ad5766.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Analog Devices AD5766, AD5767
 * Digital to Analog Converters driver
 * Copyright 2019-2020 Analog Devices Inc.
 */
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/iio/iio.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/module.h>
#include <linux/spi/spi.h>
#include <asm/unaligned.h>

#define AD5766_UPPER_WORD_SPI_MASK		GENMASK(31, 16)
#define AD5766_LOWER_WORD_SPI_MASK		GENMASK(15, 0)
#define AD5766_DITHER_SOURCE_MASK(ch)		GENMASK(((2 * ch) + 1), (2 * ch))
#define AD5766_DITHER_SOURCE(ch, source)	BIT((ch * 2) + source)
#define AD5766_DITHER_SCALE_MASK(x)		AD5766_DITHER_SOURCE_MASK(x)
#define AD5766_DITHER_SCALE(ch, scale)		(scale << (ch * 2))
#define AD5766_DITHER_ENABLE_MASK(ch)		BIT(ch)
#define AD5766_DITHER_ENABLE(ch, state)		((!state) << ch)
#define AD5766_DITHER_INVERT_MASK(ch)		BIT(ch)
#define AD5766_DITHER_INVERT(ch, state)		(state << ch)

#define AD5766_CMD_NOP_MUX_OUT			0x00
#define AD5766_CMD_SDO_CNTRL			0x01
#define AD5766_CMD_WR_IN_REG(x)			(0x10 | ((x) & GENMASK(3, 0)))
#define AD5766_CMD_WR_DAC_REG(x)		(0x20 | ((x) & GENMASK(3, 0)))
#define AD5766_CMD_SW_LDAC			0x30
#define AD5766_CMD_SPAN_REG			0x40
#define AD5766_CMD_WR_PWR_DITHER		0x51
#define AD5766_CMD_WR_DAC_REG_ALL		0x60
#define AD5766_CMD_SW_FULL_RESET		0x70
#define AD5766_CMD_READBACK_REG(x)		(0x80 | ((x) & GENMASK(3, 0)))
#define AD5766_CMD_DITHER_SIG_1			0x90
#define AD5766_CMD_DITHER_SIG_2			0xA0
#define AD5766_CMD_INV_DITHER			0xB0
#define AD5766_CMD_DITHER_SCALE_1		0xC0
#define AD5766_CMD_DITHER_SCALE_2		0xD0

#define AD5766_FULL_RESET_CODE			0x1234

enum ad5766_type {
	ID_AD5766,
	ID_AD5767,
};

enum ad5766_voltage_range {
	AD5766_VOLTAGE_RANGE_M20V_0V,
	AD5766_VOLTAGE_RANGE_M16V_to_0V,
	AD5766_VOLTAGE_RANGE_M10V_to_0V,
	AD5766_VOLTAGE_RANGE_M12V_to_14V,
	AD5766_VOLTAGE_RANGE_M16V_to_10V,
	AD5766_VOLTAGE_RANGE_M10V_to_6V,
	AD5766_VOLTAGE_RANGE_M5V_to_5V,
	AD5766_VOLTAGE_RANGE_M10V_to_10V,
};

/**
 * struct ad5766_chip_info - chip specific information
 * @num_channels:	number of channels
 * @channels:	        channel specification
 */
struct ad5766_chip_info {
	unsigned int			num_channels;
	const struct iio_chan_spec	*channels;
};

enum {
	AD5766_DITHER_ENABLE,
	AD5766_DITHER_INVERT,
	AD5766_DITHER_SOURCE,
};

/*
 * Dither signal can also be scaled.
 * Available dither scale strings corresponding to "dither_scale" field in
 * "struct ad5766_state".
 */
static const char * const ad5766_dither_scales[] = {
	"1",
	"0.75",
	"0.5",
	"0.25",
};

/**
 * struct ad5766_state - driver instance specific data
 * @spi:		SPI device
 * @lock:		Lock used to restrict concurrent access to SPI device
 * @chip_info:		Chip model specific constants
 * @gpio_reset:		Reset GPIO, used to reset the device
 * @crt_range:		Current selected output range
 * @dither_enable:	Power enable bit for each channel dither block (for
 *			example, D15 = DAC 15,D8 = DAC 8, and D0 = DAC 0)
 *			0 - Normal operation, 1 - Power down
 * @dither_invert:	Inverts the dither signal applied to the selected DAC
 *			outputs
 * @dither_source:	Selects between 2 possible sources:
 *			1: N0, 2: N1
 *			Two bits are used for each channel
 * @dither_scale:	Two bits are used for each of the 16 channels:
 *			0: 1 SCALING, 1: 0.75 SCALING, 2: 0.5 SCALING,
 *			3: 0.25 SCALING.
 * @data:		SPI transfer buffers
 */
struct ad5766_state {
	struct spi_device		*spi;
	struct mutex			lock;
	const struct ad5766_chip_info	*chip_info;
	struct gpio_desc		*gpio_reset;
	enum ad5766_voltage_range	crt_range;
	u16		dither_enable;
	u16		dither_invert;
	u32		dither_source;
	u32		dither_scale;
	union {
		u32	d32;
		u16	w16[2];
		u8	b8[4];
	} data[3] ____cacheline_aligned;
};

