drivers/regulator/max8973-regulator.c - kernel/msm-4.9 - Gitiles

 /*
  * max8973-regulator.c -- Maxim max8973
  *
  * Regulator driver for MAXIM 8973 DC-DC step-down switching regulator.
  *
  * Copyright (c) 2012, NVIDIA Corporation.
  *
  * Author: Laxman Dewangan <ldewangan@nvidia.com>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation version 2.
  *
  * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
  * whether express or implied; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  * 02111-1307, USA
  */

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/err.h>
 #include <linux/platform_device.h>
 #include <linux/regulator/driver.h>
 #include <linux/regulator/machine.h>
 #include <linux/regulator/max8973-regulator.h>
 #include <linux/gpio.h>
 #include <linux/i2c.h>
 #include <linux/slab.h>
 #include <linux/regmap.h>

 /* Register definitions */
 #define MAX8973_VOUT					0x0
 #define MAX8973_VOUT_DVS				0x1
 #define MAX8973_CONTROL1				0x2
 #define MAX8973_CONTROL2				0x3
 #define MAX8973_CHIPID1					0x4
 #define MAX8973_CHIPID2					0x5

 #define MAX8973_MAX_VOUT_REG				2

 /* MAX8973_VOUT */
 #define MAX8973_VOUT_ENABLE				BIT(7)
 #define MAX8973_VOUT_MASK				0x7F

 /* MAX8973_VOUT_DVS */
 #define MAX8973_DVS_VOUT_MASK				0x7F

 /* MAX8973_CONTROL1 */
 #define MAX8973_SNS_ENABLE				BIT(7)
 #define MAX8973_FPWM_EN_M				BIT(6)
 #define MAX8973_NFSR_ENABLE				BIT(5)
 #define MAX8973_AD_ENABLE				BIT(4)
 #define MAX8973_BIAS_ENABLE				BIT(3)
 #define MAX8973_FREQSHIFT_9PER				BIT(2)

 #define MAX8973_RAMP_12mV_PER_US			0x0
 #define MAX8973_RAMP_25mV_PER_US			0x1
 #define MAX8973_RAMP_50mV_PER_US			0x2
 #define MAX8973_RAMP_200mV_PER_US			0x3

 /* MAX8973_CONTROL2 */
 #define MAX8973_WDTMR_ENABLE				BIT(6)
 #define MAX8973_DISCH_ENBABLE				BIT(5)
 #define MAX8973_FT_ENABLE				BIT(4)

 #define MAX8973_CKKADV_TRIP_DISABLE			0xC
 #define MAX8973_CKKADV_TRIP_75mV_PER_US			0x0
 #define MAX8973_CKKADV_TRIP_150mV_PER_US		0x4
 #define MAX8973_CKKADV_TRIP_75mV_PER_US_HIST_DIS	0x8
 #define MAX8973_CONTROL_CLKADV_TRIP_MASK		0x00030000

 #define MAX8973_INDUCTOR_MIN_30_PER			0x0
 #define MAX8973_INDUCTOR_NOMINAL			0x1
 #define MAX8973_INDUCTOR_PLUS_30_PER			0x2
 #define MAX8973_INDUCTOR_PLUS_60_PER			0x3
 #define MAX8973_CONTROL_INDUCTOR_VALUE_MASK		0x00300000

 #define MAX8973_MIN_VOLATGE				606250
 #define MAX8973_MAX_VOLATGE				1400000
 #define MAX8973_VOLATGE_STEP				6250
 #define MAX8973_BUCK_N_VOLTAGE				0x80

 /* Maxim 8973 chip information */
 struct max8973_chip {
 	struct device *dev;
 	struct regulator_desc desc;
 	struct regulator_dev *rdev;
 	struct regmap *regmap;
 	bool enable_external_control;
 	int dvs_gpio;
 	int lru_index[MAX8973_MAX_VOUT_REG];
 	int curr_vout_val[MAX8973_MAX_VOUT_REG];
 	int curr_vout_reg;
 	int curr_gpio_val;
 	bool valid_dvs_gpio;
 };

