SM5803: Improve flow control setting

This change adds a new Vbus sink enable command which will be called on
initial sink connection and detach.  This will separate out most of the
FLOW1 and FLOW2 register control from the set_mode() driver API which is
regularly called from the charger task.  This means that, if charging on
a port fails, the charging will no longer be automatically re-enabled by
the charger task.

Additionally, this folds the verification that we aren't disabling
sourcing into the sink enable so board files no longer need to verify
this before calling the sink enable/disable API.  It also allows the OTG
disable to fully clear the FLOW1 mode since calls to OTG are more
targeted than the sink enable/disable, which happens any time another
charge port is set.

BRANCH=None
BUG=b:163511546,b:165677311
TEST=on waddledee and drawlat, confirm expected FLOW1 contents and Vbus
level:
- sinking C0 or C1
- sourcing C0 or C1
- sourcing both C0 and C1
- sinking C0 while sourcing C1
- sinking C1 while sourcing C0
- battery cutoff with charger in C0 or C1
- no battery boot with charger in C0 or C1
- power role swap with HooToo hub in C0 and C1

Signed-off-by: Diana Z <dzigterman@chromium.org>
Change-Id: Ifdc7786243bdf0a634d8db99b4deb53457232ad3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2372738
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>

6 files changed, 180 insertions, 187 deletions

diff --git a/board/drawcia/board.c b/board/drawcia/board.c
index 497bd9b7b7..0ba3b5c0b0 100644
--- a/board/drawcia/board.c
+++ b/board/drawcia/board.c
@@ -508,61 +508,34 @@ void board_set_charge_limit(int port, int supplier, int charge_ma, int max_ma,
 int board_set_active_charge_port(int port)
 {
 	int is_valid_port = (port >= 0 && port < board_get_usb_pd_port_count());
-	int p0_otg = 0, p1_otg = 0;
 
 	if (!is_valid_port && port != CHARGE_PORT_NONE)
 		return EC_ERROR_INVAL;
 
-	/* TODO(b/147440290): charger functions should take chgnum */
-	p0_otg = chg_chips[0].drv->is_sourcing_otg_power(0, 0);
-
-	if (board_get_charger_chip_count() > 1)
-		p1_otg = chg_chips[1].drv->is_sourcing_otg_power(1, 1);
-
 	if (port == CHARGE_PORT_NONE) {
 		CPRINTUSB("Disabling all charge ports");
 
-		if (!p0_otg)
-			chg_chips[0].drv->set_mode(0,
-						   CHARGE_FLAG_INHIBIT_CHARGE);
+		sm5803_vbus_sink_enable(CHARGER_PRIMARY, 0);
+
+		if (board_get_charger_chip_count() > 1)
+			sm5803_vbus_sink_enable(CHARGER_SECONDARY, 0);
 
-		if (board_get_charger_chip_count() > 1) {
-			if (!p1_otg)
-				chg_chips[1].drv->set_mode(1,
-						   CHARGE_FLAG_INHIBIT_CHARGE);
-		}
 		return EC_SUCCESS;
 	}
 
 	CPRINTUSB("New chg p%d", port);
 
 	/*
-	 * Charger task will take care of enabling charging on the new charge
-	 * port.  Here, we ensure the other port is not charging by changing
-	 * CHG_EN
+	 * Ensure other port is turned off, then enable new charge port
 	 */
 	if (port == 0) {
-		if (p0_otg) {
-			CPRINTUSB("Skip enable p%d", port);
-			return EC_ERROR_INVAL;
-		}
-		if (board_get_charger_chip_count() > 1) {
-			if (!p1_otg) {
-				chg_chips[1].drv->set_mode(1,
-						   CHARGE_FLAG_INHIBIT_CHARGE);
-			}
-		}
+		if (board_get_charger_chip_count() > 1)
+			sm5803_vbus_sink_enable(CHARGER_SECONDARY, 0);
+		sm5803_vbus_sink_enable(CHARGER_PRIMARY, 1);
+
 	} else {
-		if (board_get_charger_chip_count() > 1) {
-			if (p1_otg) {
-				CPRINTUSB("Skip enable p%d", port);
-				return EC_ERROR_INVAL;
-			}
-		}
-		if (!p0_otg) {
-			chg_chips[0].drv->set_mode(0,
-						   CHARGE_FLAG_INHIBIT_CHARGE);
-		}
+		sm5803_vbus_sink_enable(CHARGER_PRIMARY, 0);
+		sm5803_vbus_sink_enable(CHARGER_SECONDARY, 1);
 	}
 
