/*
 * tps6130x-regulator.c
 *
 * Regulator driver for TPS6130x
 *
 * Copyright (C) 2011 Texas Instrument Incorporated - http://www.ti.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.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/tps6130x.h>

/* Regulator id */
#define TPS6130X_VOUT			0

/* Register definitions */
#define TPS6130X_REGISTER1		0x01
#define TPS6130X_REGISTER2		0x02
#define TPS6130X_REGISTER3		0x03
#define TPS6130X_REGISTER4		0x04
#define TPS6130X_REGISTER5		0x05
#define TPS6130X_REGISTER6		0x06
#define TPS6130X_REGISTER7		0x07

/* REGISTER1 bitfields */
#define TPS6130X_ENVM			0x80
#define TPS6130X_MODE_CTRL_MASK		0x60
#define TPS6130X_SHUTDOWN_MODE		(0 << 5)
#define TPS6130X_DC_LIGHT_MODE		(1 << 5)
#define TPS6130X_DC_LIGHT_FLASH_MODE	(2 << 5)
#define TPS6130X_VOUT_MODE		(3 << 5)

/* REGISTER6 bitfields */
#define TPS6130X_OV_MASK		0x0F

/* REGISTER7 bitfields */
#define TPS6130X_REVID_MASK		0x07

/* Supported voltage values for voltage regulation mode */
#define TPS6130X_VOUT_MIN_UV		3825000
#define TPS6130X_VOUT_MAX_UV		5700000
#define TPS6130X_VOUT_STEP		125000
#define TPS6130X_VOUT_MAX_SEL		0x0F

/* Regulator specific details */
struct tps_info {
	const char *name;
	int min_uV;
	int max_uV;
	int step;
	int vsel_max;
	int vsel;
};

/* PMIC details */
struct tps_pmic {
	struct regulator_desc *desc;
	struct i2c_client *client;
	struct regulator_dev *rdev;
	struct tps6130x_platform_data *pdata;
	struct tps_info *info;
	struct mutex io_lock;
	int enabled;
};

static int tps6130x_reg_read(struct tps_pmic *tps, u8 reg)
{
	int data;

	data = i2c_smbus_read_byte_data(tps->client, reg);
	if (data < 0)
		dev_err(&tps->client->dev, "Read from reg 0x%x failed\n", reg);

	return data;
}

static int tps6130x_reg_write(struct tps_pmic *tps, u8 reg, u8 val)
{
	int ret;

	ret = i2c_smbus_write_byte_data(tps->client, reg, val);
	if (ret < 0)
		dev_err(&tps->client->dev, "Write to reg 0x%x failed\n", reg);

	return ret;
}

static int tps6130x_update_bits(struct tps_pmic *tps, u8 reg,
				u8 mask, u8 value)
{
	int old_val, new_val, ret = 0;

	mutex_lock(&tps->io_lock);

	old_val = tps6130x_reg_read(tps, reg);
	if (old_val < 0) {
		ret = old_val;
		goto err;
	}

	new_val = (old_val & ~mask) | value;
	if (old_val != new_val)
		ret = tps6130x_reg_write(tps, reg, new_val);

err:
	mutex_unlock(&tps->io_lock);
	return ret;
}

static int tps6130x_chip_enable(struct tps_pmic *tps, int on)
{
	struct i2c_client *client = tps->client;
	int ret = 0;

	/* tps61301/tps61305 supports external NRESET */
	if (tps->pdata && tps->pdata->chip_enable) {
		ret = tps->pdata->chip_enable(on);
		if (ret) {
			dev_err(&client->dev, "failed to enable %d\n", ret);
			return ret;
		}
	}

	tps->enabled = on;

	return ret;
}

/* Operations permitted on VOUT */

static int tps6130x_vout_is_enabled(struct regulator_dev *dev)
{
	struct tps_pmic *tps = rdev_get_drvdata(dev);
	int data, vout = 0;

	if (!tps->enabled)
		return 0;

	data = tps6130x_reg_read(tps, TPS6130X_REGISTER1);
	if (data < 0)
		return data;

