foo->is_suspended = 0;
+                pm_runtime_mark_last_busy(&foo->dev);
+                if (foo->num_pending_requests > 0)
+                        foo_process_requests(foo);
+                unlock(&foo->private_lock);
+                return 0;
+        }
+
+The important point is that after foo_io_completion() asks for an autosuspend,
+the foo_runtime_suspend() callback may race with foo_read_or_write().
+Therefore foo_runtime_suspend() has to check whether there are any pending I/O
+requests (while holding the private lock) before allowing the suspend to
+proceed.
+
+In addition, the power.autosuspend_delay field can be changed by user space at
+any time.  If a driver cares about this, it can call
+pm_runtime_autosuspend_expiration() from within the ->runtime_suspend()
+callback while holding its private lock.  If the function returns a nonzero
+value then the delay has not yet expired and the callback should return
+-EAGAIN.
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 5bd4daa93ef1..cd4e100a1362 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -9,7 +9,6 @@
 
 #include <linux/sched.h>
 #include <linux/pm_runtime.h>
-#include <linux/jiffies.h>
 #include "power.h"
 
 static int rpm_resume(struct device *dev, int rpmflags);
@@ -79,6 +78,53 @@ static void pm_runtime_cancel_pending(struct device *dev)
         dev->power.request = RPM_REQ_NONE;
 }
 
+/*
+ * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
+ * @dev: Device to handle.
+ *
+ * Compute the autosuspend-delay expiration time based on the device's
+ * power.last_busy time.  If the delay has already expired or is disabled
+ * (negative) or the power.use_autosuspend flag isn't set, return 0.
+ * Otherwise return the expiration time in jiffies (adjusted to be nonzero).
+ *
+ * This function may be called either with or without dev->power.lock held.
+ * Either way it can be racy, since power.last_busy may be updated at any time.
+ */
+unsigned long pm_runtime_autosuspend_expiration(struct device *dev)
+{
+        int autosuspend_delay;
+        long elapsed;
+        unsigned long last_busy;
+        unsigned long expires = 0;
+
+        if (!dev->power.use_autosuspend)
+                goto out;
+
+        autosuspend_delay = ACCESS_ONCE(dev->power.autosuspend_delay);
+        if (autosuspend_delay < 0)
+                goto out;
+
+        last_busy = ACCESS_ONCE(dev->power.last_busy);
+        elapsed = jiffies - last_busy;
+        if (elapsed < 0)
+                goto out;       /* jiffies has wrapped around. */
+
+        /*
+         * If the autosuspend_delay is >= 1 second, align the timer by rounding
+         * up to the nearest second.
+         */
+        expires = last_busy + msecs_to_jiffies(autosuspend_delay);
+        if (autosuspend_delay >= 1000)
+                expires = round_jiffies(expires);
+        expires += !expires;
+        if (elapsed >= expires - last_busy)
+                expires = 0;    /* Already expired. */
+
+ out:
+        return expires;
+}
+EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
+
 /**
  * rpm_check_suspend_allowed - Test whether a device may be suspended.
  * @dev: Device to test.
@@ -234,6 +280,32 @@ static int rpm_suspend(struct device *dev, int rpmflags)
         if (retval)
                 goto out;
 
+        /* If the autosuspend_delay time hasn't expired yet, reschedule. */
+        if ((rpmflags & RPM_AUTO)
+            && dev->power.runtime_status != RPM_SUSPENDING) {
+                unsigned long expires = pm_runtime_autosuspend_expiration(dev);
+
+                if (expires != 0) {
+                        /* Pending requests need to be canceled. */
+                        dev->power.request = RPM_REQ_NONE;
+
+                        /*
+                         * Optimization: If the timer is already running and is
+                         * set to expire at or before the autosuspend delay,
+                         * avoid the overhead of resetting it.  Just let it
+                         * expire; pm_suspend_timer_fn() will take care of the
+                         * rest.
+                         */
+                        if (!(dev->power.timer_expires && time_before_eq(
+                            dev->power.timer_expires, expires))) {
+                                dev->power.timer_expires = expires;
+                                mod_timer(&dev->power.suspend_timer, expires);
+                        }
+                        dev->power.timer_autosuspends = 1;
+                        goto out;
+                }
+        }
+
         /* Other scheduled or pending requests need to be canceled. */
         pm_runtime_cancel_pending(dev);
 
