drivers/iio/light/max44000.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * MAX44000 Ambient and Infrared Proximity Sensor
  *
  * Copyright (c) 2016, Intel Corporation.
  *
  * Data sheet: https://datasheets.maximintegrated.com/en/ds/MAX44000.pdf
  *
  * 7-bit I2C slave address 0x4a
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/i2c.h>
 #include <linux/regmap.h>
 #include <linux/util_macros.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/buffer.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/acpi.h>

 #define MAX44000_DRV_NAME		"max44000"

 /* Registers in datasheet order */
 #define MAX44000_REG_STATUS		0x00
 #define MAX44000_REG_CFG_MAIN		0x01
 #define MAX44000_REG_CFG_RX		0x02
 #define MAX44000_REG_CFG_TX		0x03
 #define MAX44000_REG_ALS_DATA_HI	0x04
 #define MAX44000_REG_ALS_DATA_LO	0x05
 #define MAX44000_REG_PRX_DATA		0x16
 #define MAX44000_REG_ALS_UPTHR_HI	0x06
 #define MAX44000_REG_ALS_UPTHR_LO	0x07
 #define MAX44000_REG_ALS_LOTHR_HI	0x08
 #define MAX44000_REG_ALS_LOTHR_LO	0x09
 #define MAX44000_REG_PST		0x0a
 #define MAX44000_REG_PRX_IND		0x0b
 #define MAX44000_REG_PRX_THR		0x0c
 #define MAX44000_REG_TRIM_GAIN_GREEN	0x0f
 #define MAX44000_REG_TRIM_GAIN_IR	0x10

 /* REG_CFG bits */
 #define MAX44000_CFG_ALSINTE            0x01
 #define MAX44000_CFG_PRXINTE            0x02
 #define MAX44000_CFG_MASK               0x1c
 #define MAX44000_CFG_MODE_SHUTDOWN      0x00
 #define MAX44000_CFG_MODE_ALS_GIR       0x04
 #define MAX44000_CFG_MODE_ALS_G         0x08
 #define MAX44000_CFG_MODE_ALS_IR        0x0c
 #define MAX44000_CFG_MODE_ALS_PRX       0x10
 #define MAX44000_CFG_MODE_PRX           0x14
 #define MAX44000_CFG_TRIM               0x20

 /*
  * Upper 4 bits are not documented but start as 1 on powerup
  * Setting them to 0 causes proximity to misbehave so set them to 1
  */
 #define MAX44000_REG_CFG_RX_DEFAULT 0xf0

 /* REG_RX bits */
 #define MAX44000_CFG_RX_ALSTIM_MASK	0x0c
 #define MAX44000_CFG_RX_ALSTIM_SHIFT	2
 #define MAX44000_CFG_RX_ALSPGA_MASK	0x03
 #define MAX44000_CFG_RX_ALSPGA_SHIFT	0

 /* REG_TX bits */
 #define MAX44000_LED_CURRENT_MASK	0xf
 #define MAX44000_LED_CURRENT_MAX	11
 #define MAX44000_LED_CURRENT_DEFAULT	6

 #define MAX44000_ALSDATA_OVERFLOW	0x4000

 struct max44000_data {
 	struct mutex lock;
 	struct regmap *regmap;
 	/* Ensure naturally aligned timestamp */
 	struct {
 		u16 channels[2];
 		s64 ts __aligned(8);
 	} scan;
 };

 /* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */
 #define MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2 5

 /* Scale can be multiplied by up to 128x via ALSPGA for measurement gain */
 static const int max44000_alspga_shift[] = {0, 2, 4, 7};
 #define MAX44000_ALSPGA_MAX_SHIFT 7

 /*
  * Scale can be multiplied by up to 64x via ALSTIM because of lost resolution
  *
  * This scaling factor is hidden from userspace and instead accounted for when
  * reading raw values from the device.
  *
  * This makes it possible to cleanly expose ALSPGA as IIO_CHAN_INFO_SCALE and
  * ALSTIM as IIO_CHAN_INFO_INT_TIME without the values affecting each other.
  *
  * Handling this internally is also required for buffer support because the
  * channel's scan_type can't be modified dynamically.
  */
 #define MAX44000_ALSTIM_SHIFT(alstim) (2 * (alstim))