 	return EC_SUCCESS;
diff --git a/board/drawcia/usb_pd_policy.c b/board/drawcia/usb_pd_policy.c
index f9ff88c26c..58b442a0ac 100644
--- a/board/drawcia/usb_pd_policy.c
+++ b/board/drawcia/usb_pd_policy.c
@@ -52,8 +52,8 @@ int pd_set_power_supply_ready(int port)
 {
 	enum ec_error_list rv;
 
-	/* Disable charging */
-	rv = chg_chips[port].drv->set_mode(port, CHARGE_FLAG_INHIBIT_CHARGE);
+	/* Disable sinking */
+	rv = sm5803_vbus_sink_enable(port, 0);
 	if (rv)
 		return rv;
 
diff --git a/board/waddledee/board.c b/board/waddledee/board.c
index 341f00ea4a..6e455d2ca1 100644
--- a/board/waddledee/board.c
+++ b/board/waddledee/board.c
@@ -331,25 +331,18 @@ void board_set_charge_limit(int port, int supplier, int charge_ma, int max_ma,
 
 int board_set_active_charge_port(int port)
 {
-	int is_valid_port = (port >= 0 && port < CONFIG_USB_PD_PORT_MAX_COUNT);
-	int p0_otg, p1_otg;
+	int is_valid_port = (port >= 0 && port < board_get_usb_pd_port_count());
 
 	if (!is_valid_port && port != CHARGE_PORT_NONE)
 		return EC_ERROR_INVAL;
 
-	/* TODO(b/147440290): charger functions should take chgnum */
-	p0_otg = chg_chips[0].drv->is_sourcing_otg_power(0, 0);
-	p1_otg = chg_chips[1].drv->is_sourcing_otg_power(1, 1);
-
 	if (port == CHARGE_PORT_NONE) {
 		CPRINTUSB("Disabling all charge ports");
 
-		if (!p0_otg)
-			chg_chips[0].drv->set_mode(0,
-						   CHARGE_FLAG_INHIBIT_CHARGE);
-		if (!p1_otg)
-			chg_chips[1].drv->set_mode(1,
-						   CHARGE_FLAG_INHIBIT_CHARGE);
+		sm5803_vbus_sink_enable(CHARGER_PRIMARY, 0);
+
+		if (board_get_charger_chip_count() > 1)
+			sm5803_vbus_sink_enable(CHARGER_SECONDARY, 0);
 
 		return EC_SUCCESS;
 	}
@@ -357,28 +350,16 @@ int board_set_active_charge_port(int port)
 	CPRINTUSB("New chg p%d", port);
 
 	/*
-	 * Charger task will take care of enabling charging on the new charge
-	 * port.  Here, we ensure the other port is not charging by changing
-	 * CHG_EN
+	 * Ensure other port is turned off, then enable new charge port
 	 */
 	if (port == 0) {
-		if (p0_otg) {
-			CPRINTUSB("Skip enable p%d", port);
-			return EC_ERROR_INVAL;
-		}
-		if (!p1_otg) {
-			chg_chips[1].drv->set_mode(1,
-						   CHARGE_FLAG_INHIBIT_CHARGE);
-		}
+		if (board_get_charger_chip_count() > 1)
+			sm5803_vbus_sink_enable(CHARGER_SECONDARY, 0);
+		sm5803_vbus_sink_enable(CHARGER_PRIMARY, 1);
+
 	} else {
-		if (p1_otg) {
-			CPRINTUSB("Skip enable p%d", port);
-			return EC_ERROR_INVAL;
-		}
-		if (!p0_otg) {
-			chg_chips[0].drv->set_mode(0,
-						   CHARGE_FLAG_INHIBIT_CHARGE);
-		}
+		sm5803_vbus_sink_enable(CHARGER_PRIMARY, 0);
+		sm5803_vbus_sink_enable(CHARGER_SECONDARY, 1);
 	}
 
