// SPDX-License-Identifier: GPL-2.0
/*
 * isl29501.c: ISL29501 Time of Flight sensor driver.
 *
 * Copyright (C) 2018
 * Author: Mathieu Othacehe <m.othacehe@gmail.com>
 *
 * 7-bit I2C slave address: 0x57
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/err.h>
#include <linux/of_device.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

#include <linux/iio/trigger_consumer.h>
#include <linux/iio/buffer.h>
#include <linux/iio/triggered_buffer.h>

/* Control, setting and status registers */
#define ISL29501_DEVICE_ID			0x00
#define ISL29501_ID				0x0A

/* Sampling control registers */
#define ISL29501_INTEGRATION_PERIOD		0x10
#define ISL29501_SAMPLE_PERIOD			0x11

/* Closed loop calibration registers */
#define ISL29501_CROSSTALK_I_MSB		0x24
#define ISL29501_CROSSTALK_I_LSB		0x25
#define ISL29501_CROSSTALK_I_EXPONENT		0x26
#define ISL29501_CROSSTALK_Q_MSB		0x27
#define ISL29501_CROSSTALK_Q_LSB		0x28
#define ISL29501_CROSSTALK_Q_EXPONENT		0x29
#define ISL29501_CROSSTALK_GAIN_MSB		0x2A
#define ISL29501_CROSSTALK_GAIN_LSB		0x2B
#define ISL29501_MAGNITUDE_REF_EXP		0x2C
#define ISL29501_MAGNITUDE_REF_MSB		0x2D
#define ISL29501_MAGNITUDE_REF_LSB		0x2E
#define ISL29501_PHASE_OFFSET_MSB		0x2F
#define ISL29501_PHASE_OFFSET_LSB		0x30

/* Analog control registers */
#define ISL29501_DRIVER_RANGE			0x90
#define ISL29501_EMITTER_DAC			0x91

#define ISL29501_COMMAND_REGISTER		0xB0

/* Commands */
#define ISL29501_EMUL_SAMPLE_START_PIN		0x49
#define ISL29501_RESET_ALL_REGISTERS		0xD7
#define ISL29501_RESET_INT_SM			0xD1

/* Ambiant light and temperature corrections */
#define ISL29501_TEMP_REFERENCE			0x31
#define ISL29501_PHASE_EXPONENT			0x33
#define ISL29501_TEMP_COEFF_A			0x34
#define ISL29501_TEMP_COEFF_B			0x39
#define ISL29501_AMBIANT_COEFF_A		0x36
#define ISL29501_AMBIANT_COEFF_B		0x3B

/* Data output registers */
#define ISL29501_DISTANCE_MSB_DATA		0xD1
#define ISL29501_DISTANCE_LSB_DATA		0xD2
#define ISL29501_PRECISION_MSB			0xD3
#define ISL29501_PRECISION_LSB			0xD4
#define ISL29501_MAGNITUDE_EXPONENT		0xD5
#define ISL29501_MAGNITUDE_MSB			0xD6
#define ISL29501_MAGNITUDE_LSB			0xD7
#define ISL29501_PHASE_MSB			0xD8
#define ISL29501_PHASE_LSB			0xD9
#define ISL29501_I_RAW_EXPONENT			0xDA
#define ISL29501_I_RAW_MSB			0xDB
#define ISL29501_I_RAW_LSB			0xDC
#define ISL29501_Q_RAW_EXPONENT			0xDD
#define ISL29501_Q_RAW_MSB			0xDE
#define ISL29501_Q_RAW_LSB			0xDF
#define ISL29501_DIE_TEMPERATURE		0xE2
#define ISL29501_AMBIENT_LIGHT			0xE3
#define ISL29501_GAIN_MSB			0xE6
#define ISL29501_GAIN_LSB			0xE7

#define ISL29501_MAX_EXP_VAL 15

#define ISL29501_INT_TIME_AVAILABLE \
	"0.00007 0.00014 0.00028 0.00057 0.00114 " \
	"0.00228 0.00455 0.00910 0.01820 0.03640 " \
	"0.07281 0.14561"

