power: supply: axp20x_usb_power: replace current_max with input_current_limit

The current_max property is supposed to be read-only, and represent the
maximum current the supply can provide. input_current_limit is the
limit that is currently set, which is what we have here.

When determining what value to write to the register, we need to pick a
reasonable value if the requested limit doesn't exactly match one
supported by the hardware. If the requested limit is less than the
lowest value we can set, round up to the lowest value. Otherwise round
down to the nearest value supported by hardware.

Also add a dev field to the axp20x_usb_power struct, so we can use
dev_dbg and dev_err in more places.
Signed-off-by: Aren Moynihan <aren@peacevolution.org>
Link: https://lore.kernel.org/r/20240130203714.3020464-2-aren@peacevolution.orgSigned-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/power/supply/axp20x_usb_power.c

@@ -59,6 +59,7 @@ struct axp_data {
 };
 
 struct axp20x_usb_power {
+	struct device *dev;
 	struct regmap *regmap;
 	struct regmap_field *curr_lim_fld;
 	struct regmap_field *vbus_valid_bit;
@@ -160,7 +161,7 @@ static int axp20x_usb_power_get_property(struct power_supply *psy,
 
 		val->intval = ret * 1700; /* 1 step = 1.7 mV */
 		return 0;
-	case POWER_SUPPLY_PROP_CURRENT_MAX:
+	case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
 		ret = regmap_field_read(power->curr_lim_fld, &v);
 		if (ret)
 			return ret;
@@ -256,19 +257,24 @@ static int axp20x_usb_power_set_voltage_min(struct axp20x_usb_power *power,
 	return -EINVAL;
 }
 
-static int axp20x_usb_power_set_current_max(struct axp20x_usb_power *power, int intval)
+static int axp20x_usb_power_set_input_current_limit(struct axp20x_usb_power *power,
+						    int intval)
 {
+	unsigned int reg;
 	const unsigned int max = GENMASK(power->axp_data->curr_lim_fld.msb,
 					 power->axp_data->curr_lim_fld.lsb);
 
 	if (intval == -1)
 		return -EINVAL;
 
-	for (unsigned int i = 0; i <= max; ++i)
-		if (power->axp_data->curr_lim_table[i] == intval)
-			return regmap_field_write(power->curr_lim_fld, i);
+	for (reg = max - 1; reg > 0; reg--)
+		if (power->axp_data->curr_lim_table[reg] <= intval)
+			break;
 
-	return -EINVAL;
+	dev_dbg(power->dev, "setting input current limit reg to %d (%d uA), requested %d uA",
+		reg, power->axp_data->curr_lim_table[reg], intval);
+
+	return regmap_field_write(power->curr_lim_fld, reg);
 }
 
 static int axp20x_usb_power_set_property(struct power_supply *psy,
@@ -287,8 +293,8 @@ static int axp20x_usb_power_set_property(struct power_supply *psy,
 	case POWER_SUPPLY_PROP_VOLTAGE_MIN:
 		return axp20x_usb_power_set_voltage_min(power, val->intval);
 
-	case POWER_SUPPLY_PROP_CURRENT_MAX:
-		return axp20x_usb_power_set_current_max(power, val->intval);
+	case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+		return axp20x_usb_power_set_input_current_limit(power, val->intval);
 
 	default:
 		return -EINVAL;
@@ -313,7 +319,7 @@ static int axp20x_usb_power_prop_writeable(struct power_supply *psy,
 		return power->vbus_disable_bit != NULL;
 
 	return psp == POWER_SUPPLY_PROP_VOLTAGE_MIN ||
-	       psp == POWER_SUPPLY_PROP_CURRENT_MAX;
+	       psp == POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT;
 }
 
 static enum power_supply_property axp20x_usb_power_properties[] = {
@@ -322,7 +328,7 @@ static enum power_supply_property axp20x_usb_power_properties[] = {
 	POWER_SUPPLY_PROP_ONLINE,
 	POWER_SUPPLY_PROP_VOLTAGE_MIN,
 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
-	POWER_SUPPLY_PROP_CURRENT_MAX,
+	POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
 	POWER_SUPPLY_PROP_CURRENT_NOW,
 };
 
@@ -331,7 +337,7 @@ static enum power_supply_property axp22x_usb_power_properties[] = {
 	POWER_SUPPLY_PROP_PRESENT,
 	POWER_SUPPLY_PROP_ONLINE,
 	POWER_SUPPLY_PROP_VOLTAGE_MIN,
-	POWER_SUPPLY_PROP_CURRENT_MAX,
+	POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
 };
 
 static const struct power_supply_desc axp20x_usb_power_desc = {
@@ -558,6 +564,7 @@ static int axp20x_usb_power_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, power);
 
+	power->dev = &pdev->dev;
 	power->axp_data = axp_data;
 	power->regmap = axp20x->regmap;
 	power->num_irqs = axp_data->num_irq_names;