path: root/drivers/iio/adc/ad7606.c

// SPDX-License-Identifier: GPL-2.0
/*
 * AD7606 SPI ADC driver
 *
 * Copyright 2011 Analog Devices Inc.
 */

#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/pwm.h>
#include <linux/regulator/consumer.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/units.h>
#include <linux/util_macros.h>

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

#include "ad7606.h"

/*
 * Scales are computed as 5000/32768 and 10000/32768 respectively,
 * so that when applied to the raw values they provide mV values.
 * The scale arrays are kept as IIO_VAL_INT_PLUS_MICRO, so index
 * X is the integer part and X + 1 is the fractional part.
 */
static const unsigned int ad7606_16bit_hw_scale_avail[2][2] = {
	{ 0, 152588 }, { 0, 305176 }
};

static const unsigned int ad7606_18bit_hw_scale_avail[2][2] = {
	{ 0, 38147 }, { 0, 76294 }
};

static const unsigned int ad7606c_16bit_single_ended_unipolar_scale_avail[3][2] = {
	{ 0, 76294 }, { 0, 152588 }, { 0, 190735 }
};

static const unsigned int ad7606c_16bit_single_ended_bipolar_scale_avail[5][2] = {
	{ 0, 76294 }, { 0, 152588 }, { 0, 190735 }, { 0, 305176 }, { 0, 381470 }
};

static const unsigned int ad7606c_16bit_differential_bipolar_scale_avail[4][2] = {
	{ 0, 152588 }, { 0, 305176 }, { 0, 381470 }, { 0, 610352 }
};

static const unsigned int ad7606c_18bit_single_ended_unipolar_scale_avail[3][2] = {
	{ 0, 19073 }, { 0, 38147 }, { 0, 47684 }
};

static const unsigned int ad7606c_18bit_single_ended_bipolar_scale_avail[5][2] = {
	{ 0, 19073 }, { 0, 38147 }, { 0, 47684 }, { 0, 76294 }, { 0, 95367 }
};

static const unsigned int ad7606c_18bit_differential_bipolar_scale_avail[4][2] = {
	{ 0, 38147 }, { 0, 76294 }, { 0, 95367 }, { 0, 152588 }
};

static const unsigned int ad7606_16bit_sw_scale_avail[3][2] = {
	{ 0, 76293 }, { 0, 152588 }, { 0, 305176 }
};

static const unsigned int ad7607_hw_scale_avail[2][2] = {
	{ 0, 610352 }, { 1, 220703 }
};

static const unsigned int ad7609_hw_scale_avail[2][2] = {
	{ 0, 152588 }, { 0, 305176 }
};

static const unsigned int ad7606_oversampling_avail[7] = {
	1, 2, 4, 8, 16, 32, 64,
};

static const unsigned int ad7616_oversampling_avail[8] = {
	1, 2, 4, 8, 16, 32, 64, 128,
};

static const struct iio_chan_spec ad7605_channels[] = {
	IIO_CHAN_SOFT_TIMESTAMP(4),
	AD7605_CHANNEL(0),
	AD7605_CHANNEL(1),
	AD7605_CHANNEL(2),
	AD7605_CHANNEL(3),
};

static const struct iio_chan_spec ad7606_channels_16bit[] = {
	IIO_CHAN_SOFT_TIMESTAMP(8),
	AD7606_CHANNEL(0, 16),
	AD7606_CHANNEL(1, 16),
	AD7606_CHANNEL(2, 16),
	AD7606_CHANNEL(3, 16),
	AD7606_CHANNEL(4, 16),
	AD7606_CHANNEL(5, 16),
	AD7606_CHANNEL(6, 16),
	AD7606_CHANNEL(7, 16),
};

static const struct iio_chan_spec ad7606_channels_18bit[] = {
	IIO_CHAN_SOFT_TIMESTAMP(8),
	AD7606_CHANNEL(0, 18),
	AD7606_CHANNEL(1, 18),
	AD7606_CHANNEL(2, 18),
	AD7606_CHANNEL(3, 18),
	AD7606_CHANNEL(4, 18),
	AD7606_CHANNEL(5, 18),
	AD7606_CHANNEL(6, 18),
	AD7606_CHANNEL(7, 18),
};

static const struct iio_chan_spec ad7607_channels[] = {
	IIO_CHAN_SOFT_TIMESTAMP(8),
	AD7606_CHANNEL(0, 14),
	AD7606_CHANNEL(1, 14),
	AD7606_CHANNEL(2, 14),
	AD7606_CHANNEL(3, 14),
	AD7606_CHANNEL(4, 14),
	AD7606_CHANNEL(5, 14),
	AD7606_CHANNEL(6, 14),
	AD7606_CHANNEL(7, 14),
};

static const struct iio_chan_spec ad7608_channels[] = {
	IIO_CHAN_SOFT_TIMESTAMP(8),
	AD7606_CHANNEL(0, 18),
	AD7606_CHANNEL(1, 18),
	AD7606_CHANNEL(2, 18),
	AD7606_CHANNEL(3, 18),
	AD7606_CHANNEL(4, 18),
	AD7606_CHANNEL(5, 18),
	AD7606_CHANNEL(6, 18),
	AD7606_CHANNEL(7, 18),
};

