Flapjack: Limit VBUS when charge current is < 1A

Currently, when soc is above 85%, the input voltage is limited to 5V.

With this patch, the VBUS limitation is applied when soc > 85% and the
battery input current is below 1A.

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

BRANCH=None
BUG=b/124370341
TEST=Verify Flapjack can charge with a PD charger above 85%.
TEST=Verify VBUS is reduced to 5V when charged through USB-C.
TEST=Verify VBUS is reduced to 5V when charged through WPC.

Change-Id: Ib47d4881e04c68e5e93a2a2292b37c1471b5e79b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1606740
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>

1 files changed, 34 insertions, 17 deletions

diff --git a/board/flapjack/battery.c b/board/flapjack/battery.c
index 506ea593c3..0e2f25a464 100644
--- a/board/flapjack/battery.c
+++ b/board/flapjack/battery.c
@@ -16,12 +16,14 @@
 #include "extpower.h"
 #include "gpio.h"
 #include "hooks.h"
+#include "i2c.h"
 #include "usb_pd.h"
 #include "util.h"
 #include "board.h"
 #include "adc.h"
 #include "adc_chip.h"
 #include "math_util.h"
+#include "p9221.h"
 
 #define CPRINTS(format, args...) cprints(CC_USBCHARGE, format, ## args)
 #define CPRINTF(format, args...) cprintf(CC_USBCHARGE, format, ## args)
@@ -346,10 +348,42 @@ int charger_profile_override(struct charge_state_data *curr)
 	/* battery temp in 0.1 deg C */
 	int temp = curr->batt.temperature - 2731;
 	enum temp_zone zone;
+	int usb_mv, wpc_mv;
+	static int previous_usb_mv;
+	int val;
 
 	if (curr->state != ST_CHARGE)
 		return 0;
 
+	/* 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 &&
+			curr->batt.current < 1000) {
+		usb_mv = 5500;
+		wpc_mv = 5500;
+	} else {
+		usb_mv = PD_MAX_VOLTAGE_MV;
+		wpc_mv = P9221_DC_IVL_EPP_MV;
+	}
+
+	if (usb_mv != previous_usb_mv)
+		CPRINTS("VBUS limited to %dmV", usb_mv);
+	previous_usb_mv = usb_mv;
+
+	/* Pull down VBUS from USB */
+	if (pd_get_max_voltage() != usb_mv)
+		pd_set_external_voltage_limit(0, usb_mv);
+
+	/*
+	 * Pull down VBUS from WPC. Need to use use raw i2c APIs because RO
+	 * doesn't have p9221 driver. If WPC is off, this is a no-op.
+	 */
+	if (i2c_read_offset16(I2C_PORT_WPC, P9221_R7_ADDR,
+			      P9221R7_VOUT_SET_REG, &val, 1) == EC_SUCCESS
+			&& val * 100 != wpc_mv)
+		i2c_write_offset16(I2C_PORT_WPC, P9221_R7_ADDR,
+			      P9221R7_VOUT_SET_REG, wpc_mv / 100, 1);
+
 	if ((curr->batt.flags & BATT_FLAG_BAD_TEMPERATURE) ||
 	    (temp < temp_zones[batt_type][TEMP_ZONE_0].temp_min)) {
 		zone = TEMP_OUT_OF_RANGE;
@@ -398,23 +432,6 @@ DECLARE_HOOK(HOOK_BATTERY_SOC_CHANGE,
 	     board_charge_termination,
 	     HOOK_PRIO_DEFAULT);
 
-static void pd_limit_5v(uint8_t en)
-{
-	int wanted_pd_voltage;
-
-	wanted_pd_voltage = en ? 5500 : PD_MAX_VOLTAGE_MV;
-
-	if (pd_get_max_voltage() != wanted_pd_voltage)
-		pd_set_external_voltage_limit(0, wanted_pd_voltage);
-}
-
-/* When battery level > BAT_LEVEL_PD_LIMIT, we limit PD voltage to 5V. */
-static void board_pd_voltage(void)
-{
-	pd_limit_5v(charge_get_percent() > BAT_LEVEL_PD_LIMIT);
-}
-DECLARE_HOOK(HOOK_BATTERY_SOC_CHANGE, board_pd_voltage, HOOK_PRIO_DEFAULT);
-
 /* Customs options controllable by host command. */
 #define PARAM_FASTCHARGE (CS_PARAM_CUSTOM_PROFILE_MIN + 0)