/*
   * 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/of.h>

  #include <linux/of_device.h>

  #include <linux/platform_device.h>
  #include <linux/regulator/driver.h>
  #include <linux/regulator/machine.h>
  #include <linux/regulator/max8973-regulator.h>

  #include <linux/regulator/of_regulator.h>

  #include <linux/gpio.h>

  #include <linux/gpio/consumer.h>

  #include <linux/of_gpio.h>

  #include <linux/i2c.h>
  #include <linux/slab.h>
  #include <linux/regmap.h>

  #include <linux/thermal.h>
  #include <linux/irq.h>
  #include <linux/interrupt.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

  #define MAX8973_RAMP_MASK				0x3

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

  #define MAX77621_T_JUNCTION_120				BIT(7)

  #define MAX8973_CKKADV_TRIP_MASK			0xC

  #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

  #define MAX77621_CHIPID_TJINT_S				BIT(0)
  
  #define MAX77621_NORMAL_OPERATING_TEMP			100000
  #define MAX77621_TJINT_WARNING_TEMP_120			120000
  #define MAX77621_TJINT_WARNING_TEMP_140			140000

  enum device_id {
  	MAX8973,
  	MAX77621
  };

  /* Maxim 8973 chip information */
  struct max8973_chip {
  	struct device *dev;
  	struct regulator_desc desc;

  	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;

  	struct regulator_ops ops;

  	enum device_id id;

  	int junction_temp_warning;
  	int irq;
  	struct thermal_zone_device *tz_device;

  };
  
  /*
   * 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
  ",
  			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 (gpio_is_valid(max->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
  ",
  				 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 (gpio_is_valid(max->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
  ",
  				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
  ",
  				MAX8973_CONTROL1, ret);
  		return ret;
  	}
  	return (data & MAX8973_FPWM_EN_M) ?
  		REGULATOR_MODE_FAST : REGULATOR_MODE_NORMAL;
  }

  static int max8973_set_ramp_delay(struct regulator_dev *rdev,
  		int ramp_delay)
  {
  	struct max8973_chip *max = rdev_get_drvdata(rdev);
  	unsigned int control;
  	int ret;

  
  	/* Set ramp delay */

  	if (ramp_delay <= 12000)

  		control = MAX8973_RAMP_12mV_PER_US;

  	else if (ramp_delay <= 25000)

  		control = MAX8973_RAMP_25mV_PER_US;

  	else if (ramp_delay <= 50000)

  		control = MAX8973_RAMP_50mV_PER_US;

  	else if (ramp_delay <= 200000)

  		control = MAX8973_RAMP_200mV_PER_US;

  	else
  		return -EINVAL;

  
  	ret = regmap_update_bits(max->regmap, MAX8973_CONTROL1,
  			MAX8973_RAMP_MASK, control);
  	if (ret < 0)
  		dev_err(max->dev, "register %d update failed, %d",
  				MAX8973_CONTROL1, ret);
  	return ret;
  }

  static int max8973_set_current_limit(struct regulator_dev *rdev,
  		int min_ua, int max_ua)
  {
  	struct max8973_chip *max = rdev_get_drvdata(rdev);
  	unsigned int val;
  	int ret;
  
  	if (max_ua <= 9000000)
  		val = MAX8973_CKKADV_TRIP_75mV_PER_US;
  	else if (max_ua <= 12000000)
  		val = MAX8973_CKKADV_TRIP_150mV_PER_US;
  	else
  		val = MAX8973_CKKADV_TRIP_DISABLE;
  
  	ret = regmap_update_bits(max->regmap, MAX8973_CONTROL2,
  			MAX8973_CKKADV_TRIP_MASK, val);
  	if (ret < 0) {
  		dev_err(max->dev, "register %d update failed: %d
  ",
  				MAX8973_CONTROL2, ret);
  		return ret;
  	}
  	return 0;
  }
  
  static int max8973_get_current_limit(struct regulator_dev *rdev)
  {
  	struct max8973_chip *max = rdev_get_drvdata(rdev);
  	unsigned int control2;
  	int ret;
  
  	ret = regmap_read(max->regmap, MAX8973_CONTROL2, &control2);
  	if (ret < 0) {
  		dev_err(max->dev, "register %d read failed: %d
  ",
  				MAX8973_CONTROL2, ret);
  		return ret;
  	}
  	switch (control2 & MAX8973_CKKADV_TRIP_MASK) {
  	case MAX8973_CKKADV_TRIP_DISABLE:
  		return 15000000;
  	case MAX8973_CKKADV_TRIP_150mV_PER_US:
  		return 12000000;
  	case MAX8973_CKKADV_TRIP_75mV_PER_US:
  		return 9000000;
  	default:
  		break;
  	}
  	return 9000000;
  }

  static const 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,

  	.set_voltage_time_sel	= regulator_set_voltage_time_sel,
  	.set_ramp_delay		= max8973_set_ramp_delay,