	/* tps61300/tps61301 have ENVM to force voltage regulation mode */
	if (data & TPS6130X_ENVM)
		vout = 1;

	/* device operating in voltage regulation mode */
	if ((data & TPS6130X_MODE_CTRL_MASK) == TPS6130X_VOUT_MODE)
		vout = 1;

	return vout;
}

static int tps6130x_vout_enable(struct regulator_dev *dev)
{
	struct tps_pmic *tps = rdev_get_drvdata(dev);
	struct tps_info *info = tps->info;
	int ret;

	ret = tps6130x_chip_enable(tps, 1);
	if (ret)
		return ret;

	/* set constant voltage source mode */
	ret = tps6130x_update_bits(tps, TPS6130X_REGISTER1,
				   TPS6130X_MODE_CTRL_MASK,
				   TPS6130X_VOUT_MODE);
	if (ret)
		goto err1;

	/* output voltage must be set after voltage mode has been enabled  */
	ret = tps6130x_update_bits(tps, TPS6130X_REGISTER6,
				   TPS6130X_OV_MASK, info->vsel);
	if (ret)
		goto err2;

	return 0;

err2:
	tps6130x_update_bits(tps, TPS6130X_REGISTER1,
			     TPS6130X_MODE_CTRL_MASK,
			     TPS6130X_SHUTDOWN_MODE);
err1:
	tps6130x_chip_enable(tps, 0);
	return ret;
}

static int tps6130x_vout_disable(struct regulator_dev *dev)
{
	struct tps_pmic *tps = rdev_get_drvdata(dev);
	int ret;

	/* may not disable voltage output if ENVM is forced */
	ret = tps6130x_update_bits(tps, TPS6130X_REGISTER1,
				   TPS6130X_MODE_CTRL_MASK,
				   TPS6130X_SHUTDOWN_MODE);
	if (ret)
		return ret;

	ret = tps6130x_chip_enable(tps, 0);

	return ret;
}

static int tps6130x_vout_list_voltage(struct regulator_dev *dev,
				      unsigned selector)
{
	struct tps_pmic *tps = rdev_get_drvdata(dev);
	struct tps_info *info = tps->info;

	if (selector > info->vsel_max)
		return -EINVAL;

	return info->min_uV + selector * info->step;
}

static int tps6130x_vout_get_voltage(struct regulator_dev *dev)
{
	struct tps_pmic *tps = rdev_get_drvdata(dev);
	struct tps_info *info = tps->info;

	/* output voltage cannot be read from REGISTER6 */
	return info->min_uV + info->vsel * info->step;
}

static int tps6130x_vout_set_voltage(struct regulator_dev *dev,
				     int min_uV, int max_uV, unsigned *selector)
{
	struct tps_pmic *tps = rdev_get_drvdata(dev);
	struct tps_info *info = tps->info;
	int vsel, ret;

	if ((min_uV < info->min_uV) || (min_uV > info->max_uV))
		return -EINVAL;

	if ((max_uV < info->min_uV) || (max_uV > info->max_uV))
		return -EINVAL;

	vsel = (min_uV - info->min_uV + (info->step - 1)) / info->step;

	ret = tps6130x_vout_list_voltage(dev, vsel);
	if ((ret < 0) || (ret > max_uV))
		return -EINVAL;

	/*
	 * new target voltage must be set after
	 * voltage mode operation has been enabled
	 */
	info->vsel = vsel;
	*selector = vsel;

	BUG_ON(vsel < 0);
	BUG_ON(vsel > TPS6130X_VOUT_MAX_SEL);

	return 0;
}

static struct regulator_ops tps6130x_ops = {
	.is_enabled	= tps6130x_vout_is_enabled,
	.enable		= tps6130x_vout_enable,
	.disable	= tps6130x_vout_disable,
	.get_voltage	= tps6130x_vout_get_voltage,
	.set_voltage	= tps6130x_vout_set_voltage,
	.list_voltage	= tps6130x_vout_list_voltage,
};