 /*
  * find_voltage_set_register: Find new voltage configuration register (VOUT).
  * The finding of the new VOUT register will be based on the LRU mechanism.
  * Each VOUT register will have different voltage configured . This
  * Function will look if any of the VOUT register have requested voltage set
  * or not.
  *     - If it is already there then it will make that register as most
  *       recently used and return as found so that caller need not to set
  *       the VOUT register but need to set the proper gpios to select this
  *       VOUT register.
  *     - If requested voltage is not found then it will use the least
  *       recently mechanism to get new VOUT register for new configuration
  *       and will return not_found so that caller need to set new VOUT
  *       register and then gpios (both).
  */
 static bool find_voltage_set_register(struct max8973_chip *tps,
 		int req_vsel, int *vout_reg, int *gpio_val)
 {
 	int i;
 	bool found = false;
 	int new_vout_reg = tps->lru_index[MAX8973_MAX_VOUT_REG - 1];
 	int found_index = MAX8973_MAX_VOUT_REG - 1;

 	for (i = 0; i < MAX8973_MAX_VOUT_REG; ++i) {
 		if (tps->curr_vout_val[tps->lru_index[i]] == req_vsel) {
 			new_vout_reg = tps->lru_index[i];
 			found_index = i;
 			found = true;
 			goto update_lru_index;
 		}
 	}

 update_lru_index:
 	for (i = found_index; i > 0; i--)
 		tps->lru_index[i] = tps->lru_index[i - 1];

 	tps->lru_index[0] = new_vout_reg;
 	*gpio_val = new_vout_reg;
 	*vout_reg = MAX8973_VOUT + new_vout_reg;
 	return found;
 }

 static int max8973_dcdc_get_voltage_sel(struct regulator_dev *rdev)
 {
 	struct max8973_chip *max = rdev_get_drvdata(rdev);
 	unsigned int data;
 	int ret;

 	ret = regmap_read(max->regmap, max->curr_vout_reg, &data);
 	if (ret < 0) {
 		dev_err(max->dev, "register %d read failed, err = %d\n",
 			max->curr_vout_reg, ret);
 		return ret;
 	}
 	return data & MAX8973_VOUT_MASK;
 }

 static int max8973_dcdc_set_voltage_sel(struct regulator_dev *rdev,
 	     unsigned vsel)
 {
 	struct max8973_chip *max = rdev_get_drvdata(rdev);
 	int ret;
 	bool found = false;
 	int vout_reg = max->curr_vout_reg;
 	int gpio_val = max->curr_gpio_val;

 	/*
 	 * If gpios are available to select the VOUT register then least
 	 * recently used register for new configuration.
 	 */
 	if (max->valid_dvs_gpio)
 		found = find_voltage_set_register(max, vsel,
 					&vout_reg, &gpio_val);

 	if (!found) {
 		ret = regmap_update_bits(max->regmap, vout_reg,
 					MAX8973_VOUT_MASK, vsel);
 		if (ret < 0) {
 			dev_err(max->dev, "register %d update failed, err %d\n",
 				 vout_reg, ret);
 			return ret;
 		}
 		max->curr_vout_reg = vout_reg;
 		max->curr_vout_val[gpio_val] = vsel;
 	}

 	/* Select proper VOUT register vio gpios */
 	if (max->valid_dvs_gpio) {
 		gpio_set_value_cansleep(max->dvs_gpio, gpio_val & 0x1);
 		max->curr_gpio_val = gpio_val;
 	}
 	return 0;
 }

 static int max8973_dcdc_set_mode(struct regulator_dev *rdev, unsigned int mode)
 {
 	struct max8973_chip *max = rdev_get_drvdata(rdev);
 	int ret;
 	int pwm;

 	/* Enable force PWM mode in FAST mode only. */
 	switch (mode) {
 	case REGULATOR_MODE_FAST:
 		pwm = MAX8973_FPWM_EN_M;
 		break;

 	case REGULATOR_MODE_NORMAL:
 		pwm = 0;
 		break;

 	default:
 		return -EINVAL;
 	}

 	ret = regmap_update_bits(max->regmap, MAX8973_CONTROL1,
 				MAX8973_FPWM_EN_M, pwm);
 	if (ret < 0)
 		dev_err(max->dev, "register %d update failed, err %d\n",
 				MAX8973_CONTROL1, ret);
 	return ret;
 }

 static unsigned int max8973_dcdc_get_mode(struct regulator_dev *rdev)
 {
 	struct max8973_chip *max = rdev_get_drvdata(rdev);
 	unsigned int data;
 	int ret;

 	ret = regmap_read(max->regmap, MAX8973_CONTROL1, &data);
 	if (ret < 0) {
 		dev_err(max->dev, "register %d read failed, err %d\n",
 				MAX8973_CONTROL1, ret);
 		return ret;
 	}
 	return (data & MAX8973_FPWM_EN_M) ?
 		REGULATOR_MODE_FAST : REGULATOR_MODE_NORMAL;
 }

 static struct regulator_ops max8973_dcdc_ops = {
 	.get_voltage_sel	= max8973_dcdc_get_voltage_sel,
 	.set_voltage_sel	= max8973_dcdc_set_voltage_sel,
 	.list_voltage		= regulator_list_voltage_linear,
 	.set_mode		= max8973_dcdc_set_mode,
 	.get_mode		= max8973_dcdc_get_mode,
 };

