// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Regulator driver for PWM Regulators
   *
   * Copyright (C) 2014 - STMicroelectronics Inc.
   *
   * Author: Lee Jones <lee.jones@linaro.org>

   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/err.h>
  #include <linux/regulator/driver.h>
  #include <linux/regulator/machine.h>
  #include <linux/regulator/of_regulator.h>
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/pwm.h>

  #include <linux/gpio/consumer.h>

  struct pwm_continuous_reg_data {
  	unsigned int min_uV_dutycycle;
  	unsigned int max_uV_dutycycle;
  	unsigned int dutycycle_unit;
  };

  struct pwm_regulator_data {

  	/*  Shared */

  	struct pwm_device *pwm;

  
  	/* Voltage table */
  	struct pwm_voltages *duty_cycle_table;

  	/* Continuous mode info */
  	struct pwm_continuous_reg_data continuous;

  	/* regulator descriptor */
  	struct regulator_desc desc;

  	int state;

  	/* Enable GPIO */
  	struct gpio_desc *enb_gpio;

  };
  
  struct pwm_voltages {
  	unsigned int uV;
  	unsigned int dutycycle;
  };

  /*

   * Voltage table call-backs
   */

  static void pwm_regulator_init_state(struct regulator_dev *rdev)
  {
  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);
  	struct pwm_state pwm_state;
  	unsigned int dutycycle;
  	int i;
  
  	pwm_get_state(drvdata->pwm, &pwm_state);
  	dutycycle = pwm_get_relative_duty_cycle(&pwm_state, 100);
  
  	for (i = 0; i < rdev->desc->n_voltages; i++) {
  		if (dutycycle == drvdata->duty_cycle_table[i].dutycycle) {
  			drvdata->state = i;
  			return;
  		}
  	}
  }

  static int pwm_regulator_get_voltage_sel(struct regulator_dev *rdev)

  {

  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);

  	if (drvdata->state < 0)
  		pwm_regulator_init_state(rdev);

  	return drvdata->state;
  }

  static int pwm_regulator_set_voltage_sel(struct regulator_dev *rdev,

  					 unsigned selector)
  {

  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);

  	struct pwm_state pstate;

  	int ret;

  	pwm_init_state(drvdata->pwm, &pstate);
  	pwm_set_relative_duty_cycle(&pstate,
  			drvdata->duty_cycle_table[selector].dutycycle, 100);

  	ret = pwm_apply_state(drvdata->pwm, &pstate);

  	if (ret) {

  		dev_err(&rdev->dev, "Failed to configure PWM: %d
  ", ret);

  		return ret;
  	}
  
  	drvdata->state = selector;

  	return 0;
  }

  static int pwm_regulator_list_voltage(struct regulator_dev *rdev,

  				      unsigned selector)
  {

  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);

  	if (selector >= rdev->desc->n_voltages)

  		return -EINVAL;
  
  	return drvdata->duty_cycle_table[selector].uV;
  }

  static int pwm_regulator_enable(struct regulator_dev *dev)
  {
  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);

  	gpiod_set_value_cansleep(drvdata->enb_gpio, 1);

  	return pwm_enable(drvdata->pwm);
  }
  
  static int pwm_regulator_disable(struct regulator_dev *dev)
  {
  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);
  
  	pwm_disable(drvdata->pwm);

  	gpiod_set_value_cansleep(drvdata->enb_gpio, 0);

  	return 0;
  }
  
  static int pwm_regulator_is_enabled(struct regulator_dev *dev)
  {
  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(dev);

  	if (drvdata->enb_gpio && !gpiod_get_value_cansleep(drvdata->enb_gpio))
  		return false;

  	return pwm_is_enabled(drvdata->pwm);
  }

  static int pwm_regulator_get_voltage(struct regulator_dev *rdev)
  {
  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);

  	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
  	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
  	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;

  	int min_uV = rdev->constraints->min_uV;

  	int max_uV = rdev->constraints->max_uV;
  	int diff_uV = max_uV - min_uV;

  	struct pwm_state pstate;

  	unsigned int diff_duty;
  	unsigned int voltage;

  	pwm_get_state(drvdata->pwm, &pstate);

  	voltage = pwm_get_relative_duty_cycle(&pstate, duty_unit);
  
  	/*
  	 * The dutycycle for min_uV might be greater than the one for max_uV.
  	 * This is happening when the user needs an inversed polarity, but the
  	 * PWM device does not support inversing it in hardware.
  	 */
  	if (max_uV_duty < min_uV_duty) {
  		voltage = min_uV_duty - voltage;
  		diff_duty = min_uV_duty - max_uV_duty;
  	} else {
  		voltage = voltage - min_uV_duty;
  		diff_duty = max_uV_duty - min_uV_duty;
  	}
  
  	voltage = DIV_ROUND_CLOSEST_ULL((u64)voltage * diff_uV, diff_duty);
  
  	return voltage + min_uV;

