baseboard/kukui: dynamic adjuct input current by thermal budget

Limit the charger input current if we are overheat,
and loose the limit if the thermal in control.

kukui/krane/kodama are suffering from thermal issue (>100 celsius
degree in charger junction) and the solution was limit the system
can only sink 5V/2A in S0.  However, this cause slowing charging
as well.  We'd like to loose the 5V/2A charging limit and controls
the thermal by restricting the charger input current.

This CL only applies the limitation when PD voltage > 5V, because
we don't see the overheat problem when krane charged with 5V.

TEST=on krane, ensure the temperature of junction is always under
     84 celsius degree; ensure the curve of battery current at
     charging is a smooth curve when PD voltage switching from high
     to low.
BUG=b:141903096 b:144073892
BRANCH=kukui

Change-Id: I9657f5a04897010d7018f910cb77b210147d8356
Signed-off-by: Yilun Lin <yllin@chromium.org>
Signed-off-by: Eric Yilun Lin <yllin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1899660
Reviewed-by: Ting Shen <phoenixshen@chromium.org>

4 files changed, 128 insertions, 3 deletions

diff --git a/baseboard/kukui/charger_mt6370.c b/baseboard/kukui/charger_mt6370.c
index 79da7a160a..2ad7627fd9 100644
--- a/baseboard/kukui/charger_mt6370.c
+++ b/baseboard/kukui/charger_mt6370.c
@@ -4,12 +4,14 @@
  */
 
 #include "charge_manager.h"
+#include "charge_state_v2.h"
 #include "charger_mt6370.h"
 #include "console.h"
-#include "driver/tcpm/mt6370.h"
 #include "driver/charger/rt946x.h"
+#include "driver/tcpm/mt6370.h"
 #include "hooks.h"
 #include "power.h"
+#include "timer.h"
 #include "usb_common.h"
 #include "usb_pd.h"
 #include "util.h"
@@ -51,6 +53,15 @@ DECLARE_HOOK(HOOK_CHIPSET_RESUME, update_plt_resume, HOOK_PRIO_DEFAULT);
 
 #define CPRINTS(format, args...) cprints(CC_CHARGER, format, ## args)
 
+/* wait time to evaluate charger thermal status */
+static timestamp_t thermal_wait_until;
+/* input current bound when charger throttled */
+static int throttled_ma = PD_MAX_CURRENT_MA;
+/* charge_ma in last board_set_charge_limit call */
+static int prev_charge_ma;
+/* charge_mv in last board_set_charge_limit call */
+static int prev_charge_mv;
+
 #ifndef CONFIG_BATTERY_SMART
 int board_cut_off_battery(void)
 {
@@ -63,6 +74,91 @@ int board_cut_off_battery(void)
 }
 #endif
 
+static void board_set_charge_limit_throttle(int charge_ma, int charge_mv)
+{
+	charge_set_input_current_limit(
+		MIN(throttled_ma, MAX(charge_ma, CONFIG_CHARGER_INPUT_CURRENT)),
+		charge_mv);
+}
+
+static void battery_thermal_control(struct charge_state_data *curr)
+{
+	int input_current, jc_temp;
+	static int skip_reset;
+	/*
+	 * mt6370's input current setting is 50mA step, use 50 as well for
+	 * easy value mapping.
+	 */
+	const int k_p = 50;
+
+	if (charge_manager_get_charger_voltage() == 5000 ||
+	    curr->state != ST_CHARGE) {
+		/* We already set the charge limit, do not reset it again. */
+		if (skip_reset)
+			return;
+		skip_reset = 1;
+		thermal_wait_until.val = 0;
+		throttled_ma = PD_MAX_CURRENT_MA;
+		board_set_charge_limit_throttle(prev_charge_ma, prev_charge_mv);
+		return;
+	}
+
+	skip_reset = 0;
+
+	if (thermal_wait_until.val == 0)
+		goto thermal_exit;
+
+	if (get_time().val < thermal_wait_until.val)
+		return;
+
+	/* If we fail to read adc, skip for this cycle. */
+	if (rt946x_get_adc(MT6370_ADC_TEMP_JC, &jc_temp))
+		return;
+
+	/* If we fail to read input curr limit, skip for this cycle. */
+	if (charger_get_input_current(&input_current))
+		return;
+
+	/*
+	 * If input current limit is maximum, and we are under thermal budget,
+	 * just skip.
+	 */
+	if (input_current == PD_MAX_CURRENT_MA &&
+	    jc_temp < thermal_bound.target + thermal_bound.err)
+		return;
+
+	/* If the temp is within +- err, thermal is under control */
+	if (jc_temp < thermal_bound.target + thermal_bound.err &&
+	    jc_temp > thermal_bound.target - thermal_bound.err)
+		return;
+
+	/*
+	 * PID algorithm (https://en.wikipedia.org/wiki/PID_controller),
+	 * and operates on only P value.
+	 */
+	throttled_ma =
+		MIN(PD_MAX_CURRENT_MA,
+		    input_current + k_p * (thermal_bound.target - jc_temp));
+	board_set_charge_limit_throttle(throttled_ma, prev_charge_mv);
+
+thermal_exit:
+	thermal_wait_until.val = get_time().val + (3 * SECOND);
+}
+
+int command_jc(int argc, char **argv)
+{
+	static int prev_jc_temp;
+	int jc_temp;
+
+	if (rt946x_get_adc(MT6370_ADC_TEMP_JC, &jc_temp))
+		jc_temp = prev_jc_temp;
+
+	ccprintf("JC Temp: %d\n", jc_temp);
+	prev_jc_temp = jc_temp;
+	return EC_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(jc, command_jc, "", "mt6370 junction temp");
+
 /*
  * b/143318064: A workwround for mt6370 bad buck efficiency.
  * If the delta of VBUS and VBAT(on krane, desired voltage 4.4V) is too small
@@ -121,6 +217,12 @@ static void battery_desired_curr_dynamic(struct charge_state_data *curr)
 		charge_reset_stable_current_us(5 * MINUTE);
 		/* Rewrite the stable current to re-evalute desired watt */
 		charge_set_stable_current(prev_stable_current);
+
+		/*
+		 * do not alter current by thermal if we just raising PD
+		 * voltage
+		 */
+		thermal_wait_until.val = get_time().val + (10 * SECOND);
 	} else {
 		pd_pref_config.mv = DEFAULT_PREFER_MV;
 		/*
@@ -148,6 +250,8 @@ void mt6370_charger_profile_override(struct charge_state_data *curr)
 
