Regulator: max8998: fix transitory low voltage selection

buck1,2 gpio should be set after initializing its output voltage
and selected voltage should match with default bootup frequency
unless garbage or default voltage will come out right after gpio setup

Because dvsarm1 and dvsarm2 gpio cannot be set at one time,
there could be a voltage drop during dvs change.

Based on .35 kernel's "regulator: max8998: use DVS mode for BUCK1,BUCK2"
Author: Todd Poynor <toddpoynor@google.com>

Change-Id: I7c7618c166ef1618939b95532be0befa4d81e505
Signed-off-by: Kisoo Yu <ksoo.yu@samsung.com>

1 files changed, 188 insertions, 85 deletions

diff --git a/drivers/regulator/max8998.c b/drivers/regulator/max8998.c
index 41a1495..967e3c2 100644
--- a/drivers/regulator/max8998.c
+++ b/drivers/regulator/max8998.c
@@ -44,6 +44,7 @@ struct max8998_data {
 	unsigned int		buck1_idx; /* index to last changed voltage */
 					   /* value in a set */
 	unsigned int		buck2_idx;
+	unsigned int		gpio_reset_val;
 };
 
 struct voltage_map_desc {
@@ -112,6 +113,19 @@ static const struct voltage_map_desc *ldo_voltage_map[] = {
 	&buck4_voltage_map_desc,	/* BUCK4 */
 };
 
+/*
+ * Map ordinal values of increasing voltages to BUCK1_DVSARM registers
+ * using Gray code, to allow the 2 set GPIOs to be individually
+ * modified without temporarily lowering voltage out of spec and
+ * without temporarily moving voltage in the wrong direction.  The
+ * four voltages are indexed from 0-3 in increasing voltage value,
+ * but are actually assigned to BUCK1_DVSARMn registers using
+ * ordering {0,1,3,2} when default Buck1 is 0 or 1,
+ * {1,0,2,3} when default Buck1 is 2 or 3.
+ */
+
+#define DVSARMREG(index) ((index ^ (index >> 1)) ^ ((pdata->buck1_default_idx & 0x2) >> 1))
+
 static inline int max8998_get_ldo(struct regulator_dev *rdev)
 {
 	return rdev_get_id(rdev);
@@ -342,17 +356,23 @@ static int max8998_set_voltage_ldo(struct regulator_dev *rdev,
 	return ret;
 }
 
-static inline void buck1_gpio_set(int gpio1, int gpio2, int v)
+static inline void buck1_gpio_set(int gpio1, int gpio2, int v, int w)
 {
-	gpio_set_value(gpio1, v & 0x1);
+	if ((v & 1) == !w)
+		gpio_set_value(gpio1, !w);
+
 	gpio_set_value(gpio2, (v >> 1) & 0x1);
-}
 
+	if ((v & 1) != !w)
+		gpio_set_value(gpio1, w);
+
+}
 static inline void buck2_gpio_set(int gpio, int v)
 {
 	gpio_set_value(gpio, v & 0x1);
 }
 
+
 static int max8998_set_voltage_buck(struct regulator_dev *rdev,
 				    int min_uV, int max_uV, unsigned *selector)
 {
@@ -364,9 +384,8 @@ static int max8998_set_voltage_buck(struct regulator_dev *rdev,
 	const struct voltage_map_desc *desc;
 	int buck = max8998_get_ldo(rdev);
 	int reg, shift = 0, mask, ret;
-	int difference = 0, i = 0, j = 0, previous_vol = 0;
+	int difference = 0, i = 0, j = 0, previous_vol = 0, previous_idx = 0;
 	u8 val = 0;
-	static u8 buck1_last_val;
 
 	if (buck >= ARRAY_SIZE(ldo_voltage_map))
 		return -EINVAL;
@@ -405,10 +424,10 @@ static int max8998_set_voltage_buck(struct regulator_dev *rdev,
 	switch (buck) {
 	case MAX8998_BUCK1:
 		dev_dbg(max8998->dev,
-			"BUCK1, i:%d, buck1_vol1:%d, buck1_vol2:%d\n"
-			"buck1_vol3:%d, buck1_vol4:%d\n",
-			i, max8998->buck1_vol[0], max8998->buck1_vol[1],
-			max8998->buck1_vol[2], max8998->buck1_vol[3]);
+			"BUCK1, i:%d, buck1_vol1:%d, buck1_vol2:%d\n\
+			 buck1_vol3:%d, buck1_vol4:%d\n",
+			i, max8998->buck1_vol[DVSARMREG(0)], max8998->buck1_vol[DVSARMREG(1)],
+			max8998->buck1_vol[DVSARMREG(2)], max8998->buck1_vol[DVSARMREG(3)]);
 
