linux-kernel - [PATCH v4 14/15] power: axp20x_battery: Support battery status without fuel gauge

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Message-Id: <20220629143046.213584-15-aidanmacdonald.0x0@gmail.com>
Date:   Wed, 29 Jun 2022 15:30:45 +0100
From:   Aidan MacDonald <aidanmacdonald.0x0@...il.com>
To:     linus.walleij@...aro.org, brgl@...ev.pl, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, wens@...e.org, jic23@...nel.org,
        sre@...nel.org, lee.jones@...aro.org, lgirdwood@...il.com,
        broonie@...nel.org
Cc:     lars@...afoo.de, quic_gurus@...cinc.com,
        sebastian.reichel@...labora.com, andy.shevchenko@...il.com,
        michael@...le.cc, rdunlap@...radead.org,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: [PATCH v4 14/15] power: axp20x_battery: Support battery status without fuel gauge

Add a "has_fg" flag to indicate that the chip has a fuel gauge.
Report battery full status on chips with no fuel gauge using the
battery voltage.

Acked-by: Sebastian Reichel <sebastian.reichel@...labora.com>
Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@...il.com>
---
 drivers/power/supply/axp20x_battery.c | 34 ++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/drivers/power/supply/axp20x_battery.c b/drivers/power/supply/axp20x_battery.c
index 401779d84d2b..574c1d001556 100644
--- a/drivers/power/supply/axp20x_battery.c
+++ b/drivers/power/supply/axp20x_battery.c
@@ -69,6 +69,7 @@ struct axp_data {
 	 * must have AXP20X_CHRG_CTRL1_TGT_CURR+1 elements.
 	 */
 	const int *ccc_table;
+	bool	has_fg;
 	bool	has_fg_valid;
 	int	(*get_max_voltage)(struct axp20x_batt_ps *batt, int *val);
 	int	(*set_max_voltage)(struct axp20x_batt_ps *batt, int val);
@@ -197,7 +198,7 @@ static int axp20x_battery_get_prop(struct power_supply *psy,
 				   union power_supply_propval *val)
 {
 	struct axp20x_batt_ps *axp20x_batt = power_supply_get_drvdata(psy);
-	int ret = 0, reg, val1;
+	int ret = 0, reg, val1, val2;
 
 	switch (psp) {
 	case POWER_SUPPLY_PROP_PRESENT:
@@ -231,6 +232,34 @@ static int axp20x_battery_get_prop(struct power_supply *psy,
 			return 0;
 		}
 
+		/*
+		 * If the chip does not have a fuel gauge, we check battery full status
+		 * using voltage instead.
+		 */
+		if (!axp20x_batt->data->has_fg) {
+			ret = axp20x_batt->data->get_max_voltage(axp20x_batt, &val1);
+			if (ret)
+				return ret;
+
+			ret = iio_read_channel_processed(axp20x_batt->batt_v, &val2);
+			if (ret)
+				return ret;
+
+			/* IIO subsystem reports voltage in mV but we need uV */
+			val2 *= 1000;
+
+			/*
+			 * According to the AXP192 datasheet, charging will restart if
+			 * the battery voltage drops below V_rch = V_tgt - 0.1 V, so we
+			 * report the battery is full if its voltage is at least V_rch.
+			 */
+			if (val2 >= val1 - 100000)
+				val->intval = POWER_SUPPLY_STATUS_FULL;
+			else
+				val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
+			break;
+		}
+
 		ret = regmap_read(axp20x_batt->regmap, AXP20X_FG_RES, &val1);
 		if (ret)
 			return ret;
@@ -552,6 +581,7 @@ static const struct power_supply_desc axp20x_batt_ps_desc = {
 static const struct axp_data axp209_data = {
 	.ccc_scale = 100000,
 	.ccc_offset = 300000,
+	.has_fg = true,
 	.get_max_voltage = axp20x_battery_get_max_voltage,
 	.set_max_voltage = axp20x_battery_set_max_voltage,
 };
@@ -559,6 +589,7 @@ static const struct axp_data axp209_data = {
 static const struct axp_data axp221_data = {
 	.ccc_scale = 150000,
 	.ccc_offset = 300000,
+	.has_fg = true,
 	.has_fg_valid = true,
 	.get_max_voltage = axp22x_battery_get_max_voltage,
 	.set_max_voltage = axp22x_battery_set_max_voltage,
@@ -567,6 +598,7 @@ static const struct axp_data axp221_data = {
 static const struct axp_data axp813_data = {
 	.ccc_scale = 200000,
 	.ccc_offset = 200000,
+	.has_fg = true,
 	.has_fg_valid = true,
 	.get_max_voltage = axp813_battery_get_max_voltage,
 	.set_max_voltage = axp20x_battery_set_max_voltage,
-- 
2.35.1