/*
 * The current assumption that this driver makes for AD7616, is that it's
 * working in Hardware Mode with Serial, Burst and Sequencer modes activated.
 * To activate them, following pins must be pulled high:
 *	-SER/PAR
 *	-SEQEN
 * And following pins must be pulled low:
 *	-WR/BURST
 *	-DB4/SER1W
 */
static const struct iio_chan_spec ad7616_channels[] = {
	IIO_CHAN_SOFT_TIMESTAMP(16),
	AD7606_CHANNEL(0, 16),
	AD7606_CHANNEL(1, 16),
	AD7606_CHANNEL(2, 16),
	AD7606_CHANNEL(3, 16),
	AD7606_CHANNEL(4, 16),
	AD7606_CHANNEL(5, 16),
	AD7606_CHANNEL(6, 16),
	AD7606_CHANNEL(7, 16),
	AD7606_CHANNEL(8, 16),
	AD7606_CHANNEL(9, 16),
	AD7606_CHANNEL(10, 16),
	AD7606_CHANNEL(11, 16),
	AD7606_CHANNEL(12, 16),
	AD7606_CHANNEL(13, 16),
	AD7606_CHANNEL(14, 16),
	AD7606_CHANNEL(15, 16),
};

static int ad7606c_18bit_chan_scale_setup(struct ad7606_state *st,
					  struct iio_chan_spec *chan, int ch);
static int ad7606c_16bit_chan_scale_setup(struct ad7606_state *st,
					  struct iio_chan_spec *chan, int ch);
static int ad7606_16bit_chan_scale_setup(struct ad7606_state *st,
					 struct iio_chan_spec *chan, int ch);
static int ad7607_chan_scale_setup(struct ad7606_state *st,
				   struct iio_chan_spec *chan, int ch);
static int ad7608_chan_scale_setup(struct ad7606_state *st,
				   struct iio_chan_spec *chan, int ch);
static int ad7609_chan_scale_setup(struct ad7606_state *st,
				   struct iio_chan_spec *chan, int ch);

const struct ad7606_chip_info ad7605_4_info = {
	.channels = ad7605_channels,
	.name = "ad7605-4",
	.num_adc_channels = 4,
	.num_channels = 5,
	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7605_4_info, IIO_AD7606);

const struct ad7606_chip_info ad7606_8_info = {
	.channels = ad7606_channels_16bit,
	.name = "ad7606-8",
	.num_adc_channels = 8,
	.num_channels = 9,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7606_8_info, IIO_AD7606);

const struct ad7606_chip_info ad7606_6_info = {
	.channels = ad7606_channels_16bit,
	.name = "ad7606-6",
	.num_adc_channels = 6,
	.num_channels = 7,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7606_6_info, IIO_AD7606);

const struct ad7606_chip_info ad7606_4_info = {
	.channels = ad7606_channels_16bit,
	.name = "ad7606-4",
	.num_adc_channels = 4,
	.num_channels = 5,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7606_4_info, IIO_AD7606);

const struct ad7606_chip_info ad7606b_info = {
	.channels = ad7606_channels_16bit,
	.max_samplerate = 800 * KILO,
	.name = "ad7606b",
	.num_adc_channels = 8,
	.num_channels = 9,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7606b_info, IIO_AD7606);

const struct ad7606_chip_info ad7606c_16_info = {
	.channels = ad7606_channels_16bit,
	.name = "ad7606c16",
	.num_adc_channels = 8,
	.num_channels = 9,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7606c_16bit_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7606c_16_info, IIO_AD7606);

const struct ad7606_chip_info ad7607_info = {
	.channels = ad7607_channels,
	.name = "ad7607",
	.num_adc_channels = 8,
	.num_channels = 9,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7607_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7607_info, IIO_AD7606);

const struct ad7606_chip_info ad7608_info = {
	.channels = ad7608_channels,
	.name = "ad7608",
	.num_adc_channels = 8,
	.num_channels = 9,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7608_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7608_info, IIO_AD7606);

const struct ad7606_chip_info ad7609_info = {
	.channels = ad7608_channels,
	.name = "ad7609",
	.num_adc_channels = 8,
	.num_channels = 9,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7609_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7609_info, IIO_AD7606);

const struct ad7606_chip_info ad7606c_18_info = {
	.channels = ad7606_channels_18bit,
	.name = "ad7606c18",
	.num_adc_channels = 8,
	.num_channels = 9,
	.oversampling_avail = ad7606_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
	.scale_setup_cb = ad7606c_18bit_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7606c_18_info, IIO_AD7606);

const struct ad7606_chip_info ad7616_info = {
	.channels = ad7616_channels,
	.init_delay_ms = 15,
	.name = "ad7616",
	.num_adc_channels = 16,
	.num_channels = 17,
	.oversampling_avail = ad7616_oversampling_avail,
	.oversampling_num = ARRAY_SIZE(ad7616_oversampling_avail),
	.os_req_reset = true,
	.scale_setup_cb = ad7606_16bit_chan_scale_setup,
};
EXPORT_SYMBOL_NS_GPL(ad7616_info, IIO_AD7606);

int ad7606_reset(struct ad7606_state *st)
{
	if (st->gpio_reset) {
		gpiod_set_value(st->gpio_reset, 1);
		ndelay(100); /* t_reset >= 100ns */
		gpiod_set_value(st->gpio_reset, 0);
		return 0;
	}

	return -ENODEV;
}
EXPORT_SYMBOL_NS_GPL(ad7606_reset, IIO_AD7606);

static int ad7606_16bit_chan_scale_setup(struct ad7606_state *st,
					 struct iio_chan_spec *chan, int ch)
{
	struct ad7606_chan_scale *cs = &st->chan_scales[ch];

	if (!st->sw_mode_en) {
		/* tied to logic low, analog input range is +/- 5V */
		cs->range = 0;
		cs->scale_avail = ad7606_16bit_hw_scale_avail;
		cs->num_scales = ARRAY_SIZE(ad7606_16bit_hw_scale_avail);
		return 0;
	}

