/*
 * AD7291 8-Channel, I2C, 12-Bit SAR ADC with Temperature Sensor
 *
 * Copyright 2010-2011 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

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

#include <linux/platform_data/ad7291.h>

/*
 * Simplified handling
 *
 * If no events enabled - single polled channel read
 * If event enabled direct reads disable unless channel
 * is in the read mask.
 *
 * The noise-delayed bit as per datasheet suggestion is always enabled.
 */

/*
 * AD7291 registers definition
 */
#define AD7291_COMMAND			0x00
#define AD7291_VOLTAGE			0x01
#define AD7291_T_SENSE			0x02
#define AD7291_T_AVERAGE		0x03
#define AD7291_DATA_HIGH(x)		((x) * 3 + 0x4)
#define AD7291_DATA_LOW(x)		((x) * 3 + 0x5)
#define AD7291_HYST(x)			((x) * 3 + 0x6)
#define AD7291_VOLTAGE_ALERT_STATUS	0x1F
#define AD7291_T_ALERT_STATUS		0x20

#define AD7291_BITS			12
#define AD7291_VOLTAGE_LIMIT_COUNT	8


/*
 * AD7291 command
 */
#define AD7291_AUTOCYCLE		BIT(0)
#define AD7291_RESET			BIT(1)
#define AD7291_ALERT_CLEAR		BIT(2)
#define AD7291_ALERT_POLARITY		BIT(3)
#define AD7291_EXT_REF			BIT(4)
#define AD7291_NOISE_DELAY		BIT(5)
#define AD7291_T_SENSE_MASK		BIT(7)
#define AD7291_VOLTAGE_MASK		GENMASK(15, 8)
#define AD7291_VOLTAGE_OFFSET		8

/*
 * AD7291 value masks
 */
#define AD7291_VALUE_MASK		GENMASK(11, 0)

/*
 * AD7291 alert register bits
 */
#define AD7291_T_LOW			BIT(0)
#define AD7291_T_HIGH			BIT(1)
#define AD7291_T_AVG_LOW		BIT(2)
#define AD7291_T_AVG_HIGH		BIT(3)
#define AD7291_V_LOW(x)			BIT((x) * 2)
#define AD7291_V_HIGH(x)		BIT((x) * 2 + 1)


struct ad7291_chip_info {
	struct i2c_client	*client;
	struct regulator	*reg;
	u16			command;
	u16			c_mask;	/* Active voltage channels for events */
	struct mutex		state_lock;
};

static int ad7291_i2c_read(struct ad7291_chip_info *chip, u8 reg, u16 *data)
{
	struct i2c_client *client = chip->client;
	int ret = 0;

	ret = i2c_smbus_read_word_swapped(client, reg);
	if (ret < 0) {
		dev_err(&client->dev, "I2C read error\n");
		return ret;
	}

	*data = ret;

	return 0;
}

static int ad7291_i2c_write(struct ad7291_chip_info *chip, u8 reg, u16 data)
{
	return i2c_smbus_write_word_swapped(chip->client, reg, data);
}

static irqreturn_t ad7291_event_handler(int irq, void *private)
{
	struct iio_dev *indio_dev = private;
	struct ad7291_chip_info *chip = iio_priv(private);
	u16 t_status, v_status;
	u16 command;
	int i;
	s64 timestamp = iio_get_time_ns(indio_dev);

	if (ad7291_i2c_read(chip, AD7291_T_ALERT_STATUS, &t_status))
		return IRQ_HANDLED;

	if (ad7291_i2c_read(chip, AD7291_VOLTAGE_ALERT_STATUS, &v_status))
		return IRQ_HANDLED;

	if (!(t_status || v_status))
		return IRQ_HANDLED;

	command = chip->command | AD7291_ALERT_CLEAR;
	ad7291_i2c_write(chip, AD7291_COMMAND, command);

	command = chip->command & ~AD7291_ALERT_CLEAR;
	ad7291_i2c_write(chip, AD7291_COMMAND, command);

