/* Copyright (c) 2012, The Linux Foundation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 and
 * only version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/regulator/driver.h>
#include <linux/regmap.h>
#include <linux/regulator/onsemi-ncp6335d.h>

/* registers */
#define REG_NCP6335D_PID		0x03
#define REG_NCP6335D_PROGVSEL1		0x10
#define REG_NCP6335D_PROGVSEL0		0x11
#define REG_NCP6335D_PGOOD		0x12
#define REG_NCP6335D_TIMING		0x13
#define REG_NCP6335D_COMMAND		0x14

/* constraints */
#define NCP6335D_MIN_VOLTAGE_UV		600000
#define NCP6335D_STEP_VOLTAGE_UV	6250
#define NCP6335D_MIN_SLEW_NS		166
#define NCP6335D_MAX_SLEW_NS		1333

/* bits */
#define NCP6335D_ENABLE			BIT(7)
#define NCP6335D_DVS_PWM_MODE		BIT(5)
#define NCP6335D_PWM_MODE1		BIT(6)
#define NCP6335D_PWM_MODE0		BIT(7)
#define NCP6335D_PGOOD_DISCHG		BIT(4)
#define NCP6335D_SLEEP_MODE		BIT(4)

#define NCP6335D_VOUT_SEL_MASK		0x7F
#define NCP6335D_SLEW_MASK		0x18
#define NCP6335D_SLEW_SHIFT		0x3

struct ncp6335d_info {
	struct regulator_dev *regulator;
	struct regulator_init_data *init_data;
	struct regmap *regmap;
	struct device *dev;
	unsigned int vsel_reg;
	unsigned int mode_bit;
	int curr_voltage;
	int slew_rate;
};

static void dump_registers(struct ncp6335d_info *dd,
			unsigned int reg, const char *func)
{
	unsigned int val = 0;

	regmap_read(dd->regmap, reg, &val);
	dev_dbg(dd->dev, "%s: NCP6335D: Reg = %x, Val = %x\n", func, reg, val);
}

static void ncp633d_slew_delay(struct ncp6335d_info *dd,
					int prev_uV, int new_uV)
{
	u8 val;
	int delay;

	val = abs(prev_uV - new_uV) / NCP6335D_STEP_VOLTAGE_UV;
	delay =  (val * dd->slew_rate / 1000) + 1;

	dev_dbg(dd->dev, "Slew Delay = %d\n", delay);

	udelay(delay);
}

static int ncp6335d_enable(struct regulator_dev *rdev)
{
	int rc;
	struct ncp6335d_info *dd = rdev_get_drvdata(rdev);

	rc = regmap_update_bits(dd->regmap, dd->vsel_reg,
				NCP6335D_ENABLE, NCP6335D_ENABLE);
	if (rc)
		dev_err(dd->dev, "Unable to enable regualtor rc(%d)", rc);

	dump_registers(dd, dd->vsel_reg, __func__);

	return rc;
}

static int ncp6335d_disable(struct regulator_dev *rdev)
{
	int rc;
	struct ncp6335d_info *dd = rdev_get_drvdata(rdev);

	rc = regmap_update_bits(dd->regmap, dd->vsel_reg,
					NCP6335D_ENABLE, 0);
	if (rc)
		dev_err(dd->dev, "Unable to disable regualtor rc(%d)", rc);

	dump_registers(dd, dd->vsel_reg, __func__);

	return rc;
}

static int ncp6335d_get_voltage(struct regulator_dev *rdev)
{
	unsigned int val;
	int rc;
	struct ncp6335d_info *dd = rdev_get_drvdata(rdev);

	rc = regmap_read(dd->regmap, dd->vsel_reg, &val);
	if (rc) {
		dev_err(dd->dev, "Unable to get volatge rc(%d)", rc);
		return rc;
	}
	dd->curr_voltage = ((val & NCP6335D_VOUT_SEL_MASK) *
			NCP6335D_STEP_VOLTAGE_UV) + NCP6335D_MIN_VOLTAGE_UV;

	dump_registers(dd, dd->vsel_reg, __func__);

	return dd->curr_voltage;
}

static int ncp6335d_set_voltage(struct regulator_dev *rdev,
			int min_uV, int max_uV, unsigned *selector)
{
	int rc, set_val, new_uV;
	struct ncp6335d_info *dd = rdev_get_drvdata(rdev);

	set_val = DIV_ROUND_UP(min_uV - NCP6335D_MIN_VOLTAGE_UV,
					NCP6335D_STEP_VOLTAGE_UV);
	new_uV = (set_val * NCP6335D_STEP_VOLTAGE_UV) +
					NCP6335D_MIN_VOLTAGE_UV;
	if (new_uV > max_uV) {
		dev_err(dd->dev, "Unable to set volatge (%d %d)\n",
							min_uV, max_uV);
		return -EINVAL;
	}

