PM / Hibernate: Introduce CONFIG_HIBERNATE_CALLBACKS

Xen save/restore is going to use hibernate device callbacks for
quiescing devices and putting them back to normal operations and it
would need to select CONFIG_HIBERNATION for this purpose.  However,
that also would cause the hibernate interfaces for user space to be
enabled, which might confuse user space, because the Xen kernels
don't support hibernation.  Moreover, it would be wasteful, as it
would make the Xen kernels include a substantial amount of code that
they would never use.

To address this issue introduce new power management Kconfig option
CONFIG_HIBERNATE_CALLBACKS, such that it will only select the code
that is necessary for the hibernate device callbacks to work and make
CONFIG_HIBERNATION select it.  Then, Xen save/restore will be able to
select CONFIG_HIBERNATE_CALLBACKS without dragging the entire
hibernate code along with it.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Shriram Rajagopalan <rshriram@cs.ubc.ca>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/ibmebus.c b/arch/powerpc/kernel/ibmebus.c
index c00d4ca1ee15..28581f1ad2c0 100644
--- a/arch/powerpc/kernel/ibmebus.c
+++ b/arch/powerpc/kernel/ibmebus.c
@@ -527,7 +527,7 @@ static int ibmebus_bus_pm_resume_noirq(struct device *dev)
 
 #endif /* !CONFIG_SUSPEND */
 
-#ifdef CONFIG_HIBERNATION
+#ifdef CONFIG_HIBERNATE_CALLBACKS
 
 static int ibmebus_bus_pm_freeze(struct device *dev)
 {
@@ -665,7 +665,7 @@ static int ibmebus_bus_pm_restore_noirq(struct device *dev)
         return ret;
 }
 
-#else /* !CONFIG_HIBERNATION */
+#else /* !CONFIG_HIBERNATE_CALLBACKS */
 
 #define ibmebus_bus_pm_freeze           NULL
 #define ibmebus_bus_pm_thaw             NULL
@@ -676,7 +676,7 @@ static int ibmebus_bus_pm_restore_noirq(struct device *dev)
 #define ibmebus_bus_pm_poweroff_noirq   NULL
 #define ibmebus_bus_pm_restore_noirq    NULL
 
-#endif /* !CONFIG_HIBERNATION */
+#endif /* !CONFIG_HIBERNATE_CALLBACKS */
 
 static struct dev_pm_ops ibmebus_bus_dev_pm_ops = {
         .prepare = ibmebus_bus_pm_prepare,