 		if (gpio_is_valid(pdata->buck1_set1) &&
 		    gpio_is_valid(pdata->buck1_set2)) {
@@ -416,10 +435,10 @@ static int max8998_set_voltage_buck(struct regulator_dev *rdev,
 			/* check if requested voltage */
 			/* value is already defined */
 			for (j = 0; j < ARRAY_SIZE(max8998->buck1_vol); j++) {
-				if (max8998->buck1_vol[j] == i) {
-					max8998->buck1_idx = j;
-					buck1_gpio_set(pdata->buck1_set1,
-						       pdata->buck1_set2, j);
+				if (max8998->buck1_vol[DVSARMREG(j)] == i) {
+					buck1_gpio_set(pdata->buck1_set1, pdata->buck1_set2, DVSARMREG(j), max8998->gpio_reset_val);
+					max8998->buck1_idx = DVSARMREG(j);
+					dev_dbg(max8998->dev, "buck1_level=%d, buck1_index=%d \n", j, DVSARMREG(j));
 					goto buck1_exit;
 				}
 			}
@@ -427,18 +446,73 @@ static int max8998_set_voltage_buck(struct regulator_dev *rdev,
 			if (pdata->buck_voltage_lock)
 				return -EINVAL;
 
-			/* no predefine regulator found */
-			max8998->buck1_idx = (buck1_last_val % 2) + 2;
+			/* No predefine regulator found
+			 * Once we reach here,
+			 * all remaining predefined voltage is cleared,
+			 * and two buck1_idx 0 and 1 are used as now.
+			 */
+			previous_idx = max8998->buck1_idx;
+			if (previous_idx == 0) {
+				max8998->buck1_idx = 1;
+			} else if (previous_idx == 1) {
+				max8998->buck1_idx = 0;
+			} else {
+				/* change possible intermediate level */
+				val = max8998->buck1_vol[max8998->buck1_idx];
+				if (previous_idx == 2) {
+					max8998->buck1_idx = 3;
+				} else if (previous_idx == 3) {
+					max8998->buck1_idx = 2;
+				}
+				ret = max8998_get_voltage_register(rdev, &reg, &shift, &mask);
+				if (ret) {
+					max8998->buck1_idx = previous_idx;
+					return ret;
+				}
+				ret = max8998_write_reg(i2c, reg, val);
+				if (ret) {
+					max8998->buck1_vol[max8998->buck1_idx] = 0;
+					max8998->buck1_idx = previous_idx;
+					return ret;
+				}
+
+				/* set index 1 with current voltage */
+				max8998->buck1_idx = 1;
+				ret = max8998_get_voltage_register(rdev, &reg, &shift, &mask);
+				if (ret) {
+					max8998->buck1_idx = previous_idx;
+					return ret;
+				}
+				ret = max8998_write_reg(i2c, reg, val);
+				if (ret) {
+					max8998->buck1_vol[max8998->buck1_idx] = 0;
+					max8998->buck1_idx = previous_idx;
+					return ret;
+				}
+				buck1_gpio_set(pdata->buck1_set1, pdata->buck1_set2, max8998->buck1_idx, max8998->gpio_reset_val);
+
+				/*Now, change to index 0*/
+				previous_idx = 1;
+				max8998->buck1_idx = 0;
+			}
 			dev_dbg(max8998->dev, "max8998->buck1_idx:%d\n",
 				max8998->buck1_idx);
 			max8998->buck1_vol[max8998->buck1_idx] = i;
-			ret = max8998_get_voltage_register(rdev, &reg,
-							   &shift,
-							   &mask);
+			ret = max8998_get_voltage_register(rdev, &reg, &shift, &mask);
+			if (ret) {
+				max8998->buck1_idx = previous_idx;
+				return ret;
+			}
 			ret = max8998_write_reg(i2c, reg, i);
-			buck1_gpio_set(pdata->buck1_set1,
-				       pdata->buck1_set2, max8998->buck1_idx);
-			buck1_last_val++;
+			if (ret) {
+				max8998->buck1_vol[max8998->buck1_idx] = 0;
+				max8998->buck1_idx = previous_idx;
+				return ret;
+			}
+			buck1_gpio_set(pdata->buck1_set1, pdata->buck1_set2, max8998->buck1_idx, max8998->gpio_reset_val);
+			for (j = 2; j < 4; j++)
+				max8998->buck1_vol[j] = 0;
+
 buck1_exit:
 			dev_dbg(max8998->dev, "%s: SET1:%d, SET2:%d\n",
 				i2c->name, gpio_get_value(pdata->buck1_set1),
@@ -693,7 +767,7 @@ static __devinit int max8998_pmic_probe(struct platform_device *pdev)
 	struct regulator_dev **rdev;
 	struct max8998_data *max8998;
 	struct i2c_client *i2c;
-	int i, ret, size;
+	int i, j, ret, size;
 
 	if (!pdata) {
 		dev_err(pdev->dev.parent, "No platform init data supplied\n");
@@ -718,16 +792,62 @@ static __devinit int max8998_pmic_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, max8998);
 	i2c = max8998->iodev->i2c;
 
