drivers/iio/adc/hi8435.c - kernel/msm-4.9 - Gitiles

 /*
  * Holt Integrated Circuits HI-8435 threshold detector driver
  *
  * Copyright (C) 2015 Zodiac Inflight Innovations
  * Copyright (C) 2015 Cogent Embedded, Inc.
  *
  * This program is free software; you can redistribute  it and/or modify it
  * under  the terms of  the GNU General  Public License as published by the
  * Free Software Foundation;  either version 2 of the  License, or (at your
  * option) any later version.
  */

 #include <linux/delay.h>
 #include <linux/iio/events.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/trigger.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_event.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/of_gpio.h>
 #include <linux/spi/spi.h>
 #include <linux/gpio/consumer.h>

 #define DRV_NAME "hi8435"

 /* Register offsets for HI-8435 */
 #define HI8435_CTRL_REG		0x02
 #define HI8435_PSEN_REG		0x04
 #define HI8435_TMDATA_REG	0x1E
 #define HI8435_GOCENHYS_REG	0x3A
 #define HI8435_SOCENHYS_REG	0x3C
 #define HI8435_SO7_0_REG	0x10
 #define HI8435_SO15_8_REG	0x12
 #define HI8435_SO23_16_REG	0x14
 #define HI8435_SO31_24_REG	0x16
 #define HI8435_SO31_0_REG	0x78

 #define HI8435_WRITE_OPCODE	0x00
 #define HI8435_READ_OPCODE	0x80

 /* CTRL register bits */
 #define HI8435_CTRL_TEST	0x01
 #define HI8435_CTRL_SRST	0x02

 struct hi8435_priv {
 	struct spi_device *spi;
 	struct mutex lock;

 	unsigned long event_scan_mask; /* soft mask/unmask channels events */
 	unsigned int event_prev_val;

 	unsigned threshold_lo[2]; /* GND-Open and Supply-Open thresholds */
 	unsigned threshold_hi[2]; /* GND-Open and Supply-Open thresholds */
 	u8 reg_buffer[3] ____cacheline_aligned;
 };

 static int hi8435_readb(struct hi8435_priv *priv, u8 reg, u8 *val)
 {
 	reg |= HI8435_READ_OPCODE;
 	return spi_write_then_read(priv->spi, &reg, 1, val, 1);
 }

 static int hi8435_readw(struct hi8435_priv *priv, u8 reg, u16 *val)
 {
 	int ret;
 	__be16 be_val;

 	reg |= HI8435_READ_OPCODE;
 	ret = spi_write_then_read(priv->spi, &reg, 1, &be_val, 2);
 	*val = be16_to_cpu(be_val);

 	return ret;
 }

 static int hi8435_readl(struct hi8435_priv *priv, u8 reg, u32 *val)
 {
 	int ret;
 	__be32 be_val;

 	reg |= HI8435_READ_OPCODE;
 	ret = spi_write_then_read(priv->spi, &reg, 1, &be_val, 4);
 	*val = be32_to_cpu(be_val);

 	return ret;
 }

 static int hi8435_writeb(struct hi8435_priv *priv, u8 reg, u8 val)
 {
 	priv->reg_buffer[0] = reg | HI8435_WRITE_OPCODE;
 	priv->reg_buffer[1] = val;

 	return spi_write(priv->spi, priv->reg_buffer, 2);
 }

 static int hi8435_writew(struct hi8435_priv *priv, u8 reg, u16 val)
 {
 	priv->reg_buffer[0] = reg | HI8435_WRITE_OPCODE;
 	priv->reg_buffer[1] = (val >> 8) & 0xff;
 	priv->reg_buffer[2] = val & 0xff;

 	return spi_write(priv->spi, priv->reg_buffer, 3);
 }

 static int hi8435_read_event_config(struct iio_dev *idev,
 				    const struct iio_chan_spec *chan,
 				    enum iio_event_type type,
 				    enum iio_event_direction dir)
 {
 	struct hi8435_priv *priv = iio_priv(idev);

 	return !!(priv->event_scan_mask & BIT(chan->channel));
 }

 static int hi8435_write_event_config(struct iio_dev *idev,
 				     const struct iio_chan_spec *chan,
 				     enum iio_event_type type,
 				     enum iio_event_direction dir, int state)
 {
 	struct hi8435_priv *priv = iio_priv(idev);
 	int ret;
 	u32 tmp;

 	if (state) {
 		ret = hi8435_readl(priv, HI8435_SO31_0_REG, &tmp);
 		if (ret < 0)
 			return ret;
 		if (tmp & BIT(chan->channel))
 			priv->event_prev_val |= BIT(chan->channel);
 		else
 			priv->event_prev_val &= ~BIT(chan->channel);

 		priv->event_scan_mask |= BIT(chan->channel);
 	} else
 		priv->event_scan_mask &= ~BIT(chan->channel);

 	return 0;
 }

 static int hi8435_read_event_value(struct iio_dev *idev,
 				   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 hi8435_priv *priv = iio_priv(idev);
 	int ret;
 	u8 mode, psen;
 	u16 reg;

 	ret = hi8435_readb(priv, HI8435_PSEN_REG, &psen);
 	if (ret < 0)
 		return ret;

