// SPDX-License-Identifier: GPL-2.0
  //
  // MCP16502 PMIC driver
  //
  // Copyright (C) 2018 Microchip Technology Inc. and its subsidiaries
  //
  // Author: Andrei Stefanescu <andrei.stefanescu@microchip.com>
  //
  // Inspired from tps65086-regulator.c
  
  #include <linux/gpio.h>
  #include <linux/i2c.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/regmap.h>
  #include <linux/regulator/driver.h>
  #include <linux/suspend.h>

  #include <linux/gpio/consumer.h>

  
  #define VDD_LOW_SEL 0x0D
  #define VDD_HIGH_SEL 0x3F
  
  #define MCP16502_FLT BIT(7)
  #define MCP16502_ENS BIT(0)
  
  /*
   * The PMIC has four sets of registers corresponding to four power modes:
   * Performance, Active, Low-power, Hibernate.
   *
   * Registers:
   * Each regulator has a register for each power mode. To access a register
   * for a specific regulator and mode BASE_* and OFFSET_* need to be added.
   *
   * Operating modes:
   * In order for the PMIC to transition to operating modes it has to be
   * controlled via GPIO lines called LPM and HPM.
   *
   * The registers are fully configurable such that you can put all regulators in
   * a low-power state while the PMIC is in Active mode. They are supposed to be
   * configured at startup and then simply transition to/from a global low-power
   * state by setting the GPIO lpm pin high/low.
   *
   * This driver keeps the PMIC in Active mode, Low-power state is set for the
   * regulators by enabling/disabling operating mode (FPWM or Auto PFM).
   *
   * The PMIC's Low-power and Hibernate modes are used during standby/suspend.
   * To enter standby/suspend the PMIC will go to Low-power mode. From there, it
   * will transition to Hibernate when the PWRHLD line is set to low by the MPU.
   */
  
  /*
   * This function is useful for iterating over all regulators and accessing their
   * registers in a generic way or accessing a regulator device by its id.
   */
  #define MCP16502_BASE(i) (((i) + 1) << 4)
  #define MCP16502_STAT_BASE(i) ((i) + 5)
  
  #define MCP16502_OFFSET_MODE_A 0
  #define MCP16502_OFFSET_MODE_LPM 1
  #define MCP16502_OFFSET_MODE_HIB 2
  
  #define MCP16502_OPMODE_ACTIVE REGULATOR_MODE_NORMAL
  #define MCP16502_OPMODE_LPM REGULATOR_MODE_IDLE
  #define MCP16502_OPMODE_HIB REGULATOR_MODE_STANDBY
  
  #define MCP16502_MODE_AUTO_PFM 0
  #define MCP16502_MODE_FPWM BIT(6)
  
  #define MCP16502_VSEL 0x3F
  #define MCP16502_EN BIT(7)
  #define MCP16502_MODE BIT(6)
  
  #define MCP16502_MIN_REG 0x0
  #define MCP16502_MAX_REG 0x65
  
  static unsigned int mcp16502_of_map_mode(unsigned int mode)
  {
  	if (mode == REGULATOR_MODE_NORMAL || mode == REGULATOR_MODE_IDLE)
  		return mode;
  
  	return REGULATOR_MODE_INVALID;
  }
  
  #define MCP16502_REGULATOR(_name, _id, _ranges, _ops)			\
  	[_id] = {							\
  		.name			= _name,			\
  		.regulators_node	= of_match_ptr("regulators"),	\
  		.id			= _id,				\
  		.ops			= &(_ops),			\
  		.type			= REGULATOR_VOLTAGE,		\
  		.owner			= THIS_MODULE,			\

  		.n_voltages		= MCP16502_VSEL + 1,		\

  		.linear_ranges		= _ranges,			\
  		.n_linear_ranges	= ARRAY_SIZE(_ranges),		\
  		.of_match		= of_match_ptr(_name),		\
  		.of_map_mode		= mcp16502_of_map_mode,		\
  		.vsel_reg		= (((_id) + 1) << 4),		\
  		.vsel_mask		= MCP16502_VSEL,		\
  		.enable_reg		= (((_id) + 1) << 4),		\
  		.enable_mask		= MCP16502_EN,			\
  	}
  
  enum {
  	BUCK1 = 0,
  	BUCK2,
  	BUCK3,
  	BUCK4,
  	LDO1,
  	LDO2,
  	NUM_REGULATORS
  };
  