  };

  static int max8973_init_dcdc(struct max8973_chip *max,
  			     struct max8973_regulator_platform_data *pdata)

  {
  	int ret;
  	uint8_t	control1 = 0;
  	uint8_t control2 = 0;

  	unsigned int data;
  
  	ret = regmap_read(max->regmap, MAX8973_CONTROL1, &data);
  	if (ret < 0) {
  		dev_err(max->dev, "register %d read failed, err = %d",
  				MAX8973_CONTROL1, ret);
  		return ret;
  	}
  	control1 = data & MAX8973_RAMP_MASK;
  	switch (control1) {
  	case MAX8973_RAMP_12mV_PER_US:
  		max->desc.ramp_delay = 12000;
  		break;
  	case MAX8973_RAMP_25mV_PER_US:

  		max->desc.ramp_delay = 25000;

  		break;
  	case MAX8973_RAMP_50mV_PER_US:
  		max->desc.ramp_delay = 50000;
  		break;
  	case MAX8973_RAMP_200mV_PER_US:
  		max->desc.ramp_delay = 200000;
  		break;
  	}

  
  	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;

  		max->desc.enable_time = 20;
  	} else {
  		max->desc.enable_time = 240;
  	}

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

  	if ((pdata->junction_temp_warning == MAX77621_TJINT_WARNING_TEMP_120) &&
  	    (max->id == MAX77621))
  		control2 |= MAX77621_T_JUNCTION_120;

  	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 && (max->id == MAX8973)) {

  		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 int max8973_thermal_read_temp(void *data, int *temp)
  {
  	struct max8973_chip *mchip = data;
  	unsigned int val;
  	int ret;
  
  	ret = regmap_read(mchip->regmap, MAX8973_CHIPID1, &val);
  	if (ret < 0) {
  		dev_err(mchip->dev, "Failed to read register CHIPID1, %d", ret);
  		return ret;
  	}
  
  	/* +1 degC to trigger cool devive */
  	if (val & MAX77621_CHIPID_TJINT_S)
  		*temp = mchip->junction_temp_warning + 1000;
  	else
  		*temp = MAX77621_NORMAL_OPERATING_TEMP;
  
  	return 0;
  }
  
  static irqreturn_t max8973_thermal_irq(int irq, void *data)
  {
  	struct max8973_chip *mchip = data;

  	thermal_zone_device_update(mchip->tz_device,
  				   THERMAL_EVENT_UNSPECIFIED);

  
  	return IRQ_HANDLED;
  }
  
  static const struct thermal_zone_of_device_ops max77621_tz_ops = {
  	.get_temp = max8973_thermal_read_temp,
  };
  
  static int max8973_thermal_init(struct max8973_chip *mchip)
  {
  	struct thermal_zone_device *tzd;
  	struct irq_data *irq_data;
  	unsigned long irq_flags = 0;
  	int ret;
  
  	if (mchip->id != MAX77621)
  		return 0;
  
  	tzd = devm_thermal_zone_of_sensor_register(mchip->dev, 0, mchip,
  						   &max77621_tz_ops);
  	if (IS_ERR(tzd)) {
  		ret = PTR_ERR(tzd);
  		dev_err(mchip->dev, "Failed to register thermal sensor: %d
  ",
  			ret);
  		return ret;
  	}
  
  	if (mchip->irq <= 0)
  		return 0;
  
  	irq_data = irq_get_irq_data(mchip->irq);
  	if (irq_data)
  		irq_flags = irqd_get_trigger_type(irq_data);
  
  	ret = devm_request_threaded_irq(mchip->dev, mchip->irq, NULL,
  					max8973_thermal_irq,
  					IRQF_ONESHOT | IRQF_SHARED | irq_flags,
  					dev_name(mchip->dev), mchip);
  	if (ret < 0) {
  		dev_err(mchip->dev, "Failed to request irq %d, %d
  ",
  			mchip->irq, ret);
  		return ret;
  	}
  
  	return 0;
  }

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

  static struct max8973_regulator_platform_data *max8973_parse_dt(
  		struct device *dev)
  {
  	struct max8973_regulator_platform_data *pdata;
  	struct device_node *np = dev->of_node;
  	int ret;
  	u32 pval;

  	bool etr_enable;
  	bool etr_sensitivity_high;

