/*
 * tmp006.c - Support for TI TMP006 IR thermopile sensor
 *
 * Copyright (c) 2013 Peter Meerwald <pmeerw@pmeerw.net>
 *
 * This file is subject to the terms and conditions of version 2 of
 * the GNU General Public License.  See the file COPYING in the main
 * directory of this archive for more details.
 *
 * Driver for the Texas Instruments I2C 16-bit IR thermopile sensor
 *
 * (7-bit I2C slave address 0x40, changeable via ADR pins)
 *
 * TODO: data ready irq
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/pm.h>
#include <linux/bitops.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

#define TMP006_VOBJECT 0x00
#define TMP006_TAMBIENT 0x01
#define TMP006_CONFIG 0x02
#define TMP006_MANUFACTURER_ID 0xfe
#define TMP006_DEVICE_ID 0xff

#define TMP006_TAMBIENT_SHIFT 2

#define TMP006_CONFIG_RESET BIT(15)
#define TMP006_CONFIG_DRDY_EN BIT(8)
#define TMP006_CONFIG_DRDY BIT(7)

#define TMP006_CONFIG_MOD_MASK GENMASK(14, 12)

#define TMP006_CONFIG_CR_MASK GENMASK(11, 9)
#define TMP006_CONFIG_CR_SHIFT 9

#define TMP006_MANUFACTURER_MAGIC 0x5449
#define TMP006_DEVICE_MAGIC 0x0067

struct tmp006_data {
	struct i2c_client *client;
	u16 config;
};

static int tmp006_read_measurement(struct tmp006_data *data, u8 reg)
{
	s32 ret;
	int tries = 50;

	while (tries-- > 0) {
		ret = i2c_smbus_read_word_swapped(data->client,
			TMP006_CONFIG);
		if (ret < 0)
			return ret;
		if (ret & TMP006_CONFIG_DRDY)
			break;
		msleep(100);
	}

	if (tries < 0)
		return -EIO;

	return i2c_smbus_read_word_swapped(data->client, reg);
}

static const int tmp006_freqs[5][2] = { {4, 0}, {2, 0}, {1, 0},
					{0, 500000}, {0, 250000} };

static int tmp006_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *channel, int *val,
			    int *val2, long mask)
{
	struct tmp006_data *data = iio_priv(indio_dev);
	s32 ret;
	int cr;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		if (channel->type == IIO_VOLTAGE) {
			/* LSB is 156.25 nV */
			ret = tmp006_read_measurement(data, TMP006_VOBJECT);
			if (ret < 0)
				return ret;
			*val = sign_extend32(ret, 15);
		} else if (channel->type == IIO_TEMP) {
			/* LSB is 0.03125 degrees Celsius */
			ret = tmp006_read_measurement(data, TMP006_TAMBIENT);
			if (ret < 0)
				return ret;
			*val = sign_extend32(ret, 15) >> TMP006_TAMBIENT_SHIFT;
		} else {
			break;
		}
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		if (channel->type == IIO_VOLTAGE) {
			*val = 0;
			*val2 = 156250;
		} else if (channel->type == IIO_TEMP) {
			*val = 31;
			*val2 = 250000;
		} else {
			break;
		}
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_SAMP_FREQ:
		cr = (data->config & TMP006_CONFIG_CR_MASK)
			>> TMP006_CONFIG_CR_SHIFT;
		*val = tmp006_freqs[cr][0];
		*val2 = tmp006_freqs[cr][1];
		return IIO_VAL_INT_PLUS_MICRO;
	default:
		break;
	}

	return -EINVAL;
}

static int tmp006_write_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int val,
			    int val2,
			    long mask)
{
	struct tmp006_data *data = iio_priv(indio_dev);
	int i;

	for (i = 0; i < ARRAY_SIZE(tmp006_freqs); i++)
		if ((val == tmp006_freqs[i][0]) &&
		    (val2 == tmp006_freqs[i][1])) {
			data->config &= ~TMP006_CONFIG_CR_MASK;
			data->config |= i << TMP006_CONFIG_CR_SHIFT;

			return i2c_smbus_write_word_swapped(data->client,
							    TMP006_CONFIG,
							    data->config);

		}
	return -EINVAL;
}

static IIO_CONST_ATTR(sampling_frequency_available, "4 2 1 0.5 0.25");

static struct attribute *tmp006_attributes[] = {
	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
	NULL
};

static const struct attribute_group tmp006_attribute_group = {
	.attrs = tmp006_attributes,
};

static const struct iio_chan_spec tmp006_channels[] = {
	{
		.type = IIO_VOLTAGE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
			BIT(IIO_CHAN_INFO_SCALE),
		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
	},
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
			BIT(IIO_CHAN_INFO_SCALE),
		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
	}
};

static const struct iio_info tmp006_info = {
	.read_raw = tmp006_read_raw,
	.write_raw = tmp006_write_raw,
	.attrs = &tmp006_attribute_group,
	.driver_module = THIS_MODULE,
};

static bool tmp006_check_identification(struct i2c_client *client)
{
	int mid, did;

	mid = i2c_smbus_read_word_swapped(client, TMP006_MANUFACTURER_ID);
	if (mid < 0)
		return false;

	did = i2c_smbus_read_word_swapped(client, TMP006_DEVICE_ID);
	if (did < 0)
		return false;

	return mid == TMP006_MANUFACTURER_MAGIC && did == TMP006_DEVICE_MAGIC;
}

static int tmp006_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct iio_dev *indio_dev;
	struct tmp006_data *data;
	int ret;

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

	if (!tmp006_check_identification(client)) {
		dev_err(&client->dev, "no TMP006 sensor\n");
		return -ENODEV;
	}

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

	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);
	data->client = client;

	indio_dev->dev.parent = &client->dev;
	indio_dev->name = dev_name(&client->dev);
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &tmp006_info;

	indio_dev->channels = tmp006_channels;
	indio_dev->num_channels = ARRAY_SIZE(tmp006_channels);

	ret = i2c_smbus_read_word_swapped(data->client, TMP006_CONFIG);
	if (ret < 0)
		return ret;
	data->config = ret;

	return iio_device_register(indio_dev);
}

static int tmp006_powerdown(struct tmp006_data *data)
{
	return i2c_smbus_write_word_swapped(data->client, TMP006_CONFIG,
		data->config & ~TMP006_CONFIG_MOD_MASK);
}

static int tmp006_remove(struct i2c_client *client)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);

	iio_device_unregister(indio_dev);
	tmp006_powerdown(iio_priv(indio_dev));

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int tmp006_suspend(struct device *dev)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
	return tmp006_powerdown(iio_priv(indio_dev));
}

static int tmp006_resume(struct device *dev)
{
	struct tmp006_data *data = iio_priv(i2c_get_clientdata(
		to_i2c_client(dev)));
	return i2c_smbus_write_word_swapped(data->client, TMP006_CONFIG,
		data->config | TMP006_CONFIG_MOD_MASK);
}
#endif

static SIMPLE_DEV_PM_OPS(tmp006_pm_ops, tmp006_suspend, tmp006_resume);

static const struct i2c_device_id tmp006_id[] = {
	{ "tmp006", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, tmp006_id);

static struct i2c_driver tmp006_driver = {
	.driver = {
		.name	= "tmp006",
		.pm	= &tmp006_pm_ops,
		.owner	= THIS_MODULE,
	},
	.probe = tmp006_probe,
	.remove = tmp006_remove,
	.id_table = tmp006_id,
};
module_i2c_driver(tmp006_driver);

MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
MODULE_DESCRIPTION("TI TMP006 IR thermopile sensor driver");
MODULE_LICENSE("GPL");