  /*
   * struct mcp16502 - PMIC representation
   * @rdev: the regulators belonging to this chip
   * @rmap: regmap to be used for I2C communication
   * @lpm: LPM GPIO descriptor
   */
  struct mcp16502 {

  	struct gpio_desc *lpm;
  };
  
  /*
   * mcp16502_gpio_set_mode() - set the GPIO corresponding value
   *
   * Used to prepare transitioning into hibernate or resuming from it.
   */
  static void mcp16502_gpio_set_mode(struct mcp16502 *mcp, int mode)
  {
  	switch (mode) {
  	case MCP16502_OPMODE_ACTIVE:
  		gpiod_set_value(mcp->lpm, 0);
  		break;
  	case MCP16502_OPMODE_LPM:
  	case MCP16502_OPMODE_HIB:
  		gpiod_set_value(mcp->lpm, 1);
  		break;
  	default:
  		pr_err("%s: %d invalid
  ", __func__, mode);
  	}
  }
  
  /*
   * mcp16502_get_reg() - get the PMIC's configuration register for opmode
   *
   * @rdev: the regulator whose register we are searching
   * @opmode: the PMIC's operating mode ACTIVE, Low-power, Hibernate
   */
  static int mcp16502_get_reg(struct regulator_dev *rdev, int opmode)
  {
  	int reg = MCP16502_BASE(rdev_get_id(rdev));
  
  	switch (opmode) {
  	case MCP16502_OPMODE_ACTIVE:
  		return reg + MCP16502_OFFSET_MODE_A;
  	case MCP16502_OPMODE_LPM:
  		return reg + MCP16502_OFFSET_MODE_LPM;
  	case MCP16502_OPMODE_HIB:
  		return reg + MCP16502_OFFSET_MODE_HIB;
  	default:
  		return -EINVAL;
  	}
  }
  
  /*
   * mcp16502_get_mode() - return the current operating mode of a regulator
   *
   * Note: all functions that are not part of entering/exiting standby/suspend
   *	 use the Active mode registers.
   *
   * Note: this is different from the PMIC's operatig mode, it is the
   *	 MODE bit from the regulator's register.
   */
  static unsigned int mcp16502_get_mode(struct regulator_dev *rdev)
  {
  	unsigned int val;
  	int ret, reg;

  
  	reg = mcp16502_get_reg(rdev, MCP16502_OPMODE_ACTIVE);
  	if (reg < 0)
  		return reg;

  	ret = regmap_read(rdev->regmap, reg, &val);

  	if (ret)
  		return ret;
  
  	switch (val & MCP16502_MODE) {
  	case MCP16502_MODE_FPWM:
  		return REGULATOR_MODE_NORMAL;
  	case MCP16502_MODE_AUTO_PFM:
  		return REGULATOR_MODE_IDLE;
  	default:
  		return REGULATOR_MODE_INVALID;
  	}
  }
  
  /*
   * _mcp16502_set_mode() - helper for set_mode and set_suspend_mode
   *
   * @rdev: the regulator for which we are setting the mode
   * @mode: the regulator's mode (the one from MODE bit)
   * @opmode: the PMIC's operating mode: Active/Low-power/Hibernate
   */
  static int _mcp16502_set_mode(struct regulator_dev *rdev, unsigned int mode,
  			      unsigned int op_mode)
  {
  	int val;
  	int reg;

  
  	reg = mcp16502_get_reg(rdev, op_mode);
  	if (reg < 0)
  		return reg;
  
  	switch (mode) {
  	case REGULATOR_MODE_NORMAL:
  		val = MCP16502_MODE_FPWM;
  		break;
  	case REGULATOR_MODE_IDLE:
  		val = MCP16502_MODE_AUTO_PFM;
  		break;
  	default:
  		return -EINVAL;
  	}

  	reg = regmap_update_bits(rdev->regmap, reg, MCP16502_MODE, val);

  	return reg;
  }
  
  /*
   * mcp16502_set_mode() - regulator_ops set_mode
   */
  static int mcp16502_set_mode(struct regulator_dev *rdev, unsigned int mode)
  {
  	return _mcp16502_set_mode(rdev, mode, MCP16502_OPMODE_ACTIVE);
  }
  