#define ISL29501_CURRENT_SCALE_AVAILABLE \
	"0.0039 0.0078 0.0118 0.0157 0.0196 " \
	"0.0235 0.0275 0.0314 0.0352 0.0392 " \
	"0.0431 0.0471 0.0510 0.0549 0.0588"

enum isl29501_correction_coeff {
	COEFF_TEMP_A,
	COEFF_TEMP_B,
	COEFF_LIGHT_A,
	COEFF_LIGHT_B,
	COEFF_MAX,
};

struct isl29501_private {
	struct i2c_client *client;
	struct mutex lock;
	/* Exact representation of correction coefficients. */
	unsigned int shadow_coeffs[COEFF_MAX];
};

enum isl29501_register_name {
	REG_DISTANCE,
	REG_PHASE,
	REG_TEMPERATURE,
	REG_AMBIENT_LIGHT,
	REG_GAIN,
	REG_GAIN_BIAS,
	REG_PHASE_EXP,
	REG_CALIB_PHASE_TEMP_A,
	REG_CALIB_PHASE_TEMP_B,
	REG_CALIB_PHASE_LIGHT_A,
	REG_CALIB_PHASE_LIGHT_B,
	REG_DISTANCE_BIAS,
	REG_TEMPERATURE_BIAS,
	REG_INT_TIME,
	REG_SAMPLE_TIME,
	REG_DRIVER_RANGE,
	REG_EMITTER_DAC,
};

struct isl29501_register_desc {
	u8 msb;
	u8 lsb;
};

static const struct isl29501_register_desc isl29501_registers[] = {
	[REG_DISTANCE] = {
		.msb = ISL29501_DISTANCE_MSB_DATA,
		.lsb = ISL29501_DISTANCE_LSB_DATA,
	},
	[REG_PHASE] = {
		.msb = ISL29501_PHASE_MSB,
		.lsb = ISL29501_PHASE_LSB,
	},
	[REG_TEMPERATURE] = {
		.lsb = ISL29501_DIE_TEMPERATURE,
	},
	[REG_AMBIENT_LIGHT] = {
		.lsb = ISL29501_AMBIENT_LIGHT,
	},
	[REG_GAIN] = {
		.msb = ISL29501_GAIN_MSB,
		.lsb = ISL29501_GAIN_LSB,
	},
	[REG_GAIN_BIAS] = {
		.msb = ISL29501_CROSSTALK_GAIN_MSB,
		.lsb = ISL29501_CROSSTALK_GAIN_LSB,
	},
	[REG_PHASE_EXP] = {
		.lsb = ISL29501_PHASE_EXPONENT,
	},
	[REG_CALIB_PHASE_TEMP_A] = {
		.lsb = ISL29501_TEMP_COEFF_A,
	},
	[REG_CALIB_PHASE_TEMP_B] = {
		.lsb = ISL29501_TEMP_COEFF_B,
	},
	[REG_CALIB_PHASE_LIGHT_A] = {
		.lsb = ISL29501_AMBIANT_COEFF_A,
	},
	[REG_CALIB_PHASE_LIGHT_B] = {
		.lsb = ISL29501_AMBIANT_COEFF_B,
	},
	[REG_DISTANCE_BIAS] = {
		.msb = ISL29501_PHASE_OFFSET_MSB,
		.lsb = ISL29501_PHASE_OFFSET_LSB,
	},
	[REG_TEMPERATURE_BIAS] = {
		.lsb = ISL29501_TEMP_REFERENCE,
	},
	[REG_INT_TIME] = {
		.lsb = ISL29501_INTEGRATION_PERIOD,
	},
	[REG_SAMPLE_TIME] = {
		.lsb = ISL29501_SAMPLE_PERIOD,
	},
	[REG_DRIVER_RANGE] = {
		.lsb = ISL29501_DRIVER_RANGE,
	},
	[REG_EMITTER_DAC] = {
		.lsb = ISL29501_EMITTER_DAC,
	},
};

static int isl29501_register_read(struct isl29501_private *isl29501,
				  enum isl29501_register_name name,
				  u32 *val)
{
	const struct isl29501_register_desc *reg = &isl29501_registers[name];
	u8 msb = 0, lsb = 0;
	s32 ret;

	mutex_lock(&isl29501->lock);
	if (reg->msb) {
		ret = i2c_smbus_read_byte_data(isl29501->client, reg->msb);
		if (ret < 0)
			goto err;
		msb = ret;
	}

	if (reg->lsb) {
		ret = i2c_smbus_read_byte_data(isl29501->client, reg->lsb);
		if (ret < 0)
			goto err;
		lsb = ret;
	}
	mutex_unlock(&isl29501->lock);