	/* For now treat t_sense and t_sense_average the same */
	if ((t_status & AD7291_T_LOW) || (t_status & AD7291_T_AVG_LOW))
		iio_push_event(indio_dev,
			       IIO_UNMOD_EVENT_CODE(IIO_TEMP,
						    0,
						    IIO_EV_TYPE_THRESH,
						    IIO_EV_DIR_FALLING),
			       timestamp);
	if ((t_status & AD7291_T_HIGH) || (t_status & AD7291_T_AVG_HIGH))
		iio_push_event(indio_dev,
			       IIO_UNMOD_EVENT_CODE(IIO_TEMP,
						    0,
						    IIO_EV_TYPE_THRESH,
						    IIO_EV_DIR_RISING),
			       timestamp);

	for (i = 0; i < AD7291_VOLTAGE_LIMIT_COUNT; i++) {
		if (v_status & AD7291_V_LOW(i))
			iio_push_event(indio_dev,
				       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
							    i,
							    IIO_EV_TYPE_THRESH,
							    IIO_EV_DIR_FALLING),
				       timestamp);
		if (v_status & AD7291_V_HIGH(i))
			iio_push_event(indio_dev,
				       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
							    i,
							    IIO_EV_TYPE_THRESH,
							    IIO_EV_DIR_RISING),
				       timestamp);
	}

	return IRQ_HANDLED;
}

static unsigned int ad7291_threshold_reg(const struct iio_chan_spec *chan,
					 enum iio_event_direction dir,
					 enum iio_event_info info)
{
	unsigned int offset;

	switch (chan->type) {
	case IIO_VOLTAGE:
		offset = chan->channel;
		break;
	case IIO_TEMP:
		offset = AD7291_VOLTAGE_OFFSET;
		break;
	default:
	    return 0;
	}

	switch (info) {
	case IIO_EV_INFO_VALUE:
		if (dir == IIO_EV_DIR_FALLING)
			return AD7291_DATA_HIGH(offset);
		else
			return AD7291_DATA_LOW(offset);
	case IIO_EV_INFO_HYSTERESIS:
		return AD7291_HYST(offset);
	default:
		break;
	}
	return 0;
}

static int ad7291_read_event_value(struct iio_dev *indio_dev,
				   const struct iio_chan_spec *chan,
				   enum iio_event_type type,
				   enum iio_event_direction dir,
				   enum iio_event_info info,
				   int *val, int *val2)
{
	struct ad7291_chip_info *chip = iio_priv(indio_dev);
	int ret;
	u16 uval;

	ret = ad7291_i2c_read(chip, ad7291_threshold_reg(chan, dir, info),
			      &uval);
	if (ret < 0)
		return ret;

	if (info == IIO_EV_INFO_HYSTERESIS || chan->type == IIO_VOLTAGE)
		*val = uval & AD7291_VALUE_MASK;

	else
		*val = sign_extend32(uval, 11);

	return IIO_VAL_INT;
}

static int ad7291_write_event_value(struct iio_dev *indio_dev,
				    const struct iio_chan_spec *chan,
				    enum iio_event_type type,
				    enum iio_event_direction dir,
				    enum iio_event_info info,
				    int val, int val2)
{
	struct ad7291_chip_info *chip = iio_priv(indio_dev);

	if (info == IIO_EV_INFO_HYSTERESIS || chan->type == IIO_VOLTAGE) {
		if (val > AD7291_VALUE_MASK || val < 0)
			return -EINVAL;
	} else {
		if (val > 2047 || val < -2048)
			return -EINVAL;
	}

	return ad7291_i2c_write(chip, ad7291_threshold_reg(chan, dir, info),
				val);
}

static int ad7291_read_event_config(struct iio_dev *indio_dev,
				    const struct iio_chan_spec *chan,
				    enum iio_event_type type,
				    enum iio_event_direction dir)
{
	struct ad7291_chip_info *chip = iio_priv(indio_dev);
	/*
	 * To be enabled the channel must simply be on. If any are enabled
	 * we are in continuous sampling mode
	 */

	switch (chan->type) {
	case IIO_VOLTAGE:
		return !!(chip->c_mask & BIT(15 - chan->channel));
	case IIO_TEMP:
		/* always on */
		return 1;
	default:
		return -EINVAL;
	}