  }
  
  static int pwm_regulator_set_voltage(struct regulator_dev *rdev,

  				     int req_min_uV, int req_max_uV,
  				     unsigned int *selector)

  {
  	struct pwm_regulator_data *drvdata = rdev_get_drvdata(rdev);

  	unsigned int min_uV_duty = drvdata->continuous.min_uV_dutycycle;
  	unsigned int max_uV_duty = drvdata->continuous.max_uV_dutycycle;
  	unsigned int duty_unit = drvdata->continuous.dutycycle_unit;

  	int min_uV = rdev->constraints->min_uV;
  	int max_uV = rdev->constraints->max_uV;
  	int diff_uV = max_uV - min_uV;

  	struct pwm_state pstate;

  	unsigned int diff_duty;
  	unsigned int dutycycle;

  	int ret;

  	pwm_init_state(drvdata->pwm, &pstate);

  	/*
  	 * The dutycycle for min_uV might be greater than the one for max_uV.
  	 * This is happening when the user needs an inversed polarity, but the
  	 * PWM device does not support inversing it in hardware.
  	 */
  	if (max_uV_duty < min_uV_duty)
  		diff_duty = min_uV_duty - max_uV_duty;
  	else
  		diff_duty = max_uV_duty - min_uV_duty;
  
  	dutycycle = DIV_ROUND_CLOSEST_ULL((u64)(req_min_uV - min_uV) *
  					  diff_duty,
  					  diff_uV);
  
  	if (max_uV_duty < min_uV_duty)
  		dutycycle = min_uV_duty - dutycycle;
  	else
  		dutycycle = min_uV_duty + dutycycle;
  
  	pwm_set_relative_duty_cycle(&pstate, dutycycle, duty_unit);

  	ret = pwm_apply_state(drvdata->pwm, &pstate);

  	if (ret) {

  		dev_err(&rdev->dev, "Failed to configure PWM: %d
  ", ret);

  		return ret;
  	}

  	return 0;
  }

  static const struct regulator_ops pwm_regulator_voltage_table_ops = {

  	.set_voltage_sel = pwm_regulator_set_voltage_sel,
  	.get_voltage_sel = pwm_regulator_get_voltage_sel,
  	.list_voltage    = pwm_regulator_list_voltage,
  	.map_voltage     = regulator_map_voltage_iterate,

  	.enable          = pwm_regulator_enable,
  	.disable         = pwm_regulator_disable,
  	.is_enabled      = pwm_regulator_is_enabled,

  };

  static const struct regulator_ops pwm_regulator_voltage_continuous_ops = {

  	.get_voltage = pwm_regulator_get_voltage,
  	.set_voltage = pwm_regulator_set_voltage,

  	.enable          = pwm_regulator_enable,
  	.disable         = pwm_regulator_disable,
  	.is_enabled      = pwm_regulator_is_enabled,

  };

  static const struct regulator_desc pwm_regulator_desc = {

  	.name		= "pwm-regulator",

  	.type		= REGULATOR_VOLTAGE,
  	.owner		= THIS_MODULE,
  	.supply_name    = "pwm",
  };

  static int pwm_regulator_init_table(struct platform_device *pdev,
  				    struct pwm_regulator_data *drvdata)
  {
  	struct device_node *np = pdev->dev.of_node;
  	struct pwm_voltages *duty_cycle_table;

  	unsigned int length = 0;

  	int ret;
  
  	of_find_property(np, "voltage-table", &length);
  
  	if ((length < sizeof(*duty_cycle_table)) ||
  	    (length % sizeof(*duty_cycle_table))) {

  		dev_err(&pdev->dev, "voltage-table length(%d) is invalid
  ",

  			length);
  		return -EINVAL;
  	}
  
  	duty_cycle_table = devm_kzalloc(&pdev->dev, length, GFP_KERNEL);
  	if (!duty_cycle_table)
  		return -ENOMEM;
  
  	ret = of_property_read_u32_array(np, "voltage-table",
  					 (u32 *)duty_cycle_table,
  					 length / sizeof(u32));
  	if (ret) {

  		dev_err(&pdev->dev, "Failed to read voltage-table: %d
  ", ret);

  		return ret;
  	}

  	drvdata->state			= -ENOTRECOVERABLE;

  	drvdata->duty_cycle_table	= duty_cycle_table;

  	drvdata->desc.ops = &pwm_regulator_voltage_table_ops;