 	/* Supply-Open or GND-Open sensing mode */
 	mode = !!(psen & BIT(chan->channel / 8));

 	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
 				 HI8435_GOCENHYS_REG, &reg);
 	if (ret < 0)
 		return ret;

 	if (dir == IIO_EV_DIR_FALLING)
 		*val = ((reg & 0xff) - (reg >> 8)) / 2;
 	else if (dir == IIO_EV_DIR_RISING)
 		*val = ((reg & 0xff) + (reg >> 8)) / 2;

 	return IIO_VAL_INT;
 }

 static int hi8435_write_event_value(struct iio_dev *idev,
 				    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 hi8435_priv *priv = iio_priv(idev);
 	int ret;
 	u8 mode, psen;
 	u16 reg;

 	ret = hi8435_readb(priv, HI8435_PSEN_REG, &psen);
 	if (ret < 0)
 		return ret;

 	/* Supply-Open or GND-Open sensing mode */
 	mode = !!(psen & BIT(chan->channel / 8));

 	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
 				 HI8435_GOCENHYS_REG, &reg);
 	if (ret < 0)
 		return ret;

 	if (dir == IIO_EV_DIR_FALLING) {
 		/* falling threshold range 2..21V, hysteresis minimum 2V */
 		if (val < 2 || val > 21 || (val + 2) > priv->threshold_hi[mode])
 			return -EINVAL;

 		if (val == priv->threshold_lo[mode])
 			return 0;

 		priv->threshold_lo[mode] = val;

 		/* hysteresis must not be odd */
 		if ((priv->threshold_hi[mode] - priv->threshold_lo[mode]) % 2)
 			priv->threshold_hi[mode]--;
 	} else if (dir == IIO_EV_DIR_RISING) {
 		/* rising threshold range 3..22V, hysteresis minimum 2V */
 		if (val < 3 || val > 22 || val < (priv->threshold_lo[mode] + 2))
 			return -EINVAL;

 		if (val == priv->threshold_hi[mode])
 			return 0;

 		priv->threshold_hi[mode] = val;

 		/* hysteresis must not be odd */
 		if ((priv->threshold_hi[mode] - priv->threshold_lo[mode]) % 2)
 			priv->threshold_lo[mode]++;
 	}

 	/* program thresholds */
 	mutex_lock(&priv->lock);

 	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
 				 HI8435_GOCENHYS_REG, &reg);
 	if (ret < 0) {
 		mutex_unlock(&priv->lock);
 		return ret;
 	}

 	/* hysteresis */
 	reg = priv->threshold_hi[mode] - priv->threshold_lo[mode];
 	reg <<= 8;
 	/* threshold center */
 	reg |= (priv->threshold_hi[mode] + priv->threshold_lo[mode]);

 	ret = hi8435_writew(priv, mode ? HI8435_SOCENHYS_REG :
 				  HI8435_GOCENHYS_REG, reg);

 	mutex_unlock(&priv->lock);

 	return ret;
 }

 static int hi8435_debugfs_reg_access(struct iio_dev *idev,
 				     unsigned reg, unsigned writeval,
 				     unsigned *readval)
 {
 	struct hi8435_priv *priv = iio_priv(idev);
 	int ret;
 	u8 val;

 	if (readval != NULL) {
 		ret = hi8435_readb(priv, reg, &val);
 		*readval = val;
 	} else {
 		val = (u8)writeval;
 		ret = hi8435_writeb(priv, reg, val);
 	}

 	return ret;
 }

 static const struct iio_event_spec hi8435_events[] = {
 	{
 		.type = IIO_EV_TYPE_THRESH,
 		.dir = IIO_EV_DIR_RISING,
 		.mask_separate = BIT(IIO_EV_INFO_VALUE),
 	}, {
 		.type = IIO_EV_TYPE_THRESH,
 		.dir = IIO_EV_DIR_FALLING,
 		.mask_separate = BIT(IIO_EV_INFO_VALUE),
 	}, {
 		.type = IIO_EV_TYPE_THRESH,
 		.dir = IIO_EV_DIR_EITHER,
 		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
 	},
 };

