regulator: tps80031: Optimize voltage change by register cache

Using the register caching for optimizing the update of pmu register
through i2c. In this way, the frequent read of pmu register is
avoided.

bug 870689

Change-Id: Ic6666d4c04d7a46236dae5cc42d3b0815606efef
Reviewed-on: http://git-master/r/52335
Reviewed-by: Laxman Dewangan <ldewangan@nvidia.com>
Tested-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Bitan Biswas <bbiswas@nvidia.com>

1 files changed, 73 insertions, 59 deletions

diff --git a/drivers/regulator/tps80031-regulator.c b/drivers/regulator/tps80031-regulator.c
index 60393d55035c..c34945b8544b 100644
--- a/drivers/regulator/tps80031-regulator.c
+++ b/drivers/regulator/tps80031-regulator.c
@@ -88,6 +88,10 @@ struct tps80031_regulator {
 	u8		force_reg;
 	u8		volt_reg;
 	u8		volt_id;
+	uint8_t		trans_reg_cache;
+	uint8_t		state_reg_cache;
+	uint8_t		force_reg_cache;
+	uint8_t		volt_reg_cache;
 
 	/* twl resource ID, for resource control state machine */
 	u8			id;
@@ -153,19 +157,10 @@ static u8 tps80031_get_smps_mult(struct device *parent)
 static int tps80031_reg_is_enabled(struct regulator_dev *rdev)
 {
 	struct tps80031_regulator *ri = rdev_get_drvdata(rdev);
-	struct device *parent = to_tps80031_dev(rdev);
-	uint8_t state;
-	int ret;
 
 	if (ri->platform_flags & EXT_PWR_REQ)
 		return true;
-
-	ret = tps80031_read(parent, SLAVE_ID1, ri->state_reg, &state);
-	if (ret < 0) {
-		dev_err(&rdev->dev, "Error in reading the STATE register\n");
-		return ret;
-	}
-	return ((state & STATE_MASK) == STATE_ON);
+	return ((ri->state_reg_cache & STATE_MASK) == STATE_ON);
 }
 
 static int tps80031_reg_enable(struct regulator_dev *rdev)
@@ -173,16 +168,19 @@ static int tps80031_reg_enable(struct regulator_dev *rdev)
 	struct tps80031_regulator *ri = rdev_get_drvdata(rdev);
 	struct device *parent = to_tps80031_dev(rdev);
 	int ret;
+	uint8_t reg_val;
 
 	if (ri->platform_flags & EXT_PWR_REQ)
 		return 0;
 
-	ret = tps80031_force_update(parent, SLAVE_ID1, ri->state_reg, STATE_ON,
-				    STATE_MASK);
+	reg_val = (ri->state_reg_cache & ~STATE_MASK) |
+					(STATE_ON & STATE_MASK);
+	ret = tps80031_write(parent, SLAVE_ID1, ri->state_reg, reg_val);
 	if (ret < 0) {
-		dev_err(&rdev->dev, "Error in updating the STATE register\n");
+		dev_err(&rdev->dev, "Error in writing the STATE register\n");
 		return ret;
 	}
+	ri->state_reg_cache = reg_val;
 	udelay(ri->delay);
 	return ret;
 }
@@ -192,15 +190,18 @@ static int tps80031_reg_disable(struct regulator_dev *rdev)
 	struct tps80031_regulator *ri = rdev_get_drvdata(rdev);
 	struct device *parent = to_tps80031_dev(rdev);
 	int ret;
+	uint8_t reg_val;
 
 	if (ri->platform_flags & EXT_PWR_REQ)
 		return 0;
 
-	ret = tps80031_force_update(parent, SLAVE_ID1, ri->state_reg, STATE_OFF,
-				    STATE_MASK);
+	reg_val = (ri->state_reg_cache & ~STATE_MASK) |
+					(STATE_OFF & STATE_MASK);
+	ret = tps80031_write(parent, SLAVE_ID1, ri->state_reg, reg_val);
 	if (ret < 0)
-		dev_err(&rdev->dev, "Error in updating the STATE register\n");
-
+		dev_err(&rdev->dev, "Error in writing the STATE register\n");
+	else
+		ri->state_reg_cache = reg_val;
 	return ret;
 }
 
