/*
 * drivers/regulator/ab3100.c
 *
 * Copyright (C) 2008-2009 ST-Ericsson AB
 * License terms: GNU General Public License (GPL) version 2
 * Low-level control of the AB3100 IC Low Dropout (LDO)
 * regulators, external regulator and buck converter
 * Author: Mattias Wallin <mattias.wallin@stericsson.com>
 * Author: Linus Walleij <linus.walleij@stericsson.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/mfd/ab3100.h>

/* LDO registers and some handy masking definitions for AB3100 */
#define AB3100_LDO_A		0x40
#define AB3100_LDO_C		0x41
#define AB3100_LDO_D		0x42
#define AB3100_LDO_E		0x43
#define AB3100_LDO_E_SLEEP	0x44
#define AB3100_LDO_F		0x45
#define AB3100_LDO_G		0x46
#define AB3100_LDO_H		0x47
#define AB3100_LDO_H_SLEEP_MODE	0
#define AB3100_LDO_H_SLEEP_EN	2
#define AB3100_LDO_ON		4
#define AB3100_LDO_H_VSEL_AC	5
#define AB3100_LDO_K		0x48
#define AB3100_LDO_EXT		0x49
#define AB3100_BUCK		0x4A
#define AB3100_BUCK_SLEEP	0x4B
#define AB3100_REG_ON_MASK	0x10

/**
 * struct ab3100_regulator
 * A struct passed around the individual regulator functions
 * @platform_device: platform device holding this regulator
 * @ab3100: handle to the AB3100 parent chip
 * @plfdata: AB3100 platform data passed in at probe time
 * @regreg: regulator register number in the AB3100
 * @fixed_voltage: a fixed voltage for this regulator, if this
 *          0 the voltages array is used instead.
 * @typ_voltages: an array of available typical voltages for
 *          this regulator
 * @voltages_len: length of the array of available voltages
 */
struct ab3100_regulator {
	struct regulator_dev *rdev;
	struct ab3100 *ab3100;
	struct ab3100_platform_data *plfdata;
	u8 regreg;
	int fixed_voltage;
	int const *typ_voltages;
	u8 voltages_len;
};

/* The order in which registers are initialized */
static const u8 ab3100_reg_init_order[AB3100_NUM_REGULATORS+2] = {
	AB3100_LDO_A,
	AB3100_LDO_C,
	AB3100_LDO_E,
	AB3100_LDO_E_SLEEP,
	AB3100_LDO_F,
	AB3100_LDO_G,
	AB3100_LDO_H,
	AB3100_LDO_K,
	AB3100_LDO_EXT,
	AB3100_BUCK,
	AB3100_BUCK_SLEEP,
	AB3100_LDO_D,
};

/* Preset (hardware defined) voltages for these regulators */
#define LDO_A_VOLTAGE 2750000
#define LDO_C_VOLTAGE 2650000
#define LDO_D_VOLTAGE 2650000

static const int const ldo_e_buck_typ_voltages[] = {
	1800000,
	1400000,
	1300000,
	1200000,
	1100000,
	1050000,
	900000,
};

static const int const ldo_f_typ_voltages[] = {
	1800000,
	1400000,
	1300000,
	1200000,
	1100000,
	1050000,
	2500000,
	2650000,
};

static const int const ldo_g_typ_voltages[] = {
	2850000,
	2750000,
	1800000,
	1500000,
};

static const int const ldo_h_typ_voltages[] = {
	2750000,
	1800000,
	1500000,
	1200000,
};

static const int const ldo_k_typ_voltages[] = {
	2750000,
	1800000,
};