 	return EC_SUCCESS;
diff --git a/board/waddledee/usb_pd_policy.c b/board/waddledee/usb_pd_policy.c
index 0fc682b28e..58b442a0ac 100644
--- a/board/waddledee/usb_pd_policy.c
+++ b/board/waddledee/usb_pd_policy.c
@@ -26,7 +26,7 @@ void pd_power_supply_reset(int port)
 {
 	int prev_en;
 
-	if (port < 0 || port >= CONFIG_USB_PD_PORT_MAX_COUNT)
+	if (port < 0 || port >= board_get_usb_pd_port_count())
 		return;
 
 	/* TODO(b/147440290): charger functions should take chgnum */
@@ -52,8 +52,8 @@ int pd_set_power_supply_ready(int port)
 {
 	enum ec_error_list rv;
 
-	/* Disable charging */
-	rv = chg_chips[port].drv->set_mode(port, CHARGE_FLAG_INHIBIT_CHARGE);
+	/* Disable sinking */
+	rv = sm5803_vbus_sink_enable(port, 0);
 	if (rv)
 		return rv;
 
diff --git a/driver/charger/sm5803.c b/driver/charger/sm5803.c
index 072fc2ca14..63ad62ab16 100644
--- a/driver/charger/sm5803.c
+++ b/driver/charger/sm5803.c
@@ -47,6 +47,7 @@ static const struct charger_info sm5803_charger_info = {
 static uint32_t irq_pending; /* Bitmask of chips with interrupts pending */
 
 static struct mutex flow1_access_lock[CHARGER_NUM];
+static struct mutex flow2_access_lock[CHARGER_NUM];
 
 static int charger_vbus[CHARGER_NUM];
 
@@ -153,6 +154,23 @@ static enum ec_error_list sm5803_flow1_update(int chgnum, const uint8_t mask,
 	return rv;
 }
 
+static enum ec_error_list sm5803_flow2_update(int chgnum, const uint8_t mask,
+					const enum mask_update_action action)
+{
+	int rv;
+
+	mutex_lock(&flow2_access_lock[chgnum]);
+
+	rv = i2c_update8(chg_chips[chgnum].i2c_port,
+			 chg_chips[chgnum].i2c_addr_flags,
+			 SM5803_REG_FLOW2,
+			 mask, action);
+
+	mutex_unlock(&flow2_access_lock[chgnum]);
+
+	return rv;
+}
+
 int sm5803_is_vbus_present(int chgnum)
 {
 	return charger_vbus[chgnum];
@@ -248,6 +266,81 @@ enum ec_error_list sm5803_set_vbus_disch(int chgnum, int enable)
 	return rv;
 }
 