@@ -268,7 +340,8 @@ static int rpm_suspend(struct device *dev, int rpmflags)
 
         /* Carry out an asynchronous or a synchronous suspend. */
         if (rpmflags & RPM_ASYNC) {
-                dev->power.request = RPM_REQ_SUSPEND;
+                dev->power.request = (rpmflags & RPM_AUTO) ?
+                    RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
                 if (!dev->power.request_pending) {
                         dev->power.request_pending = true;
                         queue_work(pm_wq, &dev->power.work);
@@ -383,8 +456,15 @@ static int rpm_resume(struct device *dev, int rpmflags)
         if (retval)
                 goto out;
 
-        /* Other scheduled or pending requests need to be canceled. */
-        pm_runtime_cancel_pending(dev);
+        /*
+         * Other scheduled or pending requests need to be canceled.  Small
+         * optimization: If an autosuspend timer is running, leave it running
+         * rather than cancelling it now only to restart it again in the near
+         * future.
+         */
+        dev->power.request = RPM_REQ_NONE;
+        if (!dev->power.timer_autosuspends)
+                pm_runtime_deactivate_timer(dev);
 
         if (dev->power.runtime_status == RPM_ACTIVE) {
                 retval = 1;
@@ -568,6 +648,9 @@ static void pm_runtime_work(struct work_struct *work)
         case RPM_REQ_SUSPEND:
                 rpm_suspend(dev, RPM_NOWAIT);
                 break;
+        case RPM_REQ_AUTOSUSPEND:
+                rpm_suspend(dev, RPM_NOWAIT | RPM_AUTO);
+                break;
         case RPM_REQ_RESUME:
                 rpm_resume(dev, RPM_NOWAIT);
                 break;
@@ -595,7 +678,8 @@ static void pm_suspend_timer_fn(unsigned long data)
         /* If 'expire' is after 'jiffies' we've been called too early. */
         if (expires > 0 && !time_after(expires, jiffies)) {
                 dev->power.timer_expires = 0;
-                rpm_suspend(dev, RPM_ASYNC);
+                rpm_suspend(dev, dev->power.timer_autosuspends ?
+                    (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC);
         }
 
         spin_unlock_irqrestore(&dev->power.lock, flags);
@@ -627,6 +711,7 @@ int pm_schedule_suspend(struct device *dev, unsigned int delay)
 
         dev->power.timer_expires = jiffies + msecs_to_jiffies(delay);
         dev->power.timer_expires += !dev->power.timer_expires;
+        dev->power.timer_autosuspends = 0;
         mod_timer(&dev->power.suspend_timer, dev->power.timer_expires);
 
  out:
@@ -670,7 +755,9 @@ EXPORT_SYMBOL_GPL(__pm_runtime_idle);
  * @dev: Device to suspend.
  * @rpmflags: Flag bits.
  *
- * Carry out a suspend, either synchronous or asynchronous.
+ * If the RPM_GET_PUT flag is set, decrement the device's usage count and
+ * return immediately if it is larger than zero.  Then carry out a suspend,
+ * either synchronous or asynchronous.
  *
  * This routine may be called in atomic context if the RPM_ASYNC flag is set.
  */
@@ -679,6 +766,11 @@ int __pm_runtime_suspend(struct device *dev, int rpmflags)
         unsigned long flags;
         int retval;
 