/* The regulator devices */
static struct ab3100_regulator
ab3100_regulators[AB3100_NUM_REGULATORS] = {
	{
		.regreg = AB3100_LDO_A,
		.fixed_voltage = LDO_A_VOLTAGE,
	},
	{
		.regreg = AB3100_LDO_C,
		.fixed_voltage = LDO_C_VOLTAGE,
	},
	{
		.regreg = AB3100_LDO_D,
		.fixed_voltage = LDO_D_VOLTAGE,
	},
	{
		.regreg = AB3100_LDO_E,
		.typ_voltages = ldo_e_buck_typ_voltages,
		.voltages_len = ARRAY_SIZE(ldo_e_buck_typ_voltages),
	},
	{
		.regreg = AB3100_LDO_F,
		.typ_voltages = ldo_f_typ_voltages,
		.voltages_len = ARRAY_SIZE(ldo_f_typ_voltages),
	},
	{
		.regreg = AB3100_LDO_G,
		.typ_voltages = ldo_g_typ_voltages,
		.voltages_len = ARRAY_SIZE(ldo_g_typ_voltages),
	},
	{
		.regreg = AB3100_LDO_H,
		.typ_voltages = ldo_h_typ_voltages,
		.voltages_len = ARRAY_SIZE(ldo_h_typ_voltages),
	},
	{
		.regreg = AB3100_LDO_K,
		.typ_voltages = ldo_k_typ_voltages,
		.voltages_len = ARRAY_SIZE(ldo_k_typ_voltages),
	},
	{
		.regreg = AB3100_LDO_EXT,
		/* No voltages for the external regulator */
	},
	{
		.regreg = AB3100_BUCK,
		.typ_voltages = ldo_e_buck_typ_voltages,
		.voltages_len = ARRAY_SIZE(ldo_e_buck_typ_voltages),
	},
};

/*
 * General functions for enable, disable and is_enabled used for
 * LDO: A,C,E,F,G,H,K,EXT and BUCK
 */
static int ab3100_enable_regulator(struct regulator_dev *reg)
{
	struct ab3100_regulator *abreg = reg->reg_data;
	int err;
	u8 regval;

	err = ab3100_get_register_interruptible(abreg->ab3100, abreg->regreg,
						&regval);
	if (err) {
		dev_warn(&reg->dev, "failed to get regid %d value\n",
			 abreg->regreg);
		return err;
	}

	/* The regulator is already on, no reason to go further */
	if (regval & AB3100_REG_ON_MASK)
		return 0;

	regval |= AB3100_REG_ON_MASK;

	err = ab3100_set_register_interruptible(abreg->ab3100, abreg->regreg,
						regval);
	if (err) {
		dev_warn(&reg->dev, "failed to set regid %d value\n",
			 abreg->regreg);
		return err;
	}

	/* Per-regulator power on delay from spec */
	switch (abreg->regreg) {
	case AB3100_LDO_A: /* Fallthrough */
	case AB3100_LDO_C: /* Fallthrough */
	case AB3100_LDO_D: /* Fallthrough */
	case AB3100_LDO_E: /* Fallthrough */
	case AB3100_LDO_H: /* Fallthrough */
	case AB3100_LDO_K:
		udelay(200);
		break;
	case AB3100_LDO_F:
		udelay(600);
		break;
	case AB3100_LDO_G:
		udelay(400);
		break;
	case AB3100_BUCK:
		mdelay(1);
		break;
	default:
		break;
	}

	return 0;
}

static int ab3100_disable_regulator(struct regulator_dev *reg)
{
	struct ab3100_regulator *abreg = reg->reg_data;
	int err;
	u8 regval;

	/*
	 * LDO D is a special regulator. When it is disabled, the entire
	 * system is shut down. So this is handled specially.
	 */
	if (abreg->regreg == AB3100_LDO_D) {
		int i;

		dev_info(&reg->dev, "disabling LDO D - shut down system\n");
		/*
		 * Set regulators to default values, ignore any errors,
		 * we're going DOWN
		 */
		for (i = 0; i < ARRAY_SIZE(ab3100_reg_init_order); i++) {
			(void) ab3100_set_register_interruptible(abreg->ab3100,
					ab3100_reg_init_order[i],
					abreg->plfdata->reg_initvals[i]);
		}

		/* Setting LDO D to 0x00 cuts the power to the SoC */
		return ab3100_set_register_interruptible(abreg->ab3100,
							 AB3100_LDO_D, 0x00U);

