PM / Runtime: Add synchronous runtime interface for interrupt handlers (v3)

This patch (as1431c) makes the synchronous runtime-PM interface
suitable for use in interrupt handlers.  Subsystems can call the new
pm_runtime_irq_safe() function to tell the PM core that a device's
runtime_suspend and runtime_resume callbacks should be invoked with
interrupts disabled and the spinlock held.  This permits the
pm_runtime_get_sync() and the new pm_runtime_put_sync_suspend()
routines to be called from within interrupt handlers.

When a device is declared irq-safe in this way, the PM core increments
the parent's usage count, so the parent will never be runtime
suspended.  This prevents difficult situations in which an irq-safe
device can't resume because it is forced to wait for its non-irq-safe
parent.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

2 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/pm.h b/include/linux/pm.h
index 40f3f45702ba..61f2066e6852 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -486,6 +486,7 @@ struct dev_pm_info {
         unsigned int            run_wake:1;
         unsigned int            runtime_auto:1;
         unsigned int            no_callbacks:1;
+        unsigned int            irq_safe:1;
         unsigned int            use_autosuspend:1;
         unsigned int            timer_autosuspends:1;
         enum rpm_request        request;
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index d19f1cca7f74..e9cc049ccb62 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -40,6 +40,7 @@ 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_irq_safe(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);
@@ -124,6 +125,7 @@ static inline int pm_generic_runtime_idle(struct device *dev) { return 0; }
 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_irq_safe(struct device *dev) {}
 
 static inline void pm_runtime_mark_last_busy(struct device *dev) {}
 static inline void __pm_runtime_use_autosuspend(struct device *dev,
@@ -196,6 +198,11 @@ 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_suspend(struct device *dev)
+{
+        return __pm_runtime_suspend(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);