	rc = regmap_update_bits(dd->regmap, dd->vsel_reg,
		NCP6335D_VOUT_SEL_MASK, (set_val & NCP6335D_VOUT_SEL_MASK));
	if (rc) {
		dev_err(dd->dev, "Unable to set volatge (%d %d)\n",
							min_uV, max_uV);
	} else {
		ncp633d_slew_delay(dd, dd->curr_voltage, new_uV);
		dd->curr_voltage = new_uV;
	}

	dump_registers(dd, dd->vsel_reg, __func__);

	return rc;
}

static int ncp6335d_set_mode(struct regulator_dev *rdev,
					unsigned int mode)
{
	int rc;
	struct ncp6335d_info *dd = rdev_get_drvdata(rdev);

	/* only FAST and NORMAL mode types are supported */
	if (mode != REGULATOR_MODE_FAST && mode != REGULATOR_MODE_NORMAL) {
		dev_err(dd->dev, "Mode %d not supported\n", mode);
		return -EINVAL;
	}

	rc = regmap_update_bits(dd->regmap, REG_NCP6335D_COMMAND, dd->mode_bit,
			(mode == REGULATOR_MODE_FAST) ? dd->mode_bit : 0);
	if (rc) {
		dev_err(dd->dev, "Unable to set operating mode rc(%d)", rc);
		return rc;
	}

	rc = regmap_update_bits(dd->regmap, REG_NCP6335D_COMMAND,
					NCP6335D_DVS_PWM_MODE,
					(mode == REGULATOR_MODE_FAST) ?
					NCP6335D_DVS_PWM_MODE : 0);
	if (rc)
		dev_err(dd->dev, "Unable to set DVS trans. mode rc(%d)", rc);

	dump_registers(dd, REG_NCP6335D_COMMAND, __func__);

	return rc;
}

static unsigned int ncp6335d_get_mode(struct regulator_dev *rdev)
{
	unsigned int val;
	int rc;
	struct ncp6335d_info *dd = rdev_get_drvdata(rdev);

	rc = regmap_read(dd->regmap, REG_NCP6335D_COMMAND, &val);
	if (rc) {
		dev_err(dd->dev, "Unable to get regulator mode rc(%d)\n", rc);
		return rc;
	}

	dump_registers(dd, REG_NCP6335D_COMMAND, __func__);

	if (val & dd->mode_bit)
		return REGULATOR_MODE_FAST;

	return REGULATOR_MODE_NORMAL;
}

static struct regulator_ops ncp6335d_ops = {
	.set_voltage = ncp6335d_set_voltage,
	.get_voltage = ncp6335d_get_voltage,
	.enable = ncp6335d_enable,
	.disable = ncp6335d_disable,
	.set_mode = ncp6335d_set_mode,
	.get_mode = ncp6335d_get_mode,
};

static struct regulator_desc rdesc = {
	.name = "ncp6335d",
	.owner = THIS_MODULE,
	.n_voltages = 128,
	.ops = &ncp6335d_ops,
};

static int ncp6335d_init(struct ncp6335d_info *dd,
			const struct ncp6335d_platform_data *pdata)
{
	int rc;
	unsigned int val;

	switch (pdata->default_vsel) {
	case NCP6335D_VSEL0:
		dd->vsel_reg = REG_NCP6335D_PROGVSEL0;
		dd->mode_bit = NCP6335D_PWM_MODE0;
	break;
	case NCP6335D_VSEL1:
		dd->vsel_reg = REG_NCP6335D_PROGVSEL1;
		dd->mode_bit = NCP6335D_PWM_MODE1;
	break;
	default:
		dev_err(dd->dev, "Invalid VSEL ID %d\n", pdata->default_vsel);
		return -EINVAL;
	}

	/* get the current programmed voltage */
	rc = regmap_read(dd->regmap, dd->vsel_reg, &val);
	if (rc) {
		dev_err(dd->dev, "Unable to get volatge rc(%d)", rc);
		return rc;
	}
	dd->curr_voltage = ((val & NCP6335D_VOUT_SEL_MASK) *
			NCP6335D_STEP_VOLTAGE_UV) + NCP6335D_MIN_VOLTAGE_UV;

	/* set discharge */
	rc = regmap_update_bits(dd->regmap, REG_NCP6335D_PGOOD,
					NCP6335D_PGOOD_DISCHG,
					(pdata->discharge_enable ?
					NCP6335D_PGOOD_DISCHG : 0));
	if (rc) {
		dev_err(dd->dev, "Unable to set Active Discharge rc(%d)\n", rc);
		return -EINVAL;
	}