  /*
   * mcp16502_get_status() - regulator_ops get_status
   */
  static int mcp16502_get_status(struct regulator_dev *rdev)
  {
  	int ret;
  	unsigned int val;

  	ret = regmap_read(rdev->regmap, MCP16502_STAT_BASE(rdev_get_id(rdev)),

  			  &val);
  	if (ret)
  		return ret;
  
  	if (val & MCP16502_FLT)
  		return REGULATOR_STATUS_ERROR;
  	else if (val & MCP16502_ENS)
  		return REGULATOR_STATUS_ON;
  	else if (!(val & MCP16502_ENS))
  		return REGULATOR_STATUS_OFF;
  
  	return REGULATOR_STATUS_UNDEFINED;
  }
  
  #ifdef CONFIG_SUSPEND
  /*
   * mcp16502_suspend_get_target_reg() - get the reg of the target suspend PMIC
   *				       mode
   */
  static int mcp16502_suspend_get_target_reg(struct regulator_dev *rdev)
  {
  	switch (pm_suspend_target_state) {
  	case PM_SUSPEND_STANDBY:
  		return mcp16502_get_reg(rdev, MCP16502_OPMODE_LPM);
  	case PM_SUSPEND_ON:
  	case PM_SUSPEND_MEM:
  		return mcp16502_get_reg(rdev, MCP16502_OPMODE_HIB);
  	default:
  		dev_err(&rdev->dev, "invalid suspend target: %d
  ",
  			pm_suspend_target_state);
  	}
  
  	return -EINVAL;
  }
  
  /*
   * mcp16502_set_suspend_voltage() - regulator_ops set_suspend_voltage
   */
  static int mcp16502_set_suspend_voltage(struct regulator_dev *rdev, int uV)
  {

  	int sel = regulator_map_voltage_linear_range(rdev, uV, uV);
  	int reg = mcp16502_suspend_get_target_reg(rdev);
  
  	if (sel < 0)
  		return sel;
  
  	if (reg < 0)
  		return reg;

  	return regmap_update_bits(rdev->regmap, reg, MCP16502_VSEL, sel);

  }
  
  /*
   * mcp16502_set_suspend_mode() - regulator_ops set_suspend_mode
   */
  static int mcp16502_set_suspend_mode(struct regulator_dev *rdev,
  				     unsigned int mode)
  {
  	switch (pm_suspend_target_state) {
  	case PM_SUSPEND_STANDBY:
  		return _mcp16502_set_mode(rdev, mode, MCP16502_OPMODE_LPM);
  	case PM_SUSPEND_ON:
  	case PM_SUSPEND_MEM:
  		return _mcp16502_set_mode(rdev, mode, MCP16502_OPMODE_HIB);
  	default:
  		dev_err(&rdev->dev, "invalid suspend target: %d
  ",
  			pm_suspend_target_state);
  	}
  
  	return -EINVAL;
  }
  
  /*
   * mcp16502_set_suspend_enable() - regulator_ops set_suspend_enable
   */
  static int mcp16502_set_suspend_enable(struct regulator_dev *rdev)
  {

  	int reg = mcp16502_suspend_get_target_reg(rdev);
  
  	if (reg < 0)
  		return reg;

  	return regmap_update_bits(rdev->regmap, reg, MCP16502_EN, MCP16502_EN);

