[PATCH v4 09/11] power: supply: max17042_battery: Initialize MAX17055 from battery info

From: Vincent Cloutier <[email protected]>

Use charge-full-design-microamp-hours and
charge-term-current-microamp from monitored-battery to prepare MAX17055
DesignCap, IChgTerm, and EZ Config dQAcc values in the power-supply
registration callback.

Apply positive battery values and treat zero like an absent property.
Validate all supplied positive values before changing the sparse
configuration. Reject values that quantize to zero, capacities that cannot
produce dQAcc, and termination currents outside the signed register range.
Limit this path to MAX17055 because the other supported gauges require
complete characterization data.

Assisted-by: OpenCode:gpt-5.6-sol
Signed-off-by: Vincent Cloutier <[email protected]>
---
 drivers/power/supply/max17042_battery.c | 82 +++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
index 33a2cc378b46..db3b1bc5388f 100644
--- a/drivers/power/supply/max17042_battery.c
+++ b/drivers/power/supply/max17042_battery.c
@@ -62,6 +62,7 @@
 #define MAX17042_RESISTANCE_LSB		1 / 4096 /* Ω */
 #define MAX17042_TEMPERATURE_LSB	1 / 256 /* °C */
 
+#define MAX17055_DQACC_DIV		32
 #define MAX17055_DPACC_FACTOR		44138
 #define MAX17055_DPACC_VCHG_FACTOR	51200
 #define MAX17055_FSTAT_DNR_BIT		BIT(0)
@@ -1240,6 +1241,85 @@ static int max17042_init_defaults(struct max17042_chip *chip)
 	return 0;
 }
 
+static int max17042_apply_battery_properties(struct max17042_chip *chip,
+					     struct power_supply_battery_info *info)
+{
+	struct max17042_config_data *config;
+	struct device *dev = chip->dev;
+	bool have_design_cap;
+	bool have_ichgt_term;
+	u16 design_cap = 0;
+	u16 ichgt_term = 0;
+	u16 dqacc = 0;
+	u64 data64;
+
+	if (!info || chip->chip_type != MAXIM_DEVICE_TYPE_MAX17055)
+		return 0;
+
+	have_design_cap = chip->enable_current_sense &&
+		info->charge_full_design_uah > 0;
+	have_ichgt_term = chip->enable_current_sense &&
+		info->charge_term_current_ua > 0;
+	if (!have_design_cap && !have_ichgt_term)
+		return 0;
+
+	if (have_design_cap) {
+		data64 = (u64)info->charge_full_design_uah * chip->r_sns;
+		do_div(data64, MAX17042_CAPACITY_LSB);
+		if (!data64)
+			return dev_err_probe(dev, -ERANGE,
+					     "battery design capacity is too small for sense resistor\n");
+		if (data64 > U16_MAX)
+			return dev_err_probe(dev, -ERANGE,
+					     "battery design capacity exceeds register range\n");
+
+		design_cap = (u16)data64;
+		dqacc = design_cap / MAX17055_DQACC_DIV;
+		if (!dqacc)
+			return dev_err_probe(dev, -ERANGE,
+					     "battery design capacity is too small for EZ config\n");
+	}
+
+	if (have_ichgt_term) {
+		data64 = (u64)info->charge_term_current_ua * chip->r_sns;
+		do_div(data64, MAX17042_CURRENT_LSB);
+		if (!data64)
+			return dev_err_probe(dev, -ERANGE,
+					     "charge termination current is too small for sense resistor\n");
+		if (data64 > S16_MAX)
+			return dev_err_probe(dev, -ERANGE,
+					     "charge termination current exceeds positive register range\n");
+
+		ichgt_term = (u16)data64;
+	}
+
+	config = chip->config_data;
+	if (!config) {
+		config = devm_kzalloc(dev, sizeof(*config), GFP_KERNEL);
+		if (!config)
+			return -ENOMEM;
+	}
+
+	if (have_design_cap) {
+		config->design_cap = design_cap;
+		config->dqacc = dqacc;
+	}
+	if (have_ichgt_term)
+		config->ichgt_term = ichgt_term;
+
+	chip->config_data = config;
+	chip->enable_por_init = true;
+
+	return 0;
+}
+
+static int max17042_init_battery(struct power_supply *psy)
+{
+	struct max17042_chip *chip = power_supply_get_drvdata(psy);
+
+	return max17042_apply_battery_properties(chip, psy->battery_info);
+}
+
 static const struct regmap_config max17042_regmap_config = {
 	.name = "max17042",
 	.reg_bits = 8,
@@ -1293,6 +1373,7 @@ static const struct power_supply_desc max17042_psy_desc = {
 	.set_property	= max17042_set_property,
 	.property_is_writeable	= max17042_property_is_writeable,
 	.external_power_changed	= power_supply_changed,
+	.init		= max17042_init_battery,
 	.properties	= max17042_battery_props,
 	.num_properties	= ARRAY_SIZE(max17042_battery_props),
 };
@@ -1303,6 +1384,7 @@ static const struct power_supply_desc max17042_no_current_sense_psy_desc = {
 	.get_property	= max17042_get_property,
 	.set_property	= max17042_set_property,
 	.property_is_writeable	= max17042_property_is_writeable,
+	.init		= max17042_init_battery,
 	.properties	= max17042_battery_props,
 	.num_properties	= ARRAY_SIZE(max17042_battery_props) - 2,
 };
-- 
2.55.0