	}

	/*
	 * All other regulators are handled here
	 */
	err = ab3100_get_register_interruptible(abreg->ab3100, abreg->regreg,
						&regval);
	if (err) {
		dev_err(&reg->dev, "unable to get register 0x%x\n",
			abreg->regreg);
		return err;
	}
	regval &= ~AB3100_REG_ON_MASK;
	return ab3100_set_register_interruptible(abreg->ab3100, abreg->regreg,
						 regval);
}

static int ab3100_is_enabled_regulator(struct regulator_dev *reg)
{
	struct ab3100_regulator *abreg = reg->reg_data;
	u8 regval;
	int err;

	err = ab3100_get_register_interruptible(abreg->ab3100, abreg->regreg,
						&regval);
	if (err) {
		dev_err(&reg->dev, "unable to get register 0x%x\n",
			abreg->regreg);
		return err;
	}

	return regval & AB3100_REG_ON_MASK;
}

static int ab3100_list_voltage_regulator(struct regulator_dev *reg,
					 unsigned selector)
{
	struct ab3100_regulator *abreg = reg->reg_data;

	if (selector > abreg->voltages_len)
		return -EINVAL;
	return abreg->typ_voltages[selector];
}

static int ab3100_get_voltage_regulator(struct regulator_dev *reg)
{
	struct ab3100_regulator *abreg = reg->reg_data;
	u8 regval;
	int err;

	/* Return the voltage for fixed regulators immediately */
	if (abreg->fixed_voltage)
		return abreg->fixed_voltage;

	/*
	 * For variable types, read out setting and index into
	 * supplied voltage list.
	 */
	err = ab3100_get_register_interruptible(abreg->ab3100,
						abreg->regreg, &regval);
	if (err) {
		dev_warn(&reg->dev,
			 "failed to get regulator value in register %02x\n",
			 abreg->regreg);
		return err;
	}

	/* The 3 highest bits index voltages */
	regval &= 0xE0;
	regval >>= 5;

	if (regval > abreg->voltages_len) {
		dev_err(&reg->dev,
			"regulator register %02x contains an illegal voltage setting\n",
			abreg->regreg);
		return -EINVAL;
	}

	return abreg->typ_voltages[regval];
}

static int ab3100_get_best_voltage_index(struct regulator_dev *reg,
				   int min_uV, int max_uV)
{
	struct ab3100_regulator *abreg = reg->reg_data;
	int i;
	int bestmatch;
	int bestindex;

	/*
	 * Locate the minimum voltage fitting the criteria on
	 * this regulator. The switchable voltages are not
	 * in strict falling order so we need to check them
	 * all for the best match.
	 */
	bestmatch = INT_MAX;
	bestindex = -1;
	for (i = 0; i < abreg->voltages_len; i++) {
		if (abreg->typ_voltages[i] <= max_uV &&
		    abreg->typ_voltages[i] >= min_uV &&
		    abreg->typ_voltages[i] < bestmatch) {
			bestmatch = abreg->typ_voltages[i];
			bestindex = i;
		}
	}

	if (bestindex < 0) {
		dev_warn(&reg->dev, "requested %d<=x<=%d uV, out of range!\n",
			 min_uV, max_uV);
		return -EINVAL;
	}
	return bestindex;
}

static int ab3100_set_voltage_regulator(struct regulator_dev *reg,
					int min_uV, int max_uV)
{
	struct ab3100_regulator *abreg = reg->reg_data;
	u8 regval;
	int err;
	int bestindex;

	bestindex = ab3100_get_best_voltage_index(reg, min_uV, max_uV);
	if (bestindex < 0)
		return bestindex;

	err = ab3100_get_register_interruptible(abreg->ab3100,
						abreg->regreg, &regval);
	if (err) {
		dev_warn(&reg->dev,
			 "failed to get regulator register %02x\n",
			 abreg->regreg);
		return err;
	}

	/* The highest three bits control the variable regulators */
	regval &= ~0xE0;
	regval |= (bestindex << 5);

	err = ab3100_set_register_interruptible(abreg->ab3100,
						abreg->regreg, regval);
	if (err)
		dev_warn(&reg->dev, "failed to set regulator register %02x\n",
			abreg->regreg);

	return err;
}

static int ab3100_set_suspend_voltage_regulator(struct regulator_dev *reg,
						int uV)
{
	struct ab3100_regulator *abreg = reg->reg_data;
	u8 regval;
	int err;
	int bestindex;
	u8 targetreg;

	if (abreg->regreg == AB3100_LDO_E)
		targetreg = AB3100_LDO_E_SLEEP;
	else if (abreg->regreg == AB3100_BUCK)
		targetreg = AB3100_BUCK_SLEEP;
	else
		return -EINVAL;

