chgstv2: Refactor shutdown_on_critical_battery

This patch refactors shutdown_on_critical_battery. There is no change
in its functionality.

Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

BUG=b/123727148
BRANCH=nami,strago,coral
TEST=Verify Vayne cuts off battery when soc <= 4% in S0 and S5.

Change-Id: Ia6d3e2166d01803ae8983afd2d4e15d254845065
Reviewed-on: https://chromium-review.googlesource.com/1512620
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1518294
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>

2 files changed, 54 insertions, 43 deletions

diff --git a/common/charge_state_v2.c b/common/charge_state_v2.c
index ef7bd30980..b55a826309 100644
--- a/common/charge_state_v2.c
+++ b/common/charge_state_v2.c
@@ -87,7 +87,7 @@ static enum ec_charge_control_mode chg_ctl_mode;
 static int manual_voltage;  /* Manual voltage override (-1 = no override) */
 static int manual_current;  /* Manual current override (-1 = no override) */
 static unsigned int user_current_limit = -1U;
-test_export_static timestamp_t shutdown_warning_time;
+test_export_static timestamp_t shutdown_target_time;
 static timestamp_t precharge_start_time;
 
 #ifdef CONFIG_EC_EC_COMM_BATTERY_MASTER
@@ -1301,70 +1301,81 @@ enum critical_shutdown board_critical_shutdown_check(
 #endif
 }
 
-/*
- * 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.
- */
-static int shutdown_on_critical_battery(void)
+static int is_battery_critical(void)
 {
-	int batt_temp_c;
-	int battery_critical = 0;
+	int batt_temp_c = DECI_KELVIN_TO_CELSIUS(curr.batt.temperature);
 
 	/*
 	 * TODO(crosbug.com/p/27642): The thermal loop should watch the battery
 	 * temp, so it can turn fans on.
 	 */
-	batt_temp_c = DECI_KELVIN_TO_CELSIUS(curr.batt.temperature);
 	if (battery_too_hot(batt_temp_c)) {
 		CPRINTS("Batt temp out of range: %dC", batt_temp_c);
-		battery_critical = 1;
+		return 1;
 	}
 
 	if (battery_too_low() && !curr.batt_is_charging) {
 		CPRINTS("Low battery: %d%%, %dmV",
 			curr.batt.state_of_charge, curr.batt.voltage);
-		battery_critical = 1;
+		return 1;
 	}
 
-	if (!battery_critical) {
+	return 0;
+}
+
+ /*
+  * 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)
+{
+	if (!is_battery_critical()) {
 		/* Reset shutdown warning time */
-		shutdown_warning_time.val = 0;
-		return battery_critical;
+		shutdown_target_time.val = 0;
+		return 0;
 	}
 
-	if (!shutdown_warning_time.val) {
-		CPRINTS("charge warn shutdown due to critical battery");
-		shutdown_warning_time = get_time();
+	if (!shutdown_target_time.val) {
+		/* Start count down timer */
+		CPRINTS("Start shutdown due to critical battery");
+		shutdown_target_time.val = get_time().val
+				+ CRITICAL_BATTERY_SHUTDOWN_TIMEOUT_US;
 #ifdef CONFIG_HOSTCMD_EVENTS
 		if (!chipset_in_state(CHIPSET_STATE_ANY_OFF))
 			host_set_single_event(EC_HOST_EVENT_BATTERY_SHUTDOWN);
 #endif
-	} else if (get_time().val > shutdown_warning_time.val +
-		   CRITICAL_BATTERY_SHUTDOWN_TIMEOUT_US) {
-		if (chipset_in_state(CHIPSET_STATE_ANY_OFF)) {
-			/* Timeout waiting for charger to provide more power */
-			switch (board_critical_shutdown_check(&curr)) {
-			case CRITICAL_SHUTDOWN_HIBERNATE:
-				CPRINTS("Hibernate due to critical battery");
-				system_hibernate(0, 0);
-				break;
-			case CRITICAL_SHUTDOWN_CUTOFF:
-				CPRINTS("Cutoff due to critical battery");
-				board_cut_off_battery();
-				break;
-			case CRITICAL_SHUTDOWN_IGNORE:
-			default:
-				break;
-			}
-		} else {
-			/* Timeout waiting for AP to shut down, so kill it */
-			CPRINTS(
-			  "charge force shutdown due to critical battery");
-			chipset_force_shutdown();
+		return 1;
+	}
+
+	if (!timestamp_expired(shutdown_target_time, 0))
+		return 1;
+
+	/* Timer has expired */
+	if (chipset_in_state(CHIPSET_STATE_ANY_OFF)) {
+		switch (board_critical_shutdown_check(&curr)) {
+		case CRITICAL_SHUTDOWN_HIBERNATE:
+			CPRINTS("Hibernate due to critical battery");
+			system_hibernate(0, 0);
+			break;
+		case CRITICAL_SHUTDOWN_CUTOFF:
+			CPRINTS("Cutoff due to critical battery");
+			board_cut_off_battery();
+			break;
+		case CRITICAL_SHUTDOWN_IGNORE:
+		default:
+			break;
 		}
+	} else {
+		/* Timeout waiting for AP to shut down, so kill it */
+		CPRINTS(
+		  "charge force shutdown due to critical battery");
+		chipset_force_shutdown();
 	}
 
-	return battery_critical;
+	return 1;
 }
 
 /*
@@ -1530,7 +1541,7 @@ void charger_task(void *u)
 
 	prev_ac = prev_charge = prev_disp_charge = -1;
 	chg_ctl_mode = CHARGE_CONTROL_NORMAL;
-	shutdown_warning_time.val = 0UL;
+	shutdown_target_time.val = 0UL;
 	battery_seems_to_be_dead = 0;
 #ifdef CONFIG_EC_EC_COMM_BATTERY_MASTER
 	base_responsive = 0;
diff --git a/test/sbs_charging_v2.c b/test/sbs_charging_v2.c
index d2dde07cc4..f8cda0cc6c 100644
--- a/test/sbs_charging_v2.c
+++ b/test/sbs_charging_v2.c
@@ -26,14 +26,14 @@ static int is_hibernated;
 static int override_voltage, override_current, override_usec;
 
 /* The simulation doesn't really hibernate, so we must reset this ourselves */
-extern timestamp_t shutdown_warning_time;
+extern timestamp_t shutdown_target_time;
 
 static void reset_mocks(void)
 {
 	mock_chipset_state = CHIPSET_STATE_ON;
 	is_shutdown = is_force_discharge = is_hibernated = 0;
 	override_voltage = override_current = override_usec = 0;
-	shutdown_warning_time.val = 0ULL;
+	shutdown_target_time.val = 0ULL;
 }
 
 int board_cut_off_battery(void)