PM / Sleep: Introduce "late suspend" and "early resume" of devices

The current device suspend/resume phases during system-wide power
transitions appear to be insufficient for some platforms that want
to use the same callback routines for saving device states and
related operations during runtime suspend/resume as well as during
system suspend/resume.  In principle, they could point their
.suspend_noirq() and .resume_noirq() to the same callback routines
as their .runtime_suspend() and .runtime_resume(), respectively,
but at least some of them require device interrupts to be enabled
while the code in those routines is running.

It also makes sense to have device suspend-resume callbacks that will
be executed with runtime PM disabled and with device interrupts
enabled in case someone needs to run some special code in that
context during system-wide power transitions.

Apart from this, .suspend_noirq() and .resume_noirq() were introduced
as a workaround for drivers using shared interrupts and failing to
prevent their interrupt handlers from accessing suspended hardware.
It appears to be better not to use them for other porposes, or we may
have to deal with some serious confusion (which seems to be happening
already).

For the above reasons, introduce new device suspend/resume phases,
"late suspend" and "early resume" (and analogously for hibernation)
whose callback will be executed with runtime PM disabled and with
device interrupts enabled and whose callback pointers generally may
point to runtime suspend/resume routines.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 91784a4..ac1c114 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -42,8 +42,10 @@ enum suspend_stat_step {
 	SUSPEND_FREEZE = 1,
 	SUSPEND_PREPARE,
 	SUSPEND_SUSPEND,
+	SUSPEND_SUSPEND_LATE,
 	SUSPEND_SUSPEND_NOIRQ,
 	SUSPEND_RESUME_NOIRQ,
+	SUSPEND_RESUME_EARLY,
 	SUSPEND_RESUME
 };
 
@@ -53,8 +55,10 @@ struct suspend_stats {
 	int	failed_freeze;
 	int	failed_prepare;
 	int	failed_suspend;
+	int	failed_suspend_late;
 	int	failed_suspend_noirq;
 	int	failed_resume;
+	int	failed_resume_early;
 	int	failed_resume_noirq;
 #define	REC_FAILED_NUM	2
 	int	last_failed_dev;