 static int __devinit max8973_init_dcdc(struct max8973_chip *max,
 		struct max8973_regulator_platform_data *pdata)
 {
 	int ret;
 	uint8_t	control1 = 0;
 	uint8_t control2 = 0;

 	if (pdata->control_flags & MAX8973_CONTROL_REMOTE_SENSE_ENABLE)
 		control1 |= MAX8973_SNS_ENABLE;

 	if (!(pdata->control_flags & MAX8973_CONTROL_FALLING_SLEW_RATE_ENABLE))
 		control1 |= MAX8973_NFSR_ENABLE;

 	if (pdata->control_flags & MAX8973_CONTROL_OUTPUT_ACTIVE_DISCH_ENABLE)
 		control1 |= MAX8973_AD_ENABLE;

 	if (pdata->control_flags & MAX8973_CONTROL_BIAS_ENABLE)
 		control1 |= MAX8973_BIAS_ENABLE;

 	if (pdata->control_flags & MAX8973_CONTROL_FREQ_SHIFT_9PER_ENABLE)
 		control1 |= MAX8973_FREQSHIFT_9PER;

 	/* Set ramp delay */
 	if (pdata->reg_init_data &&
 			pdata->reg_init_data->constraints.ramp_delay) {
 		if (pdata->reg_init_data->constraints.ramp_delay < 25000)
 			control1 = MAX8973_RAMP_12mV_PER_US;
 		else if (pdata->reg_init_data->constraints.ramp_delay < 50000)
 			control1 = MAX8973_RAMP_25mV_PER_US;
 		else if (pdata->reg_init_data->constraints.ramp_delay < 200000)
 			control1 = MAX8973_RAMP_50mV_PER_US;
 		else
 			control1 = MAX8973_RAMP_200mV_PER_US;
 	} else {
 		control1 = MAX8973_RAMP_12mV_PER_US;
 		max->desc.ramp_delay = 12500;
 	}

 	if (!(pdata->control_flags & MAX8973_CONTROL_PULL_DOWN_ENABLE))
 		control2 |= MAX8973_DISCH_ENBABLE;

 	/*  Clock advance trip configuration */
 	switch (pdata->control_flags & MAX8973_CONTROL_CLKADV_TRIP_MASK) {
 	case MAX8973_CONTROL_CLKADV_TRIP_DISABLED:
 		control2 |= MAX8973_CKKADV_TRIP_DISABLE;
 		break;

 	case MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US:
 		control2 |= MAX8973_CKKADV_TRIP_75mV_PER_US;
 		break;

 	case MAX8973_CONTROL_CLKADV_TRIP_150mV_PER_US:
 		control2 |= MAX8973_CKKADV_TRIP_150mV_PER_US;
 		break;

 	case MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US_HIST_DIS:
 		control2 |= MAX8973_CKKADV_TRIP_75mV_PER_US_HIST_DIS;
 		break;
 	}

 	/* Configure inductor value */
 	switch (pdata->control_flags & MAX8973_CONTROL_INDUCTOR_VALUE_MASK) {
 	case MAX8973_CONTROL_INDUCTOR_VALUE_NOMINAL:
 		control2 |= MAX8973_INDUCTOR_NOMINAL;
 		break;

 	case MAX8973_CONTROL_INDUCTOR_VALUE_MINUS_30_PER:
 		control2 |= MAX8973_INDUCTOR_MIN_30_PER;
 		break;

 	case MAX8973_CONTROL_INDUCTOR_VALUE_PLUS_30_PER:
 		control2 |= MAX8973_INDUCTOR_PLUS_30_PER;
 		break;

 	case MAX8973_CONTROL_INDUCTOR_VALUE_PLUS_60_PER:
 		control2 |= MAX8973_INDUCTOR_PLUS_60_PER;
 		break;
 	}

 	ret = regmap_write(max->regmap, MAX8973_CONTROL1, control1);
 	if (ret < 0) {
 		dev_err(max->dev, "register %d write failed, err = %d",
 				MAX8973_CONTROL1, ret);
 		return ret;
 	}

 	ret = regmap_write(max->regmap, MAX8973_CONTROL2, control2);
 	if (ret < 0) {
 		dev_err(max->dev, "register %d write failed, err = %d",
 				MAX8973_CONTROL2, ret);
 		return ret;
 	}

