text: // SPDX-License-Identifier: GPL-2.0
  /*
   * AD7170/AD7171 and AD7780/AD7781 SPI ADC driver
   *
   * Copyright 2011 Analog Devices Inc.
   * Copyright 2019 Renato Lui Geh
   */
  
  #include <linux/interrupt.h>
  #include <linux/device.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/sysfs.h>
  #include <linux/spi/spi.h>
  #include <linux/regulator/consumer.h>
  #include <linux/err.h>
  #include <linux/sched.h>
  #include <linux/gpio/consumer.h>
  #include <linux/module.h>
  #include <linux/bits.h>
  
  #include <linux/iio/iio.h>
  #include <linux/iio/sysfs.h>
  #include <linux/iio/adc/ad_sigma_delta.h>
  
  #define AD7780_RDY		BIT(7)
  #define AD7780_FILTER		BIT(6)
  #define AD7780_ERR		BIT(5)
  #define AD7780_ID1		BIT(4)
  #define AD7780_ID0		BIT(3)
  #define AD7780_GAIN		BIT(2)
  
  #define AD7170_ID		0
  #define AD7171_ID		1
  #define AD7780_ID		1
  #define AD7781_ID		0
  
  #define AD7780_ID_MASK		(AD7780_ID0 | AD7780_ID1)
  
  #define AD7780_PATTERN_GOOD	1
  #define AD7780_PATTERN_MASK	GENMASK(1, 0)
  
  #define AD7170_PATTERN_GOOD	5
  #define AD7170_PATTERN_MASK	GENMASK(2, 0)
  
  #define AD7780_GAIN_MIDPOINT	64
  #define AD7780_FILTER_MIDPOINT	13350
  
  static const unsigned int ad778x_gain[2]      = { 1, 128 };
  static const unsigned int ad778x_odr_avail[2] = { 10000, 16700 };
  
  struct ad7780_chip_info {
  	struct iio_chan_spec	channel;
  	unsigned int		pattern_mask;
  	unsigned int		pattern;
  	bool			is_ad778x;
  };
  
  struct ad7780_state {
  	const struct ad7780_chip_info	*chip_info;
  	struct regulator		*reg;
  	struct gpio_desc		*powerdown_gpio;
  	struct gpio_desc		*gain_gpio;
  	struct gpio_desc		*filter_gpio;
  	unsigned int			gain;
  	unsigned int			odr;
  	unsigned int			int_vref_mv;
  
  	struct ad_sigma_delta sd;
  };
  
  enum ad7780_supported_device_ids {
  	ID_AD7170,
  	ID_AD7171,
  	ID_AD7780,
  	ID_AD7781,
  };
  
  static struct ad7780_state *ad_sigma_delta_to_ad7780(struct ad_sigma_delta *sd)
  {
  	return container_of(sd, struct ad7780_state, sd);
  }
  
  static int ad7780_set_mode(struct ad_sigma_delta *sigma_delta,
  			   enum ad_sigma_delta_mode mode)
  {
  	struct ad7780_state *st = ad_sigma_delta_to_ad7780(sigma_delta);
  	unsigned int val;
  
  	switch (mode) {
  	case AD_SD_MODE_SINGLE:
  	case AD_SD_MODE_CONTINUOUS:
  		val = 1;
  		break;
  	default:
  		val = 0;
  		break;
  	}
  
  	gpiod_set_value(st->powerdown_gpio, val);
  
  	return 0;
  }
  
  static int ad7780_read_raw(struct iio_dev *indio_dev,
  			   struct iio_chan_spec const *chan,
  			   int *val,
  			   int *val2,
  			   long m)
  {
  	struct ad7780_state *st = iio_priv(indio_dev);
  	int voltage_uv;
  
  	switch (m) {
  	case IIO_CHAN_INFO_RAW:
  		return ad_sigma_delta_single_conversion(indio_dev, chan, val);
  	case IIO_CHAN_INFO_SCALE:
  		voltage_uv = regulator_get_voltage(st->reg);
  		if (voltage_uv < 0)
  			return voltage_uv;
  		voltage_uv /= 1000;
  		*val = voltage_uv * st->gain;
  		*val2 = chan->scan_type.realbits - 1;
  		st->int_vref_mv = voltage_uv;
  		return IIO_VAL_FRACTIONAL_LOG2;
  	case IIO_CHAN_INFO_OFFSET:
  		*val = -(1 << (chan->scan_type.realbits - 1));
  		return IIO_VAL_INT;
  	case IIO_CHAN_INFO_SAMP_FREQ:
  		*val = st->odr;
  		return IIO_VAL_INT;
  	default:
  		break;
  	}
  