  	drvdata->desc.n_voltages	= length / sizeof(*duty_cycle_table);

  
  	return 0;
  }

  static int pwm_regulator_init_continuous(struct platform_device *pdev,
  					 struct pwm_regulator_data *drvdata)
  {

  	u32 dutycycle_range[2] = { 0, 100 };
  	u32 dutycycle_unit = 100;

  	drvdata->desc.ops = &pwm_regulator_voltage_continuous_ops;

  	drvdata->desc.continuous_voltage_range = true;

  	of_property_read_u32_array(pdev->dev.of_node,
  				   "pwm-dutycycle-range",
  				   dutycycle_range, 2);
  	of_property_read_u32(pdev->dev.of_node, "pwm-dutycycle-unit",
  			     &dutycycle_unit);
  
  	if (dutycycle_range[0] > dutycycle_unit ||
  	    dutycycle_range[1] > dutycycle_unit)
  		return -EINVAL;
  
  	drvdata->continuous.dutycycle_unit = dutycycle_unit;
  	drvdata->continuous.min_uV_dutycycle = dutycycle_range[0];
  	drvdata->continuous.max_uV_dutycycle = dutycycle_range[1];

  	return 0;
  }

  static int pwm_regulator_probe(struct platform_device *pdev)
  {

  	const struct regulator_init_data *init_data;

  	struct pwm_regulator_data *drvdata;

  	struct regulator_dev *regulator;
  	struct regulator_config config = { };
  	struct device_node *np = pdev->dev.of_node;

  	enum gpiod_flags gpio_flags;

  	int ret;

  
  	if (!np) {
  		dev_err(&pdev->dev, "Device Tree node missing
  ");
  		return -EINVAL;
  	}
  
  	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
  	if (!drvdata)
  		return -ENOMEM;

  	memcpy(&drvdata->desc, &pwm_regulator_desc, sizeof(drvdata->desc));

  	if (of_find_property(np, "voltage-table", NULL))

  		ret = pwm_regulator_init_table(pdev, drvdata);

  	else
  		ret = pwm_regulator_init_continuous(pdev, drvdata);
  	if (ret)
  		return ret;

  	init_data = of_get_regulator_init_data(&pdev->dev, np,

  					       &drvdata->desc);

  	if (!init_data)

  		return -ENOMEM;
  
  	config.of_node = np;
  	config.dev = &pdev->dev;
  	config.driver_data = drvdata;

  	config.init_data = init_data;

  
  	drvdata->pwm = devm_pwm_get(&pdev->dev, NULL);
  	if (IS_ERR(drvdata->pwm)) {

  		ret = PTR_ERR(drvdata->pwm);

  		if (ret == -EPROBE_DEFER)
  			dev_dbg(&pdev->dev,
  				"Failed to get PWM, deferring probe
  ");
  		else
  			dev_err(&pdev->dev, "Failed to get PWM: %d
  ", ret);

  		return ret;

  	}

  	if (init_data->constraints.boot_on || init_data->constraints.always_on)
  		gpio_flags = GPIOD_OUT_HIGH;
  	else
  		gpio_flags = GPIOD_OUT_LOW;
  	drvdata->enb_gpio = devm_gpiod_get_optional(&pdev->dev, "enable",
  						    gpio_flags);
  	if (IS_ERR(drvdata->enb_gpio)) {
  		ret = PTR_ERR(drvdata->enb_gpio);
  		dev_err(&pdev->dev, "Failed to get enable GPIO: %d
  ", ret);
  		return ret;
  	}

  	ret = pwm_adjust_config(drvdata->pwm);
  	if (ret)
  		return ret;

  	regulator = devm_regulator_register(&pdev->dev,

  					    &drvdata->desc, &config);

  	if (IS_ERR(regulator)) {

  		ret = PTR_ERR(regulator);
  		dev_err(&pdev->dev, "Failed to register regulator %s: %d
  ",
  			drvdata->desc.name, ret);
  		return ret;

  	}
  
  	return 0;
  }

  static const struct of_device_id __maybe_unused pwm_of_match[] = {

  	{ .compatible = "pwm-regulator" },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, pwm_of_match);
  
  static struct platform_driver pwm_regulator_driver = {
  	.driver = {
  		.name		= "pwm-regulator",

  		.of_match_table = of_match_ptr(pwm_of_match),
  	},
  	.probe = pwm_regulator_probe,
  };
  
  module_platform_driver(pwm_regulator_driver);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Lee Jones <lee.jones@linaro.org>");
  MODULE_DESCRIPTION("PWM Regulator Driver");
  MODULE_ALIAS("platform:pwm-regulator");