+enum ec_error_list sm5803_vbus_sink_enable(int chgnum, int enable)
+{
+	enum ec_error_list rv;
+	int regval;
+
+	rv = sm5803_get_dev_id(chgnum, &dev_id);
+	if (rv)
+		return rv;
+
+	if (enable) {
+		if (chgnum == CHARGER_PRIMARY) {
+			/* Magic for new silicon */
+			if (dev_id >= 3) {
+				rv |= main_write8(chgnum, 0x1F, 0x1);
+				rv |= test_write8(chgnum, 0x44, 0x2);
+				rv |= main_write8(chgnum, 0x1F, 0);
+			}
+			rv = sm5803_flow2_update(chgnum,
+						 SM5803_FLOW2_AUTO_ENABLED,
+						 MASK_SET);
+		} else {
+			if (dev_id >= 3) {
+				/* Touch of magic on the primary charger */
+				rv |= main_write8(CHARGER_PRIMARY, 0x1F, 0x1);
+				rv |= test_write8(CHARGER_PRIMARY, 0x44, 0x20);
+				rv |= main_write8(CHARGER_PRIMARY, 0x1F, 0x0);
+
+				/*
+				 * Enable linear, pre-charge, and linear fast
+				 * charge for primary charger.
+				 */
+				rv = chg_read8(CHARGER_PRIMARY,
+					       SM5803_REG_FLOW3, &regval);
+				regval |= BIT(6) | BIT(5) | BIT(4);
+				rv |= chg_write8(CHARGER_PRIMARY,
+						 SM5803_REG_FLOW3, regval);
+
+				/* Enable linear mode on the primary IC */
+				rv |= sm5803_flow1_update(CHARGER_PRIMARY,
+						SM5803_FLOW1_LINEAR_CHARGE_EN,
+						MASK_SET);
+			}
+		}
+
+		/* Last but not least, enable sinking */
+		rv |= sm5803_flow1_update(chgnum, CHARGER_MODE_SINK, MASK_SET);
+	} else {
+		if (chgnum == CHARGER_PRIMARY)
+			rv |= sm5803_flow2_update(chgnum,
+						  SM5803_FLOW2_AUTO_ENABLED,
+						  MASK_CLR);
+
+		if (chgnum == CHARGER_SECONDARY) {
+			rv |= sm5803_flow1_update(CHARGER_PRIMARY,
+						  SM5803_FLOW1_LINEAR_CHARGE_EN,
+						  MASK_CLR);
+
+			rv = chg_read8(CHARGER_PRIMARY, SM5803_REG_FLOW3,
+				       &regval);
+			regval &= ~(BIT(6) | BIT(5) | BIT(4));
+			rv |= chg_write8(CHARGER_PRIMARY, SM5803_REG_FLOW3,
+					 regval);
+		}
+
+
+		/* Disable sink mode, unless currently sourcing out */
+		if (!sm5803_is_sourcing_otg_power(chgnum, chgnum))
+			rv |= sm5803_flow1_update(chgnum, CHARGER_MODE_SINK,
+						  MASK_CLR);
+	}
+
+	return rv;
+
+}
+
 static void sm5803_init(int chgnum)
 {
 	enum ec_error_list rv;
@@ -439,6 +532,16 @@ static void sm5803_init(int chgnum)
 	reg &= ~SM5803_PHOT1_IBUS_PHOT_COMP_EN;
 	rv |= chg_write8(chgnum, SM5803_REG_PHOT1, reg);
 
+	if (chgnum != CHARGER_PRIMARY) {
+		/*
+		 * Enable the IBAT_CHG adc in order to calculate
+		 * system resistance.
+		 */
+		rv |= meas_read8(chgnum, SM5803_REG_GPADC_CONFIG1, &reg);
+		reg |= SM5803_GPADCC1_IBAT_CHG_EN;
+		rv |= meas_write8(chgnum, SM5803_REG_GPADC_CONFIG1, reg);
+	}
+
 	/* Set default input current */
 	reg = SM5803_CURRENT_TO_REG(CONFIG_CHARGER_INPUT_CURRENT)
 		& SM5803_CHG_ILIM_RAW;
@@ -465,28 +568,42 @@ static void sm5803_init(int chgnum)
 	 */
 	rv |= chg_write8(chgnum, SM5803_REG_FLOW2, SM5803_FLOW2_HOST_MODE_EN);
 