 static int hi8435_get_sensing_mode(struct iio_dev *idev,
 				   const struct iio_chan_spec *chan)
 {
 	struct hi8435_priv *priv = iio_priv(idev);
 	int ret;
 	u8 reg;

 	ret = hi8435_readb(priv, HI8435_PSEN_REG, &reg);
 	if (ret < 0)
 		return ret;

 	return !!(reg & BIT(chan->channel / 8));
 }

 static int hi8435_set_sensing_mode(struct iio_dev *idev,
 				   const struct iio_chan_spec *chan,
 				   unsigned int mode)
 {
 	struct hi8435_priv *priv = iio_priv(idev);
 	int ret;
 	u8 reg;

 	mutex_lock(&priv->lock);

 	ret = hi8435_readb(priv, HI8435_PSEN_REG, &reg);
 	if (ret < 0) {
 		mutex_unlock(&priv->lock);
 		return ret;
 	}

 	reg &= ~BIT(chan->channel / 8);
 	if (mode)
 		reg |= BIT(chan->channel / 8);

 	ret = hi8435_writeb(priv, HI8435_PSEN_REG, reg);

 	mutex_unlock(&priv->lock);

 	return ret;
 }

 static const char * const hi8435_sensing_modes[] = { "GND-Open",
 						     "Supply-Open" };

 static const struct iio_enum hi8435_sensing_mode = {
 	.items = hi8435_sensing_modes,
 	.num_items = ARRAY_SIZE(hi8435_sensing_modes),
 	.get = hi8435_get_sensing_mode,
 	.set = hi8435_set_sensing_mode,
 };

 static const struct iio_chan_spec_ext_info hi8435_ext_info[] = {
 	IIO_ENUM("sensing_mode", IIO_SEPARATE, &hi8435_sensing_mode),
 	{},
 };

 #define HI8435_VOLTAGE_CHANNEL(num)			\
 {							\
 	.type = IIO_VOLTAGE,				\
 	.indexed = 1,					\
 	.channel = num,					\
 	.event_spec = hi8435_events,			\
 	.num_event_specs = ARRAY_SIZE(hi8435_events),	\
 	.ext_info = hi8435_ext_info,			\
 }

 static const struct iio_chan_spec hi8435_channels[] = {
 	HI8435_VOLTAGE_CHANNEL(0),
 	HI8435_VOLTAGE_CHANNEL(1),
 	HI8435_VOLTAGE_CHANNEL(2),
 	HI8435_VOLTAGE_CHANNEL(3),
 	HI8435_VOLTAGE_CHANNEL(4),
 	HI8435_VOLTAGE_CHANNEL(5),
 	HI8435_VOLTAGE_CHANNEL(6),
 	HI8435_VOLTAGE_CHANNEL(7),
 	HI8435_VOLTAGE_CHANNEL(8),
 	HI8435_VOLTAGE_CHANNEL(9),
 	HI8435_VOLTAGE_CHANNEL(10),
 	HI8435_VOLTAGE_CHANNEL(11),
 	HI8435_VOLTAGE_CHANNEL(12),
 	HI8435_VOLTAGE_CHANNEL(13),
 	HI8435_VOLTAGE_CHANNEL(14),
 	HI8435_VOLTAGE_CHANNEL(15),
 	HI8435_VOLTAGE_CHANNEL(16),
 	HI8435_VOLTAGE_CHANNEL(17),
 	HI8435_VOLTAGE_CHANNEL(18),
 	HI8435_VOLTAGE_CHANNEL(19),
 	HI8435_VOLTAGE_CHANNEL(20),
 	HI8435_VOLTAGE_CHANNEL(21),
 	HI8435_VOLTAGE_CHANNEL(22),
 	HI8435_VOLTAGE_CHANNEL(23),
 	HI8435_VOLTAGE_CHANNEL(24),
 	HI8435_VOLTAGE_CHANNEL(25),
 	HI8435_VOLTAGE_CHANNEL(26),
 	HI8435_VOLTAGE_CHANNEL(27),
 	HI8435_VOLTAGE_CHANNEL(28),
 	HI8435_VOLTAGE_CHANNEL(29),
 	HI8435_VOLTAGE_CHANNEL(30),
 	HI8435_VOLTAGE_CHANNEL(31),
 	IIO_CHAN_SOFT_TIMESTAMP(32),
 };

 static const struct iio_info hi8435_info = {
 	.driver_module = THIS_MODULE,
 	.read_event_config = &hi8435_read_event_config,
 	.write_event_config = hi8435_write_event_config,
 	.read_event_value = &hi8435_read_event_value,
 	.write_event_value = &hi8435_write_event_value,
 	.debugfs_reg_access = &hi8435_debugfs_reg_access,
 };