 /* Available integration times with pretty manual alignment: */
 static const int max44000_int_time_avail_ns_array[] = {
 	   100000000,
 	    25000000,
 	     6250000,
 	     1562500,
 };
 static const char max44000_int_time_avail_str[] =
 	"0.100 "
 	"0.025 "
 	"0.00625 "
 	"0.0015625";

 /* Available scales (internal to ulux) with pretty manual alignment: */
 static const int max44000_scale_avail_ulux_array[] = {
 	    31250,
 	   125000,
 	   500000,
 	  4000000,
 };
 static const char max44000_scale_avail_str[] =
 	"0.03125 "
 	"0.125 "
 	"0.5 "
 	 "4";

 #define MAX44000_SCAN_INDEX_ALS 0
 #define MAX44000_SCAN_INDEX_PRX 1

 static const struct iio_chan_spec max44000_channels[] = {
 	{
 		.type = IIO_LIGHT,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
 					    BIT(IIO_CHAN_INFO_INT_TIME),
 		.scan_index = MAX44000_SCAN_INDEX_ALS,
 		.scan_type = {
 			.sign		= 'u',
 			.realbits	= 14,
 			.storagebits	= 16,
 		}
 	},
 	{
 		.type = IIO_PROXIMITY,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.scan_index = MAX44000_SCAN_INDEX_PRX,
 		.scan_type = {
 			.sign		= 'u',
 			.realbits	= 8,
 			.storagebits	= 16,
 		}
 	},
 	IIO_CHAN_SOFT_TIMESTAMP(2),
 	{
 		.type = IIO_CURRENT,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				      BIT(IIO_CHAN_INFO_SCALE),
 		.extend_name = "led",
 		.output = 1,
 		.scan_index = -1,
 	},
 };

 static int max44000_read_alstim(struct max44000_data *data)
 {
 	unsigned int val;
 	int ret;

 	ret = regmap_read(data->regmap, MAX44000_REG_CFG_RX, &val);
 	if (ret < 0)
 		return ret;
 	return (val & MAX44000_CFG_RX_ALSTIM_MASK) >> MAX44000_CFG_RX_ALSTIM_SHIFT;
 }

 static int max44000_write_alstim(struct max44000_data *data, int val)
 {
 	return regmap_write_bits(data->regmap, MAX44000_REG_CFG_RX,
 				 MAX44000_CFG_RX_ALSTIM_MASK,
 				 val << MAX44000_CFG_RX_ALSTIM_SHIFT);
 }

 static int max44000_read_alspga(struct max44000_data *data)
 {
 	unsigned int val;
 	int ret;

 	ret = regmap_read(data->regmap, MAX44000_REG_CFG_RX, &val);
 	if (ret < 0)
 		return ret;
 	return (val & MAX44000_CFG_RX_ALSPGA_MASK) >> MAX44000_CFG_RX_ALSPGA_SHIFT;
 }

 static int max44000_write_alspga(struct max44000_data *data, int val)
 {
 	return regmap_write_bits(data->regmap, MAX44000_REG_CFG_RX,
 				 MAX44000_CFG_RX_ALSPGA_MASK,
 				 val << MAX44000_CFG_RX_ALSPGA_SHIFT);
 }

 static int max44000_read_alsval(struct max44000_data *data)
 {
 	u16 regval;
 	__be16 val;
 	int alstim, ret;

 	ret = regmap_bulk_read(data->regmap, MAX44000_REG_ALS_DATA_HI,
 			       &val, sizeof(val));
 	if (ret < 0)
 		return ret;
 	alstim = ret = max44000_read_alstim(data);
 	if (ret < 0)
 		return ret;

 	regval = be16_to_cpu(val);

 	/*
 	 * Overflow is explained on datasheet page 17.
 	 *
 	 * It's a warning that either the G or IR channel has become saturated
 	 * and that the value in the register is likely incorrect.
 	 *
 	 * The recommendation is to change the scale (ALSPGA).
 	 * The driver just returns the max representable value.
 	 */
 	if (regval & MAX44000_ALSDATA_OVERFLOW)
 		return 0x3FFF;

 	return regval << MAX44000_ALSTIM_SHIFT(alstim);
 }

 static int max44000_write_led_current_raw(struct max44000_data *data, int val)
 {
 	/* Maybe we should clamp the value instead? */
 	if (val < 0 || val > MAX44000_LED_CURRENT_MAX)
 		return -ERANGE;
 	if (val >= 8)
 		val += 4;
 	return regmap_write_bits(data->regmap, MAX44000_REG_CFG_TX,
 				 MAX44000_LED_CURRENT_MASK, val);
 }