	/* Scale of 0.076293 is only available in sw mode */
	/* After reset, in software mode, ±10 V is set by default */
	cs->range = 2;
	cs->scale_avail = ad7606_16bit_sw_scale_avail;
	cs->num_scales = ARRAY_SIZE(ad7606_16bit_sw_scale_avail);

	return 0;
}

static int ad7606_get_chan_config(struct ad7606_state *st, int ch,
				  bool *bipolar, bool *differential)
{
	unsigned int num_channels = st->chip_info->num_channels - 1;
	struct device *dev = st->dev;
	int ret;

	*bipolar = false;
	*differential = false;

	device_for_each_child_node_scoped(dev, child) {
		u32 pins[2];
		int reg;

		ret = fwnode_property_read_u32(child, "reg", &reg);
		if (ret)
			continue;

		/* channel number (here) is from 1 to num_channels */
		if (reg == 0 || reg > num_channels) {
			dev_warn(dev,
				 "Invalid channel number (ignoring): %d\n", reg);
			continue;
		}

		if (reg != (ch + 1))
			continue;

		*bipolar = fwnode_property_read_bool(child, "bipolar");

		ret = fwnode_property_read_u32_array(child, "diff-channels",
						     pins, ARRAY_SIZE(pins));
		/* Channel is differential, if pins are the same as 'reg' */
		if (ret == 0 && (pins[0] != reg || pins[1] != reg)) {
			dev_err(dev,
				"Differential pins must be the same as 'reg'");
			return -EINVAL;
		}

		*differential = (ret == 0);

		if (*differential && !*bipolar) {
			dev_err(dev,
				"'bipolar' must be added for diff channel %d\n",
				reg);
			return -EINVAL;
		}

		return 0;
	}

	return 0;
}

static int ad7606c_18bit_chan_scale_setup(struct ad7606_state *st,
					  struct iio_chan_spec *chan, int ch)
{
	struct ad7606_chan_scale *cs = &st->chan_scales[ch];
	bool bipolar, differential;
	int ret;

	if (!st->sw_mode_en) {
		cs->range = 0;
		cs->scale_avail = ad7606_18bit_hw_scale_avail;
		cs->num_scales = ARRAY_SIZE(ad7606_18bit_hw_scale_avail);
		return 0;
	}

	ret = ad7606_get_chan_config(st, ch, &bipolar, &differential);
	if (ret)
		return ret;

	if (differential) {
		cs->scale_avail = ad7606c_18bit_differential_bipolar_scale_avail;
		cs->num_scales =
			ARRAY_SIZE(ad7606c_18bit_differential_bipolar_scale_avail);
		/* Bipolar differential ranges start at 8 (b1000) */
		cs->reg_offset = 8;
		cs->range = 1;
		chan->differential = 1;
		chan->channel2 = chan->channel;

		return 0;
	}

	chan->differential = 0;

	if (bipolar) {
		cs->scale_avail = ad7606c_18bit_single_ended_bipolar_scale_avail;
		cs->num_scales =
			ARRAY_SIZE(ad7606c_18bit_single_ended_bipolar_scale_avail);
		/* Bipolar single-ended ranges start at 0 (b0000) */
		cs->reg_offset = 0;
		cs->range = 3;
		chan->scan_type.sign = 's';

		return 0;
	}

	cs->scale_avail = ad7606c_18bit_single_ended_unipolar_scale_avail;
	cs->num_scales =
		ARRAY_SIZE(ad7606c_18bit_single_ended_unipolar_scale_avail);
	/* Unipolar single-ended ranges start at 5 (b0101) */
	cs->reg_offset = 5;
	cs->range = 1;
	chan->scan_type.sign = 'u';

	return 0;
}

static int ad7606c_16bit_chan_scale_setup(struct ad7606_state *st,
					  struct iio_chan_spec *chan, int ch)
{
	struct ad7606_chan_scale *cs = &st->chan_scales[ch];
	bool bipolar, differential;
	int ret;

	if (!st->sw_mode_en) {
		cs->range = 0;
		cs->scale_avail = ad7606_16bit_hw_scale_avail;
		cs->num_scales = ARRAY_SIZE(ad7606_16bit_hw_scale_avail);
		return 0;
	}

	ret = ad7606_get_chan_config(st, ch, &bipolar, &differential);
	if (ret)
		return ret;

	if (differential) {
		cs->scale_avail = ad7606c_16bit_differential_bipolar_scale_avail;
		cs->num_scales =
			ARRAY_SIZE(ad7606c_16bit_differential_bipolar_scale_avail);
		/* Bipolar differential ranges start at 8 (b1000) */
		cs->reg_offset = 8;
		cs->range = 1;
		chan->differential = 1;
		chan->channel2 = chan->channel;
		chan->scan_type.sign = 's';