 static void hi8435_iio_push_event(struct iio_dev *idev, unsigned int val)
 {
 	struct hi8435_priv *priv = iio_priv(idev);
 	enum iio_event_direction dir;
 	unsigned int i;
 	unsigned int status = priv->event_prev_val ^ val;

 	if (!status)
 		return;

 	for_each_set_bit(i, &priv->event_scan_mask, 32) {
 		if (status & BIT(i)) {
 			dir = val & BIT(i) ? IIO_EV_DIR_RISING :
 					     IIO_EV_DIR_FALLING;
 			iio_push_event(idev,
 				       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE, i,
 						    IIO_EV_TYPE_THRESH, dir),
 				       iio_get_time_ns(idev));
 		}
 	}

 	priv->event_prev_val = val;
 }

 static irqreturn_t hi8435_trigger_handler(int irq, void *private)
 {
 	struct iio_poll_func *pf = private;
 	struct iio_dev *idev = pf->indio_dev;
 	struct hi8435_priv *priv = iio_priv(idev);
 	u32 val;
 	int ret;

 	ret = hi8435_readl(priv, HI8435_SO31_0_REG, &val);
 	if (ret < 0)
 		goto err_read;

 	hi8435_iio_push_event(idev, val);

 err_read:
 	iio_trigger_notify_done(idev->trig);

 	return IRQ_HANDLED;
 }

 static int hi8435_probe(struct spi_device *spi)
 {
 	struct iio_dev *idev;
 	struct hi8435_priv *priv;
 	struct gpio_desc *reset_gpio;
 	int ret;

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

 	priv = iio_priv(idev);
 	priv->spi = spi;

 	reset_gpio = devm_gpiod_get(&spi->dev, NULL, GPIOD_OUT_LOW);
 	if (!IS_ERR(reset_gpio)) {
 		/* need >=100ns low pulse to reset chip */
 		gpiod_set_raw_value_cansleep(reset_gpio, 0);
 		udelay(1);
 		gpiod_set_raw_value_cansleep(reset_gpio, 1);
 	} else {
 		/* s/w reset chip if h/w reset is not available */
 		hi8435_writeb(priv, HI8435_CTRL_REG, HI8435_CTRL_SRST);
 		hi8435_writeb(priv, HI8435_CTRL_REG, 0);
 	}

 	spi_set_drvdata(spi, idev);
 	mutex_init(&priv->lock);

 	idev->dev.parent	= &spi->dev;
 	idev->dev.of_node	= spi->dev.of_node;
 	idev->name		= spi_get_device_id(spi)->name;
 	idev->modes		= INDIO_DIRECT_MODE;
 	idev->info		= &hi8435_info;
 	idev->channels		= hi8435_channels;
 	idev->num_channels	= ARRAY_SIZE(hi8435_channels);

 	/* unmask all events */
 	priv->event_scan_mask = ~(0);
 	/*
 	 * There is a restriction in the chip - the hysteresis can not be odd.
 	 * If the hysteresis is set to odd value then chip gets into lock state
 	 * and not functional anymore.
 	 * After chip reset the thresholds are in undefined state, so we need to
 	 * initialize thresholds to some initial values and then prevent
 	 * userspace setting odd hysteresis.
 	 *
 	 * Set threshold low voltage to 2V, threshold high voltage to 4V
 	 * for both GND-Open and Supply-Open sensing modes.
 	 */
 	priv->threshold_lo[0] = priv->threshold_lo[1] = 2;
 	priv->threshold_hi[0] = priv->threshold_hi[1] = 4;
 	hi8435_writew(priv, HI8435_GOCENHYS_REG, 0x206);
 	hi8435_writew(priv, HI8435_SOCENHYS_REG, 0x206);

 	ret = iio_triggered_event_setup(idev, NULL, hi8435_trigger_handler);
 	if (ret)
 		return ret;

 	ret = iio_device_register(idev);
 	if (ret < 0) {
 		dev_err(&spi->dev, "unable to register device\n");
 		goto unregister_triggered_event;
 	}

 	return 0;

 unregister_triggered_event:
 	iio_triggered_event_cleanup(idev);
 	return ret;
 }

 static int hi8435_remove(struct spi_device *spi)
 {
 	struct iio_dev *idev = spi_get_drvdata(spi);

 	iio_device_unregister(idev);
 	iio_triggered_event_cleanup(idev);

 	return 0;
 }

 static const struct of_device_id hi8435_dt_ids[] = {
 	{ .compatible = "holt,hi8435" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, hi8435_dt_ids);

 static const struct spi_device_id hi8435_id[] = {
 	{ "hi8435", 0},
 	{ }
 };
 MODULE_DEVICE_TABLE(spi, hi8435_id);