@@ -290,7 +291,6 @@ static int __tps80031_dcdc_set_voltage(struct device *parent,
 {
 	int vsel = 0;
 	int ret;
-	uint8_t force = 0;
 
 	switch (ri->flags) {
 	case 0:
@@ -365,23 +365,22 @@ static int __tps80031_dcdc_set_voltage(struct device *parent,
 	}
 
 	if (ri->force_reg) {
-		ret = tps80031_read(parent, ri->volt_id, ri->force_reg,
-						&force);
-		if (ret < 0) {
-			dev_err(ri->dev, "Error in reading the force register\n");
-			return ret;
-		}
-		if (((force >> 6) & 0x3) == 0) {
+		if (((ri->force_reg_cache >> 6) & 0x3) == 0) {
 			ret = tps80031_write(parent, ri->volt_id,
 						ri->force_reg, vsel);
-			goto out;
+			if (ret < 0)
+				dev_err(ri->dev, "Error in writing the "
+						"force register\n");
+			else
+				ri->force_reg_cache = vsel;
+			return ret;
 		}
 	}
 	ret = tps80031_write(parent, ri->volt_id, ri->volt_reg, vsel);
-
-out:
 	if (ret < 0)
-		dev_err(ri->dev, "Error in updating the Voltage register\n");
+		dev_err(ri->dev, "Error in writing the Voltage register\n");
+	else
+		ri->volt_reg_cache = vsel;
 	return ret;
 }
 
@@ -396,26 +395,16 @@ static int tps80031dcdc_set_voltage(struct regulator_dev *rdev,
 static int tps80031dcdc_get_voltage(struct regulator_dev *rdev)
 {
 	struct tps80031_regulator *ri = rdev_get_drvdata(rdev);
-	struct device *parent = to_tps80031_dev(rdev);
 	uint8_t vsel = 0;
-	int ret;
 	int voltage = 0;
 
 	if (ri->force_reg) {
-		ret = tps80031_read(parent, ri->volt_id, ri->force_reg, &vsel);
-		if (ret < 0) {
-			dev_err(&rdev->dev, "Error in reading the force register\n");
-			return ret;
-		}
+		vsel  = ri->force_reg_cache;
 		if ((vsel & SMPS_CMD_MASK) == 0)
 			goto decode;
 	}
 
-	ret = tps80031_read(parent, ri->volt_id, ri->volt_reg, &vsel);
-	if (ret < 0) {
-		dev_err(&rdev->dev, "Error in reading the Voltage register\n");
-		return ret;
-	}
+	vsel =  ri->volt_reg_cache;
 
 decode:
 	vsel &= SMPS_VSEL_MASK;
@@ -520,6 +509,8 @@ static int __tps80031_ldo_set_voltage(struct device *parent,
 	ret = tps80031_write(parent, ri->volt_id, ri->volt_reg, vsel);
 	if (ret < 0)
 		dev_err(ri->dev, "Error in writing the Voltage register\n");
+	else
+		ri->volt_reg_cache = vsel;
 	return ret;
 }
 
@@ -535,16 +526,9 @@ static int tps80031ldo_set_voltage(struct regulator_dev *rdev,
 static int tps80031ldo_get_voltage(struct regulator_dev *rdev)
 {
 	struct tps80031_regulator *ri = rdev_get_drvdata(rdev);
-	struct device *parent = to_tps80031_dev(rdev);
 	uint8_t vsel;
-	int ret;
 
-	ret = tps80031_read(parent, ri->volt_id, ri->volt_reg, &vsel);
-	if (ret < 0) {
-		dev_err(&rdev->dev, "Error in reading the Voltage register\n");
-		return ret;
-	}
-	vsel &= LDO_VSEL_MASK;
+	vsel = ri->volt_reg_cache & LDO_VSEL_MASK;
 