		return 0;
	}

	chan->differential = 0;

	if (bipolar) {
		cs->scale_avail = ad7606c_16bit_single_ended_bipolar_scale_avail;
		cs->num_scales =
			ARRAY_SIZE(ad7606c_16bit_single_ended_bipolar_scale_avail);
		/* Bipolar single-ended ranges start at 0 (b0000) */
		cs->reg_offset = 0;
		cs->range = 3;
		chan->scan_type.sign = 's';

		return 0;
	}

	cs->scale_avail = ad7606c_16bit_single_ended_unipolar_scale_avail;
	cs->num_scales =
		ARRAY_SIZE(ad7606c_16bit_single_ended_unipolar_scale_avail);
	/* Unipolar single-ended ranges start at 5 (b0101) */
	cs->reg_offset = 5;
	cs->range = 1;
	chan->scan_type.sign = 'u';

	return 0;
}

static int ad7607_chan_scale_setup(struct ad7606_state *st,
				   struct iio_chan_spec *chan, int ch)
{
	struct ad7606_chan_scale *cs = &st->chan_scales[ch];

	cs->range = 0;
	cs->scale_avail = ad7607_hw_scale_avail;
	cs->num_scales = ARRAY_SIZE(ad7607_hw_scale_avail);
	return 0;
}

static int ad7608_chan_scale_setup(struct ad7606_state *st,
				   struct iio_chan_spec *chan, int ch)
{
	struct ad7606_chan_scale *cs = &st->chan_scales[ch];

	cs->range = 0;
	cs->scale_avail = ad7606_18bit_hw_scale_avail;
	cs->num_scales = ARRAY_SIZE(ad7606_18bit_hw_scale_avail);
	return 0;
}

static int ad7609_chan_scale_setup(struct ad7606_state *st,
				   struct iio_chan_spec *chan, int ch)
{
	struct ad7606_chan_scale *cs = &st->chan_scales[ch];

	cs->range = 0;
	cs->scale_avail = ad7609_hw_scale_avail;
	cs->num_scales = ARRAY_SIZE(ad7609_hw_scale_avail);
	return 0;
}

static int ad7606_reg_access(struct iio_dev *indio_dev,
			     unsigned int reg,
			     unsigned int writeval,
			     unsigned int *readval)
{
	struct ad7606_state *st = iio_priv(indio_dev);
	int ret;

	guard(mutex)(&st->lock);

	if (readval) {
		ret = st->bops->reg_read(st, reg);
		if (ret < 0)
			return ret;
		*readval = ret;
		return 0;
	} else {
		return st->bops->reg_write(st, reg, writeval);
	}
}

static int ad7606_pwm_set_high(struct ad7606_state *st)
{
	struct pwm_state cnvst_pwm_state;
	int ret;

	pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
	cnvst_pwm_state.enabled = true;
	cnvst_pwm_state.duty_cycle = cnvst_pwm_state.period;

	ret = pwm_apply_might_sleep(st->cnvst_pwm, &cnvst_pwm_state);

	return ret;
}

static int ad7606_pwm_set_low(struct ad7606_state *st)
{
	struct pwm_state cnvst_pwm_state;
	int ret;

	pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
	cnvst_pwm_state.enabled = true;
	cnvst_pwm_state.duty_cycle = 0;

	ret = pwm_apply_might_sleep(st->cnvst_pwm, &cnvst_pwm_state);

	return ret;
}

static int ad7606_pwm_set_swing(struct ad7606_state *st)
{
	struct pwm_state cnvst_pwm_state;

	pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
	cnvst_pwm_state.enabled = true;
	cnvst_pwm_state.duty_cycle = cnvst_pwm_state.period / 2;

	return pwm_apply_might_sleep(st->cnvst_pwm, &cnvst_pwm_state);
}

static bool ad7606_pwm_is_swinging(struct ad7606_state *st)
{
	struct pwm_state cnvst_pwm_state;

	pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);

	return cnvst_pwm_state.duty_cycle != cnvst_pwm_state.period &&
	       cnvst_pwm_state.duty_cycle != 0;
}

static int ad7606_set_sampling_freq(struct ad7606_state *st, unsigned long freq)
{
	struct pwm_state cnvst_pwm_state;
	bool is_swinging = ad7606_pwm_is_swinging(st);
	bool is_high;

	if (freq == 0)
		return -EINVAL;

	/* Retrieve the previous state. */
	pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
	is_high = cnvst_pwm_state.duty_cycle == cnvst_pwm_state.period;

	cnvst_pwm_state.period = DIV_ROUND_UP_ULL(NSEC_PER_SEC, freq);
	cnvst_pwm_state.polarity = PWM_POLARITY_NORMAL;
	if (is_high)
		cnvst_pwm_state.duty_cycle = cnvst_pwm_state.period;
	else if (is_swinging)
		cnvst_pwm_state.duty_cycle = cnvst_pwm_state.period / 2;
	else
		cnvst_pwm_state.duty_cycle = 0;

	return pwm_apply_might_sleep(st->cnvst_pwm, &cnvst_pwm_state);
}

static int ad7606_read_samples(struct ad7606_state *st)
{
	unsigned int num = st->chip_info->num_adc_channels;

	return st->bops->read_block(st->dev, num, &st->data);
}

static irqreturn_t ad7606_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct ad7606_state *st = iio_priv(indio_dev);
	int ret;