+        if (rpmflags & RPM_GET_PUT) {
+                if (!atomic_dec_and_test(&dev->power.usage_count))
+                        return 0;
+        }
+
         spin_lock_irqsave(&dev->power.lock, flags);
         retval = rpm_suspend(dev, rpmflags);
         spin_unlock_irqrestore(&dev->power.lock, flags);
@@ -980,7 +1072,7 @@ void pm_runtime_allow(struct device *dev)
 
         dev->power.runtime_auto = true;
         if (atomic_dec_and_test(&dev->power.usage_count))
-                rpm_idle(dev, 0);
+                rpm_idle(dev, RPM_AUTO);
 
  out:
         spin_unlock_irq(&dev->power.lock);
@@ -1007,6 +1099,86 @@ void pm_runtime_no_callbacks(struct device *dev)
 EXPORT_SYMBOL_GPL(pm_runtime_no_callbacks);
 
 /**
+ * update_autosuspend - Handle a change to a device's autosuspend settings.
+ * @dev: Device to handle.
+ * @old_delay: The former autosuspend_delay value.
+ * @old_use: The former use_autosuspend value.
+ *
+ * Prevent runtime suspend if the new delay is negative and use_autosuspend is
+ * set; otherwise allow it.  Send an idle notification if suspends are allowed.
+ *
+ * This function must be called under dev->power.lock with interrupts disabled.
+ */
+static void update_autosuspend(struct device *dev, int old_delay, int old_use)
+{
+        int delay = dev->power.autosuspend_delay;
+
+        /* Should runtime suspend be prevented now? */
+        if (dev->power.use_autosuspend && delay < 0) {
+
+                /* If it used to be allowed then prevent it. */
+                if (!old_use || old_delay >= 0) {
+                        atomic_inc(&dev->power.usage_count);
+                        rpm_resume(dev, 0);
+                }
+        }
+
+        /* Runtime suspend should be allowed now. */
+        else {
+
+                /* If it used to be prevented then allow it. */
+                if (old_use && old_delay < 0)
+                        atomic_dec(&dev->power.usage_count);
+
+                /* Maybe we can autosuspend now. */
+                rpm_idle(dev, RPM_AUTO);
+        }
+}
+
+/**
+ * pm_runtime_set_autosuspend_delay - Set a device's autosuspend_delay value.
+ * @dev: Device to handle.
+ * @delay: Value of the new delay in milliseconds.
+ *
+ * Set the device's power.autosuspend_delay value.  If it changes to negative
+ * and the power.use_autosuspend flag is set, prevent run-time suspends.  If it
+ * changes the other way, allow run-time suspends.
+ */
+void pm_runtime_set_autosuspend_delay(struct device *dev, int delay)
+{
+        int old_delay, old_use;
+
+        spin_lock_irq(&dev->power.lock);
+        old_delay = dev->power.autosuspend_delay;
+        old_use = dev->power.use_autosuspend;
+        dev->power.autosuspend_delay = delay;
+        update_autosuspend(dev, old_delay, old_use);
+        spin_unlock_irq(&dev->power.lock);
+}
+EXPORT_SYMBOL_GPL(pm_runtime_set_autosuspend_delay);
+
+/**
+ * __pm_runtime_use_autosuspend - Set a device's use_autosuspend flag.
+ * @dev: Device to handle.
+ * @use: New value for use_autosuspend.
+ *
+ * Set the device's power.use_autosuspend flag, and allow or prevent run-time
+ * suspends as needed.
+ */
+void __pm_runtime_use_autosuspend(struct device *dev, bool use)
+{
+        int old_delay, old_use;
+
+        spin_lock_irq(&dev->power.lock);
+        old_delay = dev->power.autosuspend_delay;
+        old_use = dev->power.use_autosuspend;
+        dev->power.use_autosuspend = use;
+        update_autosuspend(dev, old_delay, old_use);
+        spin_unlock_irq(&dev->power.lock);
+}
+EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend);
+
+/**
  * pm_runtime_init - Initialize run-time PM fields in given device object.
  * @dev: Device object to initialize.
  */
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index b5708c47ce2d..0b1e46bf3e56 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -75,6 +75,18 @@
  *      attribute is set to "enabled" by bus type code or device drivers and in
  *      that cases it should be safe to leave the default value.
  *
+ *      autosuspend_delay_ms - Report/change a device's autosuspend_delay value
+ *
+ *      Some drivers don't want to carry out a runtime suspend as soon as a
+ *      device becomes idle; they want it always to remain idle for some period
+ *      of time before suspending it.  This period is the autosuspend_delay
+ *      value (expressed in milliseconds) and it can be controlled by the user.
+ *      If the value is negative then the device will never be runtime
+ *      suspended.
+ *
+ *      NOTE: The autosuspend_delay_ms attribute and the autosuspend_delay
+ *      value are used only if the driver calls pm_runtime_use_autosuspend().
+ *
  *      wakeup_count - Report the number of wakeup events related to the device
  */
 
