/*
 * Copyright (C) 2012 Avionic Design GmbH
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>

#include <linux/iio/iio.h>
#include <linux/regulator/consumer.h>

struct adc081c {
	struct i2c_client *i2c;
	struct regulator *ref;
};

#define REG_CONV_RES 0x00

static int adc081c_read_raw(struct iio_dev *iio,
			    struct iio_chan_spec const *channel, int *value,
			    int *shift, long mask)
{
	struct adc081c *adc = iio_priv(iio);
	int err;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		err = i2c_smbus_read_word_swapped(adc->i2c, REG_CONV_RES);
		if (err < 0)
			return err;

		*value = (err >> 4) & 0xff;
		return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:
		err = regulator_get_voltage(adc->ref);
		if (err < 0)
			return err;

		*value = err / 1000;
		*shift = 8;

		return IIO_VAL_FRACTIONAL_LOG2;

	default:
		break;
	}

	return -EINVAL;
}

static const struct iio_chan_spec adc081c_channel = {
	.type = IIO_VOLTAGE,
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
};

static const struct iio_info adc081c_info = {
	.read_raw = adc081c_read_raw,
	.driver_module = THIS_MODULE,
};

static int adc081c_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct iio_dev *iio;
	struct adc081c *adc;
	int err;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
		return -ENODEV;

	iio = devm_iio_device_alloc(&client->dev, sizeof(*adc));
	if (!iio)
		return -ENOMEM;

	adc = iio_priv(iio);
	adc->i2c = client;

	adc->ref = devm_regulator_get(&client->dev, "vref");
	if (IS_ERR(adc->ref))
		return PTR_ERR(adc->ref);

	err = regulator_enable(adc->ref);
	if (err < 0)
		return err;

	iio->dev.parent = &client->dev;
	iio->name = dev_name(&client->dev);
	iio->modes = INDIO_DIRECT_MODE;
	iio->info = &adc081c_info;

	iio->channels = &adc081c_channel;
	iio->num_channels = 1;

	err = iio_device_register(iio);
	if (err < 0)
		goto regulator_disable;

	i2c_set_clientdata(client, iio);

	return 0;

regulator_disable:
	regulator_disable(adc->ref);

	return err;
}

static int adc081c_remove(struct i2c_client *client)
{
	struct iio_dev *iio = i2c_get_clientdata(client);
	struct adc081c *adc = iio_priv(iio);

	iio_device_unregister(iio);
	regulator_disable(adc->ref);

	return 0;
}

static const struct i2c_device_id adc081c_id[] = {
	{ "adc081c", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, adc081c_id);

#ifdef CONFIG_OF
static const struct of_device_id adc081c_of_match[] = {
	{ .compatible = "ti,adc081c" },
	{ }
};
MODULE_DEVICE_TABLE(of, adc081c_of_match);
#endif

static struct i2c_driver adc081c_driver = {
	.driver = {
		.name = "adc081c",
		.of_match_table = of_match_ptr(adc081c_of_match),
	},
	.probe = adc081c_probe,
	.remove = adc081c_remove,
	.id_table = adc081c_id,
};
module_i2c_driver(adc081c_driver);

MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
MODULE_DESCRIPTION("Texas Instruments ADC081C021/027 driver");
MODULE_LICENSE("GPL v2");