	/* LDO E and BUCK have special suspend voltages you can set */
	bestindex = ab3100_get_best_voltage_index(reg, uV, uV);

	err = ab3100_get_register_interruptible(abreg->ab3100,
						targetreg, &regval);
	if (err) {
		dev_warn(&reg->dev,
			 "failed to get regulator register %02x\n",
			 targetreg);
		return err;
	}

	/* The highest three bits control the variable regulators */
	regval &= ~0xE0;
	regval |= (bestindex << 5);

	err = ab3100_set_register_interruptible(abreg->ab3100,
						targetreg, regval);
	if (err)
		dev_warn(&reg->dev, "failed to set regulator register %02x\n",
			abreg->regreg);

	return err;
}

/*
 * The external regulator can just define a fixed voltage.
 */
static int ab3100_get_voltage_regulator_external(struct regulator_dev *reg)
{
	struct ab3100_regulator *abreg = reg->reg_data;

	return abreg->plfdata->external_voltage;
}

static struct regulator_ops regulator_ops_fixed = {
	.enable      = ab3100_enable_regulator,
	.disable     = ab3100_disable_regulator,
	.is_enabled  = ab3100_is_enabled_regulator,
	.get_voltage = ab3100_get_voltage_regulator,
};

static struct regulator_ops regulator_ops_variable = {
	.enable      = ab3100_enable_regulator,
	.disable     = ab3100_disable_regulator,
	.is_enabled  = ab3100_is_enabled_regulator,
	.get_voltage = ab3100_get_voltage_regulator,
	.set_voltage = ab3100_set_voltage_regulator,
	.list_voltage = ab3100_list_voltage_regulator,
};

static struct regulator_ops regulator_ops_variable_sleepable = {
	.enable      = ab3100_enable_regulator,
	.disable     = ab3100_disable_regulator,
	.is_enabled  = ab3100_is_enabled_regulator,
	.get_voltage = ab3100_get_voltage_regulator,
	.set_voltage = ab3100_set_voltage_regulator,
	.set_suspend_voltage = ab3100_set_suspend_voltage_regulator,
	.list_voltage = ab3100_list_voltage_regulator,
};

/*
 * LDO EXT is an external regulator so it is really
 * not possible to set any voltage locally here, AB3100
 * is an on/off switch plain an simple. The external
 * voltage is defined in the board set-up if any.
 */
static struct regulator_ops regulator_ops_external = {
	.enable      = ab3100_enable_regulator,
	.disable     = ab3100_disable_regulator,
	.is_enabled  = ab3100_is_enabled_regulator,
	.get_voltage = ab3100_get_voltage_regulator_external,
};

static struct regulator_desc
ab3100_regulator_desc[AB3100_NUM_REGULATORS] = {
	{
		.name = "LDO_A",
		.id   = AB3100_LDO_A,
		.ops  = &regulator_ops_fixed,
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "LDO_C",
		.id   = AB3100_LDO_C,
		.ops  = &regulator_ops_fixed,
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "LDO_D",
		.id   = AB3100_LDO_D,
		.ops  = &regulator_ops_fixed,
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "LDO_E",
		.id   = AB3100_LDO_E,
		.ops  = &regulator_ops_variable_sleepable,
		.n_voltages = ARRAY_SIZE(ldo_e_buck_typ_voltages),
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "LDO_F",
		.id   = AB3100_LDO_F,
		.ops  = &regulator_ops_variable,
		.n_voltages = ARRAY_SIZE(ldo_f_typ_voltages),
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "LDO_G",
		.id   = AB3100_LDO_G,
		.ops  = &regulator_ops_variable,
		.n_voltages = ARRAY_SIZE(ldo_g_typ_voltages),
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "LDO_H",
		.id   = AB3100_LDO_H,
		.ops  = &regulator_ops_variable,
		.n_voltages = ARRAY_SIZE(ldo_h_typ_voltages),
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "LDO_K",
		.id   = AB3100_LDO_K,
		.ops  = &regulator_ops_variable,
		.n_voltages = ARRAY_SIZE(ldo_k_typ_voltages),
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "LDO_EXT",
		.id   = AB3100_LDO_EXT,
		.ops  = &regulator_ops_external,
		.type = REGULATOR_VOLTAGE,
	},
	{
		.name = "BUCK",
		.id   = AB3100_BUCK,
		.ops  = &regulator_ops_variable_sleepable,
		.n_voltages = ARRAY_SIZE(ldo_e_buck_typ_voltages),
		.type = REGULATOR_VOLTAGE,
	},
};

