[PATCH 2/2] power: supply: qcom_battmgr: expose the charge current limit

[Joonhoe Kim]

The battery manager firmware takes a charge current limit in uA
(BATT_CHG_CTRL_LIM) and reports the highest value it accepts
(BATT_CHG_CTRL_LIM_MAX). Expose them on SM8550 class batteries as
charge_control_limit and charge_control_limit_max, clamping writes to
the maximum.

Also handle the BATTMGR_BAT_PROPERTY_SET response, which was logged as
an unknown message, and return its result.

On a Lenovo Legion Tab Y700 Gen 5 with a 45 W PD charger, limits of
500 mA and 100 mA give about 480 mA and 90 mA of charge current while
the PD contract stays at 9 V. A limit of 0 stops charging, and this
firmware does not resume when the limit is raised again until the end
threshold is moved below the capacity and back.

Signed-off-by: Joonhoe Kim <26rote@xxxxxxxxx>
---
The downstream qti_battery_charger driver also writes this property in
uA. The thermal mitigation series [1] used it as a level index, and
Konrad noted that the ABI defines charge_control_limit in uA; this
follows the ABI. Only tested on Kaanapali.

[1] https://lore.kernel.org/all/20260609-cooling_device_reg-v1-2-e15bddcb0086@xxxxxxxxxxxxxxxx/

 drivers/power/supply/qcom_battmgr.c | 52 +++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/drivers/power/supply/qcom_battmgr.c b/drivers/power/supply/qcom_battmgr.c
index 0d55458b2881..69931827bc08 100644
--- a/drivers/power/supply/qcom_battmgr.c
+++ b/drivers/power/supply/qcom_battmgr.c
@@ -260,6 +260,8 @@ struct qcom_battmgr_info {
 	unsigned int charge_count;
 	unsigned int charge_ctrl_start;
 	unsigned int charge_ctrl_end;
+	unsigned int charge_ctrl_limit;
+	unsigned int charge_ctrl_limit_max;
 	char model_number[BATTMGR_STRING_LEN];
 	char serial_number[BATTMGR_STRING_LEN];
 	char oem_info[BATTMGR_STRING_LEN];
@@ -451,6 +453,8 @@ static const u8 sm8350_bat_prop_map[] = {
 	[POWER_SUPPLY_PROP_POWER_NOW] = BATT_POWER_NOW,
 	[POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD] = BATT_CHG_CTRL_START_THR,
 	[POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD] = BATT_CHG_CTRL_END_THR,
+	[POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT] = BATT_CHG_CTRL_LIM,
+	[POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX] = BATT_CHG_CTRL_LIM_MAX,
 };
 
 static int qcom_battmgr_bat_sm8350_update(struct qcom_battmgr *battmgr,
@@ -635,6 +639,12 @@ static int qcom_battmgr_bat_get_property(struct power_supply *psy,
 	case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
 		val->intval = battmgr->info.charge_ctrl_end;
 		break;
+	case POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT:
+		val->intval = battmgr->info.charge_ctrl_limit;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX:
+		val->intval = battmgr->info.charge_ctrl_limit_max;
+		break;
 	case POWER_SUPPLY_PROP_MANUFACTURE_YEAR:
 		val->intval = battmgr->info.year;
 		break;
@@ -729,6 +739,26 @@ static int qcom_battmgr_set_charge_end_threshold(struct qcom_battmgr *battmgr, i
 	return 0;
 }
 
+static int qcom_battmgr_set_charge_control_limit(struct qcom_battmgr *battmgr, int limit)
+{
+	int ret;
+
+	if (limit < 0)
+		return -EINVAL;
+
+	mutex_lock(&battmgr->lock);
+	ret = qcom_battmgr_request_property(battmgr, BATTMGR_BAT_PROPERTY_GET,
+					    BATT_CHG_CTRL_LIM_MAX, 0);
+	if (!ret) {
+		limit = min_t(u32, limit, battmgr->info.charge_ctrl_limit_max);
+		ret = qcom_battmgr_request_property(battmgr, BATTMGR_BAT_PROPERTY_SET,
+						    BATT_CHG_CTRL_LIM, limit);
+	}
+	mutex_unlock(&battmgr->lock);
+
+	return ret;
+}
+
 static int qcom_battmgr_charge_control_thresholds_init(struct qcom_battmgr *battmgr)
 {
 	int ret;
@@ -764,6 +794,7 @@ static int qcom_battmgr_bat_is_writeable(struct power_supply *psy,
 	switch (psp) {
 	case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
 	case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
+	case POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT:
 		return 1;
 	default:
 		return 0;
@@ -786,6 +817,8 @@ static int qcom_battmgr_bat_set_property(struct power_supply *psy,
 		return qcom_battmgr_set_charge_start_threshold(battmgr, pval->intval);
 	case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
 		return qcom_battmgr_set_charge_end_threshold(battmgr, pval->intval);
+	case POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT:
+		return qcom_battmgr_set_charge_control_limit(battmgr, pval->intval);
 	default:
 		return -EINVAL;
 	}
@@ -921,6 +954,8 @@ static const enum power_supply_property sm8550_bat_props[] = {
 	POWER_SUPPLY_PROP_POWER_NOW,
 	POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD,
 	POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD,
+	POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT,
+	POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX,
 };
 
 static const struct power_supply_desc sm8550_bat_psy_desc = {
@@ -1479,11 +1514,28 @@ static void qcom_battmgr_sm8350_callback(struct qcom_battmgr *battmgr,
 		case BATT_CHG_CTRL_END_THR:
 			battmgr->info.charge_ctrl_end = le32_to_cpu(resp->intval.value);
 			break;
+		case BATT_CHG_CTRL_LIM:
+			battmgr->info.charge_ctrl_limit = le32_to_cpu(resp->intval.value);
+			break;
+		case BATT_CHG_CTRL_LIM_MAX:
+			battmgr->info.charge_ctrl_limit_max = le32_to_cpu(resp->intval.value);
+			break;
 		default:
 			dev_warn(battmgr->dev, "unknown property %#x\n", property);
 			break;
 		}
 		break;
+	case BATTMGR_BAT_PROPERTY_SET:
+		if (payload_len != sizeof(resp->intval)) {
+			dev_warn(battmgr->dev,
+				 "invalid payload length for battery property set: %zd\n",
+				 payload_len);
+			battmgr->error = -ENODATA;
+			return;
+		}
+
+		battmgr->error = le32_to_cpu(resp->intval.result) ? -EIO : 0;
+		break;
 	case BATTMGR_USB_PROPERTY_GET:
 		property = le32_to_cpu(resp->intval.property);
 		if (payload_len != sizeof(resp->intval)) {
-- 
2.43.0