PM / Domains: Add device domain data reference counter

Add a mechanism for counting references to the
struct generic_pm_domain_data object pointed to by
dev->power.subsys_data->domain_data if the device in question
belongs to a generic PM domain.

This change is necessary for a subsequent patch making it possible to
allocate that object from within pm_genpd_add_callbacks(), so that
drivers can attach their PM domain device callbacks to devices before
those devices are added to PM domains.

This patch has been tested on the SH7372 Mackerel board.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 2febe31d2675..a7d6172922d4 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -112,6 +112,7 @@ struct generic_pm_domain_data {
         struct gpd_timing_data td;
         struct notifier_block nb;
         struct mutex lock;
+        unsigned int refcount;
         bool need_restore;
         bool always_on;
 };