struct ad5766_span_tbl {
	int		min;
	int		max;
};

static const struct ad5766_span_tbl ad5766_span_tbl[] = {
	[AD5766_VOLTAGE_RANGE_M20V_0V] =	{-20, 0},
	[AD5766_VOLTAGE_RANGE_M16V_to_0V] =	{-16, 0},
	[AD5766_VOLTAGE_RANGE_M10V_to_0V] =	{-10, 0},
	[AD5766_VOLTAGE_RANGE_M12V_to_14V] =	{-12, 14},
	[AD5766_VOLTAGE_RANGE_M16V_to_10V] =	{-16, 10},
	[AD5766_VOLTAGE_RANGE_M10V_to_6V] =	{-10, 6},
	[AD5766_VOLTAGE_RANGE_M5V_to_5V] =	{-5, 5},
	[AD5766_VOLTAGE_RANGE_M10V_to_10V] =	{-10, 10},
};

static int __ad5766_spi_read(struct ad5766_state *st, u8 dac, int *val)
{
	int ret;
	struct spi_transfer xfers[] = {
		{
			.tx_buf = &st->data[0].d32,
			.bits_per_word = 8,
			.len = 3,
			.cs_change = 1,
		}, {
			.tx_buf = &st->data[1].d32,
			.rx_buf = &st->data[2].d32,
			.bits_per_word = 8,
			.len = 3,
		},
	};

	st->data[0].d32 = AD5766_CMD_READBACK_REG(dac);
	st->data[1].d32 = AD5766_CMD_NOP_MUX_OUT;

	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
	if (ret)
		return ret;

	*val = st->data[2].w16[1];

	return ret;
}

static int __ad5766_spi_write(struct ad5766_state *st, u8 command, u16 data)
{
	st->data[0].b8[0] = command;
	put_unaligned_be16(data, &st->data[0].b8[1]);

	return spi_write(st->spi, &st->data[0].b8[0], 3);
}

static int ad5766_read(struct iio_dev *indio_dev, u8 dac, int *val)
{
	struct ad5766_state *st = iio_priv(indio_dev);
	int ret;

	mutex_lock(&st->lock);
	ret = __ad5766_spi_read(st, dac, val);
	mutex_unlock(&st->lock);

	return ret;
}

static int ad5766_write(struct iio_dev *indio_dev, u8 dac, u16 data)
{
	struct ad5766_state *st = iio_priv(indio_dev);
	int ret;

	mutex_lock(&st->lock);
	ret = __ad5766_spi_write(st, AD5766_CMD_WR_DAC_REG(dac), data);
	mutex_unlock(&st->lock);

	return ret;
}

static int ad5766_reset(struct ad5766_state *st)
{
	int ret;

	if (st->gpio_reset) {
		gpiod_set_value_cansleep(st->gpio_reset, 1);
		ndelay(100); /* t_reset >= 100ns */
		gpiod_set_value_cansleep(st->gpio_reset, 0);
	} else {
		ret = __ad5766_spi_write(st, AD5766_CMD_SW_FULL_RESET,
					AD5766_FULL_RESET_CODE);
		if (ret < 0)
			return ret;
	}

	/*
	 * Minimum time between a reset and the subsequent successful write is
	 * typically 25 ns
	 */
	ndelay(25);

	return 0;
}

static int ad5766_read_raw(struct iio_dev *indio_dev,
			   struct iio_chan_spec const *chan,
			   int *val,
			   int *val2,
			   long m)
{
	struct ad5766_state *st = iio_priv(indio_dev);
	int ret;

	switch (m) {
	case IIO_CHAN_INFO_RAW:
		ret = ad5766_read(indio_dev, chan->address, val);
		if (ret)
			return ret;

		return IIO_VAL_INT;
	case IIO_CHAN_INFO_OFFSET:
		*val = ad5766_span_tbl[st->crt_range].min;

