5 files changed, 107 insertions, 3 deletions

diff --git a/Documentation/power/devices.txt b/Documentation/power/devices.txt
index dd9b49251db3..df1a5cb10c42 100644
--- a/Documentation/power/devices.txt
+++ b/Documentation/power/devices.txt
@@ -1,6 +1,6 @@
 Device Power Management
 
-Copyright (c) 2010 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+Copyright (c) 2010-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
 Copyright (c) 2010 Alan Stern <stern@rowland.harvard.edu>
 
 
@@ -507,6 +507,49 @@ routines.  Nevertheless, different callback pointers are used in case there is a
 situation where it actually matters.
 
 
+Device Power Domains
+--------------------
+Sometimes devices share reference clocks or other power resources.  In those
+cases it generally is not possible to put devices into low-power states
+individually.  Instead, a set of devices sharing a power resource can be put
+into a low-power state together at the same time by turning off the shared
+power resource.  Of course, they also need to be put into the full-power state
+together, by turning the shared power resource on.  A set of devices with this
+property is often referred to as a power domain.
+
+Support for power domains is provided through the pwr_domain field of struct
+device.  This field is a pointer to an object of type struct dev_power_domain,
+defined in include/linux/pm.h, providing a set of power management callbacks
+analogous to the subsystem-level and device driver callbacks that are executed
+for the given device during all power transitions, in addition to the respective
+subsystem-level callbacks.  Specifically, the power domain "suspend" callbacks
+(i.e. ->runtime_suspend(), ->suspend(), ->freeze(), ->poweroff(), etc.) are
+executed after the analogous subsystem-level callbacks, while the power domain
+"resume" callbacks (i.e. ->runtime_resume(), ->resume(), ->thaw(), ->restore,
+etc.) are executed before the analogous subsystem-level callbacks.  Error codes
+returned by the "suspend" and "resume" power domain callbacks are ignored.
+
+Power domain ->runtime_idle() callback is executed before the subsystem-level
+->runtime_idle() callback and the result returned by it is not ignored.  Namely,
+if it returns error code, the subsystem-level ->runtime_idle() callback will not
+be called and the helper function rpm_idle() executing it will return error
+code.  This mechanism is intended to help platforms where saving device state
+is a time consuming operation and should only be carried out if all devices
+in the power domain are idle, before turning off the shared power resource(s).
+Namely, the power domain ->runtime_idle() callback may return error code until
+the pm_runtime_idle() helper (or its asychronous version) has been called for
+all devices in the power domain (it is recommended that the returned error code
+be -EBUSY in those cases), preventing the subsystem-level ->runtime_idle()
+callback from being run prematurely.
+
+The support for device power domains is only relevant to platforms needing to
+use the same subsystem-level (e.g. platform bus type) and device driver power
+management callbacks in many different power domain configurations and wanting
+to avoid incorporating the support for power domains into the subsystem-level
+callbacks.  The other platforms need not implement it or take it into account
+in any way.
+
+
 System Devices
 --------------
 System devices (sysdevs) follow a slightly different API, which can be found in
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index f7a755923751..05b989139b54 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -423,6 +423,11 @@ static int device_resume_noirq(struct device *dev, pm_message_t state)
         TRACE_DEVICE(dev);
         TRACE_RESUME(0);
 
+        if (dev->pwr_domain) {
+                pm_dev_dbg(dev, state, "EARLY power domain ");
+                pm_noirq_op(dev, &dev->pwr_domain->ops, state);
+        }
+
         if (dev->bus && dev->bus->pm) {
                 pm_dev_dbg(dev, state, "EARLY ");
                 error = pm_noirq_op(dev, dev->bus->pm, state);
@@ -518,6 +523,11 @@ static int device_resume(struct device *dev, pm_message_t state, bool async)
 
         dev->power.in_suspend = false;
 
+        if (dev->pwr_domain) {
+                pm_dev_dbg(dev, state, "power domain ");
+                pm_op(dev, &dev->pwr_domain->ops, state);
+        }
+
         if (dev->bus) {
                 if (dev->bus->pm) {
                         pm_dev_dbg(dev, state, "");
@@ -629,6 +639,11 @@ static void device_complete(struct device *dev, pm_message_t state)
 {
         device_lock(dev);
 