	*val = (msb << 8) + lsb;

	return 0;
err:
	mutex_unlock(&isl29501->lock);

	return ret;
}

static u32 isl29501_register_write(struct isl29501_private *isl29501,
				   enum isl29501_register_name name,
				   u32 value)
{
	const struct isl29501_register_desc *reg = &isl29501_registers[name];
	u8 msb, lsb;
	int ret;

	if (!reg->msb && value > U8_MAX)
		return -ERANGE;

	if (value > U16_MAX)
		return -ERANGE;

	if (!reg->msb) {
		lsb = value & 0xFF;
	} else {
		msb = (value >> 8) & 0xFF;
		lsb = value & 0xFF;
	}

	mutex_lock(&isl29501->lock);
	if (reg->msb) {
		ret = i2c_smbus_write_byte_data(isl29501->client,
						reg->msb, msb);
		if (ret < 0)
			goto err;
	}

	ret = i2c_smbus_write_byte_data(isl29501->client, reg->lsb, lsb);

err:
	mutex_unlock(&isl29501->lock);
	return ret;
}

static ssize_t isl29501_read_ext(struct iio_dev *indio_dev,
				 uintptr_t private,
				 const struct iio_chan_spec *chan,
				 char *buf)
{
	struct isl29501_private *isl29501 = iio_priv(indio_dev);
	enum isl29501_register_name reg = private;
	int ret;
	u32 value, gain, coeff, exp;

	switch (reg) {
	case REG_GAIN:
	case REG_GAIN_BIAS:
		ret = isl29501_register_read(isl29501, reg, &gain);
		if (ret < 0)
			return ret;

		value = gain;
		break;
	case REG_CALIB_PHASE_TEMP_A:
	case REG_CALIB_PHASE_TEMP_B:
	case REG_CALIB_PHASE_LIGHT_A:
	case REG_CALIB_PHASE_LIGHT_B:
		ret = isl29501_register_read(isl29501, REG_PHASE_EXP, &exp);
		if (ret < 0)
			return ret;

		ret = isl29501_register_read(isl29501, reg, &coeff);
		if (ret < 0)
			return ret;

		value = coeff << exp;
		break;
	default:
		return -EINVAL;
	}

	return sprintf(buf, "%u\n", value);
}

static int isl29501_set_shadow_coeff(struct isl29501_private *isl29501,
				     enum isl29501_register_name reg,
				     unsigned int val)
{
	enum isl29501_correction_coeff coeff;

	switch (reg) {
	case REG_CALIB_PHASE_TEMP_A:
		coeff = COEFF_TEMP_A;
		break;
	case REG_CALIB_PHASE_TEMP_B:
		coeff = COEFF_TEMP_B;
		break;
	case REG_CALIB_PHASE_LIGHT_A:
		coeff = COEFF_LIGHT_A;
		break;
	case REG_CALIB_PHASE_LIGHT_B:
		coeff = COEFF_LIGHT_B;
		break;
	default:
		return -EINVAL;
	}
	isl29501->shadow_coeffs[coeff] = val;

	return 0;
}

static int isl29501_write_coeff(struct isl29501_private *isl29501,
				enum isl29501_correction_coeff coeff,
				int val)
{
	enum isl29501_register_name reg;

	switch (coeff) {
	case COEFF_TEMP_A:
		reg = REG_CALIB_PHASE_TEMP_A;
		break;
	case COEFF_TEMP_B:
		reg = REG_CALIB_PHASE_TEMP_B;
		break;
	case COEFF_LIGHT_A:
		reg = REG_CALIB_PHASE_LIGHT_A;
		break;
	case COEFF_LIGHT_B:
		reg = REG_CALIB_PHASE_LIGHT_B;
		break;
	default:
		return -EINVAL;
	}

	return isl29501_register_write(isl29501, reg, val);
}

static unsigned int isl29501_find_corr_exp(unsigned int val,
					   unsigned int max_exp,
					   unsigned int max_mantissa)
{
	unsigned int exp = 1;

