After shutting down AP, hibernate EC if battery is low

This preserves more battery for the real-time clock.  It also gets rid
of one battery level/state, since the EC will now shut down at the
same level (2%) as the AP.

Having the EC hibernate at the same level as the AP shuts down also
prevents the following weird scenario:

- EC powers on at 2% battery.
- EC won't power on the AP to do software sync because battery is low.
- But the charge state machine won't actually hibernate the EC until 1%.
- Between 2% and 1%, AC is inserted and system starts charging.
- But EC-RO is what's doing the charging; we should go through software sync
  before charging.

BUG=chrome-os-partner:17124
BRANCH=link
TEST=manual

On battery power,
1) With system on, battfake 2 -> system shuts down and EC hibernates
2) With system off, battfake 2 -> EC hibernates

Change-Id: I87d17f70d60673f3e3f1c6eb88f3f00a8c9ed4e7
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/44314

1 files changed, 4 insertions, 3 deletions

diff --git a/include/battery.h b/include/battery.h
index da4071e158..50b4e53f7c 100644
--- a/include/battery.h
+++ b/include/battery.h
@@ -23,10 +23,11 @@
  * level.
  */
 #define BATTERY_LEVEL_CRITICAL		  5
-/* Shut down main processor when discharging and battery level < this level */
+/*
+ * Shut down main processor and/or hibernate EC when discharging and battery
+ * level < this level.
+ */
 #define BATTERY_LEVEL_SHUTDOWN		  3
-/* Hibernate EC immediately when discharging and battery level < this level */
-#define BATTERY_LEVEL_HIBERNATE_EC	  2
 
 #endif /* __CROS_EC_BATTERY_H */