 	/* If external control is enabled then disable EN bit */
 	if (max->enable_external_control) {
 		ret = regmap_update_bits(max->regmap, MAX8973_VOUT,
 						MAX8973_VOUT_ENABLE, 0);
 		if (ret < 0)
 			dev_err(max->dev, "register %d update failed, err = %d",
 				MAX8973_VOUT, ret);
 	}
 	return ret;
 }

 static const struct regmap_config max8973_regmap_config = {
 	.reg_bits		= 8,
 	.val_bits		= 8,
 	.max_register		= MAX8973_CHIPID2,
 	.cache_type		= REGCACHE_RBTREE,
 };

 static int __devinit max8973_probe(struct i2c_client *client,
 				     const struct i2c_device_id *id)
 {
 	struct max8973_regulator_platform_data *pdata;
 	struct regulator_config config = { };
 	struct regulator_dev *rdev;
 	struct max8973_chip *max;
 	int ret;

 	pdata = client->dev.platform_data;
 	if (!pdata) {
 		dev_err(&client->dev, "No Platform data");
 		return -EIO;
 	}

 	max = devm_kzalloc(&client->dev, sizeof(*max), GFP_KERNEL);
 	if (!max) {
 		dev_err(&client->dev, "Memory allocation for max failed\n");
 		return -ENOMEM;
 	}

 	max->regmap = devm_regmap_init_i2c(client, &max8973_regmap_config);
 	if (IS_ERR(max->regmap)) {
 		ret = PTR_ERR(max->regmap);
 		dev_err(&client->dev, "regmap init failed, err %d\n", ret);
 		return ret;
 	}

 	i2c_set_clientdata(client, max);
 	max->dev = &client->dev;
 	max->desc.name = id->name;
 	max->desc.id = 0;
 	max->desc.ops = &max8973_dcdc_ops;
 	max->desc.type = REGULATOR_VOLTAGE;
 	max->desc.owner = THIS_MODULE;
 	max->desc.min_uV = MAX8973_MIN_VOLATGE;
 	max->desc.uV_step = MAX8973_VOLATGE_STEP;
 	max->desc.n_voltages = MAX8973_BUCK_N_VOLTAGE;

 	if (!pdata->enable_ext_control) {
 		max->desc.enable_reg = MAX8973_VOUT;
 		max->desc.enable_mask = MAX8973_VOUT_ENABLE;
 		max8973_dcdc_ops.enable = regulator_enable_regmap;
 		max8973_dcdc_ops.disable = regulator_disable_regmap;
 		max8973_dcdc_ops.is_enabled = regulator_is_enabled_regmap;
 	}

 	max->enable_external_control = pdata->enable_ext_control;
 	max->dvs_gpio = pdata->dvs_gpio;
 	max->curr_gpio_val = pdata->dvs_def_state;
 	max->curr_vout_reg = MAX8973_VOUT + pdata->dvs_def_state;
 	max->lru_index[0] = max->curr_vout_reg;
 	max->valid_dvs_gpio = false;

 	if (gpio_is_valid(max->dvs_gpio)) {
 		int gpio_flags;
 		int i;

 		gpio_flags = (pdata->dvs_def_state) ?
 				GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
 		ret = devm_gpio_request_one(&client->dev, max->dvs_gpio,
 				gpio_flags, "max8973-dvs");
 		if (ret) {
 			dev_err(&client->dev,
 				"gpio_request for gpio %d failed, err = %d\n",
 				max->dvs_gpio, ret);
 			return ret;
 		}
 		max->valid_dvs_gpio = true;

 		/*
 		 * Initialize the lru index with vout_reg id
 		 * The index 0 will be most recently used and
 		 * set with the max->curr_vout_reg */
 		for (i = 0; i < MAX8973_MAX_VOUT_REG; ++i)
 			max->lru_index[i] = i;
 		max->lru_index[0] = max->curr_vout_reg;
 		max->lru_index[max->curr_vout_reg] = 0;
 	}

 	ret = max8973_init_dcdc(max, pdata);
 	if (ret < 0) {
 		dev_err(max->dev, "Max8973 Init failed, err = %d\n", ret);
 		return ret;
 	}

 	config.dev = &client->dev;
 	config.init_data = pdata->reg_init_data;
 	config.driver_data = max;
 	config.of_node = client->dev.of_node;
 	config.regmap = max->regmap;

 	/* Register the regulators */
 	rdev = regulator_register(&max->desc, &config);
 	if (IS_ERR(rdev)) {
 		ret = PTR_ERR(rdev);
 		dev_err(max->dev, "regulator register failed, err %d\n", ret);
 		return ret;
 	}

 	max->rdev = rdev;
 	return 0;
 }

 static int __devexit max8973_remove(struct i2c_client *client)
 {
 	struct max8973_chip *max = i2c_get_clientdata(client);

 	regulator_unregister(max->rdev);
 	return 0;
 }

 static const struct i2c_device_id max8973_id[] = {
 	{.name = "max8973",},
 	{},
 };