	/*
	 * Correction coefficients are represented under
	 * mantissa * 2^exponent form, where mantissa and exponent
	 * are stored in two separate registers of the sensor.
	 *
	 * Compute and return the lowest exponent such as:
	 *	     mantissa = value / 2^exponent
	 *
	 *  where mantissa < max_mantissa.
	 */
	if (val <= max_mantissa)
		return 0;

	while ((val >> exp) > max_mantissa) {
		exp++;

		if (exp > max_exp)
			return max_exp;
	}

	return exp;
}

static ssize_t isl29501_write_ext(struct iio_dev *indio_dev,
				  uintptr_t private,
				  const struct iio_chan_spec *chan,
				  const char *buf, size_t len)
{
	struct isl29501_private *isl29501 = iio_priv(indio_dev);
	enum isl29501_register_name reg = private;
	unsigned int val;
	int max_exp = 0;
	int ret;
	int i;

	ret = kstrtouint(buf, 10, &val);
	if (ret)
		return ret;

	switch (reg) {
	case REG_GAIN_BIAS:
		if (val > U16_MAX)
			return -ERANGE;

		ret = isl29501_register_write(isl29501, reg, val);
		if (ret < 0)
			return ret;

		break;
	case REG_CALIB_PHASE_TEMP_A:
	case REG_CALIB_PHASE_TEMP_B:
	case REG_CALIB_PHASE_LIGHT_A:
	case REG_CALIB_PHASE_LIGHT_B:

		if (val > (U8_MAX << ISL29501_MAX_EXP_VAL))
			return -ERANGE;

		/* Store the correction coefficient under its exact form. */
		ret = isl29501_set_shadow_coeff(isl29501, reg, val);
		if (ret < 0)
			return ret;

		/*
		 * Find the highest exponent needed to represent
		 * correction coefficients.
		 */
		for (i = 0; i < COEFF_MAX; i++) {
			int corr;
			int corr_exp;

			corr = isl29501->shadow_coeffs[i];
			corr_exp = isl29501_find_corr_exp(corr,
							  ISL29501_MAX_EXP_VAL,
							  U8_MAX / 2);
			dev_dbg(&isl29501->client->dev,
				"found exp of corr(%d) = %d\n", corr, corr_exp);

			max_exp = max(max_exp, corr_exp);
		}

		/*
		 * Represent every correction coefficient under
		 * mantissa * 2^max_exponent form and force the
		 * writing of those coefficients on the sensor.
		 */
		for (i = 0; i < COEFF_MAX; i++) {
			int corr;
			int mantissa;

			corr = isl29501->shadow_coeffs[i];
			if (!corr)
				continue;

			mantissa = corr >> max_exp;

			ret = isl29501_write_coeff(isl29501, i, mantissa);
			if (ret < 0)
				return ret;
		}

		ret = isl29501_register_write(isl29501, REG_PHASE_EXP, max_exp);
		if (ret < 0)
			return ret;

		break;
	default:
		return -EINVAL;
	}

	return len;
}

#define _ISL29501_EXT_INFO(_name, _ident) { \
	.name = _name, \
	.read = isl29501_read_ext, \
	.write = isl29501_write_ext, \
	.private = _ident, \
	.shared = IIO_SEPARATE, \
}

static const struct iio_chan_spec_ext_info isl29501_ext_info[] = {
	_ISL29501_EXT_INFO("agc_gain", REG_GAIN),
	_ISL29501_EXT_INFO("agc_gain_bias", REG_GAIN_BIAS),
	_ISL29501_EXT_INFO("calib_phase_temp_a", REG_CALIB_PHASE_TEMP_A),
	_ISL29501_EXT_INFO("calib_phase_temp_b", REG_CALIB_PHASE_TEMP_B),
	_ISL29501_EXT_INFO("calib_phase_light_a", REG_CALIB_PHASE_LIGHT_A),
	_ISL29501_EXT_INFO("calib_phase_light_b", REG_CALIB_PHASE_LIGHT_B),
	{ },
};