		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		*val = ad5766_span_tbl[st->crt_range].max -
		       ad5766_span_tbl[st->crt_range].min;
		*val2 = st->chip_info->channels[0].scan_type.realbits;

		return IIO_VAL_FRACTIONAL_LOG2;
	default:
		return -EINVAL;
	}
}

static int ad5766_write_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int val,
			    int val2,
			    long info)
{
	switch (info) {
	case IIO_CHAN_INFO_RAW:
	{
		const int max_val = GENMASK(chan->scan_type.realbits - 1, 0);

		if (val > max_val || val < 0)
			return -EINVAL;
		val <<= chan->scan_type.shift;
		return ad5766_write(indio_dev, chan->address, val);
	}
	default:
		return -EINVAL;
	}
}

static const struct iio_info ad5766_info = {
	.read_raw = ad5766_read_raw,
	.write_raw = ad5766_write_raw,
};

static int ad5766_get_dither_source(struct iio_dev *dev,
				    const struct iio_chan_spec *chan)
{
	struct ad5766_state *st = iio_priv(dev);
	u32 source;

	source = st->dither_source & AD5766_DITHER_SOURCE_MASK(chan->channel);
	source = source >> (chan->channel * 2);
	source -= 1;

	return source;
}

static int ad5766_set_dither_source(struct iio_dev *dev,
			  const struct iio_chan_spec *chan,
			  unsigned int source)
{
	struct ad5766_state *st = iio_priv(dev);
	uint16_t val;
	int ret;

	st->dither_source &= ~AD5766_DITHER_SOURCE_MASK(chan->channel);
	st->dither_source |= AD5766_DITHER_SOURCE(chan->channel, source);

	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_source);
	ret = ad5766_write(dev, AD5766_CMD_DITHER_SIG_1, val);
	if (ret)
		return ret;

	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_source);

	return ad5766_write(dev, AD5766_CMD_DITHER_SIG_2, val);
}

static int ad5766_get_dither_scale(struct iio_dev *dev,
				   const struct iio_chan_spec *chan)
{
	struct ad5766_state *st = iio_priv(dev);
	u32 scale;

	scale = st->dither_scale & AD5766_DITHER_SCALE_MASK(chan->channel);

	return (scale >> (chan->channel * 2));
}

static int ad5766_set_dither_scale(struct iio_dev *dev,
			  const struct iio_chan_spec *chan,
			  unsigned int scale)
{
	int ret;
	struct ad5766_state *st = iio_priv(dev);
	uint16_t val;

	st->dither_scale &= ~AD5766_DITHER_SCALE_MASK(chan->channel);
	st->dither_scale |= AD5766_DITHER_SCALE(chan->channel, scale);

	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_scale);
	ret = ad5766_write(dev, AD5766_CMD_DITHER_SCALE_1, val);
	if (ret)
		return ret;
	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_scale);

	return ad5766_write(dev, AD5766_CMD_DITHER_SCALE_2, val);
}

static const struct iio_enum ad5766_dither_scale_enum = {
	.items = ad5766_dither_scales,
	.num_items = ARRAY_SIZE(ad5766_dither_scales),
	.set = ad5766_set_dither_scale,
	.get = ad5766_get_dither_scale,
};

static ssize_t ad5766_read_ext(struct iio_dev *indio_dev,
			       uintptr_t private,
			       const struct iio_chan_spec *chan,
			       char *buf)
{
	struct ad5766_state *st = iio_priv(indio_dev);

	switch (private) {
	case AD5766_DITHER_ENABLE:
		return sprintf(buf, "%u\n",
			       !(st->dither_enable & BIT(chan->channel)));
		break;
	case AD5766_DITHER_INVERT:
		return sprintf(buf, "%u\n",
			       !!(st->dither_invert & BIT(chan->channel)));
		break;
	case AD5766_DITHER_SOURCE:
		return sprintf(buf, "%d\n",
			       ad5766_get_dither_source(indio_dev, chan));
	default:
		return -EINVAL;
	}
}

static ssize_t ad5766_write_ext(struct iio_dev *indio_dev,
				 uintptr_t private,
				 const struct iio_chan_spec *chan,
				 const char *buf, size_t len)
{
	struct ad5766_state *st = iio_priv(indio_dev);
	bool readin;
	int ret;

	ret = kstrtobool(buf, &readin);
	if (ret)
		return ret;

