charger v2: Combine prevent_*_discharge functions

prevent_hot_discharge and prevent_deep_discharge are near-identical
copies of one another, and can be combined without the loss of any
useful functionality.

BUG=chrome-os-partner:35188
TEST=Manual on Samus. Charge to 2% and boot system with 5V power supply.
Verify that warnings print to console and AP powers down after 30s. Also
pass unit tests.
BRANCH=Samus

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: I0f1da5248825a3884f7910babc742dfa7eadf5a3
Reviewed-on: https://chromium-review.googlesource.com/240033

4 files changed, 43 insertions, 67 deletions

diff --git a/common/charge_state_v1.c b/common/charge_state_v1.c
index 9be0d47c15..a39499a75d 100644
--- a/common/charge_state_v1.c
+++ b/common/charge_state_v1.c
@@ -29,7 +29,8 @@
 /* Voltage debounce time */
 #define DEBOUNCE_TIME (10 * SECOND)
 
-#define LOW_BATTERY_SHUTDOWN_TIMEOUT_US (LOW_BATTERY_SHUTDOWN_TIMEOUT * SECOND)
+#define LOW_BATTERY_SHUTDOWN_TIMEOUT_US \
+	(CRITICAL_BATTERY_SHUTDOWN_TIMEOUT * SECOND)
 
 #ifndef BATTERY_AP_OFF_LEVEL
 #define BATTERY_AP_OFF_LEVEL 0
diff --git a/common/charge_state_v2.c b/common/charge_state_v2.c
index 051113c0e2..e692f68703 100644
--- a/common/charge_state_v2.c
+++ b/common/charge_state_v2.c
@@ -28,8 +28,8 @@
 #define CPUTS(outstr) cputs(CC_CHARGER, outstr)
 #define CPRINTS(format, args...) cprints(CC_CHARGER, format, ## args)
 
-#define LOW_BATTERY_SHUTDOWN_TIMEOUT_US (LOW_BATTERY_SHUTDOWN_TIMEOUT * SECOND)
-#define HIGH_TEMP_SHUTDOWN_TIMEOUT_US   (HIGH_TEMP_SHUTDOWN_TIMEOUT * SECOND)
+#define CRITICAL_BATTERY_SHUTDOWN_TIMEOUT_US \
+	(CRITICAL_BATTERY_SHUTDOWN_TIMEOUT * SECOND)
 #define PRECHARGE_TIMEOUT_US (PRECHARGE_TIMEOUT * SECOND)
 #define LFCC_EVENT_THRESH 5 /* Full-capacity change reqd for host event */
 
@@ -45,7 +45,6 @@ static int state_machine_force_idle;
 static int manual_mode;  /* volt/curr are no longer maintained by charger */
 static unsigned int user_current_limit = -1U;
 test_export_static timestamp_t shutdown_warning_time;
-test_export_static timestamp_t shutdown_batttemp_warning_time;
 static timestamp_t precharge_start_time;
 static int battery_seems_to_be_dead;
 static int battery_seems_to_be_disconnected;
@@ -402,87 +401,65 @@ static inline int battery_too_hot(int batt_temp_c)
 		 batt_temp_c < batt_info->discharging_min_c));
 }
 
-static void prevent_hot_discharge(void)
+/* True if we know the charge is too low, or we know the voltage is too low. */
+static inline int battery_too_low(void)
+{
+	return ((!(curr.batt.flags & BATT_FLAG_BAD_STATE_OF_CHARGE) &&
+		 curr.batt.state_of_charge < BATTERY_LEVEL_SHUTDOWN) ||
+		(!(curr.batt.flags & BATT_FLAG_BAD_VOLTAGE) &&
+		 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.
+ */
+static void shutdown_on_critical_battery(void)
 {
 	int batt_temp_c;
+	int battery_critical = 0;
 
 	/*
 	 * TODO(crosbug.com/p/27642): The thermal loop should watch the battery
-	 * temp anyway, so it can turn fans on. It could also force an AP
-	 * shutdown if it's too hot, but AFAIK we don't have anything in place
-	 * to do a battery shutdown if it's really really hot. We probably
-	 * should, just in case.
+	 * temp, so it can turn fans on.
 	 */
 	batt_temp_c = DECI_KELVIN_TO_CELSIUS(curr.batt.temperature);
-
-	if (!battery_too_hot(batt_temp_c)) {
-		/* Reset shutdown warning time */
-		shutdown_batttemp_warning_time.val = 0;
-		return;
+	if (battery_too_hot(batt_temp_c)) {
+		CPRINTS("Batt temp out of range: %dC", batt_temp_c);
+		battery_critical = 1;
 	}
 