	guard(mutex)(&st->lock);

	ret = ad7606_read_samples(st);
	if (ret)
		goto error_ret;

	iio_push_to_buffers_with_timestamp(indio_dev, &st->data,
					   iio_get_time_ns(indio_dev));
error_ret:
	iio_trigger_notify_done(indio_dev->trig);
	/* The rising edge of the CONVST signal starts a new conversion. */
	gpiod_set_value(st->gpio_convst, 1);

	return IRQ_HANDLED;
}

static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
			      int *val)
{
	struct ad7606_state *st = iio_priv(indio_dev);
	unsigned int realbits = st->chip_info->channels[1].scan_type.realbits;
	const struct iio_chan_spec *chan;
	int ret;

	if (st->gpio_convst) {
		gpiod_set_value(st->gpio_convst, 1);
	} else {
		ret = ad7606_pwm_set_high(st);
		if (ret < 0)
			return ret;
	}

	/*
	 * If no backend, wait for the interruption on busy pin, otherwise just add
	 * a delay to leave time for the data to be available. For now, the latter
	 * will not happen because IIO_CHAN_INFO_RAW is not supported for the backend.
	 * TODO: Add support for reading a single value when the backend is used.
	 */
	if (!st->back) {
		ret = wait_for_completion_timeout(&st->completion,
						  msecs_to_jiffies(1000));
		if (!ret) {
			ret = -ETIMEDOUT;
			goto error_ret;
		}
	} else {
		fsleep(1);
	}

	ret = ad7606_read_samples(st);
	if (ret)
		goto error_ret;

	chan = &indio_dev->channels[ch + 1];
	if (chan->scan_type.sign == 'u') {
		if (realbits > 16)
			*val = st->data.buf32[ch];
		else
			*val = st->data.buf16[ch];
	} else {
		if (realbits > 16)
			*val = sign_extend32(st->data.buf32[ch], realbits - 1);
		else
			*val = sign_extend32(st->data.buf16[ch], realbits - 1);
	}

error_ret:
	if (!st->gpio_convst) {
		ret = ad7606_pwm_set_low(st);
		if (ret < 0)
			return ret;
	}
	gpiod_set_value(st->gpio_convst, 0);

	return ret;
}

static int ad7606_read_raw(struct iio_dev *indio_dev,
			   struct iio_chan_spec const *chan,
			   int *val,
			   int *val2,
			   long m)
{
	int ret, ch = 0;
	struct ad7606_state *st = iio_priv(indio_dev);
	struct ad7606_chan_scale *cs;
	struct pwm_state cnvst_pwm_state;

	switch (m) {
	case IIO_CHAN_INFO_RAW:
		iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
			ret = ad7606_scan_direct(indio_dev, chan->address, val);
			if (ret < 0)
				return ret;
			return IIO_VAL_INT;
		}
		unreachable();
	case IIO_CHAN_INFO_SCALE:
		if (st->sw_mode_en)
			ch = chan->address;
		cs = &st->chan_scales[ch];
		*val = cs->scale_avail[cs->range][0];
		*val2 = cs->scale_avail[cs->range][1];
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
		*val = st->oversampling;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SAMP_FREQ:
		/*
		 * TODO: return the real frequency intead of the requested one once
		 * pwm_get_state_hw comes upstream.
		 */
		pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
		*val = DIV_ROUND_CLOSEST_ULL(NSEC_PER_SEC, cnvst_pwm_state.period);
		return IIO_VAL_INT;
	}
	return -EINVAL;
}

static ssize_t in_voltage_scale_available_show(struct device *dev,
					       struct device_attribute *attr,
					       char *buf)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ad7606_state *st = iio_priv(indio_dev);
	struct ad7606_chan_scale *cs = &st->chan_scales[0];
	const unsigned int (*vals)[2] = cs->scale_avail;
	unsigned int i;
	size_t len = 0;

	for (i = 0; i < cs->num_scales; i++)
		len += scnprintf(buf + len, PAGE_SIZE - len, "%u.%06u ",
				 vals[i][0], vals[i][1]);
	buf[len - 1] = '\n';

	return len;
}

static IIO_DEVICE_ATTR_RO(in_voltage_scale_available, 0);

static int ad7606_write_scale_hw(struct iio_dev *indio_dev, int ch, int val)
{
	struct ad7606_state *st = iio_priv(indio_dev);

	gpiod_set_value(st->gpio_range, val);

	return 0;
}

static int ad7606_write_os_hw(struct iio_dev *indio_dev, int val)
{
	struct ad7606_state *st = iio_priv(indio_dev);
	DECLARE_BITMAP(values, 3);

	values[0] = val & GENMASK(2, 0);

	gpiod_set_array_value(st->gpio_os->ndescs, st->gpio_os->desc,
			      st->gpio_os->info, values);