 static int max44000_read_led_current_raw(struct max44000_data *data)
 {
 	unsigned int regval;
 	int ret;

 	ret = regmap_read(data->regmap, MAX44000_REG_CFG_TX, &regval);
 	if (ret < 0)
 		return ret;
 	regval &= MAX44000_LED_CURRENT_MASK;
 	if (regval >= 8)
 		regval -= 4;
 	return regval;
 }

 static int max44000_read_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     int *val, int *val2, long mask)
 {
 	struct max44000_data *data = iio_priv(indio_dev);
 	int alstim, alspga;
 	unsigned int regval;
 	int ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		switch (chan->type) {
 		case IIO_LIGHT:
 			mutex_lock(&data->lock);
 			ret = max44000_read_alsval(data);
 			mutex_unlock(&data->lock);
 			if (ret < 0)
 				return ret;
 			*val = ret;
 			return IIO_VAL_INT;

 		case IIO_PROXIMITY:
 			mutex_lock(&data->lock);
 			ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, &regval);
 			mutex_unlock(&data->lock);
 			if (ret < 0)
 				return ret;
 			*val = regval;
 			return IIO_VAL_INT;

 		case IIO_CURRENT:
 			mutex_lock(&data->lock);
 			ret = max44000_read_led_current_raw(data);
 			mutex_unlock(&data->lock);
 			if (ret < 0)
 				return ret;
 			*val = ret;
 			return IIO_VAL_INT;

 		default:
 			return -EINVAL;
 		}

 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_CURRENT:
 			/* Output register is in 10s of miliamps */
 			*val = 10;
 			return IIO_VAL_INT;

 		case IIO_LIGHT:
 			mutex_lock(&data->lock);
 			alspga = ret = max44000_read_alspga(data);
 			mutex_unlock(&data->lock);
 			if (ret < 0)
 				return ret;

 			/* Avoid negative shifts */
 			*val = (1 << MAX44000_ALSPGA_MAX_SHIFT);
 			*val2 = MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2
 					+ MAX44000_ALSPGA_MAX_SHIFT
 					- max44000_alspga_shift[alspga];
 			return IIO_VAL_FRACTIONAL_LOG2;

 		default:
 			return -EINVAL;
 		}

 	case IIO_CHAN_INFO_INT_TIME:
 		mutex_lock(&data->lock);
 		alstim = ret = max44000_read_alstim(data);
 		mutex_unlock(&data->lock);

 		if (ret < 0)
 			return ret;
 		*val = 0;
 		*val2 = max44000_int_time_avail_ns_array[alstim];
 		return IIO_VAL_INT_PLUS_NANO;

 	default:
 		return -EINVAL;
 	}
 }

 static int max44000_write_raw(struct iio_dev *indio_dev,
 			      struct iio_chan_spec const *chan,
 			      int val, int val2, long mask)
 {
 	struct max44000_data *data = iio_priv(indio_dev);
 	int ret;

 	if (mask == IIO_CHAN_INFO_RAW && chan->type == IIO_CURRENT) {
 		mutex_lock(&data->lock);
 		ret = max44000_write_led_current_raw(data, val);
 		mutex_unlock(&data->lock);
 		return ret;
 	} else if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT) {
 		s64 valns = val * NSEC_PER_SEC + val2;
 		int alstim = find_closest_descending(valns,
 				max44000_int_time_avail_ns_array,
 				ARRAY_SIZE(max44000_int_time_avail_ns_array));
 		mutex_lock(&data->lock);
 		ret = max44000_write_alstim(data, alstim);
 		mutex_unlock(&data->lock);
 		return ret;
 	} else if (mask == IIO_CHAN_INFO_SCALE && chan->type == IIO_LIGHT) {
 		s64 valus = val * USEC_PER_SEC + val2;
 		int alspga = find_closest(valus,
 				max44000_scale_avail_ulux_array,
 				ARRAY_SIZE(max44000_scale_avail_ulux_array));
 		mutex_lock(&data->lock);
 		ret = max44000_write_alspga(data, alspga);
 		mutex_unlock(&data->lock);
 		return ret;
 	}