  	return -EINVAL;
  }
  
  static int ad7780_write_raw(struct iio_dev *indio_dev,
  			    struct iio_chan_spec const *chan,
  			    int val,
  			    int val2,
  			    long m)
  {
  	struct ad7780_state *st = iio_priv(indio_dev);
  	const struct ad7780_chip_info *chip_info = st->chip_info;
  	unsigned long long vref;
  	unsigned int full_scale, gain;
  
  	if (!chip_info->is_ad778x)
  		return -EINVAL;
  
  	switch (m) {
  	case IIO_CHAN_INFO_SCALE:
  		if (val != 0)
  			return -EINVAL;
  
  		vref = st->int_vref_mv * 1000000LL;
  		full_scale = 1 << (chip_info->channel.scan_type.realbits - 1);
  		gain = DIV_ROUND_CLOSEST_ULL(vref, full_scale);
  		gain = DIV_ROUND_CLOSEST(gain, val2);
  		st->gain = gain;
  		if (gain < AD7780_GAIN_MIDPOINT)
  			gain = 0;
  		else
  			gain = 1;
  		gpiod_set_value(st->gain_gpio, gain);
  		break;
  	case IIO_CHAN_INFO_SAMP_FREQ:
  		if (1000*val + val2/1000 < AD7780_FILTER_MIDPOINT)
  			val = 0;
  		else
  			val = 1;
  		st->odr = ad778x_odr_avail[val];
  		gpiod_set_value(st->filter_gpio, val);
  		break;
  	default:
  		break;
  	}
  
  	return 0;
  }
  
  static int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
  				     unsigned int raw_sample)
  {
  	struct ad7780_state *st = ad_sigma_delta_to_ad7780(sigma_delta);
  	const struct ad7780_chip_info *chip_info = st->chip_info;
  
  	if ((raw_sample & AD7780_ERR) ||
  	    ((raw_sample & chip_info->pattern_mask) != chip_info->pattern))
  		return -EIO;
  
  	if (chip_info->is_ad778x) {
  		st->gain = ad778x_gain[raw_sample & AD7780_GAIN];
  		st->odr = ad778x_odr_avail[raw_sample & AD7780_FILTER];
  	}
  
  	return 0;
  }
  
  static const struct ad_sigma_delta_info ad7780_sigma_delta_info = {
  	.set_mode = ad7780_set_mode,
  	.postprocess_sample = ad7780_postprocess_sample,
  	.has_registers = false,
  	.irq_flags = IRQF_TRIGGER_FALLING,
  };
  
  #define _AD7780_CHANNEL(_bits, _wordsize, _mask_all)		\
  {								\
  	.type = IIO_VOLTAGE,					\
  	.indexed = 1,						\
  	.channel = 0,						\
  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
  		BIT(IIO_CHAN_INFO_OFFSET),			\
  	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
  	.info_mask_shared_by_all = _mask_all,			\
  	.scan_index = 1,					\
  	.scan_type = {						\
  		.sign = 'u',					\
  		.realbits = (_bits),				\
  		.storagebits = 32,				\
  		.shift = (_wordsize) - (_bits),			\
  		.endianness = IIO_BE,				\
  	},							\
  }
  
  #define AD7780_CHANNEL(_bits, _wordsize)	\
  	_AD7780_CHANNEL(_bits, _wordsize, BIT(IIO_CHAN_INFO_SAMP_FREQ))
  #define AD7170_CHANNEL(_bits, _wordsize)	\
  	_AD7780_CHANNEL(_bits, _wordsize, 0)
  
  static const struct ad7780_chip_info ad7780_chip_info_tbl[] = {
  	[ID_AD7170] = {
  		.channel = AD7170_CHANNEL(12, 24),
  		.pattern = AD7170_PATTERN_GOOD,
  		.pattern_mask = AD7170_PATTERN_MASK,
  		.is_ad778x = false,
  	},
  	[ID_AD7171] = {
  		.channel = AD7170_CHANNEL(16, 24),
  		.pattern = AD7170_PATTERN_GOOD,
  		.pattern_mask = AD7170_PATTERN_MASK,
  		.is_ad778x = false,
  	},
  	[ID_AD7780] = {
  		.channel = AD7780_CHANNEL(24, 32),
  		.pattern = AD7780_PATTERN_GOOD,
  		.pattern_mask = AD7780_PATTERN_MASK,
  		.is_ad778x = true,
  	},
  	[ID_AD7781] = {
  		.channel = AD7780_CHANNEL(20, 32),
  		.pattern = AD7780_PATTERN_GOOD,
  		.pattern_mask = AD7780_PATTERN_MASK,
  		.is_ad778x = true,
  	},
  };
  
