scarlet: Cut off battery in a custom battery condition

We want to shut down AP when the battery charge drops below
BATTERY_LEVEL_SHUTDOWN. Then we want to cut off the battery
to protect the battery from over-discharging.

But we don't want to cut off the battery right after the battery charge
drops below BATTERY_LEVEL_SHUTDOWN so that we can retain the RTC timestamp
for functionality reasons.

So let's add a custom check before we move on to cut off the battery in
shutdown_on_critical_battery().

BUG=b:68723854
BRANCH=scarlet
TEST=make buildall -j
TEST=keep the battery discharging, see AP shut down when
battery charge hits 2% and later EC cut off battery when
battery voltage hits 3.2V

Change-Id: I9950cf32558c11a2f55ee6ca64c157146d449110
Signed-off-by: Philip Chen <philipchen@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1121593
Reviewed-by: Alexandru M Stan <amstan@chromium.org>
Commit-Queue: Philip Chen <philipchen@chromium.org>
Tested-by: Philip Chen <philipchen@chromium.org>
Trybot-Ready: Philip Chen <philipchen@chromium.org>
(cherry picked from commit 91171747b4ca01ac929186c96d4d6aa3489c60ab)
Reviewed-on: https://chromium-review.googlesource.com/1140795
Commit-Ready: Philip Chen <philipchen@chromium.org>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>

1 files changed, 11 insertions, 5 deletions

diff --git a/common/charge_state_v2.c b/common/charge_state_v2.c
index 8102029c21..5a088d9783 100644
--- a/common/charge_state_v2.c
+++ b/common/charge_state_v2.c
@@ -1277,11 +1277,13 @@ static inline int battery_too_low(void)
 		 curr.batt.voltage <= batt_info->voltage_min));
 }
 
-
-/*
- * Send host event to the AP if the battery is temperature or charge level
- * is critical. Force-shutdown if the problem isn't corrected after timeout.
- */
+ /*
+  * If the battery is at extremely low charge (and discharging) or extremely
+  * high temperature, the EC will notify the AP and start a timer. If the
+  * critical condition is not corrected before the timeout expires, the EC
+  * will shut down the AP (if the AP is not already off) and then optionally
+  * hibernate or cut off battery.
+  */
 static int shutdown_on_critical_battery(void)
 {
 	int batt_temp_c;
@@ -1321,6 +1323,10 @@ static int shutdown_on_critical_battery(void)
 		if (chipset_in_state(CHIPSET_STATE_ANY_OFF)) {
 			/* Timeout waiting for charger to provide more power */
 #if defined(CONFIG_BATTERY_CRITICAL_SHUTDOWN_CUT_OFF)
+#ifdef CONFIG_BATTERY_CRITICAL_CUT_OFF_CUSTOM_CONDITION
+			if (!board_critical_shutdown_check(&curr))
+				return battery_critical;
+#endif /* CONFIG_BATTERY_CRITICAL_CUT_OFF_CUSTOM_CONDITION */
 			CPRINTS(
 			  "charge force battery cut-off due to critical level");
 			board_cut_off_battery();