 static struct spi_driver hi8435_driver = {
 	.driver	= {
 		.name		= DRV_NAME,
 		.of_match_table	= of_match_ptr(hi8435_dt_ids),
 	},
 	.probe		= hi8435_probe,
 	.remove		= hi8435_remove,
 	.id_table	= hi8435_id,
 };
 module_spi_driver(hi8435_driver);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Vladimir Barinov");
 MODULE_DESCRIPTION("HI-8435 threshold detector");
	/*
	* Holt Integrated Circuits HI-8435 threshold detector driver
	*
	* Copyright (C) 2015 Zodiac Inflight Innovations
	* Copyright (C) 2015 Cogent Embedded, Inc.
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published by the
	* Free Software Foundation; either version 2 of the License, or (at your
	* option) any later version.
	*/

	#include <linux/delay.h>
	#include <linux/iio/events.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/iio/trigger.h>
	#include <linux/iio/trigger_consumer.h>
	#include <linux/iio/triggered_event.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/of_device.h>
	#include <linux/of_gpio.h>
	#include <linux/spi/spi.h>
	#include <linux/gpio/consumer.h>

	#define DRV_NAME "hi8435"

	/* Register offsets for HI-8435 */
	#define HI8435_CTRL_REG 0x02
	#define HI8435_PSEN_REG 0x04
	#define HI8435_TMDATA_REG 0x1E
	#define HI8435_GOCENHYS_REG 0x3A
	#define HI8435_SOCENHYS_REG 0x3C
	#define HI8435_SO7_0_REG 0x10
	#define HI8435_SO15_8_REG 0x12
	#define HI8435_SO23_16_REG 0x14
	#define HI8435_SO31_24_REG 0x16
	#define HI8435_SO31_0_REG 0x78

	#define HI8435_WRITE_OPCODE 0x00
	#define HI8435_READ_OPCODE 0x80

	/* CTRL register bits */
	#define HI8435_CTRL_TEST 0x01
	#define HI8435_CTRL_SRST 0x02

	struct hi8435_priv {
	struct spi_device *spi;
	struct mutex lock;

	unsigned long event_scan_mask; /* soft mask/unmask channels events */
	unsigned int event_prev_val;

	unsigned threshold_lo[2]; /* GND-Open and Supply-Open thresholds */
	unsigned threshold_hi[2]; /* GND-Open and Supply-Open thresholds */
	u8 reg_buffer[3] ____cacheline_aligned;
	};

	static int hi8435_readb(struct hi8435_priv priv, u8 reg, u8 val)
	{
	reg \|= HI8435_READ_OPCODE;
	return spi_write_then_read(priv->spi, &reg, 1, val, 1);
	}

	static int hi8435_readw(struct hi8435_priv priv, u8 reg, u16 val)
	{
	int ret;
	__be16 be_val;

	reg \|= HI8435_READ_OPCODE;
	ret = spi_write_then_read(priv->spi, &reg, 1, &be_val, 2);
	*val = be16_to_cpu(be_val);

	return ret;
	}

	static int hi8435_readl(struct hi8435_priv priv, u8 reg, u32 val)
	{
	int ret;
	__be32 be_val;

	reg \|= HI8435_READ_OPCODE;
	ret = spi_write_then_read(priv->spi, &reg, 1, &be_val, 4);
	*val = be32_to_cpu(be_val);

	return ret;
	}

	static int hi8435_writeb(struct hi8435_priv *priv, u8 reg, u8 val)
	{
	priv->reg_buffer[0] = reg \| HI8435_WRITE_OPCODE;
	priv->reg_buffer[1] = val;

	return spi_write(priv->spi, priv->reg_buffer, 2);
	}

	static int hi8435_writew(struct hi8435_priv *priv, u8 reg, u16 val)
	{
	priv->reg_buffer[0] = reg \| HI8435_WRITE_OPCODE;
	priv->reg_buffer[1] = (val >> 8) & 0xff;
	priv->reg_buffer[2] = val & 0xff;

	return spi_write(priv->spi, priv->reg_buffer, 3);
	}

	static int hi8435_read_event_config(struct iio_dev *idev,
	const struct iio_chan_spec *chan,
	enum iio_event_type type,
	enum iio_event_direction dir)
	{
	struct hi8435_priv *priv = iio_priv(idev);

	return !!(priv->event_scan_mask & BIT(chan->channel));
	}

	static int hi8435_write_event_config(struct iio_dev *idev,
	const struct iio_chan_spec *chan,
	enum iio_event_type type,
	enum iio_event_direction dir, int state)
	{
	struct hi8435_priv *priv = iio_priv(idev);
	int ret;
	u32 tmp;

	if (state) {
	ret = hi8435_readl(priv, HI8435_SO31_0_REG, &tmp);
	if (ret < 0)
	return ret;
	if (tmp & BIT(chan->channel))
	priv->event_prev_val \|= BIT(chan->channel);
	else
	priv->event_prev_val &= ~BIT(chan->channel);

	priv->event_scan_mask \|= BIT(chan->channel);
	} else
	priv->event_scan_mask &= ~BIT(chan->channel);

	return 0;
	}

	static int hi8435_read_event_value(struct iio_dev *idev,
	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 hi8435_priv *priv = iio_priv(idev);
	int ret;
	u8 mode, psen;
	u16 reg;

	ret = hi8435_readb(priv, HI8435_PSEN_REG, &psen);
	if (ret < 0)
	return ret;