	/* AD7616 requires a reset to update value */
	if (st->chip_info->os_req_reset)
		ad7606_reset(st);

	return 0;
}

static int ad7606_write_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int val,
			    int val2,
			    long mask)
{
	struct ad7606_state *st = iio_priv(indio_dev);
	unsigned int scale_avail_uv[AD760X_MAX_SCALES];
	struct ad7606_chan_scale *cs;
	int i, ret, ch = 0;

	guard(mutex)(&st->lock);

	switch (mask) {
	case IIO_CHAN_INFO_SCALE:
		if (st->sw_mode_en)
			ch = chan->address;
		cs = &st->chan_scales[ch];
		for (i = 0; i < cs->num_scales; i++) {
			scale_avail_uv[i] = cs->scale_avail[i][0] * MICRO +
					    cs->scale_avail[i][1];
		}
		val = (val * MICRO) + val2;
		i = find_closest(val, scale_avail_uv, cs->num_scales);
		ret = st->write_scale(indio_dev, ch, i + cs->reg_offset);
		if (ret < 0)
			return ret;
		cs->range = i;

		return 0;
	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
		if (val2)
			return -EINVAL;
		i = find_closest(val, st->oversampling_avail,
				 st->num_os_ratios);
		ret = st->write_os(indio_dev, i);
		if (ret < 0)
			return ret;
		st->oversampling = st->oversampling_avail[i];

		return 0;
	case IIO_CHAN_INFO_SAMP_FREQ:
		if (val < 0 && val2 != 0)
			return -EINVAL;
		return ad7606_set_sampling_freq(st, val);
	default:
		return -EINVAL;
	}
}

static ssize_t ad7606_oversampling_ratio_avail(struct device *dev,
					       struct device_attribute *attr,
					       char *buf)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct ad7606_state *st = iio_priv(indio_dev);
	const unsigned int *vals = st->oversampling_avail;
	unsigned int i;
	size_t len = 0;

	for (i = 0; i < st->num_os_ratios; i++)
		len += scnprintf(buf + len, PAGE_SIZE - len, "%u ", vals[i]);
	buf[len - 1] = '\n';

	return len;
}

static IIO_DEVICE_ATTR(oversampling_ratio_available, 0444,
		       ad7606_oversampling_ratio_avail, NULL, 0);

static struct attribute *ad7606_attributes_os_and_range[] = {
	&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
	&iio_dev_attr_oversampling_ratio_available.dev_attr.attr,
	NULL,
};

static const struct attribute_group ad7606_attribute_group_os_and_range = {
	.attrs = ad7606_attributes_os_and_range,
};

static struct attribute *ad7606_attributes_os[] = {
	&iio_dev_attr_oversampling_ratio_available.dev_attr.attr,
	NULL,
};

static const struct attribute_group ad7606_attribute_group_os = {
	.attrs = ad7606_attributes_os,
};

static struct attribute *ad7606_attributes_range[] = {
	&iio_dev_attr_in_voltage_scale_available.dev_attr.attr,
	NULL,
};

static const struct attribute_group ad7606_attribute_group_range = {
	.attrs = ad7606_attributes_range,
};

static int ad7606_request_gpios(struct ad7606_state *st)
{
	struct device *dev = st->dev;

	st->gpio_convst = devm_gpiod_get_optional(dev, "adi,conversion-start",
						  GPIOD_OUT_LOW);

	if (IS_ERR(st->gpio_convst))
		return PTR_ERR(st->gpio_convst);

	st->gpio_reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
	if (IS_ERR(st->gpio_reset))
		return PTR_ERR(st->gpio_reset);

	st->gpio_range = devm_gpiod_get_optional(dev, "adi,range",
						 GPIOD_OUT_LOW);
	if (IS_ERR(st->gpio_range))
		return PTR_ERR(st->gpio_range);

	st->gpio_standby = devm_gpiod_get_optional(dev, "standby",
						   GPIOD_OUT_LOW);
	if (IS_ERR(st->gpio_standby))
		return PTR_ERR(st->gpio_standby);

	st->gpio_frstdata = devm_gpiod_get_optional(dev, "adi,first-data",
						    GPIOD_IN);
	if (IS_ERR(st->gpio_frstdata))
		return PTR_ERR(st->gpio_frstdata);

	if (!st->chip_info->oversampling_num)
		return 0;

	st->gpio_os = devm_gpiod_get_array_optional(dev,
						    "adi,oversampling-ratio",
						    GPIOD_OUT_LOW);
	return PTR_ERR_OR_ZERO(st->gpio_os);
}

/*
 * The BUSY signal indicates when conversions are in progress, so when a rising
 * edge of CONVST is applied, BUSY goes logic high and transitions low at the
 * end of the entire conversion process. The falling edge of the BUSY signal
 * triggers this interrupt.
 */
static irqreturn_t ad7606_interrupt(int irq, void *dev_id)
{
	struct iio_dev *indio_dev = dev_id;
	struct ad7606_state *st = iio_priv(indio_dev);
	int ret;

	if (iio_buffer_enabled(indio_dev)) {
		if (st->gpio_convst) {
			gpiod_set_value(st->gpio_convst, 0);
		} else {
			ret = ad7606_pwm_set_low(st);
			if (ret < 0) {
				dev_err(st->dev, "PWM set low failed");
				goto done;
			}
		}
		iio_trigger_poll_nested(st->trig);
	} else {
		complete(&st->completion);
	}

done:
	return IRQ_HANDLED;
};

static int ad7606_validate_trigger(struct iio_dev *indio_dev,
				   struct iio_trigger *trig)
{
	struct ad7606_state *st = iio_priv(indio_dev);

	if (st->trig != trig)
		return -EINVAL;

	return 0;
}

static int ad7606_buffer_postenable(struct iio_dev *indio_dev)
{
	struct ad7606_state *st = iio_priv(indio_dev);