 MODULE_DEVICE_TABLE(i2c, max8973_id);

 static struct i2c_driver max8973_i2c_driver = {
 	.driver = {
 		.name = "max8973",
 		.owner = THIS_MODULE,
 	},
 	.probe = max8973_probe,
 	.remove = __devexit_p(max8973_remove),
 	.id_table = max8973_id,
 };

 static int __init max8973_init(void)
 {
 	return i2c_add_driver(&max8973_i2c_driver);
 }
 subsys_initcall(max8973_init);

 static void __exit max8973_cleanup(void)
 {
 	i2c_del_driver(&max8973_i2c_driver);
 }
 module_exit(max8973_cleanup);

 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
 MODULE_DESCRIPTION("MAX8973 voltage regulator driver");
 MODULE_LICENSE("GPL v2");
	/*
	* max8973-regulator.c -- Maxim max8973
	*
	* Regulator driver for MAXIM 8973 DC-DC step-down switching regulator.
	*
	* Copyright (c) 2012, NVIDIA Corporation.
	*
	* Author: Laxman Dewangan <ldewangan@nvidia.com>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License as
	* published by the Free Software Foundation version 2.
	*
	* This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
	* whether express or implied; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
	* 02111-1307, USA
	*/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/err.h>
	#include <linux/platform_device.h>
	#include <linux/regulator/driver.h>
	#include <linux/regulator/machine.h>
	#include <linux/regulator/max8973-regulator.h>
	#include <linux/gpio.h>
	#include <linux/i2c.h>
	#include <linux/slab.h>
	#include <linux/regmap.h>

	/* Register definitions */
	#define MAX8973_VOUT 0x0
	#define MAX8973_VOUT_DVS 0x1
	#define MAX8973_CONTROL1 0x2
	#define MAX8973_CONTROL2 0x3
	#define MAX8973_CHIPID1 0x4
	#define MAX8973_CHIPID2 0x5

	#define MAX8973_MAX_VOUT_REG 2

	/* MAX8973_VOUT */
	#define MAX8973_VOUT_ENABLE BIT(7)
	#define MAX8973_VOUT_MASK 0x7F

	/* MAX8973_VOUT_DVS */
	#define MAX8973_DVS_VOUT_MASK 0x7F

	/* MAX8973_CONTROL1 */
	#define MAX8973_SNS_ENABLE BIT(7)
	#define MAX8973_FPWM_EN_M BIT(6)
	#define MAX8973_NFSR_ENABLE BIT(5)
	#define MAX8973_AD_ENABLE BIT(4)
	#define MAX8973_BIAS_ENABLE BIT(3)
	#define MAX8973_FREQSHIFT_9PER BIT(2)

	#define MAX8973_RAMP_12mV_PER_US 0x0
	#define MAX8973_RAMP_25mV_PER_US 0x1
	#define MAX8973_RAMP_50mV_PER_US 0x2
	#define MAX8973_RAMP_200mV_PER_US 0x3

	/* MAX8973_CONTROL2 */
	#define MAX8973_WDTMR_ENABLE BIT(6)
	#define MAX8973_DISCH_ENBABLE BIT(5)
	#define MAX8973_FT_ENABLE BIT(4)

	#define MAX8973_CKKADV_TRIP_DISABLE 0xC
	#define MAX8973_CKKADV_TRIP_75mV_PER_US 0x0
	#define MAX8973_CKKADV_TRIP_150mV_PER_US 0x4
	#define MAX8973_CKKADV_TRIP_75mV_PER_US_HIST_DIS 0x8
	#define MAX8973_CONTROL_CLKADV_TRIP_MASK 0x00030000

	#define MAX8973_INDUCTOR_MIN_30_PER 0x0
	#define MAX8973_INDUCTOR_NOMINAL 0x1
	#define MAX8973_INDUCTOR_PLUS_30_PER 0x2
	#define MAX8973_INDUCTOR_PLUS_60_PER 0x3
	#define MAX8973_CONTROL_INDUCTOR_VALUE_MASK 0x00300000

	#define MAX8973_MIN_VOLATGE 606250
	#define MAX8973_MAX_VOLATGE 1400000
	#define MAX8973_VOLATGE_STEP 6250
	#define MAX8973_BUCK_N_VOLTAGE 0x80

	/* Maxim 8973 chip information */
	struct max8973_chip {
	struct device *dev;
	struct regulator_desc desc;
	struct regulator_dev *rdev;
	struct regmap *regmap;
	bool enable_external_control;
	int dvs_gpio;
	int lru_index[MAX8973_MAX_VOUT_REG];
	int curr_vout_val[MAX8973_MAX_VOUT_REG];
	int curr_vout_reg;
	int curr_gpio_val;
	bool valid_dvs_gpio;
	};

