thermal: Added Bang-bang thermal governor

The bang-bang thermal governor uses a hysteresis to switch abruptly on
or off a cooling device.  It is intended to control fans, which can
not be throttled but just switched on or off.
Bang-bang cannot be set as default governor as it is intended for
special devices only.  For those special devices the driver needs to
explicitely request it.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Andreas Mohr <andi@lisas.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Javi Merino <javi.merino@arm.com>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Peter Feuerer <peter@piie.net>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
index 3db339fb636f..d15d243de27a 100644
--- a/drivers/thermal/thermal_core.h
+++ b/drivers/thermal/thermal_core.h
@@ -69,6 +69,14 @@ static inline int thermal_gov_fair_share_register(void) { return 0; }
 static inline void thermal_gov_fair_share_unregister(void) {}
 #endif /* CONFIG_THERMAL_GOV_FAIR_SHARE */
 
+#ifdef CONFIG_THERMAL_GOV_BANG_BANG
+int thermal_gov_bang_bang_register(void);
+void thermal_gov_bang_bang_unregister(void);
+#else
+static inline int thermal_gov_bang_bang_register(void) { return 0; }
+static inline void thermal_gov_bang_bang_unregister(void) {}
+#endif /* CONFIG_THERMAL_GOV_BANG_BANG */
+
 #ifdef CONFIG_THERMAL_GOV_USER_SPACE
 int thermal_gov_user_space_register(void);
 void thermal_gov_user_space_unregister(void);