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, 4 insertions, 4 deletions

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 052dc53eef38..fbc5b6e7c591 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -233,7 +233,7 @@ static int pm_op(struct device *dev,
                 }
                 break;
 #endif /* CONFIG_SUSPEND */
-#ifdef CONFIG_HIBERNATION
+#ifdef CONFIG_HIBERNATE_CALLBACKS
         case PM_EVENT_FREEZE:
         case PM_EVENT_QUIESCE:
                 if (ops->freeze) {
@@ -260,7 +260,7 @@ static int pm_op(struct device *dev,
                         suspend_report_result(ops->restore, error);
                 }
                 break;
-#endif /* CONFIG_HIBERNATION */
+#endif /* CONFIG_HIBERNATE_CALLBACKS */
         default:
                 error = -EINVAL;
         }
@@ -308,7 +308,7 @@ static int pm_noirq_op(struct device *dev,
                 }
                 break;
 #endif /* CONFIG_SUSPEND */
-#ifdef CONFIG_HIBERNATION
+#ifdef CONFIG_HIBERNATE_CALLBACKS
         case PM_EVENT_FREEZE:
         case PM_EVENT_QUIESCE:
                 if (ops->freeze_noirq) {
@@ -335,7 +335,7 @@ static int pm_noirq_op(struct device *dev,
                         suspend_report_result(ops->restore_noirq, error);
                 }
                 break;
-#endif /* CONFIG_HIBERNATION */
+#endif /* CONFIG_HIBERNATE_CALLBACKS */
         default:
                 error = -EINVAL;
         }