	/*
	* find_voltage_set_register: Find new voltage configuration register (VOUT).
	* The finding of the new VOUT register will be based on the LRU mechanism.
	* Each VOUT register will have different voltage configured . This
	* Function will look if any of the VOUT register have requested voltage set
	* or not.
	* - If it is already there then it will make that register as most
	* recently used and return as found so that caller need not to set
	* the VOUT register but need to set the proper gpios to select this
	* VOUT register.
	* - If requested voltage is not found then it will use the least
	* recently mechanism to get new VOUT register for new configuration
	* and will return not_found so that caller need to set new VOUT
	* register and then gpios (both).
	*/
	static bool find_voltage_set_register(struct max8973_chip *tps,
	int req_vsel, int vout_reg, int gpio_val)
	{
	int i;
	bool found = false;
	int new_vout_reg = tps->lru_index[MAX8973_MAX_VOUT_REG - 1];
	int found_index = MAX8973_MAX_VOUT_REG - 1;

	for (i = 0; i < MAX8973_MAX_VOUT_REG; ++i) {
	if (tps->curr_vout_val[tps->lru_index[i]] == req_vsel) {
	new_vout_reg = tps->lru_index[i];
	found_index = i;
	found = true;
	goto update_lru_index;
	}
	}

	update_lru_index:
	for (i = found_index; i > 0; i--)
	tps->lru_index[i] = tps->lru_index[i - 1];

	tps->lru_index[0] = new_vout_reg;
	*gpio_val = new_vout_reg;
	*vout_reg = MAX8973_VOUT + new_vout_reg;
	return found;
	}

	static int max8973_dcdc_get_voltage_sel(struct regulator_dev *rdev)
	{
	struct max8973_chip *max = rdev_get_drvdata(rdev);
	unsigned int data;
	int ret;

	ret = regmap_read(max->regmap, max->curr_vout_reg, &data);
	if (ret < 0) {
	dev_err(max->dev, "register %d read failed, err = %d\n",
	max->curr_vout_reg, ret);
	return ret;
	}
	return data & MAX8973_VOUT_MASK;
	}

	static int max8973_dcdc_set_voltage_sel(struct regulator_dev *rdev,
	unsigned vsel)
	{
	struct max8973_chip *max = rdev_get_drvdata(rdev);
	int ret;
	bool found = false;
	int vout_reg = max->curr_vout_reg;
	int gpio_val = max->curr_gpio_val;

	/*
	* If gpios are available to select the VOUT register then least
	* recently used register for new configuration.
	*/
	if (max->valid_dvs_gpio)
	found = find_voltage_set_register(max, vsel,
	&vout_reg, &gpio_val);

	if (!found) {
	ret = regmap_update_bits(max->regmap, vout_reg,
	MAX8973_VOUT_MASK, vsel);
	if (ret < 0) {
	dev_err(max->dev, "register %d update failed, err %d\n",
	vout_reg, ret);
	return ret;
	}
	max->curr_vout_reg = vout_reg;
	max->curr_vout_val[gpio_val] = vsel;
	}

	/* Select proper VOUT register vio gpios */
	if (max->valid_dvs_gpio) {
	gpio_set_value_cansleep(max->dvs_gpio, gpio_val & 0x1);
	max->curr_gpio_val = gpio_val;
	}
	return 0;
	}

	static int max8973_dcdc_set_mode(struct regulator_dev *rdev, unsigned int mode)
	{
	struct max8973_chip *max = rdev_get_drvdata(rdev);
	int ret;
	int pwm;

	/* Enable force PWM mode in FAST mode only. */
	switch (mode) {
	case REGULATOR_MODE_FAST:
	pwm = MAX8973_FPWM_EN_M;
	break;

	case REGULATOR_MODE_NORMAL:
	pwm = 0;
	break;

	default:
	return -EINVAL;
	}

	ret = regmap_update_bits(max->regmap, MAX8973_CONTROL1,
	MAX8973_FPWM_EN_M, pwm);
	if (ret < 0)
	dev_err(max->dev, "register %d update failed, err %d\n",
	MAX8973_CONTROL1, ret);
	return ret;
	}

	static unsigned int max8973_dcdc_get_mode(struct regulator_dev *rdev)
	{
	struct max8973_chip *max = rdev_get_drvdata(rdev);
	unsigned int data;
	int ret;

	ret = regmap_read(max->regmap, MAX8973_CONTROL1, &data);
	if (ret < 0) {
	dev_err(max->dev, "register %d read failed, err %d\n",
	MAX8973_CONTROL1, ret);
	return ret;
	}
	return (data & MAX8973_FPWM_EN_M) ?
	REGULATOR_MODE_FAST : REGULATOR_MODE_NORMAL;
	}

	static struct regulator_ops max8973_dcdc_ops = {
	.get_voltage_sel = max8973_dcdc_get_voltage_sel,
	.set_voltage_sel = max8973_dcdc_set_voltage_sel,
	.list_voltage = regulator_list_voltage_linear,
	.set_mode = max8973_dcdc_set_mode,
	.get_mode = max8973_dcdc_get_mode,
	};