-	max8998->buck1_idx = pdata->buck1_default_idx;
+	max8998->buck1_idx = DVSARMREG(pdata->buck1_default_idx);
 	max8998->buck2_idx = pdata->buck2_default_idx;
+	max8998->gpio_reset_val =  (pdata->buck1_default_idx & 0x2) >> 1;
+
 
-	/* NOTE: */
-	/* For unused GPIO NOT marked as -1 (thereof equal to 0)  WARN_ON */
-	/* will be displayed */
 
 	/* Check if MAX8998 voltage selection GPIOs are defined */
 	if (gpio_is_valid(pdata->buck1_set1) &&
 	    gpio_is_valid(pdata->buck1_set2)) {
+		/*
+		 * Calculate register value of voltage
+		 */
+		for (j = 0; j < 4; j++) {
+			int buck_vol;
+			switch (j) {
+			case 3:
+				buck_vol = pdata->buck1_voltage4;
+				break;
+			case 2:
+				buck_vol = pdata->buck1_voltage3;
+				break;
+			case 1:
+				buck_vol = pdata->buck1_voltage2;
+				break;
+			default:
+				buck_vol = pdata->buck1_voltage1;
+				break;
+			}
+			/* Set predefined value for BUCK1-4 registers */
+			i = 0;
+			while (buck12_voltage_map_desc.min +
+			       buck12_voltage_map_desc.step*i
+			       < (buck_vol / 1000))
+				i++;
+			max8998->buck1_vol[DVSARMREG(j)] = i;
+		}
+
+		/*
+		 * Reset all PMIC DVSARM1-4 registers to initial request value
+		 * By this, voltage drop will not happen with garbage gpio at bootup time
+		 */
+		for (j = 0; j < 4; j++) {
+			ret = max8998_write_reg(i2c, MAX8998_REG_BUCK1_VOLTAGE1 + DVSARMREG(j),
+						max8998->buck1_vol[max8998->buck1_idx]);
+			if (ret) {
+				max8998->buck1_vol[0] = 0;
+				max8998->buck1_vol[1] = 0;
+				max8998->buck1_vol[2] = 0;
+				max8998->buck1_vol[3] = 0;
+				goto err_free_mem;
+			}
+		}
+
+		/*
+		 * Set initial gpio
+		 */
 		/* Check if SET1 is not equal to 0 */
 		if (!pdata->buck1_set1) {
 			printk(KERN_ERR "MAX8998 SET1 GPIO defined as 0 !\n");
@@ -747,61 +867,55 @@ static __devinit int max8998_pmic_probe(struct platform_device *pdev)
 		gpio_direction_output(pdata->buck1_set1,
 				      max8998->buck1_idx & 0x1);
 
-
 		gpio_request(pdata->buck1_set2, "MAX8998 BUCK1_SET2");
 		gpio_direction_output(pdata->buck1_set2,
 				      (max8998->buck1_idx >> 1) & 0x1);
-		/* Set predefined value for BUCK1 register 1 */
-		i = 0;
-		while (buck12_voltage_map_desc.min +
-		       buck12_voltage_map_desc.step*i
-		       < (pdata->buck1_voltage1 / 1000))
-			i++;
-		max8998->buck1_vol[0] = i;
-		ret = max8998_write_reg(i2c, MAX8998_REG_BUCK1_VOLTAGE1, i);
-		if (ret)
-			goto err_free_mem;
 
-		/* Set predefined value for BUCK1 register 2 */
-		i = 0;
-		while (buck12_voltage_map_desc.min +
-		       buck12_voltage_map_desc.step*i
-		       < (pdata->buck1_voltage2 / 1000))
-			i++;
+		/*
+		 * Write specified voltage to pmic registers
+		 */
+		for (j = 0; j < 4; j++) {
+
+			ret = max8998_write_reg(i2c, MAX8998_REG_BUCK1_VOLTAGE1 + DVSARMREG(j),
+						max8998->buck1_vol[DVSARMREG(j)]);
+			if (ret) {
+				max8998->buck1_vol[0] = 0;
+				max8998->buck1_vol[1] = 0;
+				max8998->buck1_vol[2] = 0;
+				max8998->buck1_vol[3] = 0;
+				goto err_free_mem;
+			}
+			dev_dbg(max8998->dev, "PMIC probe: index=%d, Gray coded index=%d, reg val=%d\n",
+						j, DVSARMREG(j),  max8998->buck1_vol[DVSARMREG(j)]);
 