 	battery_desired_curr_dynamic(curr);
 
+	battery_thermal_control(curr);
+
 	/* Limit input (=VBUS) to 5V when soc > 85% and charge current < 1A. */
 	if (!(curr->batt.flags & BATT_FLAG_BAD_CURRENT) &&
 	    charge_get_percent() > BAT_LEVEL_PD_LIMIT &&
@@ -195,6 +299,7 @@ DECLARE_HOOK(HOOK_BATTERY_SOC_CHANGE,
 void board_set_charge_limit(int port, int supplier, int charge_ma,
 			    int max_ma, int charge_mv)
 {
-	charge_set_input_current_limit(
-		MAX(charge_ma, CONFIG_CHARGER_INPUT_CURRENT), charge_mv);
+	prev_charge_ma = charge_ma;
+	prev_charge_mv = charge_mv;
+	board_set_charge_limit_throttle(charge_ma, charge_mv);
 }
diff --git a/baseboard/kukui/charger_mt6370.h b/baseboard/kukui/charger_mt6370.h
index 9cf1b44d95..880b00a1a8 100644
--- a/baseboard/kukui/charger_mt6370.h
+++ b/baseboard/kukui/charger_mt6370.h
@@ -10,4 +10,12 @@
 
 void mt6370_charger_profile_override(struct charge_state_data *curr);
 
+struct mt6370_thermal_bound {
+	/* mt6370 junction's thermal target in Celsius degree */
+	int target;
+	/* mt6370 junction's thermal evaluation error in Celsius degree */
+	int err;
+};
+
+extern struct mt6370_thermal_bound thermal_bound;
 #endif
diff --git a/board/kodama/board.c b/board/kodama/board.c
index 7a221ace3d..bf6ec7dd84 100644
--- a/board/kodama/board.c
+++ b/board/kodama/board.c
@@ -10,6 +10,7 @@
 #include "charge_ramp.h"
 #include "charge_state.h"
 #include "charger.h"
+#include "charger_mt6370.h"
 #include "chipset.h"
 #include "common.h"
 #include "console.h"
@@ -97,6 +98,11 @@ const struct tcpc_config_t tcpc_config[CONFIG_USB_PD_PORT_MAX_COUNT] = {
 	},
 };
 
+struct mt6370_thermal_bound thermal_bound = {
+	.target = 75,
+	.err = 4,
+};
+
 static void board_hpd_status(int port, int hpd_lvl, int hpd_irq)
 {
 	/*
diff --git a/board/kukui/board.c b/board/kukui/board.c
index c3fc1fc9ce..8ff3e2cda0 100644
--- a/board/kukui/board.c
+++ b/board/kukui/board.c
@@ -10,6 +10,7 @@
 #include "charge_ramp.h"
 #include "charge_state.h"
 #include "charger.h"
+#include "charger_mt6370.h"
 #include "chipset.h"
 #include "common.h"
 #include "console.h"
@@ -103,6 +104,11 @@ const struct tcpc_config_t tcpc_config[CONFIG_USB_PD_PORT_MAX_COUNT] = {
 	},
 };
 
+struct mt6370_thermal_bound thermal_bound = {
+	.target = 80,
+	.err = 4,
+};
+
 void board_set_dp_mux_control(int output_enable, int polarity)
 {
 	if (board_get_version() >= 5)