  
  	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
  	if (!pdata)
  		return NULL;
  
  	pdata->enable_ext_control = of_property_read_bool(np,
  						"maxim,externally-enable");
  	pdata->dvs_gpio = of_get_named_gpio(np, "maxim,dvs-gpio", 0);
  
  	ret = of_property_read_u32(np, "maxim,dvs-default-state", &pval);
  	if (!ret)
  		pdata->dvs_def_state = pval;
  
  	if (of_property_read_bool(np, "maxim,enable-remote-sense"))
  		pdata->control_flags  |= MAX8973_CONTROL_REMOTE_SENSE_ENABLE;
  
  	if (of_property_read_bool(np, "maxim,enable-falling-slew-rate"))
  		pdata->control_flags  |=
  				MAX8973_CONTROL_FALLING_SLEW_RATE_ENABLE;
  
  	if (of_property_read_bool(np, "maxim,enable-active-discharge"))
  		pdata->control_flags  |=
  				MAX8973_CONTROL_OUTPUT_ACTIVE_DISCH_ENABLE;
  
  	if (of_property_read_bool(np, "maxim,enable-frequency-shift"))
  		pdata->control_flags  |= MAX8973_CONTROL_FREQ_SHIFT_9PER_ENABLE;
  
  	if (of_property_read_bool(np, "maxim,enable-bias-control"))

  		pdata->control_flags  |= MAX8973_CONTROL_BIAS_ENABLE;

  	etr_enable = of_property_read_bool(np, "maxim,enable-etr");
  	etr_sensitivity_high = of_property_read_bool(np,
  				"maxim,enable-high-etr-sensitivity");
  	if (etr_sensitivity_high)
  		etr_enable = true;
  
  	if (etr_enable) {
  		if (etr_sensitivity_high)
  			pdata->control_flags |=
  				MAX8973_CONTROL_CLKADV_TRIP_75mV_PER_US;
  		else
  			pdata->control_flags |=
  				MAX8973_CONTROL_CLKADV_TRIP_150mV_PER_US;
  	} else {
  		pdata->control_flags |= MAX8973_CONTROL_CLKADV_TRIP_DISABLED;
  	}

  	pdata->junction_temp_warning = MAX77621_TJINT_WARNING_TEMP_140;
  	ret = of_property_read_u32(np, "junction-warn-millicelsius", &pval);
  	if (!ret && (pval <= MAX77621_TJINT_WARNING_TEMP_120))
  		pdata->junction_temp_warning = MAX77621_TJINT_WARNING_TEMP_120;

  	return pdata;
  }

  static const struct of_device_id of_max8973_match_tbl[] = {
  	{ .compatible = "maxim,max8973", .data = (void *)MAX8973, },
  	{ .compatible = "maxim,max77621", .data = (void *)MAX77621, },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, of_max8973_match_tbl);

  static int max8973_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)

  {
  	struct max8973_regulator_platform_data *pdata;

  	struct regulator_init_data *ridata;

  	struct regulator_config config = { };
  	struct regulator_dev *rdev;
  	struct max8973_chip *max;

  	bool pdata_from_dt = false;

  	unsigned int chip_id;

  	struct gpio_desc *gpiod;
  	enum gpiod_flags gflags;

  	int ret;

  	pdata = dev_get_platdata(&client->dev);

  	if (!pdata && client->dev.of_node) {
  		pdata = max8973_parse_dt(&client->dev);
  		pdata_from_dt = true;
  	}
  
  	if (!pdata) {

  		dev_err(&client->dev, "No Platform data");
  		return -EIO;
  	}

  	if (pdata->dvs_gpio == -EPROBE_DEFER)

  		return -EPROBE_DEFER;

  	max = devm_kzalloc(&client->dev, sizeof(*max), GFP_KERNEL);

  	if (!max)

  		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
  ", ret);
  		return ret;
  	}

  	if (client->dev.of_node) {
  		const struct of_device_id *match;
  
  		match = of_match_device(of_match_ptr(of_max8973_match_tbl),
  				&client->dev);
  		if (!match)
  			return -ENODATA;
  		max->id = (u32)((uintptr_t)match->data);
  	} else {
  		max->id = id->driver_data;
  	}
  
  	ret = regmap_read(max->regmap, MAX8973_CHIPID1, &chip_id);
  	if (ret < 0) {
  		dev_err(&client->dev, "register CHIPID1 read failed, %d", ret);
  		return ret;
  	}
  
  	dev_info(&client->dev, "CHIP-ID OTP: 0x%02x ID_M: 0x%02x
  ",
  			(chip_id >> 4) & 0xF, (chip_id >> 1) & 0x7);

  	i2c_set_clientdata(client, max);

  	max->ops = max8973_dcdc_ops;

  	max->dev = &client->dev;
  	max->desc.name = id->name;
  	max->desc.id = 0;

  	max->desc.ops = &max->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;

  	max->dvs_gpio = (pdata->dvs_gpio) ? pdata->dvs_gpio : -EINVAL;

  	max->enable_external_control = pdata->enable_ext_control;
  	max->curr_gpio_val = pdata->dvs_def_state;
  	max->curr_vout_reg = MAX8973_VOUT + pdata->dvs_def_state;

  	max->junction_temp_warning = pdata->junction_temp_warning;

  	max->lru_index[0] = max->curr_vout_reg;