  static const struct iio_info ad7780_info = {
  	.read_raw = ad7780_read_raw,
  	.write_raw = ad7780_write_raw,
  };
  
  static int ad7780_init_gpios(struct device *dev, struct ad7780_state *st)
  {
  	int ret;
  
  	st->powerdown_gpio = devm_gpiod_get_optional(dev,
  						     "powerdown",
  						     GPIOD_OUT_LOW);
  	if (IS_ERR(st->powerdown_gpio)) {
  		ret = PTR_ERR(st->powerdown_gpio);
  		dev_err(dev, "Failed to request powerdown GPIO: %d\n", ret);
  		return ret;
  	}
  
  	if (!st->chip_info->is_ad778x)
  		return 0;
  
  
  	st->gain_gpio = devm_gpiod_get_optional(dev,
  						"adi,gain",
  						GPIOD_OUT_HIGH);
  	if (IS_ERR(st->gain_gpio)) {
  		ret = PTR_ERR(st->gain_gpio);
  		dev_err(dev, "Failed to request gain GPIO: %d\n", ret);
  		return ret;
  	}
  
  	st->filter_gpio = devm_gpiod_get_optional(dev,
  						  "adi,filter",
  						  GPIOD_OUT_HIGH);
  	if (IS_ERR(st->filter_gpio)) {
  		ret = PTR_ERR(st->filter_gpio);
  		dev_err(dev, "Failed to request filter GPIO: %d\n", ret);
  		return ret;
  	}
  
  	return 0;
  }
  
  static void ad7780_reg_disable(void *reg)
  {
  	regulator_disable(reg);
  }
  
  static int ad7780_probe(struct spi_device *spi)
  {
  	struct ad7780_state *st;
  	struct iio_dev *indio_dev;
  	int ret;
  
  	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
  	if (!indio_dev)
  		return -ENOMEM;
  
  	st = iio_priv(indio_dev);
  	st->gain = 1;
  
  	ad_sd_init(&st->sd, indio_dev, spi, &ad7780_sigma_delta_info);
  
  	st->chip_info =
  		&ad7780_chip_info_tbl[spi_get_device_id(spi)->driver_data];
  
  	indio_dev->name = spi_get_device_id(spi)->name;
  	indio_dev->modes = INDIO_DIRECT_MODE;
  	indio_dev->channels = &st->chip_info->channel;
  	indio_dev->num_channels = 1;
  	indio_dev->info = &ad7780_info;
  
  	ret = ad7780_init_gpios(&spi->dev, st);
  	if (ret)
  		return ret;
  
  	st->reg = devm_regulator_get(&spi->dev, "avdd");
  	if (IS_ERR(st->reg))
  		return PTR_ERR(st->reg);
  
  	ret = regulator_enable(st->reg);
  	if (ret) {
  		dev_err(&spi->dev, "Failed to enable specified AVdd supply\n");
  		return ret;
  	}
  
  	ret = devm_add_action_or_reset(&spi->dev, ad7780_reg_disable, st->reg);
  	if (ret)
  		return ret;
  
  	ret = devm_ad_sd_setup_buffer_and_trigger(&spi->dev, indio_dev);
  	if (ret)
  		return ret;
  
  	return devm_iio_device_register(&spi->dev, indio_dev);
  }
  
  static const struct spi_device_id ad7780_id[] = {
  	{"ad7170", ID_AD7170},
  	{"ad7171", ID_AD7171},
  	{"ad7780", ID_AD7780},
  	{"ad7781", ID_AD7781},
  	{}
  };
  MODULE_DEVICE_TABLE(spi, ad7780_id);
  
  static struct spi_driver ad7780_driver = {
  	.driver = {
  		.name	= "ad7780",
  	},
  	.probe		= ad7780_probe,
  	.id_table	= ad7780_id,
  };
  module_spi_driver(ad7780_driver);
  
  MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
  MODULE_DESCRIPTION("Analog Devices AD7780 and similar ADCs");
  MODULE_LICENSE("GPL v2");
  MODULE_IMPORT_NS(IIO_AD_SIGMA_DELTA);
  