+        if (dev->pwr_domain && dev->pwr_domain->ops.complete) {
+                pm_dev_dbg(dev, state, "completing power domain ");
+                dev->pwr_domain->ops.complete(dev);
+        }
+
         if (dev->class && dev->class->pm && dev->class->pm->complete) {
                 pm_dev_dbg(dev, state, "completing class ");
                 dev->class->pm->complete(dev);
@@ -745,6 +760,13 @@ static int device_suspend_noirq(struct device *dev, pm_message_t state)
         if (dev->bus && dev->bus->pm) {
                 pm_dev_dbg(dev, state, "LATE ");
                 error = pm_noirq_op(dev, dev->bus->pm, state);
+                if (error)
+                        goto End;
+        }
+
+        if (dev->pwr_domain) {
+                pm_dev_dbg(dev, state, "LATE power domain ");
+                pm_noirq_op(dev, &dev->pwr_domain->ops, state);
         }
 
 End:
@@ -864,6 +886,13 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
                         pm_dev_dbg(dev, state, "legacy ");
                         error = legacy_suspend(dev, state, dev->bus->suspend);
                 }
+                if (error)
+                        goto End;
+        }
+
+        if (dev->pwr_domain) {
+                pm_dev_dbg(dev, state, "power domain ");
+                pm_op(dev, &dev->pwr_domain->ops, state);
         }
 
  End:
@@ -976,7 +1005,15 @@ static int device_prepare(struct device *dev, pm_message_t state)
                 pm_dev_dbg(dev, state, "preparing class ");
                 error = dev->class->pm->prepare(dev);
                 suspend_report_result(dev->class->pm->prepare, error);
+                if (error)
+                        goto End;
+        }
+
+        if (dev->pwr_domain && dev->pwr_domain->ops.prepare) {
+                pm_dev_dbg(dev, state, "preparing power domain ");
+                dev->pwr_domain->ops.prepare(dev);
         }
+
  End:
         device_unlock(dev);
 
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 42615b419dfb..25edc9a3a489 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -168,6 +168,7 @@ static int rpm_check_suspend_allowed(struct device *dev)
 static int rpm_idle(struct device *dev, int rpmflags)
 {
         int (*callback)(struct device *);
+        int (*domain_callback)(struct device *);
         int retval;
 
         retval = rpm_check_suspend_allowed(dev);
@@ -222,10 +223,19 @@ static int rpm_idle(struct device *dev, int rpmflags)
         else
                 callback = NULL;
 
-        if (callback) {
+        if (dev->pwr_domain)
+                domain_callback = dev->pwr_domain->ops.runtime_idle;
+        else
+                domain_callback = NULL;
+
+        if (callback || domain_callback) {
                 spin_unlock_irq(&dev->power.lock);
 
-                callback(dev);
+                if (domain_callback)
+                        retval = domain_callback(dev);
+
+                if (!retval && callback)
+                        callback(dev);
 
                 spin_lock_irq(&dev->power.lock);
         }
@@ -390,6 +400,8 @@ static int rpm_suspend(struct device *dev, int rpmflags)
                 else
                         pm_runtime_cancel_pending(dev);
         } else {
+                if (dev->pwr_domain)
+                        rpm_callback(dev->pwr_domain->ops.runtime_suspend, dev);
  no_callback:
                 __update_runtime_status(dev, RPM_SUSPENDED);
                 pm_runtime_deactivate_timer(dev);
@@ -569,6 +581,9 @@ static int rpm_resume(struct device *dev, int rpmflags)
 
         __update_runtime_status(dev, RPM_RESUMING);
 
+        if (dev->pwr_domain)
+                rpm_callback(dev->pwr_domain->ops.runtime_resume, dev);
+
         if (dev->bus && dev->bus->pm && dev->bus->pm->runtime_resume)
                 callback = dev->bus->pm->runtime_resume;
         else if (dev->type && dev->type->pm && dev->type->pm->runtime_resume)
diff --git a/include/linux/device.h b/include/linux/device.h
index 1bf5cf0b4513..22e9a8a7e1bc 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -422,6 +422,7 @@ struct device {
         void            *platform_data; /* Platform specific data, device
                                            core doesn't touch it */
         struct dev_pm_info      power;
+        struct dev_power_domain *pwr_domain;
 
 #ifdef CONFIG_NUMA
         int             numa_node;      /* NUMA node this device is close to */
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 1f79c98f1e56..6618216bb973 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -465,6 +465,14 @@ struct dev_pm_info {
 
 extern void update_pm_runtime_accounting(struct device *dev);
 
+/*
+ * Power domains provide callbacks that are executed during system suspend,
+ * hibernation, system resume and during runtime PM transitions along with
+ * subsystem-level and driver-level callbacks.
+ */
+struct dev_power_domain {
+        struct dev_pm_ops       ops;
+};
 
 /*
  * The PM_EVENT_ messages are also used by drivers implementing the legacy