  
  	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
  ",
  				max->dvs_gpio, ret);
  			return ret;
  		}

  
  		/*
  		 * 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;

  	} else {
  		/*
  		 * If there is no DVS GPIO, the VOUT register
  		 * address is fixed.
  		 */
  		max->ops.set_voltage_sel = regulator_set_voltage_sel_regmap;
  		max->ops.get_voltage_sel = regulator_get_voltage_sel_regmap;
  		max->desc.vsel_reg = max->curr_vout_reg;
  		max->desc.vsel_mask = MAX8973_VOUT_MASK;

  	}

  	if (pdata_from_dt)
  		pdata->reg_init_data = of_get_regulator_init_data(&client->dev,
  					client->dev.of_node, &max->desc);

  	ridata = pdata->reg_init_data;
  	switch (max->id) {
  	case MAX8973:
  		if (!pdata->enable_ext_control) {
  			max->desc.enable_reg = MAX8973_VOUT;
  			max->desc.enable_mask = MAX8973_VOUT_ENABLE;
  			max->ops.enable = regulator_enable_regmap;
  			max->ops.disable = regulator_disable_regmap;
  			max->ops.is_enabled = regulator_is_enabled_regmap;
  			break;
  		}

  		if (ridata && (ridata->constraints.always_on ||
  			       ridata->constraints.boot_on))
  			gflags = GPIOD_OUT_HIGH;
  		else
  			gflags = GPIOD_OUT_LOW;

  		gflags |= GPIOD_FLAGS_BIT_NONEXCLUSIVE;

  		gpiod = devm_gpiod_get_optional(&client->dev,
  						"maxim,enable",
  						gflags);
  		if (IS_ERR(gpiod))
  			return PTR_ERR(gpiod);
  		if (gpiod) {
  			config.ena_gpiod = gpiod;
  			max->enable_external_control = true;

  		}

  		break;
  
  	case MAX77621:

  		/*
  		 * We do not let the core switch this regulator on/off,
  		 * we just leave it on.
  		 */
  		gpiod = devm_gpiod_get_optional(&client->dev,
  						"maxim,enable",
  						GPIOD_OUT_HIGH);
  		if (IS_ERR(gpiod))
  			return PTR_ERR(gpiod);
  		if (gpiod)
  			max->enable_external_control = true;

  
  		max->desc.enable_reg = MAX8973_VOUT;
  		max->desc.enable_mask = MAX8973_VOUT_ENABLE;
  		max->ops.enable = regulator_enable_regmap;
  		max->ops.disable = regulator_disable_regmap;
  		max->ops.is_enabled = regulator_is_enabled_regmap;

  		max->ops.set_current_limit = max8973_set_current_limit;
  		max->ops.get_current_limit = max8973_get_current_limit;

  		break;
  	default:
  		break;
  	}

  	ret = max8973_init_dcdc(max, pdata);
  	if (ret < 0) {
  		dev_err(max->dev, "Max8973 Init failed, err = %d
  ", 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
  	 * Turn the GPIO descriptor over to the regulator core for
  	 * lifecycle management if we pass an ena_gpiod.
  	 */
  	if (config.ena_gpiod)
  		devm_gpiod_unhinge(&client->dev, config.ena_gpiod);

  	rdev = devm_regulator_register(&client->dev, &max->desc, &config);

  	if (IS_ERR(rdev)) {
  		ret = PTR_ERR(rdev);
  		dev_err(max->dev, "regulator register failed, err %d
  ", ret);
  		return ret;
  	}

  	max8973_thermal_init(max);

  	return 0;
  }

  static const struct i2c_device_id max8973_id[] = {

  	{.name = "max8973", .driver_data = MAX8973},
  	{.name = "max77621", .driver_data = MAX77621},

  	{},
  };

  MODULE_DEVICE_TABLE(i2c, max8973_id);
  
  static struct i2c_driver max8973_i2c_driver = {
  	.driver = {
  		.name = "max8973",

  		.of_match_table = of_max8973_match_tbl,

  	},
  	.probe = max8973_probe,

  	.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");