}

static int ad7291_write_event_config(struct iio_dev *indio_dev,
				     const struct iio_chan_spec *chan,
				     enum iio_event_type type,
				     enum iio_event_direction dir,
				     int state)
{
	int ret = 0;
	struct ad7291_chip_info *chip = iio_priv(indio_dev);
	unsigned int mask;
	u16 regval;

	mutex_lock(&chip->state_lock);
	regval = chip->command;
	/*
	 * To be enabled the channel must simply be on. If any are enabled
	 * use continuous sampling mode.
	 * Possible to disable temp as well but that makes single read tricky.
	 */

	mask = BIT(15 - chan->channel);

	switch (chan->type) {
	case IIO_VOLTAGE:
		if ((!state) && (chip->c_mask & mask))
			chip->c_mask &= ~mask;
		else if (state && (!(chip->c_mask & mask)))
			chip->c_mask |= mask;
		else
			break;

		regval &= ~AD7291_AUTOCYCLE;
		regval |= chip->c_mask;
		if (chip->c_mask) /* Enable autocycle? */
			regval |= AD7291_AUTOCYCLE;

		ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
		if (ret < 0)
			goto error_ret;

		chip->command = regval;
		break;
	default:
		ret = -EINVAL;
	}

error_ret:
	mutex_unlock(&chip->state_lock);
	return ret;
}

static int ad7291_read_raw(struct iio_dev *indio_dev,
			   struct iio_chan_spec const *chan,
			   int *val,
			   int *val2,
			   long mask)
{
	int ret;
	struct ad7291_chip_info *chip = iio_priv(indio_dev);
	u16 regval;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		switch (chan->type) {
		case IIO_VOLTAGE:
			mutex_lock(&chip->state_lock);
			/* If in autocycle mode drop through */
			if (chip->command & AD7291_AUTOCYCLE) {
				mutex_unlock(&chip->state_lock);
				return -EBUSY;
			}
			/* Enable this channel alone */
			regval = chip->command & (~AD7291_VOLTAGE_MASK);
			regval |= BIT(15 - chan->channel);
			ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
			if (ret < 0) {
				mutex_unlock(&chip->state_lock);
				return ret;
			}
			/* Read voltage */
			ret = i2c_smbus_read_word_swapped(chip->client,
							  AD7291_VOLTAGE);
			if (ret < 0) {
				mutex_unlock(&chip->state_lock);
				return ret;
			}
			*val = ret & AD7291_VALUE_MASK;
			mutex_unlock(&chip->state_lock);
			return IIO_VAL_INT;
		case IIO_TEMP:
			/* Assumes tsense bit of command register always set */
			ret = i2c_smbus_read_word_swapped(chip->client,
							  AD7291_T_SENSE);
			if (ret < 0)
				return ret;
			*val = sign_extend32(ret, 11);
			return IIO_VAL_INT;
		default:
			return -EINVAL;
		}
	case IIO_CHAN_INFO_AVERAGE_RAW:
		ret = i2c_smbus_read_word_swapped(chip->client,
						  AD7291_T_AVERAGE);
			if (ret < 0)
				return ret;
			*val = sign_extend32(ret, 11);
			return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		switch (chan->type) {
		case IIO_VOLTAGE:
			if (chip->reg) {
				int vref;

				vref = regulator_get_voltage(chip->reg);
				if (vref < 0)
					return vref;
				*val = vref / 1000;
			} else {
				*val = 2500;
			}
			*val2 = AD7291_BITS;
			return IIO_VAL_FRACTIONAL_LOG2;
		case IIO_TEMP:
			/*
			 * One LSB of the ADC corresponds to 0.25 deg C.
			 * The temperature reading is in 12-bit twos
			 * complement format
			 */
			*val = 250;
			return IIO_VAL_INT;
		default:
			return -EINVAL;
		}
	default:
		return -EINVAL;
	}
}

static const struct iio_event_spec ad7291_events[] = {
	{
		.type = IIO_EV_TYPE_THRESH,
		.dir = IIO_EV_DIR_RISING,
		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
			BIT(IIO_EV_INFO_ENABLE),
	}, {
		.type = IIO_EV_TYPE_THRESH,
		.dir = IIO_EV_DIR_FALLING,
		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
			BIT(IIO_EV_INFO_ENABLE),
	}, {
		.type = IIO_EV_TYPE_THRESH,
		.dir = IIO_EV_DIR_EITHER,
		.mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
	},
};