-	CPRINTS("Batt temp out of range %dC", batt_temp_c);
-
-	if (!shutdown_batttemp_warning_time.val) {
-		CPRINTS("charge warn shutdown due to battery temp %dC",
-			batt_temp_c);
-		shutdown_batttemp_warning_time.val = get_time().val;
-		if (!chipset_in_state(CHIPSET_STATE_ANY_OFF))
-			host_set_single_event(EC_HOST_EVENT_BATTERY_SHUTDOWN);
-	} else if (get_time().val > shutdown_batttemp_warning_time.val +
-		   HIGH_TEMP_SHUTDOWN_TIMEOUT_US) {
-		if (chipset_in_state(CHIPSET_STATE_ANY_OFF)) {
-#ifdef CONFIG_HIBERNATE
-			/* Timeout waiting for temp to change */
-			CPRINTS("charge force EC hib due to batt temp %dC",
-				batt_temp_c);
-			system_hibernate(0, 0);
-#endif
-		} else {
-			CPRINTS("charge force shutdown due to batt temp %dC",
-				batt_temp_c);
-			chipset_force_shutdown();
-		}
+	if (battery_too_low() && !curr.batt_is_charging) {
+		CPRINTS("Low battery: %d%%, %dmV",
+			curr.batt.state_of_charge, curr.batt.voltage);
+		battery_critical = 1;
 	}
-}
-
-/* True if we know the charge is too low, or we know the voltage is too low. */
-static inline int battery_too_low(void)
-{
-	return ((!(curr.batt.flags & BATT_FLAG_BAD_STATE_OF_CHARGE) &&
-		 curr.batt.state_of_charge < BATTERY_LEVEL_SHUTDOWN) ||
-		(!(curr.batt.flags & BATT_FLAG_BAD_VOLTAGE) &&
-		 curr.batt.voltage <= batt_info->voltage_min));
-}
 
-/* Shut everything down before the battery completely dies. */
-static void prevent_deep_discharge(void)
-{
-	if (!battery_too_low() || curr.batt_is_charging) {
+	if (!battery_critical) {
 		/* Reset shutdown warning time */
 		shutdown_warning_time.val = 0;
 		return;
 	}
 
-	CPRINTS("Low battery: %d%%, %dmV",
-		curr.batt.state_of_charge, curr.batt.voltage);
-
 	if (!shutdown_warning_time.val) {
-		CPRINTS("charge warn shutdown due to low battery");
+		CPRINTS("charge warn shutdown due to critical battery");
 		shutdown_warning_time = get_time();
 		if (!chipset_in_state(CHIPSET_STATE_ANY_OFF))
 			host_set_single_event(EC_HOST_EVENT_BATTERY_SHUTDOWN);
 	} else if (get_time().val > shutdown_warning_time.val +
-		   LOW_BATTERY_SHUTDOWN_TIMEOUT_US) {
+		   CRITICAL_BATTERY_SHUTDOWN_TIMEOUT_US) {
 		if (chipset_in_state(CHIPSET_STATE_ANY_OFF)) {
 #ifdef CONFIG_HIBERNATE
 			/* Timeout waiting for charger to provide more power */
-			CPRINTS("charge force EC hibernate due to low battery");
+			CPRINTS(
+			  "charge force EC hibernate due to critical battery");
 			system_hibernate(0, 0);
 #endif
 		} else {
 			/* Timeout waiting for AP to shut down, so kill it */
-			CPRINTS("charge force shutdown due to low battery");
+			CPRINTS(
+			  "charge force shutdown due to critical battery");
 			chipset_force_shutdown();
 		}
 	}
@@ -628,8 +605,7 @@ void charger_task(void)
 		curr.batt_is_charging = curr.ac && (curr.batt.current >= 0);
 
 		/* Don't let the battery hurt itself. */
-		prevent_hot_discharge();
-		prevent_deep_discharge();
+		shutdown_on_critical_battery();
 
 		if (!curr.ac) {
 			curr.state = ST_DISCHARGE;
diff --git a/include/charge_state.h b/include/charge_state.h
index fea4231def..ab9c1043b5 100644
--- a/include/charge_state.h
+++ b/include/charge_state.h
@@ -11,8 +11,7 @@
 /* Stuff that's common to all charger implementations can go here. */
 