	/* set slew rate */
	if (pdata->slew_rate_ns < NCP6335D_MIN_SLEW_NS ||
			pdata->slew_rate_ns > NCP6335D_MAX_SLEW_NS) {
		dev_err(dd->dev, "Invalid slew rate %d\n", pdata->slew_rate_ns);
		return -EINVAL;
	}
	val = DIV_ROUND_UP(pdata->slew_rate_ns - NCP6335D_MIN_SLEW_NS,
						NCP6335D_MIN_SLEW_NS);
	val >>= 1;
	dd->slew_rate = val * NCP6335D_MIN_SLEW_NS;

	rc = regmap_update_bits(dd->regmap, REG_NCP6335D_TIMING,
			NCP6335D_SLEW_MASK, val << NCP6335D_SLEW_SHIFT);
	if (rc)
		dev_err(dd->dev, "Unable to set slew rate rc(%d)\n", rc);

	/* Set Sleep mode bit */
	rc = regmap_update_bits(dd->regmap, REG_NCP6335D_COMMAND,
				NCP6335D_SLEEP_MODE, pdata->sleep_enable ?
						NCP6335D_SLEEP_MODE : 0);
	if (rc)
		dev_err(dd->dev, "Unable to set sleep mode (%d)\n", rc);

	dump_registers(dd, REG_NCP6335D_COMMAND, __func__);
	dump_registers(dd, REG_NCP6335D_PROGVSEL0, __func__);
	dump_registers(dd, REG_NCP6335D_TIMING, __func__);
	dump_registers(dd, REG_NCP6335D_PGOOD, __func__);

	return rc;
}

static struct regmap_config ncp6335d_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
};

static int ncp6335d_regulator_probe(struct i2c_client *client,
					const struct i2c_device_id *id)
{
	int rc;
	unsigned int val = 0;
	struct ncp6335d_info *dd;
	const struct ncp6335d_platform_data *pdata;

	pdata = client->dev.platform_data;
	if (!pdata) {
		dev_err(&client->dev, "Platform data not specified\n");
		return -EINVAL;
	}

	dd = devm_kzalloc(&client->dev, sizeof(*dd), GFP_KERNEL);
	if (!dd) {
		dev_err(&client->dev, "Unable to allocate memory\n");
		return -ENOMEM;
	}

	dd->regmap = devm_regmap_init_i2c(client, &ncp6335d_regmap_config);
	if (IS_ERR(dd->regmap)) {
		dev_err(&client->dev, "Error allocating regmap\n");
		return PTR_ERR(dd->regmap);
	}

	rc = regmap_read(dd->regmap, REG_NCP6335D_PID, &val);
	if (rc) {
		dev_err(&client->dev, "Unable to identify NCP6335D, rc(%d)\n",
									rc);
		return rc;
	}
	dev_info(&client->dev, "Detected Regulator NCP6335D PID = %d\n", val);

	dd->init_data = pdata->init_data;
	dd->dev = &client->dev;
	i2c_set_clientdata(client, dd);

	rc = ncp6335d_init(dd, pdata);
	if (rc) {
		dev_err(&client->dev, "Unable to intialize the regulator\n");
		return -EINVAL;
	}

	dd->regulator = regulator_register(&rdesc, &client->dev,
					dd->init_data, dd, NULL);
	if (IS_ERR(dd->regulator)) {
		dev_err(&client->dev, "Unable to register regulator rc(%ld)",
						PTR_ERR(dd->regulator));
		return PTR_ERR(dd->regulator);
	}

	return 0;
}

static int ncp6335d_regulator_remove(struct i2c_client *client)
{
	struct ncp6335d_info *dd = i2c_get_clientdata(client);

	regulator_unregister(dd->regulator);

	return 0;
}

static const struct i2c_device_id ncp6335d_id[] = {
	{"ncp6335d", -1},
	{ },
};

static struct i2c_driver ncp6335d_regulator_driver = {
	.driver = {
		.name = "ncp6335d-regulator",
	},
	.probe = ncp6335d_regulator_probe,
	.remove = ncp6335d_regulator_remove,
	.id_table = ncp6335d_id,
};
static int __init ncp6335d_regulator_init(void)
{
	return i2c_add_driver(&ncp6335d_regulator_driver);
}
subsys_initcall(ncp6335d_regulator_init);

static void __exit ncp6335d_regulator_exit(void)
{
	i2c_del_driver(&ncp6335d_regulator_driver);
}
module_exit(ncp6335d_regulator_exit);
MODULE_DESCRIPTION("OnSemi-NCP6335D regulator driver");
MODULE_LICENSE("GPL v2");