static struct regulator_desc tps6130x_desc = {
	.name		= "VOUT",
	.id		= TPS6130X_VOUT,
	.ops		= &tps6130x_ops,
	.n_voltages	= TPS6130X_VOUT_MAX_SEL + 1,
	.type		= REGULATOR_VOLTAGE,
	.owner		= THIS_MODULE,
};

static int tps6130x_probe(struct i2c_client *client,
			  const struct i2c_device_id *id)
{
	struct tps_info *info = (void *)id->driver_data;
	struct regulator_init_data *init_data;
	struct regulator_dev *rdev;
	struct tps_pmic *tps;
	int revid, ret;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
		return -EIO;

	init_data = client->dev.platform_data;
	if (!init_data)
		return -EIO;

	tps = kzalloc(sizeof(*tps), GFP_KERNEL);
	if (!tps)
		return -ENOMEM;

	mutex_init(&tps->io_lock);
	tps->client = client;
	tps->info = info;
	tps->desc = &tps6130x_desc;

	if (init_data->driver_data)
		tps->pdata = init_data->driver_data;

	/* register the regulator */
	rdev = regulator_register(tps->desc, &client->dev, init_data, tps);
	if (IS_ERR(rdev)) {
		dev_err(&client->dev, "failed to register %s\n", id->name);
		ret = PTR_ERR(rdev);
		goto reg_err;
	}

	tps->rdev = rdev;
	i2c_set_clientdata(client, tps);

	ret = tps6130x_chip_enable(tps, 1);
	if (ret)
		goto enable_err;

	revid = tps6130x_reg_read(tps, TPS6130X_REGISTER7);
	if (revid < 0) {
		dev_err(&client->dev, "failed to access device\n");
		ret = revid;
		goto rev_err;
	}

	dev_info(&client->dev, "Revision %d\n", revid & TPS6130X_REVID_MASK);

	/* default output voltage: 4.950V */
	tps->info->vsel = 9;

	ret = tps6130x_chip_enable(tps, 0);
	if (ret)
		goto rev_err;

	return 0;

rev_err:
	tps6130x_chip_enable(tps, 0);
enable_err:
	i2c_set_clientdata(client, NULL);
	regulator_unregister(tps->rdev);
reg_err:
	mutex_destroy(&tps->io_lock);
	tps->client = NULL;
	kfree(tps);
	return ret;
}

static int __devexit tps6130x_remove(struct i2c_client *client)
{
	struct tps_pmic *tps = i2c_get_clientdata(client);

	regulator_unregister(tps->rdev);
	mutex_destroy(&tps->io_lock);
	tps->client = NULL;
	i2c_set_clientdata(client, NULL);
	kfree(tps);

	return 0;
}

static struct tps_info tps6130x_regs = {
	.name	= "VOUT",
	.min_uV	= TPS6130X_VOUT_MIN_UV,
	.max_uV	= TPS6130X_VOUT_MAX_UV,
	.step	= TPS6130X_VOUT_STEP,
	.vsel_max = TPS6130X_VOUT_MAX_SEL,
};

static const struct i2c_device_id tps6130x_id[] = {
	{
		.name = "tps6130x",
		.driver_data = (unsigned long)&tps6130x_regs,
	},
	{ },
};
MODULE_DEVICE_TABLE(i2c, tps6130x_id);

static struct i2c_driver tps6130x_i2c_driver = {
	.driver = {
		.name	= "tps6130x",
		.owner	= THIS_MODULE,
	},
	.probe		= tps6130x_probe,
	.remove		= __devexit_p(tps6130x_remove),
	.id_table	= tps6130x_id,
};

static int __init tps6130x_init(void)
{
	return i2c_add_driver(&tps6130x_i2c_driver);
}
subsys_initcall(tps6130x_init);

static void __exit tps6130x_cleanup(void)
{
	i2c_del_driver(&tps6130x_i2c_driver);
}
module_exit(tps6130x_cleanup);

MODULE_AUTHOR("Misael Lopez Cruz <misael.lopez@ti.com>");
MODULE_DESCRIPTION("TPS6130X voltage regulator driver");
MODULE_LICENSE("GPL v2");