	switch (private) {
	case AD5766_DITHER_ENABLE:
		st->dither_enable &= ~AD5766_DITHER_ENABLE_MASK(chan->channel);
		st->dither_enable |= AD5766_DITHER_ENABLE(chan->channel,
							  readin);
		ret = ad5766_write(indio_dev, AD5766_CMD_WR_PWR_DITHER,
				   st->dither_enable);
		break;
	case AD5766_DITHER_INVERT:
		st->dither_invert &= ~AD5766_DITHER_INVERT_MASK(chan->channel);
		st->dither_invert |= AD5766_DITHER_INVERT(chan->channel,
							  readin);
		ret = ad5766_write(indio_dev, AD5766_CMD_INV_DITHER,
				   st->dither_invert);
		break;
	case AD5766_DITHER_SOURCE:
		ret = ad5766_set_dither_source(indio_dev, chan, readin);
		break;
	default:
		return -EINVAL;
	}

	return ret ? ret : len;
}

#define _AD5766_CHAN_EXT_INFO(_name, _what, _shared) { \
	.name = _name, \
	.read = ad5766_read_ext, \
	.write = ad5766_write_ext, \
	.private = _what, \
	.shared = _shared, \
}

#define IIO_ENUM_AVAILABLE_SHARED(_name, _shared, _e) \
{ \
	.name = (_name "_available"), \
	.shared = _shared, \
	.read = iio_enum_available_read, \
	.private = (uintptr_t)(_e), \
}

static const struct iio_chan_spec_ext_info ad5766_ext_info[] = {

	_AD5766_CHAN_EXT_INFO("dither_enable", AD5766_DITHER_ENABLE,
			      IIO_SEPARATE),
	_AD5766_CHAN_EXT_INFO("dither_invert", AD5766_DITHER_INVERT,
			      IIO_SEPARATE),
	_AD5766_CHAN_EXT_INFO("dither_source", AD5766_DITHER_SOURCE,
			      IIO_SEPARATE),
	IIO_ENUM("dither_scale", IIO_SEPARATE, &ad5766_dither_scale_enum),
	IIO_ENUM_AVAILABLE_SHARED("dither_scale",
				  IIO_SEPARATE,
				  &ad5766_dither_scale_enum),
	{}
};

#define AD576x_CHANNEL(_chan, _bits) {					\
	.type = IIO_VOLTAGE,						\
	.indexed = 1,							\
	.output = 1,							\
	.channel = (_chan),						\
	.address = (_chan),						\
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |		\
		BIT(IIO_CHAN_INFO_SCALE),				\
	.scan_index = (_chan),						\
	.scan_type = {							\
		.sign = 'u',						\
		.realbits = (_bits),					\
		.storagebits = 16,					\
		.shift = 16 - (_bits),					\
	},								\
	.ext_info = ad5766_ext_info,					\
}

#define DECLARE_AD576x_CHANNELS(_name, _bits)			\
const struct iio_chan_spec _name[] = {				\
	AD576x_CHANNEL(0, (_bits)),				\
	AD576x_CHANNEL(1, (_bits)),				\
	AD576x_CHANNEL(2, (_bits)),				\
	AD576x_CHANNEL(3, (_bits)),				\
	AD576x_CHANNEL(4, (_bits)),				\
	AD576x_CHANNEL(5, (_bits)),				\
	AD576x_CHANNEL(6, (_bits)),				\
	AD576x_CHANNEL(7, (_bits)),				\
	AD576x_CHANNEL(8, (_bits)),				\
	AD576x_CHANNEL(9, (_bits)),				\
	AD576x_CHANNEL(10, (_bits)),				\
	AD576x_CHANNEL(11, (_bits)),				\
	AD576x_CHANNEL(12, (_bits)),				\
	AD576x_CHANNEL(13, (_bits)),				\
	AD576x_CHANNEL(14, (_bits)),				\
	AD576x_CHANNEL(15, (_bits)),				\
}

static DECLARE_AD576x_CHANNELS(ad5766_channels, 16);
static DECLARE_AD576x_CHANNELS(ad5767_channels, 12);

static const struct ad5766_chip_info ad5766_chip_infos[] = {
	[ID_AD5766] = {
		.num_channels = ARRAY_SIZE(ad5766_channels),
		.channels = ad5766_channels,
	},
	[ID_AD5767] = {
		.num_channels = ARRAY_SIZE(ad5767_channels),
		.channels = ad5767_channels,
	},
};

static int ad5766_get_output_range(struct ad5766_state *st)
{
	int i, ret, min, max, tmp[2];

	ret = device_property_read_u32_array(&st->spi->dev,
					     "output-range-microvolts",
					     tmp, 2);
	if (ret)
		return ret;

	min = tmp[0] / 1000000;
	max = tmp[1] / 1000000;
	for (i = 0; i < ARRAY_SIZE(ad5766_span_tbl); i++) {
		if (ad5766_span_tbl[i].min != min ||
		    ad5766_span_tbl[i].max != max)
			continue;

		st->crt_range = i;

		return 0;
	}

	return -EINVAL;
}

static int ad5766_default_setup(struct ad5766_state *st)
{
	uint16_t val;
	int ret, i;