	/* Supply-Open or GND-Open sensing mode */
	mode = !!(psen & BIT(chan->channel / 8));

	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
	HI8435_GOCENHYS_REG, &reg);
	if (ret < 0)
	return ret;

	if (dir == IIO_EV_DIR_FALLING)
	*val = ((reg & 0xff) - (reg >> 8)) / 2;
	else if (dir == IIO_EV_DIR_RISING)
	*val = ((reg & 0xff) + (reg >> 8)) / 2;

	return IIO_VAL_INT;
	}

	static int hi8435_write_event_value(struct iio_dev *idev,
	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 hi8435_priv *priv = iio_priv(idev);
	int ret;
	u8 mode, psen;
	u16 reg;

	ret = hi8435_readb(priv, HI8435_PSEN_REG, &psen);
	if (ret < 0)
	return ret;

	/* Supply-Open or GND-Open sensing mode */
	mode = !!(psen & BIT(chan->channel / 8));

	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
	HI8435_GOCENHYS_REG, &reg);
	if (ret < 0)
	return ret;

	if (dir == IIO_EV_DIR_FALLING) {
	/* falling threshold range 2..21V, hysteresis minimum 2V */
	if (val < 2 \|\| val > 21 \|\| (val + 2) > priv->threshold_hi[mode])
	return -EINVAL;

	if (val == priv->threshold_lo[mode])
	return 0;

	priv->threshold_lo[mode] = val;

	/* hysteresis must not be odd */
	if ((priv->threshold_hi[mode] - priv->threshold_lo[mode]) % 2)
	priv->threshold_hi[mode]--;
	} else if (dir == IIO_EV_DIR_RISING) {
	/* rising threshold range 3..22V, hysteresis minimum 2V */
	if (val < 3 \|\| val > 22 \|\| val < (priv->threshold_lo[mode] + 2))
	return -EINVAL;

	if (val == priv->threshold_hi[mode])
	return 0;

	priv->threshold_hi[mode] = val;

	/* hysteresis must not be odd */
	if ((priv->threshold_hi[mode] - priv->threshold_lo[mode]) % 2)
	priv->threshold_lo[mode]++;
	}

	/* program thresholds */
	mutex_lock(&priv->lock);

	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
	HI8435_GOCENHYS_REG, &reg);
	if (ret < 0) {
	mutex_unlock(&priv->lock);
	return ret;
	}

	/* hysteresis */
	reg = priv->threshold_hi[mode] - priv->threshold_lo[mode];
	reg <<= 8;
	/* threshold center */
	reg \|= (priv->threshold_hi[mode] + priv->threshold_lo[mode]);

	ret = hi8435_writew(priv, mode ? HI8435_SOCENHYS_REG :
	HI8435_GOCENHYS_REG, reg);

	mutex_unlock(&priv->lock);

	return ret;
	}

	static int hi8435_debugfs_reg_access(struct iio_dev *idev,
	unsigned reg, unsigned writeval,
	unsigned *readval)
	{
	struct hi8435_priv *priv = iio_priv(idev);
	int ret;
	u8 val;

	if (readval != NULL) {
	ret = hi8435_readb(priv, reg, &val);
	*readval = val;
	} else {
	val = (u8)writeval;
	ret = hi8435_writeb(priv, reg, val);
	}

	return ret;
	}

	static const struct iio_event_spec hi8435_events[] = {
	{
	.type = IIO_EV_TYPE_THRESH,
	.dir = IIO_EV_DIR_RISING,
	.mask_separate = BIT(IIO_EV_INFO_VALUE),
	}, {
	.type = IIO_EV_TYPE_THRESH,
	.dir = IIO_EV_DIR_FALLING,
	.mask_separate = BIT(IIO_EV_INFO_VALUE),
	}, {
	.type = IIO_EV_TYPE_THRESH,
	.dir = IIO_EV_DIR_EITHER,
	.mask_separate = BIT(IIO_EV_INFO_ENABLE),
	},
	};