#define AD7291_VOLTAGE_CHAN(_chan)					\
{									\
	.type = IIO_VOLTAGE,						\
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
	.indexed = 1,							\
	.channel = _chan,						\
	.event_spec = ad7291_events,					\
	.num_event_specs = ARRAY_SIZE(ad7291_events),			\
}

static const struct iio_chan_spec ad7291_channels[] = {
	AD7291_VOLTAGE_CHAN(0),
	AD7291_VOLTAGE_CHAN(1),
	AD7291_VOLTAGE_CHAN(2),
	AD7291_VOLTAGE_CHAN(3),
	AD7291_VOLTAGE_CHAN(4),
	AD7291_VOLTAGE_CHAN(5),
	AD7291_VOLTAGE_CHAN(6),
	AD7291_VOLTAGE_CHAN(7),
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				BIT(IIO_CHAN_INFO_AVERAGE_RAW) |
				BIT(IIO_CHAN_INFO_SCALE),
		.indexed = 1,
		.channel = 0,
		.event_spec = ad7291_events,
		.num_event_specs = ARRAY_SIZE(ad7291_events),
	}
};

static const struct iio_info ad7291_info = {
	.read_raw = &ad7291_read_raw,
	.read_event_config = &ad7291_read_event_config,
	.write_event_config = &ad7291_write_event_config,
	.read_event_value = &ad7291_read_event_value,
	.write_event_value = &ad7291_write_event_value,
	.driver_module = THIS_MODULE,
};

static int ad7291_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	struct ad7291_platform_data *pdata = client->dev.platform_data;
	struct ad7291_chip_info *chip;
	struct iio_dev *indio_dev;
	int ret;

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

	if (pdata && pdata->use_external_ref) {
		chip->reg = devm_regulator_get(&client->dev, "vref");
		if (IS_ERR(chip->reg))
			return PTR_ERR(chip->reg);

		ret = regulator_enable(chip->reg);
		if (ret)
			return ret;
	}

	mutex_init(&chip->state_lock);
	/* this is only used for device removal purposes */
	i2c_set_clientdata(client, indio_dev);

	chip->client = client;

	chip->command = AD7291_NOISE_DELAY |
			AD7291_T_SENSE_MASK | /* Tsense always enabled */
			AD7291_ALERT_POLARITY; /* set irq polarity low level */

	if (pdata && pdata->use_external_ref)
		chip->command |= AD7291_EXT_REF;

	indio_dev->name = id->name;
	indio_dev->channels = ad7291_channels;
	indio_dev->num_channels = ARRAY_SIZE(ad7291_channels);

	indio_dev->dev.parent = &client->dev;
	indio_dev->dev.of_node = client->dev.of_node;
	indio_dev->info = &ad7291_info;
	indio_dev->modes = INDIO_DIRECT_MODE;

	ret = ad7291_i2c_write(chip, AD7291_COMMAND, AD7291_RESET);
	if (ret) {
		ret = -EIO;
		goto error_disable_reg;
	}

	ret = ad7291_i2c_write(chip, AD7291_COMMAND, chip->command);
	if (ret) {
		ret = -EIO;
		goto error_disable_reg;
	}

	if (client->irq > 0) {
		ret = request_threaded_irq(client->irq,
					   NULL,
					   &ad7291_event_handler,
					   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
					   id->name,
					   indio_dev);
		if (ret)
			goto error_disable_reg;
	}

	ret = iio_device_register(indio_dev);
	if (ret)
		goto error_unreg_irq;

	return 0;

error_unreg_irq:
	if (client->irq)
		free_irq(client->irq, indio_dev);
error_disable_reg:
	if (chip->reg)
		regulator_disable(chip->reg);

	return ret;
}

static int ad7291_remove(struct i2c_client *client)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ad7291_chip_info *chip = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);

	if (client->irq)
		free_irq(client->irq, indio_dev);

	if (chip->reg)
		regulator_disable(chip->reg);

	return 0;
}

static const struct i2c_device_id ad7291_id[] = {
	{ "ad7291", 0 },
	{}
};

MODULE_DEVICE_TABLE(i2c, ad7291_id);

static struct i2c_driver ad7291_driver = {
	.driver = {
		.name = KBUILD_MODNAME,
	},
	.probe = ad7291_probe,
	.remove = ad7291_remove,
	.id_table = ad7291_id,
};
module_i2c_driver(ad7291_driver);

MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7291 ADC driver");
MODULE_LICENSE("GPL v2");