-	/* Setup the proper precharge thresholds. */
-	batt_info = battery_get_info();
-	cells = batt_info->voltage_max / 4;
-	pre_term = batt_info->voltage_min / cells;
-	pre_term /= 100; /* Convert to decivolts. */
-	pre_term = CLAMP(pre_term, SM5803_VBAT_PRE_TERM_MIN_DV,
-			 SM5803_VBAT_PRE_TERM_MAX_DV);
-	pre_term -= SM5803_VBAT_PRE_TERM_MIN_DV; /* Convert to regval */
+	if (chgnum == CHARGER_PRIMARY) {
+		int ibat_eoc_ma;
+
+		/* Set end of fast charge threshold */
+		batt_info = battery_get_info();
+		ibat_eoc_ma = batt_info->precharge_current - 50;
+		ibat_eoc_ma /= 100;
+		ibat_eoc_ma = CLAMP(ibat_eoc_ma, 0, SM5803_CONF5_IBAT_EOC_TH);
+		rv |= chg_read8(chgnum, SM5803_REG_FAST_CONF5, &reg);
+		reg &= ~SM5803_CONF5_IBAT_EOC_TH;
+		reg |= ibat_eoc_ma;
+		rv |= chg_write8(CHARGER_PRIMARY, SM5803_REG_FAST_CONF5, reg);
+
+		/* Setup the proper precharge thresholds. */
+		cells = batt_info->voltage_max / 4;
+		pre_term = batt_info->voltage_min / cells;
+		pre_term /= 100; /* Convert to decivolts. */
+		pre_term = CLAMP(pre_term, SM5803_VBAT_PRE_TERM_MIN_DV,
+				 SM5803_VBAT_PRE_TERM_MAX_DV);
+		pre_term -= SM5803_VBAT_PRE_TERM_MIN_DV; /* Convert to regval */
+
+		rv |= chg_read8(chgnum, SM5803_REG_PRE_FAST_CONF_REG1, &reg);
+		reg &= ~SM5803_VBAT_PRE_TERM;
+		reg |= pre_term << SM5803_VBAT_PRE_TERM_SHIFT;
+		rv |= chg_write8(chgnum, SM5803_REG_PRE_FAST_CONF_REG1, reg);
 
-	rv |= chg_read8(chgnum, SM5803_REG_PRE_FAST_CONF_REG1, &reg);
-	reg &= ~SM5803_VBAT_PRE_TERM;
-	reg |= pre_term << SM5803_VBAT_PRE_TERM_SHIFT;
-	rv |= chg_write8(chgnum, SM5803_REG_PRE_FAST_CONF_REG1, reg);
-
-	/*
-	 * Set up precharge current
-	 * Note it is preferred to under-shoot the precharge current requested
-	 * Upper bits of this register are read/write 1 to clear
-	 */
-	reg = SM5803_CURRENT_TO_REG(batt_info->precharge_current);
-	reg = MIN(reg, SM5803_PRECHG_ICHG_PRE_SET);
-	rv |= chg_write8(chgnum, SM5803_REG_PRECHG, reg);
+		/*
+		 * Set up precharge current
+		 * Note it is preferred to under-shoot the precharge current
+		 * requested. Upper bits of this register are read/write 1 to
+		 * clear
+		 */
+		reg = SM5803_CURRENT_TO_REG(batt_info->precharge_current);
+		reg = MIN(reg, SM5803_PRECHG_ICHG_PRE_SET);
+		rv |= chg_write8(chgnum, SM5803_REG_PRECHG, reg);
+	}
 
 	if (rv)
 		CPRINTS("%s %d: Failed initialization", CHARGER_NAME, chgnum);
@@ -633,47 +750,14 @@ static enum ec_error_list sm5803_get_status(int chgnum, int *status)
 