 	/*
 	 * Use the below formula to calculate vsel
@@ -746,6 +730,7 @@ static int tps80031_power_req_config(struct device *parent,
 	int preq_bit;
 	int preq_mask_bit;
 	int ret;
+	uint8_t reg_val;
 
 	if (!(ri->platform_flags & EXT_PWR_REQ))
 		return 0;
@@ -783,13 +768,13 @@ static int tps80031_power_req_config(struct device *parent,
 	}
 
 	/* Switch regulator control to resource now */
-	ret = tps80031_update(parent, SLAVE_ID1, ri->state_reg, 0x0,
-					STATE_MASK);
-	if (ret < 0) {
-		dev_err(ri->dev, "%s() Error in updating the STATE "
+	reg_val = (ri->state_reg_cache & ~STATE_MASK);
+	ret = tps80031_write(parent, SLAVE_ID1, ri->state_reg, reg_val);
+	if (ret < 0)
+		dev_err(ri->dev, "%s() Error in writing the STATE "
 				"register error %d\n", __func__, ret);
-		return ret;
-	}
+	else
+		ri->state_reg_cache = reg_val;
 	return ret;
 }
 
@@ -798,6 +783,7 @@ static int tps80031_regulator_preinit(struct device *parent,
 		struct tps80031_regulator_platform_data *tps80031_pdata)
 {
 	int ret = 0;
+	uint8_t reg_val;
 
 	if (ri->desc.id == TPS80031_ID_LDOUSB) {
 		if (ri->platform_flags & USBLDO_INPUT_VSYS)
@@ -871,15 +857,19 @@ static int tps80031_regulator_preinit(struct device *parent,
 	}
 
 	if (tps80031_pdata->init_enable)
-		ret = tps80031_force_update(parent, SLAVE_ID1, ri->state_reg,
-					    STATE_ON, STATE_MASK);
+		reg_val = (ri->state_reg_cache & ~STATE_MASK) |
+				(STATE_ON & STATE_MASK);
 	else
-		ret = tps80031_force_update(parent, SLAVE_ID1, ri->state_reg,
-					    STATE_OFF, STATE_MASK);
+		reg_val = (ri->state_reg_cache & ~STATE_MASK) |
+				(STATE_OFF & STATE_MASK);
+
+	ret = tps80031_write(parent, SLAVE_ID1, ri->state_reg, reg_val);
 	if (ret < 0)
 		dev_err(ri->dev, "Not able to %s rail %d err %d\n",
 			(tps80031_pdata->init_enable) ? "enable" : "disable",
 			ri->desc.id, ret);
+	else
+		ri->state_reg_cache = reg_val;
 	return ret;
 }
 
@@ -926,6 +916,25 @@ static void check_smps_mode_mult(struct device *parent,
 	return;
 }
 
+static inline int tps80031_cache_regulator_register(struct device *parent,
+	struct tps80031_regulator *ri)
+{
+	int ret;
+
+	ret = tps80031_read(parent, SLAVE_ID1, ri->trans_reg,
+			&ri->trans_reg_cache);
+	if (!ret && ri->state_reg)
+		ret = tps80031_read(parent, SLAVE_ID1, ri->state_reg,
+			&ri->state_reg_cache);
+	if (!ret && ri->force_reg)
+		ret = tps80031_read(parent, ri->volt_id, ri->force_reg,
+			&ri->force_reg_cache);
+	if (!ret && ri->volt_reg)
+		ret = tps80031_read(parent, ri->volt_id, ri->volt_reg,
+			&ri->volt_reg_cache);
+	return ret;
+}
+
 static int __devinit tps80031_regulator_probe(struct platform_device *pdev)
 {
 	struct tps80031_regulator *ri = NULL;
@@ -949,6 +958,11 @@ static int __devinit tps80031_regulator_probe(struct platform_device *pdev)
 	check_smps_mode_mult(pdev->dev.parent, ri);
 	ri->platform_flags = tps_pdata->flags;
 
+	err = tps80031_cache_regulator_register(pdev->dev.parent, ri);
+	if (err) {
+		dev_err(&pdev->dev, "Register access for caching is failed\n");
+		return err;
+	}
 	err = tps80031_regulator_preinit(pdev->dev.parent, ri, tps_pdata);
 	if (err)
 		return err;