#define ISL29501_DISTANCE_SCAN_INDEX 0
#define ISL29501_TIMESTAMP_SCAN_INDEX 1

static const struct iio_chan_spec isl29501_channels[] = {
	{
		.type = IIO_PROXIMITY,
		.scan_index = ISL29501_DISTANCE_SCAN_INDEX,
		.info_mask_separate =
			BIT(IIO_CHAN_INFO_RAW)   |
			BIT(IIO_CHAN_INFO_SCALE) |
			BIT(IIO_CHAN_INFO_CALIBBIAS),
		.scan_type = {
			.sign = 'u',
			.realbits = 16,
			.storagebits = 16,
			.endianness = IIO_CPU,
		},
		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME) |
				BIT(IIO_CHAN_INFO_SAMP_FREQ),
		.ext_info = isl29501_ext_info,
	},
	{
		.type = IIO_PHASE,
		.scan_index = -1,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				BIT(IIO_CHAN_INFO_SCALE),
	},
	{
		.type = IIO_CURRENT,
		.scan_index = -1,
		.output = 1,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				BIT(IIO_CHAN_INFO_SCALE),
	},
	{
		.type = IIO_TEMP,
		.scan_index = -1,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				BIT(IIO_CHAN_INFO_SCALE)     |
				BIT(IIO_CHAN_INFO_CALIBBIAS),
	},
	{
		.type = IIO_INTENSITY,
		.scan_index = -1,
		.modified = 1,
		.channel2 = IIO_MOD_LIGHT_CLEAR,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				BIT(IIO_CHAN_INFO_SCALE),
	},
	IIO_CHAN_SOFT_TIMESTAMP(ISL29501_TIMESTAMP_SCAN_INDEX),
};

static int isl29501_reset_registers(struct isl29501_private *isl29501)
{
	int ret;

	ret = i2c_smbus_write_byte_data(isl29501->client,
					ISL29501_COMMAND_REGISTER,
					ISL29501_RESET_ALL_REGISTERS);
	if (ret < 0) {
		dev_err(&isl29501->client->dev,
			"cannot reset registers %d\n", ret);
		return ret;
	}

	ret = i2c_smbus_write_byte_data(isl29501->client,
					ISL29501_COMMAND_REGISTER,
					ISL29501_RESET_INT_SM);
	if (ret < 0)
		dev_err(&isl29501->client->dev,
			"cannot reset state machine %d\n", ret);

	return ret;
}

static int isl29501_begin_acquisition(struct isl29501_private *isl29501)
{
	int ret;

	ret = i2c_smbus_write_byte_data(isl29501->client,
					ISL29501_COMMAND_REGISTER,
					ISL29501_EMUL_SAMPLE_START_PIN);
	if (ret < 0)
		dev_err(&isl29501->client->dev,
			"cannot begin acquisition %d\n", ret);

	return ret;
}

static IIO_CONST_ATTR_INT_TIME_AVAIL(ISL29501_INT_TIME_AVAILABLE);
static IIO_CONST_ATTR(out_current_scale_available,
		      ISL29501_CURRENT_SCALE_AVAILABLE);

static struct attribute *isl29501_attributes[] = {
	&iio_const_attr_integration_time_available.dev_attr.attr,
	&iio_const_attr_out_current_scale_available.dev_attr.attr,
	NULL
};

static const struct attribute_group isl29501_attribute_group = {
	.attrs = isl29501_attributes,
};

static const int isl29501_current_scale_table[][2] = {
	{0, 3900}, {0, 7800}, {0, 11800}, {0, 15700},
	{0, 19600}, {0, 23500}, {0, 27500}, {0, 31400},
	{0, 35200}, {0, 39200}, {0, 43100}, {0, 47100},
	{0, 51000}, {0, 54900}, {0, 58800},
};