  }
  
  /*
   * mcp16502_set_suspend_disable() - regulator_ops set_suspend_disable
   */
  static int mcp16502_set_suspend_disable(struct regulator_dev *rdev)
  {

  	int reg = mcp16502_suspend_get_target_reg(rdev);
  
  	if (reg < 0)
  		return reg;

  	return regmap_update_bits(rdev->regmap, reg, MCP16502_EN, 0);

  }
  #endif /* CONFIG_SUSPEND */
  
  static const struct regulator_ops mcp16502_buck_ops = {
  	.list_voltage			= regulator_list_voltage_linear_range,
  	.map_voltage			= regulator_map_voltage_linear_range,
  	.get_voltage_sel		= regulator_get_voltage_sel_regmap,
  	.set_voltage_sel		= regulator_set_voltage_sel_regmap,
  	.enable				= regulator_enable_regmap,
  	.disable			= regulator_disable_regmap,
  	.is_enabled			= regulator_is_enabled_regmap,
  	.get_status			= mcp16502_get_status,
  
  	.set_mode			= mcp16502_set_mode,
  	.get_mode			= mcp16502_get_mode,
  
  #ifdef CONFIG_SUSPEND
  	.set_suspend_voltage		= mcp16502_set_suspend_voltage,
  	.set_suspend_mode		= mcp16502_set_suspend_mode,
  	.set_suspend_enable		= mcp16502_set_suspend_enable,
  	.set_suspend_disable		= mcp16502_set_suspend_disable,
  #endif /* CONFIG_SUSPEND */
  };
  
  /*
   * LDOs cannot change operating modes.
   */
  static const struct regulator_ops mcp16502_ldo_ops = {
  	.list_voltage			= regulator_list_voltage_linear_range,
  	.map_voltage			= regulator_map_voltage_linear_range,
  	.get_voltage_sel		= regulator_get_voltage_sel_regmap,
  	.set_voltage_sel		= regulator_set_voltage_sel_regmap,
  	.enable				= regulator_enable_regmap,
  	.disable			= regulator_disable_regmap,
  	.is_enabled			= regulator_is_enabled_regmap,
  	.get_status			= mcp16502_get_status,
  
  #ifdef CONFIG_SUSPEND
  	.set_suspend_voltage		= mcp16502_set_suspend_voltage,
  	.set_suspend_enable		= mcp16502_set_suspend_enable,
  	.set_suspend_disable		= mcp16502_set_suspend_disable,
  #endif /* CONFIG_SUSPEND */
  };
  
  static const struct of_device_id mcp16502_ids[] = {
  	{ .compatible = "microchip,mcp16502", },
  	{}
  };
  MODULE_DEVICE_TABLE(of, mcp16502_ids);

  static const struct linear_range b1l12_ranges[] = {

  	REGULATOR_LINEAR_RANGE(1200000, VDD_LOW_SEL, VDD_HIGH_SEL, 50000),
  };

  static const struct linear_range b234_ranges[] = {

  	REGULATOR_LINEAR_RANGE(600000, VDD_LOW_SEL, VDD_HIGH_SEL, 25000),
  };
  
  static const struct regulator_desc mcp16502_desc[] = {
  	/* MCP16502_REGULATOR(_name, _id, ranges, regulator_ops) */
  	MCP16502_REGULATOR("VDD_IO", BUCK1, b1l12_ranges, mcp16502_buck_ops),
  	MCP16502_REGULATOR("VDD_DDR", BUCK2, b234_ranges, mcp16502_buck_ops),
  	MCP16502_REGULATOR("VDD_CORE", BUCK3, b234_ranges, mcp16502_buck_ops),
  	MCP16502_REGULATOR("VDD_OTHER", BUCK4, b234_ranges, mcp16502_buck_ops),
  	MCP16502_REGULATOR("LDO1", LDO1, b1l12_ranges, mcp16502_ldo_ops),
  	MCP16502_REGULATOR("LDO2", LDO2, b1l12_ranges, mcp16502_ldo_ops)
  };
  
  static const struct regmap_range mcp16502_ranges[] = {
  	regmap_reg_range(MCP16502_MIN_REG, MCP16502_MAX_REG)
  };
  