	static int hi8435_get_sensing_mode(struct iio_dev *idev,
	const struct iio_chan_spec *chan)
	{
	struct hi8435_priv *priv = iio_priv(idev);
	int ret;
	u8 reg;

	ret = hi8435_readb(priv, HI8435_PSEN_REG, &reg);
	if (ret < 0)
	return ret;

	return !!(reg & BIT(chan->channel / 8));
	}

	static int hi8435_set_sensing_mode(struct iio_dev *idev,
	const struct iio_chan_spec *chan,
	unsigned int mode)
	{
	struct hi8435_priv *priv = iio_priv(idev);
	int ret;
	u8 reg;

	mutex_lock(&priv->lock);

	ret = hi8435_readb(priv, HI8435_PSEN_REG, &reg);
	if (ret < 0) {
	mutex_unlock(&priv->lock);
	return ret;
	}

	reg &= ~BIT(chan->channel / 8);
	if (mode)
	reg \|= BIT(chan->channel / 8);

	ret = hi8435_writeb(priv, HI8435_PSEN_REG, reg);

	mutex_unlock(&priv->lock);

	return ret;
	}

	static const char * const hi8435_sensing_modes[] = { "GND-Open",
	"Supply-Open" };

	static const struct iio_enum hi8435_sensing_mode = {
	.items = hi8435_sensing_modes,
	.num_items = ARRAY_SIZE(hi8435_sensing_modes),
	.get = hi8435_get_sensing_mode,
	.set = hi8435_set_sensing_mode,
	};

	static const struct iio_chan_spec_ext_info hi8435_ext_info[] = {
	IIO_ENUM("sensing_mode", IIO_SEPARATE, &hi8435_sensing_mode),
	{},
	};

	#define HI8435_VOLTAGE_CHANNEL(num) \
	{ \
	.type = IIO_VOLTAGE, \
	.indexed = 1, \
	.channel = num, \
	.event_spec = hi8435_events, \
	.num_event_specs = ARRAY_SIZE(hi8435_events), \
	.ext_info = hi8435_ext_info, \
	}

	static const struct iio_chan_spec hi8435_channels[] = {
	HI8435_VOLTAGE_CHANNEL(0),
	HI8435_VOLTAGE_CHANNEL(1),
	HI8435_VOLTAGE_CHANNEL(2),
	HI8435_VOLTAGE_CHANNEL(3),
	HI8435_VOLTAGE_CHANNEL(4),
	HI8435_VOLTAGE_CHANNEL(5),
	HI8435_VOLTAGE_CHANNEL(6),
	HI8435_VOLTAGE_CHANNEL(7),
	HI8435_VOLTAGE_CHANNEL(8),
	HI8435_VOLTAGE_CHANNEL(9),
	HI8435_VOLTAGE_CHANNEL(10),
	HI8435_VOLTAGE_CHANNEL(11),
	HI8435_VOLTAGE_CHANNEL(12),
	HI8435_VOLTAGE_CHANNEL(13),
	HI8435_VOLTAGE_CHANNEL(14),
	HI8435_VOLTAGE_CHANNEL(15),
	HI8435_VOLTAGE_CHANNEL(16),
	HI8435_VOLTAGE_CHANNEL(17),
	HI8435_VOLTAGE_CHANNEL(18),
	HI8435_VOLTAGE_CHANNEL(19),
	HI8435_VOLTAGE_CHANNEL(20),
	HI8435_VOLTAGE_CHANNEL(21),
	HI8435_VOLTAGE_CHANNEL(22),
	HI8435_VOLTAGE_CHANNEL(23),
	HI8435_VOLTAGE_CHANNEL(24),
	HI8435_VOLTAGE_CHANNEL(25),
	HI8435_VOLTAGE_CHANNEL(26),
	HI8435_VOLTAGE_CHANNEL(27),
	HI8435_VOLTAGE_CHANNEL(28),
	HI8435_VOLTAGE_CHANNEL(29),
	HI8435_VOLTAGE_CHANNEL(30),
	HI8435_VOLTAGE_CHANNEL(31),
	IIO_CHAN_SOFT_TIMESTAMP(32),
	};

	static const struct iio_info hi8435_info = {
	.driver_module = THIS_MODULE,
	.read_event_config = &hi8435_read_event_config,
	.write_event_config = hi8435_write_event_config,
	.read_event_value = &hi8435_read_event_value,
	.write_event_value = &hi8435_write_event_value,
	.debugfs_reg_access = &hi8435_debugfs_reg_access,
	};

	static void hi8435_iio_push_event(struct iio_dev *idev, unsigned int val)
	{
	struct hi8435_priv *priv = iio_priv(idev);
	enum iio_event_direction dir;
	unsigned int i;
	unsigned int status = priv->event_prev_val ^ val;

