regulator: palmas: preserve modes of rails during enable/disable

The Palma device like TPS65913 have the mode mask which is also
used for enable/disable the rails. The mode bits are defined as
	00: OFF
	01: AUTO
	10: ECO
	11: Forced PWM

and modes are set accordingly as
	REGULATOR_MODE_NORMAL: AUTO
	REGULATOR_MODE_IDLE: ECO
	REGULATOR_MODE_FAST: PWM

Two issue observed:
1. If client calls following sequence:
	regulator_enable(),
	regulator_set_mode(FAST),
	regulator_disable()

	and again the regulator_enable() then the mode is reset
	to NORMAL inplace of keeping the mode as FAST.

	Fixing this by storing the current mode configured by client
	and restoring modes when enable() is called after disable().

2. In following sequence, the regulator get enabled:
	regulator_disable()
	regulator_set_mode(FAST),

	Fixing this by updating new mode in register only if it is
	enabled.

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

@@ -274,7 +274,10 @@ static int palmas_enable_smps(struct regulator_dev *dev)
 	palmas_smps_read(pmic->palmas, palmas_regs_info[id].ctrl_addr, &reg);
 
 	reg &= ~PALMAS_SMPS12_CTRL_MODE_ACTIVE_MASK;
-	reg |= SMPS_CTRL_MODE_ON;
+	if (pmic->current_reg_mode[id])
+		reg |= pmic->current_reg_mode[id];
+	else
+		reg |= SMPS_CTRL_MODE_ON;
 
 	palmas_smps_write(pmic->palmas, palmas_regs_info[id].ctrl_addr, reg);
 
@@ -296,16 +299,19 @@ static int palmas_disable_smps(struct regulator_dev *dev)
 	return 0;
 }
 
-
 static int palmas_set_mode_smps(struct regulator_dev *dev, unsigned int mode)
 {
 	struct palmas_pmic *pmic = rdev_get_drvdata(dev);
 	int id = rdev_get_id(dev);
 	unsigned int reg;
+	bool rail_enable = true;
 
 	palmas_smps_read(pmic->palmas, palmas_regs_info[id].ctrl_addr, &reg);
 	reg &= ~PALMAS_SMPS12_CTRL_MODE_ACTIVE_MASK;
 
+	if (reg == SMPS_CTRL_MODE_OFF)
+		rail_enable = false;
+
 	switch (mode) {
 	case REGULATOR_MODE_NORMAL:
 		reg |= SMPS_CTRL_MODE_ON;
@@ -319,8 +325,11 @@ static int palmas_set_mode_smps(struct regulator_dev *dev, unsigned int mode)
 	default:
 		return -EINVAL;
 	}
-	palmas_smps_write(pmic->palmas, palmas_regs_info[id].ctrl_addr, reg);
 
+	pmic->current_reg_mode[id] = reg & PALMAS_SMPS12_CTRL_MODE_ACTIVE_MASK;
+	if (rail_enable)
+		palmas_smps_write(pmic->palmas,
+			palmas_regs_info[id].ctrl_addr, reg);
 	return 0;
 }
 
@@ -330,9 +339,7 @@ static unsigned int palmas_get_mode_smps(struct regulator_dev *dev)
 	int id = rdev_get_id(dev);
 	unsigned int reg;
 
-	palmas_smps_read(pmic->palmas, palmas_regs_info[id].ctrl_addr, &reg);
+	reg = pmic->current_reg_mode[id] & PALMAS_SMPS12_CTRL_MODE_ACTIVE_MASK;
-	reg &= PALMAS_SMPS12_CTRL_STATUS_MASK;
-	reg >>= PALMAS_SMPS12_CTRL_STATUS_SHIFT;
 
 	switch (reg) {
 	case SMPS_CTRL_MODE_ON:
@@ -871,7 +878,8 @@ static int palmas_regulators_probe(struct platform_device *pdev)
 			/*
 			 * Read and store the RANGE bit for later use
 			 * This must be done before regulator is probed,
-			 * otherwise we error in probe with unsupportable ranges.
+			 * otherwise we error in probe with unsupportable
+			 * ranges. Read the current smps mode for later use.
 			 */
 			addr = palmas_regs_info[id].vsel_addr;
 
@@ -888,6 +896,14 @@ static int palmas_regulators_probe(struct platform_device *pdev)
 						palmas_regs_info[id].vsel_addr);
 			pmic->desc[id].vsel_mask =
 					PALMAS_SMPS12_VOLTAGE_VSEL_MASK;
+
+			/* Read the smps mode for later use. */
+			addr = palmas_regs_info[id].ctrl_addr;
+			ret = palmas_smps_read(pmic->palmas, addr, &reg);
+			if (ret)
+				goto err_unregister_regulator;
+			pmic->current_reg_mode[id] = reg &
+					PALMAS_SMPS12_CTRL_MODE_ACTIVE_MASK;
 		}
 
 		pmic->desc[id].type = REGULATOR_VOLTAGE;

include/linux/mfd/palmas.h

@@ -327,6 +327,7 @@ struct palmas_pmic {
 
 	int range[PALMAS_REG_SMPS10];
 	unsigned int ramp_delay[PALMAS_REG_SMPS10];
+	unsigned int current_reg_mode[PALMAS_REG_SMPS10];
 };
 
 struct palmas_resource {