/*
 * NOTE: the following functions are regulators pluralis - it is the
 * binding to the AB3100 core driver and the parent platform device
 * for all the different regulators.
 */

static int __init ab3100_regulators_probe(struct platform_device *pdev)
{
	struct ab3100_platform_data *plfdata = pdev->dev.platform_data;
	struct ab3100 *ab3100 = platform_get_drvdata(pdev);
	int err = 0;
	u8 data;
	int i;

	/* Check chip state */
	err = ab3100_get_register_interruptible(ab3100,
						AB3100_LDO_D, &data);
	if (err) {
		dev_err(&pdev->dev, "could not read initial status of LDO_D\n");
		return err;
	}
	if (data & 0x10)
		dev_notice(&pdev->dev,
			   "chip is already in active mode (Warm start)\n");
	else
		dev_notice(&pdev->dev,
			   "chip is in inactive mode (Cold start)\n");

	/* Set up regulators */
	for (i = 0; i < ARRAY_SIZE(ab3100_reg_init_order); i++) {
		err = ab3100_set_register_interruptible(ab3100,
					ab3100_reg_init_order[i],
					plfdata->reg_initvals[i]);
		if (err) {
			dev_err(&pdev->dev, "regulator initialization failed with error %d\n",
				err);
			return err;
		}
	}

	if (err) {
		dev_err(&pdev->dev,
			"LDO D regulator initialization failed with error %d\n",
			err);
		return err;
	}

	/* Register the regulators */
	for (i = 0; i < AB3100_NUM_REGULATORS; i++) {
		struct ab3100_regulator *reg = &ab3100_regulators[i];
		struct regulator_dev *rdev;

		/*
		 * Initialize per-regulator struct.
		 * Inherit platform data, this comes down from the
		 * i2c boarddata, from the machine. So if you want to
		 * see what it looks like for a certain machine, go
		 * into the machine I2C setup.
		 */
		reg->ab3100 = ab3100;
		reg->plfdata = plfdata;

		/*
		 * Register the regulator, pass around
		 * the ab3100_regulator struct
		 */
		rdev = regulator_register(&ab3100_regulator_desc[i],
					  &pdev->dev,
					  &plfdata->reg_constraints[i],
					  reg);

		if (IS_ERR(rdev)) {
			err = PTR_ERR(rdev);
			dev_err(&pdev->dev,
				"%s: failed to register regulator %s err %d\n",
				__func__, ab3100_regulator_desc[i].name,
				err);
			i--;
			/* remove the already registered regulators */
			while (i > 0) {
				regulator_unregister(ab3100_regulators[i].rdev);
				i--;
			}
			return err;
		}

		/* Then set a pointer back to the registered regulator */
		reg->rdev = rdev;
	}

	return 0;
}

static int __exit ab3100_regulators_remove(struct platform_device *pdev)
{
	int i;

	for (i = 0; i < AB3100_NUM_REGULATORS; i++) {
		struct ab3100_regulator *reg = &ab3100_regulators[i];

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

static struct platform_driver ab3100_regulators_driver = {
	.driver = {
		.name  = "ab3100-regulators",
		.owner = THIS_MODULE,
	},
	.probe = ab3100_regulators_probe,
	.remove = __exit_p(ab3100_regulators_remove),
};

static __init int ab3100_regulators_init(void)
{
	return platform_driver_register(&ab3100_regulators_driver);
}

static __exit void ab3100_regulators_exit(void)
{
	platform_driver_register(&ab3100_regulators_driver);
}

subsys_initcall(ab3100_regulators_init);
module_exit(ab3100_regulators_exit);

MODULE_AUTHOR("Mattias Wallin <mattias.wallin@stericsson.com>");
MODULE_DESCRIPTION("AB3100 Regulator driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ab3100-regulators");