-		max8998->buck1_vol[1] = i;
-		ret = max8998_write_reg(i2c, MAX8998_REG_BUCK1_VOLTAGE2, i);
-		if (ret)
-			goto err_free_mem;
+		}
+	}
+
+	if (gpio_is_valid(pdata->buck2_set3)) {
 
-		/* Set predefined value for BUCK1 register 3 */
+		/* Calculate buck2 vol1 and vol2 register value for specified voltage */
 		i = 0;
 		while (buck12_voltage_map_desc.min +
 		       buck12_voltage_map_desc.step*i
-		       < (pdata->buck1_voltage3 / 1000))
+		       < (pdata->buck2_voltage1 / 1000))
 			i++;
-
-		max8998->buck1_vol[2] = i;
-		ret = max8998_write_reg(i2c, MAX8998_REG_BUCK1_VOLTAGE3, i);
-		if (ret)
-			goto err_free_mem;
-
-		/* Set predefined value for BUCK1 register 4 */
+		max8998->buck2_vol[0] = i;
 		i = 0;
 		while (buck12_voltage_map_desc.min +
 		       buck12_voltage_map_desc.step*i
-		       < (pdata->buck1_voltage4 / 1000))
+		       < (pdata->buck2_voltage2 / 1000))
 			i++;
+		printk(KERN_ERR "i2:%d, buck2_idx:%d\n", i, max8998->buck2_idx);
+		max8998->buck2_vol[1] = i;
 
-		max8998->buck1_vol[3] = i;
-		ret = max8998_write_reg(i2c, MAX8998_REG_BUCK1_VOLTAGE4, i);
+		/* Reset pmic registers with default voltage */
+		ret = max8998_write_reg(i2c,
+			max8998->buck2_idx ? MAX8998_REG_BUCK2_VOLTAGE2 : MAX8998_REG_BUCK2_VOLTAGE1,
+			max8998->buck2_vol[max8998->buck2_idx]);
 		if (ret)
 			goto err_free_mem;
 
-	}
-
-	if (gpio_is_valid(pdata->buck2_set3)) {
-		/* Check if SET3 is not equal to 0 */
+		/* Check if SET3 is not equal to 0 and set default gpio */
 		if (!pdata->buck2_set3) {
 			printk(KERN_ERR "MAX8998 SET3 GPIO defined as 0 !\n");
 			WARN_ON(!pdata->buck2_set3);
@@ -812,28 +926,18 @@ static __devinit int max8998_pmic_probe(struct platform_device *pdev)
 		gpio_direction_output(pdata->buck2_set3,
 				      max8998->buck2_idx & 0x1);
 
-		/* BUCK2 register 1 */
-		i = 0;
-		while (buck12_voltage_map_desc.min +
-		       buck12_voltage_map_desc.step*i
-		       < (pdata->buck2_voltage1 / 1000))
-			i++;
-		max8998->buck2_vol[0] = i;
-		ret = max8998_write_reg(i2c, MAX8998_REG_BUCK2_VOLTAGE1, i);
-		if (ret)
-			goto err_free_mem;
 
-		/* BUCK2 register 2 */
-		i = 0;
-		while (buck12_voltage_map_desc.min +
-		       buck12_voltage_map_desc.step*i
-		       < (pdata->buck2_voltage2 / 1000))
-			i++;
-		printk(KERN_ERR "i2:%d, buck2_idx:%d\n", i, max8998->buck2_idx);
-		max8998->buck2_vol[1] = i;
-		ret = max8998_write_reg(i2c, MAX8998_REG_BUCK2_VOLTAGE2, i);
-		if (ret)
-			goto err_free_mem;
+		/* Set BUCK2 pmic register with predefined value */
+		if (max8998->buck2_idx) {
+			ret = max8998_write_reg(i2c, MAX8998_REG_BUCK2_VOLTAGE1, max8998->buck2_vol[0]);
+			if (ret)
+				goto err_free_mem;
+		} else {
+			ret = max8998_write_reg(i2c, MAX8998_REG_BUCK2_VOLTAGE2, max8998->buck2_vol[1]);
+			if (ret)
+				goto err_free_mem;
+		}
+
 	}
 
 	for (i = 0; i < pdata->num_regulators; i++) {
@@ -862,7 +966,6 @@ err:
 	for (i = 0; i < max8998->num_regulators; i++)
 		if (rdev[i])
 			regulator_unregister(rdev[i]);
-
 err_free_mem:
 	kfree(max8998->rdev);
 	kfree(max8998);