regulator: palmas: add support for LDO8 tracking mode

LDO8 of Palma device like tps65913 support the tracking mode
on which LDO8 track the SMPS45 voltage when SMPS45 is ON
and use the LDO8.VOLTAGE_SEL register when SMPS45 is OFF.

On track mode, the steps of voltage change for LDO8 is 25mV
where in non-tracking mode it is 50mV. Set the steps accordingly.
Number of voltage count is still same for both the cases.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Acked-by: Graeme Gregory <gg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/palmas-regulator.c

@@ -571,6 +571,46 @@ static int palmas_extreg_init(struct palmas *palmas, int id,
 	return 0;
 }
 
+static void palmas_enable_ldo8_track(struct palmas *palmas)
+{
+	unsigned int reg;
+	unsigned int addr;
+	int ret;
+
+	addr = palmas_regs_info[PALMAS_REG_LDO8].ctrl_addr;
+
+	ret = palmas_ldo_read(palmas, addr, &reg);
+	if (ret) {
+		dev_err(palmas->dev, "Error in reading ldo8 control reg\n");
+		return;
+	}
+
+	reg |= PALMAS_LDO8_CTRL_LDO_TRACKING_EN;
+	ret = palmas_ldo_write(palmas, addr, reg);
+	if (ret < 0) {
+		dev_err(palmas->dev, "Error in enabling tracking mode\n");
+		return;
+	}
+	/*
+	 * When SMPS45 is set to off and LDO8 tracking is enabled, the LDO8
+	 * output is defined by the LDO8_VOLTAGE.VSEL register divided by two,
+	 * and can be set from 0.45 to 1.65 V.
+	 */
+	addr = palmas_regs_info[PALMAS_REG_LDO8].vsel_addr;
+	ret = palmas_ldo_read(palmas, addr, &reg);
+	if (ret) {
+		dev_err(palmas->dev, "Error in reading ldo8 voltage reg\n");
+		return;
+	}
+
+	reg = (reg << 1) & PALMAS_LDO8_VOLTAGE_VSEL_MASK;
+	ret = palmas_ldo_write(palmas, addr, reg);
+	if (ret < 0)
+		dev_err(palmas->dev, "Error in setting ldo8 voltage reg\n");
+
+	return;
+}
+
 static struct of_regulator_match palmas_matches[] = {
 	{ .name = "smps12", },
 	{ .name = "smps123", },
@@ -656,6 +696,11 @@ static void palmas_dt_to_pdata(struct device *dev,
 		if (ret)
 			pdata->reg_init[idx]->vsel =
 				PALMAS_SMPS12_VOLTAGE_RANGE;
+
+		if (idx == PALMAS_REG_LDO8)
+			pdata->enable_ldo8_tracking = of_property_read_bool(
+						palmas_matches[idx].of_node,
+						"ti,enable-ldo8-tracking");
 	}
 
 	pdata->ldo6_vibrator = of_property_read_bool(node, "ti,ldo6-vibrator");
@@ -835,6 +880,13 @@ static int palmas_regulators_probe(struct platform_device *pdev)
 						palmas_regs_info[id].ctrl_addr);
 			pmic->desc[id].enable_mask =
 					PALMAS_LDO1_CTRL_MODE_ACTIVE;
+
+			/* Check if LDO8 is in tracking mode or not */
+			if (pdata && (id == PALMAS_REG_LDO8) &&
+					pdata->enable_ldo8_tracking) {
+				palmas_enable_ldo8_track(palmas);
+				pmic->desc[id].uV_step = 25000;
+			}
 		} else {
 			pmic->desc[id].n_voltages = 1;
 			pmic->desc[id].ops = &palmas_ops_extreg;
@@ -883,6 +935,7 @@ static int palmas_regulators_probe(struct platform_device *pdev)
 		}
 	}
 
+
 	return 0;
 
 err_unregister_regulator:

include/linux/mfd/palmas.h

@@ -177,6 +177,9 @@ struct palmas_pmic_platform_data {
 
 	/* use LDO6 for vibrator control */
 	int ldo6_vibrator;
+
+	/* Enable tracking mode of LDO8 */
+	bool enable_ldo8_tracking;
 };
 
 struct palmas_usb_platform_data {