	gpiod_set_value(st->gpio_convst, 1);

	return 0;
}

static int ad7606_buffer_predisable(struct iio_dev *indio_dev)
{
	struct ad7606_state *st = iio_priv(indio_dev);

	gpiod_set_value(st->gpio_convst, 0);

	return 0;
}

static int ad7606_read_avail(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     const int **vals, int *type, int *length,
			     long info)
{
	struct ad7606_state *st = iio_priv(indio_dev);
	struct ad7606_chan_scale *cs;
	unsigned int ch = 0;

	switch (info) {
	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
		*vals = st->oversampling_avail;
		*length = st->num_os_ratios;
		*type = IIO_VAL_INT;

		return IIO_AVAIL_LIST;

	case IIO_CHAN_INFO_SCALE:
		if (st->sw_mode_en)
			ch = chan->address;

		cs = &st->chan_scales[ch];
		*vals = (int *)cs->scale_avail;
		*length = cs->num_scales;
		*type = IIO_VAL_INT_PLUS_MICRO;

		return IIO_AVAIL_LIST;
	}
	return -EINVAL;
}

static int ad7606_backend_buffer_postenable(struct iio_dev *indio_dev)
{
	struct ad7606_state *st = iio_priv(indio_dev);

	return ad7606_pwm_set_swing(st);
}

static int ad7606_backend_buffer_predisable(struct iio_dev *indio_dev)
{
	struct ad7606_state *st = iio_priv(indio_dev);

	return ad7606_pwm_set_low(st);
}

static int ad7606_update_scan_mode(struct iio_dev *indio_dev,
				   const unsigned long *scan_mask)
{
	struct ad7606_state *st = iio_priv(indio_dev);

	/*
	 * The update scan mode is only for iio backend compatible drivers.
	 * If the specific update_scan_mode is not defined in the bus ops,
	 * just do nothing and return 0.
	 */
	if (!st->bops->update_scan_mode)
		return 0;

	return st->bops->update_scan_mode(indio_dev, scan_mask);
}

static const struct iio_buffer_setup_ops ad7606_buffer_ops = {
	.postenable = &ad7606_buffer_postenable,
	.predisable = &ad7606_buffer_predisable,
};

static const struct iio_buffer_setup_ops ad7606_backend_buffer_ops = {
	.postenable = &ad7606_backend_buffer_postenable,
	.predisable = &ad7606_backend_buffer_predisable,
};

static const struct iio_info ad7606_info_no_os_or_range = {
	.read_raw = &ad7606_read_raw,
	.validate_trigger = &ad7606_validate_trigger,
	.update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_info ad7606_info_os_and_range = {
	.read_raw = &ad7606_read_raw,
	.write_raw = &ad7606_write_raw,
	.attrs = &ad7606_attribute_group_os_and_range,
	.validate_trigger = &ad7606_validate_trigger,
	.update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_info ad7606_info_sw_mode = {
	.read_raw = &ad7606_read_raw,
	.write_raw = &ad7606_write_raw,
	.read_avail = &ad7606_read_avail,
	.debugfs_reg_access = &ad7606_reg_access,
	.validate_trigger = &ad7606_validate_trigger,
	.update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_info ad7606_info_os = {
	.read_raw = &ad7606_read_raw,
	.write_raw = &ad7606_write_raw,
	.attrs = &ad7606_attribute_group_os,
	.validate_trigger = &ad7606_validate_trigger,
	.update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_info ad7606_info_range = {
	.read_raw = &ad7606_read_raw,
	.write_raw = &ad7606_write_raw,
	.attrs = &ad7606_attribute_group_range,
	.validate_trigger = &ad7606_validate_trigger,
	.update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_trigger_ops ad7606_trigger_ops = {
	.validate_device = iio_trigger_validate_own_device,
};

static int ad7606_sw_mode_setup(struct iio_dev *indio_dev)
{
	struct ad7606_state *st = iio_priv(indio_dev);

	st->sw_mode_en = st->bops->sw_mode_config &&
			 device_property_present(st->dev, "adi,sw-mode");
	if (!st->sw_mode_en)
		return 0;

	indio_dev->info = &ad7606_info_sw_mode;

	return st->bops->sw_mode_config(indio_dev);
}

static int ad7606_chan_scales_setup(struct iio_dev *indio_dev)
{
	unsigned int num_channels = indio_dev->num_channels - 1;
	struct ad7606_state *st = iio_priv(indio_dev);
	struct iio_chan_spec *chans;
	size_t size;
	int ch, ret;

	/* Clone IIO channels, since some may be differential */
	size = indio_dev->num_channels * sizeof(*indio_dev->channels);
	chans = devm_kzalloc(st->dev, size, GFP_KERNEL);
	if (!chans)
		return -ENOMEM;

	memcpy(chans, indio_dev->channels, size);
	indio_dev->channels = chans;

	for (ch = 0; ch < num_channels; ch++) {
		ret = st->chip_info->scale_setup_cb(st, &chans[ch + 1], ch);
		if (ret)
			return ret;
	}

	return 0;
}

static void ad7606_pwm_disable(void *data)
{
	pwm_disable(data);
}

int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
		 const struct ad7606_chip_info *chip_info,
		 const struct ad7606_bus_ops *bops)
{
	struct ad7606_state *st;
	int ret;
	struct iio_dev *indio_dev;