	/* Always issue a reset before writing to the span register. */
	ret = ad5766_reset(st);
	if (ret)
		return ret;

	ret = ad5766_get_output_range(st);
	if (ret)
		return ret;

	/* Dither power down */
	st->dither_enable = GENMASK(15, 0);
	ret = __ad5766_spi_write(st, AD5766_CMD_WR_PWR_DITHER,
			     st->dither_enable);
	if (ret)
		return ret;

	st->dither_source = 0;
	for (i = 0; i < ARRAY_SIZE(ad5766_channels); i++)
		st->dither_source |= AD5766_DITHER_SOURCE(i, 0);
	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_source);
	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SIG_1, val);
	if (ret)
		return ret;

	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_source);
	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SIG_2, val);
	if (ret)
		return ret;

	st->dither_scale = 0;
	val = FIELD_GET(AD5766_LOWER_WORD_SPI_MASK, st->dither_scale);
	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SCALE_1, val);
	if (ret)
		return ret;

	val = FIELD_GET(AD5766_UPPER_WORD_SPI_MASK, st->dither_scale);
	ret = __ad5766_spi_write(st, AD5766_CMD_DITHER_SCALE_2, val);
	if (ret)
		return ret;

	st->dither_invert = 0;
	ret = __ad5766_spi_write(st, AD5766_CMD_INV_DITHER, st->dither_invert);
	if (ret)
		return ret;

	return  __ad5766_spi_write(st, AD5766_CMD_SPAN_REG, st->crt_range);
}

static irqreturn_t ad5766_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct iio_buffer *buffer = indio_dev->buffer;
	struct ad5766_state *st = iio_priv(indio_dev);
	int ret, ch, i;
	u16 data[ARRAY_SIZE(ad5766_channels)];

	ret = iio_pop_from_buffer(buffer, data);
	if (ret)
		goto done;

	i = 0;
	mutex_lock(&st->lock);
	for_each_set_bit(ch, indio_dev->active_scan_mask,
			 st->chip_info->num_channels - 1)
		__ad5766_spi_write(st, AD5766_CMD_WR_IN_REG(ch), data[i++]);

	__ad5766_spi_write(st, AD5766_CMD_SW_LDAC,
			   *indio_dev->active_scan_mask);
	mutex_unlock(&st->lock);

done:
	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
}

static int ad5766_probe(struct spi_device *spi)
{
	enum ad5766_type type;
	struct iio_dev *indio_dev;
	struct ad5766_state *st;
	int ret;

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

	st = iio_priv(indio_dev);
	mutex_init(&st->lock);

	st->spi = spi;
	type = spi_get_device_id(spi)->driver_data;
	st->chip_info = &ad5766_chip_infos[type];

	indio_dev->channels = st->chip_info->channels;
	indio_dev->num_channels = st->chip_info->num_channels;
	indio_dev->info = &ad5766_info;
	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->modes = INDIO_DIRECT_MODE;

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

	ret = ad5766_default_setup(st);
	if (ret)
		return ret;

	/* Configure trigger buffer */
	ret = devm_iio_triggered_buffer_setup_ext(&spi->dev, indio_dev, NULL,
						  ad5766_trigger_handler,
						  IIO_BUFFER_DIRECTION_OUT,
						  NULL,
						  NULL);
	if (ret)
		return ret;

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

static const struct of_device_id ad5766_dt_match[] = {
	{ .compatible = "adi,ad5766" },
	{ .compatible = "adi,ad5767" },
	{}
};
MODULE_DEVICE_TABLE(of, ad5766_dt_match);

static const struct spi_device_id ad5766_spi_ids[] = {
	{ "ad5766", ID_AD5766 },
	{ "ad5767", ID_AD5767 },
	{}
};
MODULE_DEVICE_TABLE(spi, ad5766_spi_ids);

static struct spi_driver ad5766_driver = {
	.driver = {
		.name = "ad5766",
		.of_match_table = ad5766_dt_match,
	},
	.probe = ad5766_probe,
	.id_table = ad5766_spi_ids,
};
module_spi_driver(ad5766_driver);

MODULE_AUTHOR("Denis-Gabriel Gheorghescu <denis.gheorghescu@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD5766/AD5767 DACs");
MODULE_LICENSE("GPL v2");