 static enum ec_error_list sm5803_set_mode(int chgnum, int mode)
 {
-	enum ec_error_list rv;
-	int flow2_reg;
-	int dev_id;
-
-	rv = sm5803_get_dev_id(chgnum, &dev_id);
-
-	/* New silicon version requires a new procedure to start charging. */
-	if ((dev_id >= 3) && (!(mode & CHARGE_FLAG_INHIBIT_CHARGE))) {
-		/* Enable Test Page */
-		rv |= main_write8(chgnum, 0x1F, 0x1);
-		/* magic */
-		rv |= test_write8(chgnum, 0x44, 0x2);
-		rv |= test_write8(chgnum, 0x48, 0x4);
-		/* Disable Test Page */
-		rv |= main_write8(chgnum, 0x1F, 0);
-	}
-
-	rv |= chg_read8(chgnum, SM5803_REG_FLOW2, &flow2_reg);
-	if (rv)
-		return rv;
+	enum ec_error_list rv = EC_SUCCESS;
 
-	/*
-	 * Note: Charge may be enabled while OTG is enabled, but charge inhibit
-	 * should also turn off OTG.  Battery charging flags should only be set
-	 * when battery is present.
-	 */
 	if (mode & CHARGE_FLAG_INHIBIT_CHARGE) {
-		rv |= sm5803_flow1_update(chgnum, 0xFF, MASK_CLR);
-		flow2_reg &= ~SM5803_FLOW2_AUTO_ENABLED;
-	} else {
-		/*
-		 * TODO(b/163511546): SM5803: Consolidate flow control changes
-		 *
-		 * Should be a part of an initial sink enable function
-		 */
-		rv |= sm5803_flow1_update(chgnum, CHARGER_MODE_SINK, MASK_SET);
-		flow2_reg |= SM5803_FLOW2_AUTO_ENABLED;
+		rv = sm5803_flow1_update(chgnum, 0xFF, MASK_CLR);
+		rv |= sm5803_flow2_update(chgnum, SM5803_FLOW2_AUTO_ENABLED,
+					  MASK_CLR);
 	}
 
-	rv |= chg_write8(chgnum, SM5803_REG_FLOW2, flow2_reg);
-
 	return rv;
 }
 
@@ -920,26 +1004,18 @@ static enum ec_error_list sm5803_enable_otg_power(int chgnum, int enabled)
 	}
 
 	/*
-	 * Enable: CHG_EN - turns on buck-boost
-	 *	   VBUSIN_DISCH_EN - enable discharge on Vbus
+	 * Enable: SOURCE_MODE - enable sourcing out
 	 *	   DIRECTCHG_SOURCE_EN - enable current loop (for designs with
 	 *	   no external Vbus FET)
 	 *
-	 * Disable: disable bits above except CHG_EN, which should only be
-	 *	    disabled through set_mode.
+	 * Disable: disable bits above
 	 */
 	if (enabled)
 		rv = sm5803_flow1_update(chgnum, CHARGER_MODE_SOURCE |
 					 SM5803_FLOW1_DIRECTCHG_SRC_EN,
 					 MASK_SET);
 	else
-		/*
-		 * TODO(b/163511546): SM5803: Consolidate flow control changes
-		 *
-		 * May be able to disable mode entirely if PD task usage remains
-		 * consistent.
-		 */
-		rv = sm5803_flow1_update(chgnum, BIT(1) |
+		rv = sm5803_flow1_update(chgnum, CHARGER_MODE_SOURCE |
 					 SM5803_FLOW1_DIRECTCHG_SRC_EN,
 					 MASK_CLR);
 
@@ -955,8 +1031,11 @@ static int sm5803_is_sourcing_otg_power(int chgnum, int port)
 	if (rv)
 		return 0;
 
-	reg &= SM5803_FLOW1_MODE;
-	return reg == CHARGER_MODE_SOURCE;
+	/*
+	 * Note: In linear mode, MB charger will read a reserved mode when
+	 * sourcing, so bit 1 is the most reliable way to detect sourcing.
+	 */
+	return (reg & BIT(1));
 }
 
 static enum ec_error_list sm5803_set_vsys_compensation(int chgnum,
@@ -967,53 +1046,12 @@ static enum ec_error_list sm5803_set_vsys_compensation(int chgnum,
 
 	int rv;
 	int regval;
-	const struct battery_info *batt_info;
-	int ibat_eoc_ma;
 	int r;
 
