PM / Core: Introduce struct syscore_ops for core subsystems PM

Some subsystems need to carry out suspend/resume and shutdown
operations with one CPU on-line and interrupts disabled.  The only
way to register such operations is to define a sysdev class and
a sysdev specifically for this purpose which is cumbersome and
inefficient.  Moreover, the arguments taken by sysdev suspend,
resume and shutdown callbacks are practically never necessary.

For this reason, introduce a simpler interface allowing subsystems
to register operations to be executed very late during system suspend
and shutdown and very early during resume in the form of
strcut syscore_ops objects.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 0 deletions

diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index de6f86bfa303..2814c32aed51 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -22,6 +22,7 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/suspend.h>
+#include <linux/syscore_ops.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -163,11 +164,14 @@ static int suspend_enter(suspend_state_t state)
         BUG_ON(!irqs_disabled());
 
         error = sysdev_suspend(PMSG_SUSPEND);
+        if (!error)
+                error = syscore_suspend();
         if (!error) {
                 if (!(suspend_test(TEST_CORE) || pm_wakeup_pending())) {
                         error = suspend_ops->enter(state);
                         events_check_enabled = false;
                 }
+                syscore_resume();
                 sysdev_resume();
         }