 /* Seconds after AP battery shutdown warning before we kill the AP */
-#define LOW_BATTERY_SHUTDOWN_TIMEOUT 30
-#define HIGH_TEMP_SHUTDOWN_TIMEOUT   30
+#define CRITICAL_BATTERY_SHUTDOWN_TIMEOUT 30
 
 /* Seconds to spend trying to wake a non-responsive battery */
 #define PRECHARGE_TIMEOUT 30
diff --git a/test/sbs_charging_v2.c b/test/sbs_charging_v2.c
index bb5097948c..a42d286378 100644
--- a/test/sbs_charging_v2.c
+++ b/test/sbs_charging_v2.c
@@ -222,7 +222,7 @@ static int test_charge_state(void)
 	TEST_ASSERT(state == PWR_STATE_DISCHARGE);
 	sb_write(SB_TEMPERATURE, CELSIUS_TO_DECI_KELVIN(90));
 	state = wait_charging_state();
-	sleep(HIGH_TEMP_SHUTDOWN_TIMEOUT);
+	sleep(CRITICAL_BATTERY_SHUTDOWN_TIMEOUT);
 	TEST_ASSERT(is_shutdown);
 	TEST_ASSERT(state == PWR_STATE_DISCHARGE);
 	sb_write(SB_TEMPERATURE, CELSIUS_TO_DECI_KELVIN(40));
@@ -277,7 +277,7 @@ static int test_low_battery(void)
 	ccprintf("[CHARGING TEST] Low battery with AC and negative current\n");
 	sb_write(SB_CURRENT, -1000);
 	wait_charging_state();
-	sleep(LOW_BATTERY_SHUTDOWN_TIMEOUT);
+	sleep(CRITICAL_BATTERY_SHUTDOWN_TIMEOUT);
 	TEST_ASSERT(is_hibernated);
 
 	ccprintf("[CHARGING TEST] Low battery shutdown S0->S5\n");
@@ -293,7 +293,7 @@ static int test_low_battery(void)
 	hook_notify(HOOK_CHIPSET_SHUTDOWN);
 	wait_charging_state();
 	/* after a while, the EC should hibernate */
-	sleep(LOW_BATTERY_SHUTDOWN_TIMEOUT);
+	sleep(CRITICAL_BATTERY_SHUTDOWN_TIMEOUT);
 	TEST_ASSERT(is_hibernated);
 
 	ccprintf("[CHARGING TEST] Low battery shutdown S5\n");
@@ -303,7 +303,7 @@ static int test_low_battery(void)
 	sb_write(SB_RELATIVE_STATE_OF_CHARGE, 2);
 	wait_charging_state();
 	/* after a while, the EC should hibernate */
-	sleep(LOW_BATTERY_SHUTDOWN_TIMEOUT);
+	sleep(CRITICAL_BATTERY_SHUTDOWN_TIMEOUT);
 	TEST_ASSERT(is_hibernated);
 
 	ccprintf("[CHARGING TEST] Low battery AP shutdown\n");
@@ -334,7 +334,7 @@ static int test_high_temp_battery(void)
 	wait_charging_state();
 	TEST_ASSERT(ev_is_set(EC_HOST_EVENT_BATTERY_SHUTDOWN));
 	TEST_ASSERT(!is_shutdown);
-	sleep(HIGH_TEMP_SHUTDOWN_TIMEOUT);
+	sleep(CRITICAL_BATTERY_SHUTDOWN_TIMEOUT);
 	TEST_ASSERT(is_shutdown);
 
 	ccprintf("[CHARGING TEST] High battery temp S0->S5 hibernate\n");
@@ -666,7 +666,7 @@ static int test_low_battery_hostevents(void)
 	TEST_ASSERT(ev_is_set(EC_HOST_EVENT_BATTERY_SHUTDOWN));
 	TEST_ASSERT(!is_shutdown);
 	/* after a while, the AP should shut down */
-	sleep(LOW_BATTERY_SHUTDOWN_TIMEOUT);
+	sleep(CRITICAL_BATTERY_SHUTDOWN_TIMEOUT);
 	TEST_ASSERT(is_shutdown);
 
 	return EC_SUCCESS;