static const int isl29501_int_time[][2] = {
	{0, 70},    /* 0.07 ms */
	{0, 140},   /* 0.14 ms */
	{0, 280},   /* 0.28 ms */
	{0, 570},   /* 0.57 ms */
	{0, 1140},  /* 1.14 ms */
	{0, 2280},  /* 2.28 ms */
	{0, 4550},  /* 4.55 ms */
	{0, 9100},  /* 9.11 ms */
	{0, 18200}, /* 18.2 ms */
	{0, 36400}, /* 36.4 ms */
	{0, 72810}, /* 72.81 ms */
	{0, 145610} /* 145.28 ms */
};

static int isl29501_get_raw(struct isl29501_private *isl29501,
			    const struct iio_chan_spec *chan,
			    int *raw)
{
	int ret;

	switch (chan->type) {
	case IIO_PROXIMITY:
		ret = isl29501_register_read(isl29501, REG_DISTANCE, raw);
		if (ret < 0)
			return ret;

		return IIO_VAL_INT;
	case IIO_INTENSITY:
		ret = isl29501_register_read(isl29501,
					     REG_AMBIENT_LIGHT,
					     raw);
		if (ret < 0)
			return ret;

		return IIO_VAL_INT;
	case IIO_PHASE:
		ret = isl29501_register_read(isl29501, REG_PHASE, raw);
		if (ret < 0)
			return ret;

		return IIO_VAL_INT;
	case IIO_CURRENT:
		ret = isl29501_register_read(isl29501, REG_EMITTER_DAC, raw);
		if (ret < 0)
			return ret;

		return IIO_VAL_INT;
	case IIO_TEMP:
		ret = isl29501_register_read(isl29501, REG_TEMPERATURE, raw);
		if (ret < 0)
			return ret;

		return IIO_VAL_INT;
	default:
		return -EINVAL;
	}
}

static int isl29501_get_scale(struct isl29501_private *isl29501,
			      const struct iio_chan_spec *chan,
			      int *val, int *val2)
{
	int ret;
	u32 current_scale;

	switch (chan->type) {
	case IIO_PROXIMITY:
		/* distance = raw_distance * 33.31 / 65536 (m) */
		*val = 3331;
		*val2 = 6553600;

		return IIO_VAL_FRACTIONAL;
	case IIO_PHASE:
		/* phase = raw_phase * 2pi / 65536 (rad) */
		*val = 0;
		*val2 = 95874;

		return IIO_VAL_INT_PLUS_NANO;
	case IIO_INTENSITY:
		/* light = raw_light * 35 / 10000 (mA) */
		*val = 35;
		*val2 = 10000;

		return IIO_VAL_FRACTIONAL;
	case IIO_CURRENT:
		ret = isl29501_register_read(isl29501,
					     REG_DRIVER_RANGE,
					     &current_scale);
		if (ret < 0)
			return ret;

		if (current_scale > ARRAY_SIZE(isl29501_current_scale_table))
			return -EINVAL;

		if (!current_scale) {
			*val = 0;
			*val2 = 0;
			return IIO_VAL_INT;
		}

		*val = isl29501_current_scale_table[current_scale - 1][0];
		*val2 = isl29501_current_scale_table[current_scale - 1][1];

		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_TEMP:
		/* temperature = raw_temperature * 125 / 100000 (milli °C) */
		*val = 125;
		*val2 = 100000;

		return IIO_VAL_FRACTIONAL;
	default:
		return -EINVAL;
	}
}

static int isl29501_get_calibbias(struct isl29501_private *isl29501,
				  const struct iio_chan_spec *chan,
				  int *bias)
{
	switch (chan->type) {
	case IIO_PROXIMITY:
		return isl29501_register_read(isl29501,
					      REG_DISTANCE_BIAS,
					      bias);
	case IIO_TEMP:
		return isl29501_register_read(isl29501,
					      REG_TEMPERATURE_BIAS,
					      bias);
	default:
		return -EINVAL;
	}
}

static int isl29501_get_inttime(struct isl29501_private *isl29501,
				int *val, int *val2)
{
	int ret;
	u32 inttime;

	ret = isl29501_register_read(isl29501, REG_INT_TIME, &inttime);
	if (ret < 0)
		return ret;

	if (inttime >= ARRAY_SIZE(isl29501_int_time))
		return -EINVAL;