	static int __devinit max8973_init_dcdc(struct max8973_chip *max,
	struct max8973_regulator_platform_data *pdata)
	{
	int ret;
	uint8_t control1 = 0;
	uint8_t control2 = 0;

	if (pdata->control_flags & MAX8973_CONTROL_REMOTE_SENSE_ENABLE)
	control1 \|= MAX8973_SNS_ENABLE;

	if (!(pdata->control_flags & MAX8973_CONTROL_FALLING_SLEW_RATE_ENABLE))
	control1 \|= MAX8973_NFSR_ENABLE;

	if (pdata->control_flags & MAX8973_CONTROL_OUTPUT_ACTIVE_DISCH_ENABLE)
	control1 \|= MAX8973_AD_ENABLE;

	if (pdata->control_flags & MAX8973_CONTROL_BIAS_ENABLE)
	control1 \|= MAX8973_BIAS_ENABLE;

	if (pdata->control_flags & MAX8973_CONTROL_FREQ_SHIFT_9PER_ENABLE)
	control1 \|= MAX8973_FREQSHIFT_9PER;

	/* Set ramp delay */
	if (pdata->reg_init_data &&
	pdata->reg_init_data->constraints.ramp_delay) {
	if (pdata->reg_init_data->constraints.ramp_delay < 25000)
	control1 = MAX8973_RAMP_12mV_PER_US;
	else if (pdata->reg_init_data->constraints.ramp_delay < 50000)
	control1 = MAX8973_RAMP_25mV_PER_US;
	else if (pdata->reg_init_data->constraints.ramp_delay < 200000)
	control1 = MAX8973_RAMP_50mV_PER_US;
	else
	control1 = MAX8973_RAMP_200mV_PER_US;
	} else {
	control1 = MAX8973_RAMP_12mV_PER_US;
	max->desc.ramp_delay = 12500;
	}

	if (!(pdata->control_flags & MAX8973_CONTROL_PULL_DOWN_ENABLE))
	control2 \|= MAX8973_DISCH_ENBABLE;

	/* Clock advance trip configuration */
	switch (pdata->control_flags & MAX8973_CONTROL_CLKADV_TRIP_MASK) {
	case MAX8973_CONTROL_CLKADV_TRIP_DISABLED:
	control2 \|= MAX8973_CKKADV_TRIP_DISABLE;
	break;

	case MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US:
	control2 \|= MAX8973_CKKADV_TRIP_75mV_PER_US;
	break;

	case MAX8973_CONTROL_CLKADV_TRIP_150mV_PER_US:
	control2 \|= MAX8973_CKKADV_TRIP_150mV_PER_US;
	break;

	case MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US_HIST_DIS:
	control2 \|= MAX8973_CKKADV_TRIP_75mV_PER_US_HIST_DIS;
	break;
	}

	/* Configure inductor value */
	switch (pdata->control_flags & MAX8973_CONTROL_INDUCTOR_VALUE_MASK) {
	case MAX8973_CONTROL_INDUCTOR_VALUE_NOMINAL:
	control2 \|= MAX8973_INDUCTOR_NOMINAL;
	break;

	case MAX8973_CONTROL_INDUCTOR_VALUE_MINUS_30_PER:
	control2 \|= MAX8973_INDUCTOR_MIN_30_PER;
	break;

	case MAX8973_CONTROL_INDUCTOR_VALUE_PLUS_30_PER:
	control2 \|= MAX8973_INDUCTOR_PLUS_30_PER;
	break;

	case MAX8973_CONTROL_INDUCTOR_VALUE_PLUS_60_PER:
	control2 \|= MAX8973_INDUCTOR_PLUS_60_PER;
	break;
	}

	ret = regmap_write(max->regmap, MAX8973_CONTROL1, control1);
	if (ret < 0) {
	dev_err(max->dev, "register %d write failed, err = %d",
	MAX8973_CONTROL1, ret);
	return ret;
	}

	ret = regmap_write(max->regmap, MAX8973_CONTROL2, control2);
	if (ret < 0) {
	dev_err(max->dev, "register %d write failed, err = %d",
	MAX8973_CONTROL2, ret);
	return ret;
	}