	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
	if (!indio_dev)
		return -ENOMEM;

	st = iio_priv(indio_dev);
	dev_set_drvdata(dev, indio_dev);

	st->dev = dev;
	mutex_init(&st->lock);
	st->bops = bops;
	st->base_address = base_address;
	st->oversampling = 1;

	ret = devm_regulator_get_enable(dev, "avcc");
	if (ret)
		return dev_err_probe(dev, ret,
				     "Failed to enable specified AVcc supply\n");

	st->chip_info = chip_info;

	if (st->chip_info->oversampling_num) {
		st->oversampling_avail = st->chip_info->oversampling_avail;
		st->num_os_ratios = st->chip_info->oversampling_num;
	}

	ret = ad7606_request_gpios(st);
	if (ret)
		return ret;

	if (st->gpio_os) {
		if (st->gpio_range)
			indio_dev->info = &ad7606_info_os_and_range;
		else
			indio_dev->info = &ad7606_info_os;
	} else {
		if (st->gpio_range)
			indio_dev->info = &ad7606_info_range;
		else
			indio_dev->info = &ad7606_info_no_os_or_range;
	}
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->name = chip_info->name;
	indio_dev->channels = st->chip_info->channels;
	indio_dev->num_channels = st->chip_info->num_channels;

	ret = ad7606_reset(st);
	if (ret)
		dev_warn(st->dev, "failed to RESET: no RESET GPIO specified\n");

	/* AD7616 requires al least 15ms to reconfigure after a reset */
	if (st->chip_info->init_delay_ms) {
		if (msleep_interruptible(st->chip_info->init_delay_ms))
			return -ERESTARTSYS;
	}

	st->write_scale = ad7606_write_scale_hw;
	st->write_os = ad7606_write_os_hw;

	ret = ad7606_sw_mode_setup(indio_dev);
	if (ret)
		return ret;

	ret = ad7606_chan_scales_setup(indio_dev);
	if (ret)
		return ret;

	/* If convst pin is not defined, setup PWM. */
	if (!st->gpio_convst) {
		st->cnvst_pwm = devm_pwm_get(dev, NULL);
		if (IS_ERR(st->cnvst_pwm))
			return PTR_ERR(st->cnvst_pwm);

		/* The PWM is initialized at 1MHz to have a fast enough GPIO emulation. */
		ret = ad7606_set_sampling_freq(st, 1 * MEGA);
		if (ret)
			return ret;

		ret = ad7606_pwm_set_low(st);
		if (ret)
			return ret;

		/*
		 * PWM is not disabled when sampling stops, but instead its duty cycle is set
		 * to 0% to be sure we have a "low" state. After we unload the driver, let's
		 * disable the PWM.
		 */
		ret = devm_add_action_or_reset(dev, ad7606_pwm_disable,
					       st->cnvst_pwm);
		if (ret)
			return ret;
	}

	if (st->bops->iio_backend_config) {
		/*
		 * If there is a backend, the PWM should not overpass the maximum sampling
		 * frequency the chip supports.
		 */
		ret = ad7606_set_sampling_freq(st,
					       chip_info->max_samplerate ? : 2 * KILO);
		if (ret)
			return ret;

		ret = st->bops->iio_backend_config(dev, indio_dev);
		if (ret)
			return ret;

		indio_dev->setup_ops = &ad7606_backend_buffer_ops;
	} else {

		/* Reserve the PWM use only for backend (force gpio_convst definition) */
		if (!st->gpio_convst)
			return dev_err_probe(dev, -EINVAL,
					     "No backend, connect convst to a GPIO");

		init_completion(&st->completion);
		st->trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
						  indio_dev->name,
						  iio_device_id(indio_dev));
		if (!st->trig)
			return -ENOMEM;

		st->trig->ops = &ad7606_trigger_ops;
		iio_trigger_set_drvdata(st->trig, indio_dev);
		ret = devm_iio_trigger_register(dev, st->trig);
		if (ret)
			return ret;

		indio_dev->trig = iio_trigger_get(st->trig);

		ret = devm_request_threaded_irq(dev, irq, NULL, &ad7606_interrupt,
						IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
						chip_info->name, indio_dev);
		if (ret)
			return ret;

		ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
						      &iio_pollfunc_store_time,
						      &ad7606_trigger_handler,
						      &ad7606_buffer_ops);
		if (ret)
			return ret;
	}

	return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_NS_GPL(ad7606_probe, IIO_AD7606);

#ifdef CONFIG_PM_SLEEP

static int ad7606_suspend(struct device *dev)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7606_state *st = iio_priv(indio_dev);

	if (st->gpio_standby) {
		gpiod_set_value(st->gpio_range, 1);
		gpiod_set_value(st->gpio_standby, 1);
	}

	return 0;
}

static int ad7606_resume(struct device *dev)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct ad7606_state *st = iio_priv(indio_dev);

	if (st->gpio_standby) {
		gpiod_set_value(st->gpio_range, st->chan_scales[0].range);
		gpiod_set_value(st->gpio_standby, 1);
		ad7606_reset(st);
	}

	return 0;
}

SIMPLE_DEV_PM_OPS(ad7606_pm_ops, ad7606_suspend, ad7606_resume);
EXPORT_SYMBOL_NS_GPL(ad7606_pm_ops, IIO_AD7606);

#endif

MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7606 ADC");
MODULE_LICENSE("GPL v2");