[PATCH v3 14/16] power: axp20x_battery: Add constant charge current table

[Aidan MacDonald <aidanmacdonald.0x0@gmail.com>]

Add a table-based lookup method for constant charge current,
which is necessary when the setting cannot be represented as
a linear range.

This also replaces the hard-coded 300 mA default ccc setting
if the DT-specified value is unsupported; the minimum value
for the device is now set exactly instead of relying on the
value being rounded down to a supported value.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
---
 drivers/power/supply/axp20x_battery.c | 60 +++++++++++++++++++++------
 1 file changed, 48 insertions(+), 12 deletions(-)

diff --git a/drivers/power/supply/axp20x_battery.c b/drivers/power/supply/axp20x_battery.c
index 9106077c0dbb..ce22c0a92878 100644
--- a/drivers/power/supply/axp20x_battery.c
+++ b/drivers/power/supply/axp20x_battery.c
@@ -61,6 +61,14 @@ struct axp20x_batt_ps;
 struct axp_data {
 	int	ccc_scale;
 	int	ccc_offset;
+	/*
+	 * Lookup table for constant charge current, if provided this is used
+	 * instead of ccc_scale/ccc_offset.
+	 *
+	 * The table is indexed by the field AXP20X_CHRG_CTRL1_TGT_CURR so it
+	 * must have AXP20X_CHRG_CTRL1_TGT_CURR+1 elements.
+	 */
+	const int *ccc_table;
 	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);
@@ -176,7 +184,10 @@ static int axp20x_get_constant_charge_current(struct axp20x_batt_ps *axp,
 
 	*val &= AXP20X_CHRG_CTRL1_TGT_CURR;
 
-	*val = *val * axp->data->ccc_scale + axp->data->ccc_offset;
+	if (axp->data->ccc_table)
+		*val = axp->data->ccc_table[*val];
+	else
+		*val = *val * axp->data->ccc_scale + axp->data->ccc_offset;
 
 	return 0;
 }
@@ -389,16 +400,36 @@ static int axp20x_battery_set_max_voltage(struct axp20x_batt_ps *axp20x_batt,
 				  AXP20X_CHRG_CTRL1_TGT_VOLT, val);
 }
 
+static int axp20x_get_constant_charge_current_sel(struct axp20x_batt_ps *axp_batt,
+						  int charge_current)
+{
+	int i;
+
+	if (axp_batt->data->ccc_table) {
+		for (i = AXP20X_CHRG_CTRL1_TGT_CURR; i >= 0; --i) {
+			if (axp_batt->data->ccc_table[i] <= charge_current)
+				return i;
+		}
+
+		return -EINVAL;
+	}
+
+	i = (charge_current - axp_batt->data->ccc_offset) / axp_batt->data->ccc_scale;
+
+	if (i > AXP20X_CHRG_CTRL1_TGT_CURR || i < 0)
+		return -EINVAL;
+
+	return i;
+}
+
 static int axp20x_set_constant_charge_current(struct axp20x_batt_ps *axp_batt,
 					      int charge_current)
 {
 	if (charge_current > axp_batt->max_ccc)
 		return -EINVAL;
 
-	charge_current = (charge_current - axp_batt->data->ccc_offset) /
-		axp_batt->data->ccc_scale;
-
-	if (charge_current > AXP20X_CHRG_CTRL1_TGT_CURR || charge_current < 0)
+	charge_current = axp20x_get_constant_charge_current_sel(axp_batt, charge_current);
+	if (charge_current < 0)
 		return -EINVAL;
 
 	return regmap_update_bits(axp_batt->regmap, AXP20X_CHRG_CTRL1,
@@ -410,14 +441,14 @@ static int axp20x_set_max_constant_charge_current(struct axp20x_batt_ps *axp,
 {
 	bool lower_max = false;
 
-	charge_current = (charge_current - axp->data->ccc_offset) /
-		axp->data->ccc_scale;
-
-	if (charge_current > AXP20X_CHRG_CTRL1_TGT_CURR || charge_current < 0)
+	charge_current = axp20x_get_constant_charge_current_sel(axp, charge_current);
+	if (charge_current < 0)
 		return -EINVAL;
 
-	charge_current = charge_current * axp->data->ccc_scale +
-		axp->data->ccc_offset;
+	if (axp->data->ccc_table)
+		charge_current = axp->data->ccc_table[charge_current];
+	else
+		charge_current = charge_current * axp->data->ccc_scale + axp->data->ccc_offset;
 
 	if (charge_current > axp->max_ccc)
 		dev_warn(axp->dev,
@@ -629,7 +660,12 @@ static int axp20x_power_probe(struct platform_device *pdev)
 								   ccc)) {
 			dev_err(&pdev->dev,
 				"couldn't set constant charge current from DT: fallback to minimum value\n");
-			ccc = 300000;
+
+			if (axp20x_batt->data->ccc_table)
+				ccc = axp20x_batt->data->ccc_table[0];
+			else
+				ccc = axp20x_batt->data->ccc_offset;
+
 			axp20x_batt->max_ccc = ccc;
 			axp20x_set_constant_charge_current(axp20x_batt, ccc);
 		}
-- 
2.35.1