	/* If external control is enabled then disable EN bit */
	if (max->enable_external_control) {
	ret = regmap_update_bits(max->regmap, MAX8973_VOUT,
	MAX8973_VOUT_ENABLE, 0);
	if (ret < 0)
	dev_err(max->dev, "register %d update failed, err = %d",
	MAX8973_VOUT, ret);
	}
	return ret;
	}

	static const struct regmap_config max8973_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.max_register = MAX8973_CHIPID2,
	.cache_type = REGCACHE_RBTREE,
	};

	static int __devinit max8973_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct max8973_regulator_platform_data *pdata;
	struct regulator_config config = { };
	struct regulator_dev *rdev;
	struct max8973_chip *max;
	int ret;

	pdata = client->dev.platform_data;
	if (!pdata) {
	dev_err(&client->dev, "No Platform data");
	return -EIO;
	}

	max = devm_kzalloc(&client->dev, sizeof(*max), GFP_KERNEL);
	if (!max) {
	dev_err(&client->dev, "Memory allocation for max failed\n");
	return -ENOMEM;
	}

	max->regmap = devm_regmap_init_i2c(client, &max8973_regmap_config);
	if (IS_ERR(max->regmap)) {
	ret = PTR_ERR(max->regmap);
	dev_err(&client->dev, "regmap init failed, err %d\n", ret);
	return ret;
	}

	i2c_set_clientdata(client, max);
	max->dev = &client->dev;
	max->desc.name = id->name;
	max->desc.id = 0;
	max->desc.ops = &max8973_dcdc_ops;
	max->desc.type = REGULATOR_VOLTAGE;
	max->desc.owner = THIS_MODULE;
	max->desc.min_uV = MAX8973_MIN_VOLATGE;
	max->desc.uV_step = MAX8973_VOLATGE_STEP;
	max->desc.n_voltages = MAX8973_BUCK_N_VOLTAGE;

	if (!pdata->enable_ext_control) {
	max->desc.enable_reg = MAX8973_VOUT;
	max->desc.enable_mask = MAX8973_VOUT_ENABLE;
	max8973_dcdc_ops.enable = regulator_enable_regmap;
	max8973_dcdc_ops.disable = regulator_disable_regmap;
	max8973_dcdc_ops.is_enabled = regulator_is_enabled_regmap;
	}

	max->enable_external_control = pdata->enable_ext_control;
	max->dvs_gpio = pdata->dvs_gpio;
	max->curr_gpio_val = pdata->dvs_def_state;
	max->curr_vout_reg = MAX8973_VOUT + pdata->dvs_def_state;
	max->lru_index[0] = max->curr_vout_reg;
	max->valid_dvs_gpio = false;

	if (gpio_is_valid(max->dvs_gpio)) {
	int gpio_flags;
	int i;

	gpio_flags = (pdata->dvs_def_state) ?
	GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
	ret = devm_gpio_request_one(&client->dev, max->dvs_gpio,
	gpio_flags, "max8973-dvs");
	if (ret) {
	dev_err(&client->dev,
	"gpio_request for gpio %d failed, err = %d\n",
	max->dvs_gpio, ret);
	return ret;
	}
	max->valid_dvs_gpio = true;

	/*
	* Initialize the lru index with vout_reg id
	* The index 0 will be most recently used and
	* set with the max->curr_vout_reg */
	for (i = 0; i < MAX8973_MAX_VOUT_REG; ++i)
	max->lru_index[i] = i;
	max->lru_index[0] = max->curr_vout_reg;
	max->lru_index[max->curr_vout_reg] = 0;
	}

	ret = max8973_init_dcdc(max, pdata);
	if (ret < 0) {
	dev_err(max->dev, "Max8973 Init failed, err = %d\n", ret);
	return ret;
	}

	config.dev = &client->dev;
	config.init_data = pdata->reg_init_data;
	config.driver_data = max;
	config.of_node = client->dev.of_node;
	config.regmap = max->regmap;

	/* Register the regulators */
	rdev = regulator_register(&max->desc, &config);
	if (IS_ERR(rdev)) {
	ret = PTR_ERR(rdev);
	dev_err(max->dev, "regulator register failed, err %d\n", ret);
	return ret;
	}

	max->rdev = rdev;
	return 0;
	}

	static int __devexit max8973_remove(struct i2c_client *client)
	{
	struct max8973_chip *max = i2c_get_clientdata(client);

	regulator_unregister(max->rdev);
	return 0;
	}

	static const struct i2c_device_id max8973_id[] = {
	{.name = "max8973",},
	{},
	};

	MODULE_DEVICE_TABLE(i2c, max8973_id);

	static struct i2c_driver max8973_i2c_driver = {
	.driver = {
	.name = "max8973",
	.owner = THIS_MODULE,
	},
	.probe = max8973_probe,
	.remove = __devexit_p(max8973_remove),
	.id_table = max8973_id,
	};

	static int __init max8973_init(void)
	{
	return i2c_add_driver(&max8973_i2c_driver);
	}
	subsys_initcall(max8973_init);

	static void __exit max8973_cleanup(void)
	{
	i2c_del_driver(&max8973_i2c_driver);
	}
	module_exit(max8973_cleanup);

	MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
	MODULE_DESCRIPTION("MAX8973 voltage regulator driver");
	MODULE_LICENSE("GPL v2");