@@ -173,6 +185,33 @@ static ssize_t rtpm_status_show(struct device *dev,
 }
 
 static DEVICE_ATTR(runtime_status, 0444, rtpm_status_show, NULL);
+
+static ssize_t autosuspend_delay_ms_show(struct device *dev,
+                struct device_attribute *attr, char *buf)
+{
+        if (!dev->power.use_autosuspend)
+                return -EIO;
+        return sprintf(buf, "%d\n", dev->power.autosuspend_delay);
+}
+
+static ssize_t autosuspend_delay_ms_store(struct device *dev,
+                struct device_attribute *attr, const char *buf, size_t n)
+{
+        long delay;
+
+        if (!dev->power.use_autosuspend)
+                return -EIO;
+
+        if (strict_strtol(buf, 10, &delay) != 0 || delay != (int) delay)
+                return -EINVAL;
+
+        pm_runtime_set_autosuspend_delay(dev, delay);
+        return n;
+}
+
+static DEVICE_ATTR(autosuspend_delay_ms, 0644, autosuspend_delay_ms_show,
+                autosuspend_delay_ms_store);
+
 #endif
 
 static ssize_t
@@ -428,6 +467,7 @@ static struct attribute *runtime_attrs[] = {
         &dev_attr_control.attr,
         &dev_attr_runtime_suspended_time.attr,
         &dev_attr_runtime_active_time.attr,
+        &dev_attr_autosuspend_delay_ms.attr,
         NULL,
 };
 static struct attribute_group pm_runtime_attr_group = {
diff --git a/include/linux/pm.h b/include/linux/pm.h
index abd81ffaba3c..40f3f45702ba 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -444,6 +444,9 @@ enum rpm_status {
  *
  * RPM_REQ_SUSPEND      Run the device bus type's ->runtime_suspend() callback
  *
+ * RPM_REQ_AUTOSUSPEND  Same as RPM_REQ_SUSPEND, but not until the device has
+ *                      been inactive for as long as power.autosuspend_delay
+ *
  * RPM_REQ_RESUME       Run the device bus type's ->runtime_resume() callback
  */
 
@@ -451,6 +454,7 @@ enum rpm_request {
         RPM_REQ_NONE = 0,
         RPM_REQ_IDLE,
         RPM_REQ_SUSPEND,
+        RPM_REQ_AUTOSUSPEND,
         RPM_REQ_RESUME,
 };
 
@@ -482,9 +486,13 @@ struct dev_pm_info {
         unsigned int            run_wake:1;
         unsigned int            runtime_auto:1;
         unsigned int            no_callbacks:1;
+        unsigned int            use_autosuspend:1;
+        unsigned int            timer_autosuspends:1;
         enum rpm_request        request;
         enum rpm_status         runtime_status;
         int                     runtime_error;
+        int                     autosuspend_delay;
+        unsigned long           last_busy;
         unsigned long           active_jiffies;
         unsigned long           suspended_jiffies;
         unsigned long           accounting_timestamp;
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 8ca52f7c357e..99ed1aa8f933 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -12,12 +12,15 @@
 #include <linux/device.h>
 #include <linux/pm.h>
 
