BD99955: Enable/Disable charger depending on charging current

Copy from CL:486101

If charging current is set to 0 mA during charging, reference of
charge current feedback amp (VREF_CHG) is set to 0V. Hence the DCDC
stops switching (because of the EA offset). To eliminate this issue,
disable/enable charger depending on the charging current is zero
or non-zero respectively.

BUG=b:37415851
BRANCH=gru
TEST=test 'ectool chargecontrol normal/idle/discharge' are working

Change-Id: Id31876afe365a476fb906e059ab519b7a0c9a7c6
Signed-off-by: james_chao <james_chao@asus.com>
Reviewed-on: https://chromium-review.googlesource.com/484180
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
Commit-Queue: Aseda Aboagye <aaboagye@chromium.org>

2 files changed, 43 insertions, 29 deletions

diff --git a/common/charge_state_v2.c b/common/charge_state_v2.c
index cebf6791d0..a4066dee4f 100644
--- a/common/charge_state_v2.c
+++ b/common/charge_state_v2.c
@@ -425,12 +425,7 @@ static int charge_request(int voltage, int current)
 	 * Set the charge inhibit bit when possible as it appears to save
 	 * power in some cases (e.g. Nyan with BQ24735).
 	 */
-#ifdef CONFIG_CHARGER_BD99955
-	/* Charger auto exits from battery learn mode if charge inhibited */
-	if (current > 0 || chg_ctl_mode == CHARGE_CONTROL_DISCHARGE)
-#else
-	if (voltage > 0 || current > 0)
-#endif
+	if (current > 0 || voltage > 0)
 		r3 = charger_set_mode(0);
 	else
 		r3 = charger_set_mode(CHARGE_FLAG_INHIBIT_CHARGE);
diff --git a/driver/charger/bd99955.c b/driver/charger/bd99955.c
index 0e5a773d97..626cce813a 100644
--- a/driver/charger/bd99955.c
+++ b/driver/charger/bd99955.c
@@ -148,6 +148,17 @@ static int bd99955_set_vsysreg(int voltage)
 			      BD99955_EXTENDED_COMMAND);
 }
 
+static int bd99955_is_discharging_on_ac(void)
+{
+	int reg;
+
+	if (ch_raw_read16(BD99955_CMD_CHGOP_SET2, &reg,
+				BD99955_EXTENDED_COMMAND))
+		return 0;
+
+	return !!(reg & BD99955_CMD_CHGOP_SET2_BATT_LEARN);
+}
+
 static int bd99955_charger_enable(int enable)
 {
 	int rv, reg;
@@ -602,10 +613,6 @@ int charger_set_mode(int mode)
 {
 	int rv;
 
-	rv = bd99955_charger_enable(mode & CHARGE_FLAG_INHIBIT_CHARGE ? 0 : 1);
-	if (rv)
-		return rv;
-
 	if (mode & CHARGE_FLAG_POR_RESET) {
 		rv = bd99955_por_reset();
 		if (rv)
@@ -630,6 +637,7 @@ int charger_get_current(int *current)
 int charger_set_current(int current)
 {
 	int rv;
+	int chg_enable = 1;
 
 	/* Charge current step 64 mA */
 	current &= ~0x3F;
@@ -637,18 +645,38 @@ int charger_set_current(int current)
 	if (current < BD99955_NO_BATTERY_CHARGE_I_MIN &&
 	    (battery_is_present() != BP_YES || battery_is_cut_off()))
 		current = BD99955_NO_BATTERY_CHARGE_I_MIN;
-	else if (current < bd99955_charger_info.current_min &&
-		!(charge_get_flags() & CHARGE_FLAG_FORCE_IDLE))
-		current = bd99955_charger_info.current_min;
+
+	/*
+	 * Disable charger before setting charge current to 0 or when
+	 * discharging on AC.
+	 * If charging current is set to 0mA during charging, reference of
+	 * the charge current feedback amp (VREF_CHG) is set to 0V. Hence
+	 * the DCDC stops switching (because of the EA offset).
+	 */
+	if (!current || bd99955_is_discharging_on_ac()) {
+		chg_enable = 0;
+		rv = bd99955_charger_enable(0);
+		if (rv)
+			return rv;
+	}
+
+	rv = ch_raw_write16(BD99955_CMD_IPRECH_SET,
+			    MIN(current, BD99955_IPRECH_MAX),
+			    BD99955_EXTENDED_COMMAND);
+
+	if (rv)
+		return rv;
 
 	rv = ch_raw_write16(BD99955_CMD_CHG_CURRENT, current,
-			    BD99955_BAT_CHG_COMMAND);
+				BD99955_BAT_CHG_COMMAND);
 	if (rv)
 		return rv;
 
-	return ch_raw_write16(BD99955_CMD_IPRECH_SET,
-			      MIN(current, BD99955_IPRECH_MAX),
-			      BD99955_EXTENDED_COMMAND);
+	/*
+	 * Enable charger if charge current is non-zero or not discharging
+	 * on AC.
+	 */
+	return chg_enable ? bd99955_charger_enable(1) : EC_SUCCESS;
 }
 
 int charger_get_voltage(int *voltage)
@@ -659,31 +687,22 @@ int charger_get_voltage(int *voltage)
 
 int charger_set_voltage(int voltage)
 {
-	int rv;
-	int reg;
 	const struct battery_info *bi = battery_get_info();
 
 	/*
 	 * Regulate the system voltage to battery max if the battery
 	 * is not present or the battery is discharging on AC.
 	 */
-	rv = ch_raw_read16(BD99955_CMD_CHGOP_SET2, &reg,
-				BD99955_EXTENDED_COMMAND);
-	if (rv)
-		return rv;
-
 	if (voltage == 0 ||
-		reg & BD99955_CMD_CHGOP_SET2_BATT_LEARN ||
+		bd99955_is_discharging_on_ac() ||
 		battery_is_present() != BP_YES ||
-		battery_is_cut_off())
+		battery_is_cut_off() ||
+		voltage > bi->voltage_max)
 		voltage = bi->voltage_max;
 
 	if (voltage < bd99955_charger_info.voltage_min)
 		voltage = bd99955_charger_info.voltage_min;
 
-	if (voltage > bi->voltage_max)
-		voltage = bi->voltage_max;
-
 	/* Charge voltage step 16 mV */
 	voltage &= ~0x0F;