  static const struct regmap_access_table mcp16502_yes_reg_table = {
  	.yes_ranges = mcp16502_ranges,
  	.n_yes_ranges = ARRAY_SIZE(mcp16502_ranges),
  };
  
  static const struct regmap_config mcp16502_regmap_config = {
  	.reg_bits	= 8,
  	.val_bits	= 8,
  	.max_register	= MCP16502_MAX_REG,
  	.cache_type	= REGCACHE_NONE,
  	.rd_table	= &mcp16502_yes_reg_table,
  	.wr_table	= &mcp16502_yes_reg_table,
  };

  static int mcp16502_probe(struct i2c_client *client,
  			  const struct i2c_device_id *id)
  {
  	struct regulator_config config = { };

  	struct regulator_dev *rdev;

  	struct device *dev;
  	struct mcp16502 *mcp;

  	struct regmap *rmap;

  	int i, ret;

  
  	dev = &client->dev;
  	config.dev = dev;
  
  	mcp = devm_kzalloc(dev, sizeof(*mcp), GFP_KERNEL);
  	if (!mcp)
  		return -ENOMEM;

  	rmap = devm_regmap_init_i2c(client, &mcp16502_regmap_config);
  	if (IS_ERR(rmap)) {
  		ret = PTR_ERR(rmap);

  		dev_err(dev, "regmap init failed: %d
  ", ret);
  		return ret;
  	}
  
  	i2c_set_clientdata(client, mcp);

  	config.regmap = rmap;

  	config.driver_data = mcp;
  
  	mcp->lpm = devm_gpiod_get(dev, "lpm", GPIOD_OUT_LOW);
  	if (IS_ERR(mcp->lpm)) {
  		dev_err(dev, "failed to get lpm pin: %ld
  ", PTR_ERR(mcp->lpm));
  		return PTR_ERR(mcp->lpm);
  	}

  	for (i = 0; i < NUM_REGULATORS; i++) {
  		rdev = devm_regulator_register(dev, &mcp16502_desc[i], &config);
  		if (IS_ERR(rdev)) {
  			dev_err(dev,
  				"failed to register %s regulator %ld
  ",
  				mcp16502_desc[i].name, PTR_ERR(rdev));
  			return PTR_ERR(rdev);
  		}
  	}

  
  	mcp16502_gpio_set_mode(mcp, MCP16502_OPMODE_ACTIVE);
  
  	return 0;
  }

  #ifdef CONFIG_PM_SLEEP

  static int mcp16502_suspend_noirq(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct mcp16502 *mcp = i2c_get_clientdata(client);
  
  	mcp16502_gpio_set_mode(mcp, MCP16502_OPMODE_LPM);
  
  	return 0;
  }
  
  static int mcp16502_resume_noirq(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct mcp16502 *mcp = i2c_get_clientdata(client);
  
  	mcp16502_gpio_set_mode(mcp, MCP16502_OPMODE_ACTIVE);
  
  	return 0;
  }

  #endif

  
  #ifdef CONFIG_PM
  static const struct dev_pm_ops mcp16502_pm_ops = {
  	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(mcp16502_suspend_noirq,

  				      mcp16502_resume_noirq)

  };
  #endif

  static const struct i2c_device_id mcp16502_i2c_id[] = {
  	{ "mcp16502", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, mcp16502_i2c_id);
  
  static struct i2c_driver mcp16502_drv = {
  	.probe		= mcp16502_probe,
  	.driver		= {
  		.name	= "mcp16502-regulator",
  		.of_match_table	= of_match_ptr(mcp16502_ids),

  #ifdef CONFIG_PM
  		.pm = &mcp16502_pm_ops,
  #endif

  	},
  	.id_table	= mcp16502_i2c_id,
  };
  
  module_i2c_driver(mcp16502_drv);

  MODULE_LICENSE("GPL v2");
  MODULE_DESCRIPTION("MCP16502 PMIC driver");
  MODULE_AUTHOR("Andrei Stefanescu andrei.stefanescu@microchip.com");