	*val = isl29501_int_time[inttime][0];
	*val2 = isl29501_int_time[inttime][1];

	return IIO_VAL_INT_PLUS_MICRO;
}

static int isl29501_get_freq(struct isl29501_private *isl29501,
			     int *val, int *val2)
{
	int ret;
	int sample_time;
	unsigned long long freq;
	u32 temp;

	ret = isl29501_register_read(isl29501, REG_SAMPLE_TIME, &sample_time);
	if (ret < 0)
		return ret;

	/* freq = 1 / (0.000450 * (sample_time + 1) * 10^-6) */
	freq = 1000000ULL * 1000000ULL;

	do_div(freq, 450 * (sample_time + 1));

	temp = do_div(freq, 1000000);
	*val = freq;
	*val2 = temp;

	return IIO_VAL_INT_PLUS_MICRO;
}

static int isl29501_read_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan, int *val,
			     int *val2, long mask)
{
	struct isl29501_private *isl29501 = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		return isl29501_get_raw(isl29501, chan, val);
	case IIO_CHAN_INFO_SCALE:
		return isl29501_get_scale(isl29501, chan, val, val2);
	case IIO_CHAN_INFO_INT_TIME:
		return isl29501_get_inttime(isl29501, val, val2);
	case IIO_CHAN_INFO_SAMP_FREQ:
		return isl29501_get_freq(isl29501, val, val2);
	case IIO_CHAN_INFO_CALIBBIAS:
		return isl29501_get_calibbias(isl29501, chan, val);
	default:
		return -EINVAL;
	}
}

static int isl29501_set_raw(struct isl29501_private *isl29501,
			    const struct iio_chan_spec *chan,
			    int raw)
{
	switch (chan->type) {
	case IIO_CURRENT:
		return isl29501_register_write(isl29501, REG_EMITTER_DAC, raw);
	default:
		return -EINVAL;
	}
}

static int isl29501_set_inttime(struct isl29501_private *isl29501,
				int val, int val2)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(isl29501_int_time); i++) {
		if (isl29501_int_time[i][0] == val &&
		    isl29501_int_time[i][1] == val2) {
			return isl29501_register_write(isl29501,
						       REG_INT_TIME,
						       i);
		}
	}

	return -EINVAL;
}

static int isl29501_set_scale(struct isl29501_private *isl29501,
			      const struct iio_chan_spec *chan,
			      int val, int val2)
{
	int i;

	if (chan->type != IIO_CURRENT)
		return -EINVAL;

	for (i = 0; i < ARRAY_SIZE(isl29501_current_scale_table); i++) {
		if (isl29501_current_scale_table[i][0] == val &&
		    isl29501_current_scale_table[i][1] == val2) {
			return isl29501_register_write(isl29501,
						       REG_DRIVER_RANGE,
						       i + 1);
		}
	}

	return -EINVAL;
}

static int isl29501_set_calibbias(struct isl29501_private *isl29501,
				  const struct iio_chan_spec *chan,
				  int bias)
{
	switch (chan->type) {
	case IIO_PROXIMITY:
		return isl29501_register_write(isl29501,
					      REG_DISTANCE_BIAS,
					      bias);
	case IIO_TEMP:
		return isl29501_register_write(isl29501,
					       REG_TEMPERATURE_BIAS,
					       bias);
	default:
		return -EINVAL;
	}
}

static int isl29501_set_freq(struct isl29501_private *isl29501,
			     int val, int val2)
{
	int freq;
	unsigned long long sample_time;