	if (!status)
	return;

	for_each_set_bit(i, &priv->event_scan_mask, 32) {
	if (status & BIT(i)) {
	dir = val & BIT(i) ? IIO_EV_DIR_RISING :
	IIO_EV_DIR_FALLING;
	iio_push_event(idev,
	IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE, i,
	IIO_EV_TYPE_THRESH, dir),
	iio_get_time_ns(idev));
	}
	}

	priv->event_prev_val = val;
	}

	static irqreturn_t hi8435_trigger_handler(int irq, void *private)
	{
	struct iio_poll_func *pf = private;
	struct iio_dev *idev = pf->indio_dev;
	struct hi8435_priv *priv = iio_priv(idev);
	u32 val;
	int ret;

	ret = hi8435_readl(priv, HI8435_SO31_0_REG, &val);
	if (ret < 0)
	goto err_read;

	hi8435_iio_push_event(idev, val);

	err_read:
	iio_trigger_notify_done(idev->trig);

	return IRQ_HANDLED;
	}

	static int hi8435_probe(struct spi_device *spi)
	{
	struct iio_dev *idev;
	struct hi8435_priv *priv;
	struct gpio_desc *reset_gpio;
	int ret;

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

	priv = iio_priv(idev);
	priv->spi = spi;

	reset_gpio = devm_gpiod_get(&spi->dev, NULL, GPIOD_OUT_LOW);
	if (!IS_ERR(reset_gpio)) {
	/* need >=100ns low pulse to reset chip */
	gpiod_set_raw_value_cansleep(reset_gpio, 0);
	udelay(1);
	gpiod_set_raw_value_cansleep(reset_gpio, 1);
	} else {
	/* s/w reset chip if h/w reset is not available */
	hi8435_writeb(priv, HI8435_CTRL_REG, HI8435_CTRL_SRST);
	hi8435_writeb(priv, HI8435_CTRL_REG, 0);
	}

	spi_set_drvdata(spi, idev);
	mutex_init(&priv->lock);

	idev->dev.parent = &spi->dev;
	idev->dev.of_node = spi->dev.of_node;
	idev->name = spi_get_device_id(spi)->name;
	idev->modes = INDIO_DIRECT_MODE;
	idev->info = &hi8435_info;
	idev->channels = hi8435_channels;
	idev->num_channels = ARRAY_SIZE(hi8435_channels);

	/* unmask all events */
	priv->event_scan_mask = ~(0);
	/*
	* There is a restriction in the chip - the hysteresis can not be odd.
	* If the hysteresis is set to odd value then chip gets into lock state
	* and not functional anymore.
	* After chip reset the thresholds are in undefined state, so we need to
	* initialize thresholds to some initial values and then prevent
	* userspace setting odd hysteresis.
	*
	* Set threshold low voltage to 2V, threshold high voltage to 4V
	* for both GND-Open and Supply-Open sensing modes.
	*/
	priv->threshold_lo[0] = priv->threshold_lo[1] = 2;
	priv->threshold_hi[0] = priv->threshold_hi[1] = 4;
	hi8435_writew(priv, HI8435_GOCENHYS_REG, 0x206);
	hi8435_writew(priv, HI8435_SOCENHYS_REG, 0x206);

	ret = iio_triggered_event_setup(idev, NULL, hi8435_trigger_handler);
	if (ret)
	return ret;

	ret = iio_device_register(idev);
	if (ret < 0) {
	dev_err(&spi->dev, "unable to register device\n");
	goto unregister_triggered_event;
	}

	return 0;

	unregister_triggered_event:
	iio_triggered_event_cleanup(idev);
	return ret;
	}

	static int hi8435_remove(struct spi_device *spi)
	{
	struct iio_dev *idev = spi_get_drvdata(spi);

	iio_device_unregister(idev);
	iio_triggered_event_cleanup(idev);

	return 0;
	}

	static const struct of_device_id hi8435_dt_ids[] = {
	{ .compatible = "holt,hi8435" },
	{},
	};
	MODULE_DEVICE_TABLE(of, hi8435_dt_ids);

	static const struct spi_device_id hi8435_id[] = {
	{ "hi8435", 0},
	{ }
	};
	MODULE_DEVICE_TABLE(spi, hi8435_id);

	static struct spi_driver hi8435_driver = {
	.driver = {
	.name = DRV_NAME,
	.of_match_table = of_match_ptr(hi8435_dt_ids),
	},
	.probe = hi8435_probe,
	.remove = hi8435_remove,
	.id_table = hi8435_id,
	};
	module_spi_driver(hi8435_driver);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Vladimir Barinov");
	MODULE_DESCRIPTION("HI-8435 threshold detector");