+#include <linux/jiffies.h>
+
 /* Runtime PM flag argument bits */
 #define RPM_ASYNC               0x01    /* Request is asynchronous */
 #define RPM_NOWAIT              0x02    /* Don't wait for concurrent
                                             state change */
 #define RPM_GET_PUT             0x04    /* Increment/decrement the
                                             usage_count */
+#define RPM_AUTO                0x08    /* Use autosuspend_delay */
 
 #ifdef CONFIG_PM_RUNTIME
 
@@ -37,6 +40,9 @@ extern int pm_generic_runtime_idle(struct device *dev);
 extern int pm_generic_runtime_suspend(struct device *dev);
 extern int pm_generic_runtime_resume(struct device *dev);
 extern void pm_runtime_no_callbacks(struct device *dev);
+extern void __pm_runtime_use_autosuspend(struct device *dev, bool use);
+extern void pm_runtime_set_autosuspend_delay(struct device *dev, int delay);
+extern unsigned long pm_runtime_autosuspend_expiration(struct device *dev);
 
 static inline bool pm_children_suspended(struct device *dev)
 {
@@ -74,6 +80,11 @@ static inline bool pm_runtime_suspended(struct device *dev)
         return dev->power.runtime_status == RPM_SUSPENDED;
 }
 
+static inline void pm_runtime_mark_last_busy(struct device *dev)
+{
+        ACCESS_ONCE(dev->power.last_busy) = jiffies;
+}
+
 #else /* !CONFIG_PM_RUNTIME */
 
 static inline int __pm_runtime_idle(struct device *dev, int rpmflags)
@@ -113,6 +124,14 @@ static inline int pm_generic_runtime_suspend(struct device *dev) { return 0; }
 static inline int pm_generic_runtime_resume(struct device *dev) { return 0; }
 static inline void pm_runtime_no_callbacks(struct device *dev) {}
 
+static inline void pm_runtime_mark_last_busy(struct device *dev) {}
+static inline void __pm_runtime_use_autosuspend(struct device *dev,
+                                                bool use) {}
+static inline void pm_runtime_set_autosuspend_delay(struct device *dev,
+                                                int delay) {}
+static inline unsigned long pm_runtime_autosuspend_expiration(
+                                struct device *dev) { return 0; }
+
 #endif /* !CONFIG_PM_RUNTIME */
 
 static inline int pm_runtime_idle(struct device *dev)
@@ -125,6 +144,11 @@ static inline int pm_runtime_suspend(struct device *dev)
         return __pm_runtime_suspend(dev, 0);
 }
 
+static inline int pm_runtime_autosuspend(struct device *dev)
+{
+        return __pm_runtime_suspend(dev, RPM_AUTO);
+}
+
 static inline int pm_runtime_resume(struct device *dev)
 {
         return __pm_runtime_resume(dev, 0);
@@ -155,11 +179,22 @@ static inline int pm_runtime_put(struct device *dev)
         return __pm_runtime_idle(dev, RPM_GET_PUT | RPM_ASYNC);
 }
 
+static inline int pm_runtime_put_autosuspend(struct device *dev)
+{
+        return __pm_runtime_suspend(dev,
+            RPM_GET_PUT | RPM_ASYNC | RPM_AUTO);
+}
+
 static inline int pm_runtime_put_sync(struct device *dev)
 {
         return __pm_runtime_idle(dev, RPM_GET_PUT);
 }
 
+static inline int pm_runtime_put_sync_autosuspend(struct device *dev)
+{
+        return __pm_runtime_suspend(dev, RPM_GET_PUT | RPM_AUTO);
+}
+
 static inline int pm_runtime_set_active(struct device *dev)
 {
         return __pm_runtime_set_status(dev, RPM_ACTIVE);
@@ -175,4 +210,14 @@ static inline void pm_runtime_disable(struct device *dev)
         __pm_runtime_disable(dev, true);
 }
 
+static inline void pm_runtime_use_autosuspend(struct device *dev)
+{
+        __pm_runtime_use_autosuspend(dev, true);
+}
+
+static inline void pm_runtime_dont_use_autosuspend(struct device *dev)
+{
+        __pm_runtime_use_autosuspend(dev, false);
+}
+
 #endif