-	/*
-	 * Enable linear, pre-charge, and linear fast charge for primary
-	 * charger.
-	 *
-	 * TODO(b/163511546): Move this into a sink enable function.
-	 */
-	rv = chg_read8(CHARGER_PRIMARY, SM5803_REG_FLOW3, &regval);
-	regval |= BIT(6) | BIT(5) | BIT(4);
-	rv |= chg_write8(CHARGER_PRIMARY, SM5803_REG_FLOW3, regval);
-
-	/* Set end of fast charge threshold */
-	batt_info = battery_get_info();
-	ibat_eoc_ma = batt_info->precharge_current - 50;
-	ibat_eoc_ma /= 100;
-	ibat_eoc_ma = CLAMP(ibat_eoc_ma, 0, SM5803_CONF5_IBAT_EOC_TH);
-	rv |= chg_read8(CHARGER_PRIMARY, SM5803_REG_FAST_CONF5, &regval);
-	regval &= ~SM5803_CONF5_IBAT_EOC_TH;
-	regval |= ibat_eoc_ma;
-	rv |= chg_write8(CHARGER_PRIMARY, SM5803_REG_FAST_CONF5, regval);
-
-	/* Enable test address and do some magic.*/
-	rv |= main_write8(CHARGER_PRIMARY, 0x1F, 0x1);
-	rv |= test_write8(CHARGER_PRIMARY, 0x44, 0x20);
-	rv |= test_write8(CHARGER_PRIMARY, 0x48, 0x4);
-	rv |= main_write8(CHARGER_PRIMARY, 0x1F, 0x0);
-
-	/* Enable linear mode on the primary charger IC */
-	rv |= sm5803_flow1_update(CHARGER_PRIMARY,
-				  SM5803_FLOW1_LINEAR_CHARGE_EN,
-				  MASK_SET);
-
-	/* Start pre-regulation on auxiliary charger. */
-	rv |= chg_write8(chgnum, SM5803_REG_FLOW1, CHARGER_MODE_SINK);
-
-	/* Enable the IBAT_CHG adc in order to calculate system resistance. */
-	rv |= meas_read8(chgnum, SM5803_REG_GPADC_CONFIG1, &regval);
-	regval |= SM5803_GPADCC1_IBAT_CHG_EN;
-	rv |= meas_write8(chgnum, SM5803_REG_GPADC_CONFIG1, regval);
-
 	/* Set IR drop compensation */
 	r = ocpc->combined_rsys_rbatt_mo * 100 / 167; /* 1.67mOhm steps */
 	r = MAX(0, r);
-	rv |= chg_write8(chgnum, SM5803_REG_IR_COMP2, r & 0x7F);
+	rv = chg_write8(chgnum, SM5803_REG_IR_COMP2, r & 0x7F);
 	rv |= chg_read8(chgnum, SM5803_REG_IR_COMP1, &regval);
 	regval &= ~SM5803_IR_COMP_RES_SET_MSB;
 	r = r >> 8; /* Bits 9:8 */
diff --git a/driver/charger/sm5803.h b/driver/charger/sm5803.h
index d16f000323..75e4885cbc 100644
--- a/driver/charger/sm5803.h
+++ b/driver/charger/sm5803.h
@@ -315,6 +315,7 @@ enum ec_error_list sm5803_get_chg_det(int chgnum, int *chg_det);
 
 /* Expose Vbus discharge function */
 enum ec_error_list sm5803_set_vbus_disch(int chgnum, int enable);
+enum ec_error_list sm5803_vbus_sink_enable(int chgnum, int enable);
 
 void sm5803_interrupt(int chgnum);