	/* sample_freq = 1 / (0.000450 * (sample_time + 1) * 10^-6) */
	freq = val * 1000000 + val2 % 1000000;
	sample_time = 2222ULL * 1000000ULL;
	do_div(sample_time, freq);

	sample_time -= 1;

	if (sample_time > 255)
		return -ERANGE;

	return isl29501_register_write(isl29501, REG_SAMPLE_TIME, sample_time);
}

static int isl29501_write_raw(struct iio_dev *indio_dev,
			      struct iio_chan_spec const *chan,
			      int val, int val2, long mask)
{
	struct isl29501_private *isl29501 = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		return isl29501_set_raw(isl29501, chan, val);
	case IIO_CHAN_INFO_INT_TIME:
		return isl29501_set_inttime(isl29501, val, val2);
	case IIO_CHAN_INFO_SAMP_FREQ:
		return isl29501_set_freq(isl29501, val, val2);
	case IIO_CHAN_INFO_SCALE:
		return isl29501_set_scale(isl29501, chan, val, val2);
	case IIO_CHAN_INFO_CALIBBIAS:
		return isl29501_set_calibbias(isl29501, chan, val);
	default:
		return -EINVAL;
	}
}

static const struct iio_info isl29501_info = {
	.read_raw = &isl29501_read_raw,
	.write_raw = &isl29501_write_raw,
	.attrs = &isl29501_attribute_group,
};

static int isl29501_init_chip(struct isl29501_private *isl29501)
{
	int ret;

	ret = i2c_smbus_read_byte_data(isl29501->client, ISL29501_DEVICE_ID);
	if (ret < 0) {
		dev_err(&isl29501->client->dev, "Error reading device id\n");
		return ret;
	}

	if (ret != ISL29501_ID) {
		dev_err(&isl29501->client->dev,
			"Wrong chip id, got %x expected %x\n",
			ret, ISL29501_DEVICE_ID);
		return -ENODEV;
	}

	ret = isl29501_reset_registers(isl29501);
	if (ret < 0)
		return ret;

	return isl29501_begin_acquisition(isl29501);
}

static irqreturn_t isl29501_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct isl29501_private *isl29501 = iio_priv(indio_dev);
	const unsigned long *active_mask = indio_dev->active_scan_mask;
	u32 buffer[4] __aligned(8) = {}; /* 1x16-bit + naturally aligned ts */

	if (test_bit(ISL29501_DISTANCE_SCAN_INDEX, active_mask))
		isl29501_register_read(isl29501, REG_DISTANCE, buffer);

	iio_push_to_buffers_with_timestamp(indio_dev, buffer, pf->timestamp);
	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
}

static int isl29501_probe(struct i2c_client *client,
			  const struct i2c_device_id *id)
{
	struct iio_dev *indio_dev;
	struct isl29501_private *isl29501;
	int ret;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*isl29501));
	if (!indio_dev)
		return -ENOMEM;

	isl29501 = iio_priv(indio_dev);

	i2c_set_clientdata(client, indio_dev);
	isl29501->client = client;

	mutex_init(&isl29501->lock);

	ret = isl29501_init_chip(isl29501);
	if (ret < 0)
		return ret;

	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->dev.parent = &client->dev;
	indio_dev->channels = isl29501_channels;
	indio_dev->num_channels = ARRAY_SIZE(isl29501_channels);
	indio_dev->name = client->name;
	indio_dev->info = &isl29501_info;

	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev,
					      iio_pollfunc_store_time,
					      isl29501_trigger_handler,
					      NULL);
	if (ret < 0) {
		dev_err(&client->dev, "unable to setup iio triggered buffer\n");
		return ret;
	}

	return devm_iio_device_register(&client->dev, indio_dev);
}

static const struct i2c_device_id isl29501_id[] = {
	{"isl29501", 0},
	{}
};

MODULE_DEVICE_TABLE(i2c, isl29501_id);

#if defined(CONFIG_OF)
static const struct of_device_id isl29501_i2c_matches[] = {
	{ .compatible = "renesas,isl29501" },
	{ }
};
MODULE_DEVICE_TABLE(of, isl29501_i2c_matches);
#endif

static struct i2c_driver isl29501_driver = {
	.driver = {
		.name	= "isl29501",
	},
	.id_table	= isl29501_id,
	.probe		= isl29501_probe,
};
module_i2c_driver(isl29501_driver);

MODULE_AUTHOR("Mathieu Othacehe <m.othacehe@gmail.com>");
MODULE_DESCRIPTION("ISL29501 Time of Flight sensor driver");
MODULE_LICENSE("GPL v2");