 	return -EINVAL;
 }

 static int max44000_write_raw_get_fmt(struct iio_dev *indio_dev,
 				      struct iio_chan_spec const *chan,
 				      long mask)
 {
 	if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT)
 		return IIO_VAL_INT_PLUS_NANO;
 	else if (mask == IIO_CHAN_INFO_SCALE && chan->type == IIO_LIGHT)
 		return IIO_VAL_INT_PLUS_MICRO;
 	else
 		return IIO_VAL_INT;
 }

 static IIO_CONST_ATTR(illuminance_integration_time_available, max44000_int_time_avail_str);
 static IIO_CONST_ATTR(illuminance_scale_available, max44000_scale_avail_str);

 static struct attribute *max44000_attributes[] = {
 	&iio_const_attr_illuminance_integration_time_available.dev_attr.attr,
 	&iio_const_attr_illuminance_scale_available.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group max44000_attribute_group = {
 	.attrs = max44000_attributes,
 };

 static const struct iio_info max44000_info = {
 	.read_raw		= max44000_read_raw,
 	.write_raw		= max44000_write_raw,
 	.write_raw_get_fmt	= max44000_write_raw_get_fmt,
 	.attrs			= &max44000_attribute_group,
 };

 static bool max44000_readable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MAX44000_REG_STATUS:
 	case MAX44000_REG_CFG_MAIN:
 	case MAX44000_REG_CFG_RX:
 	case MAX44000_REG_CFG_TX:
 	case MAX44000_REG_ALS_DATA_HI:
 	case MAX44000_REG_ALS_DATA_LO:
 	case MAX44000_REG_PRX_DATA:
 	case MAX44000_REG_ALS_UPTHR_HI:
 	case MAX44000_REG_ALS_UPTHR_LO:
 	case MAX44000_REG_ALS_LOTHR_HI:
 	case MAX44000_REG_ALS_LOTHR_LO:
 	case MAX44000_REG_PST:
 	case MAX44000_REG_PRX_IND:
 	case MAX44000_REG_PRX_THR:
 	case MAX44000_REG_TRIM_GAIN_GREEN:
 	case MAX44000_REG_TRIM_GAIN_IR:
 		return true;
 	default:
 		return false;
 	}
 }

 static bool max44000_writeable_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MAX44000_REG_CFG_MAIN:
 	case MAX44000_REG_CFG_RX:
 	case MAX44000_REG_CFG_TX:
 	case MAX44000_REG_ALS_UPTHR_HI:
 	case MAX44000_REG_ALS_UPTHR_LO:
 	case MAX44000_REG_ALS_LOTHR_HI:
 	case MAX44000_REG_ALS_LOTHR_LO:
 	case MAX44000_REG_PST:
 	case MAX44000_REG_PRX_IND:
 	case MAX44000_REG_PRX_THR:
 	case MAX44000_REG_TRIM_GAIN_GREEN:
 	case MAX44000_REG_TRIM_GAIN_IR:
 		return true;
 	default:
 		return false;
 	}
 }

 static bool max44000_volatile_reg(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case MAX44000_REG_STATUS:
 	case MAX44000_REG_ALS_DATA_HI:
 	case MAX44000_REG_ALS_DATA_LO:
 	case MAX44000_REG_PRX_DATA:
 		return true;
 	default:
 		return false;
 	}
 }

 static bool max44000_precious_reg(struct device *dev, unsigned int reg)
 {
 	return reg == MAX44000_REG_STATUS;
 }

 static const struct regmap_config max44000_regmap_config = {
 	.reg_bits		= 8,
 	.val_bits		= 8,

 	.max_register		= MAX44000_REG_PRX_DATA,
 	.readable_reg		= max44000_readable_reg,
 	.writeable_reg		= max44000_writeable_reg,
 	.volatile_reg		= max44000_volatile_reg,
 	.precious_reg		= max44000_precious_reg,

 	.use_single_read	= true,
 	.use_single_write	= true,
 	.cache_type		= REGCACHE_RBTREE,
 };

 static irqreturn_t max44000_trigger_handler(int irq, void *p)
 {
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct max44000_data *data = iio_priv(indio_dev);
 	int index = 0;
 	unsigned int regval;
 	int ret;

 	mutex_lock(&data->lock);
 	if (test_bit(MAX44000_SCAN_INDEX_ALS, indio_dev->active_scan_mask)) {
 		ret = max44000_read_alsval(data);
 		if (ret < 0)
 			goto out_unlock;
 		data->scan.channels[index++] = ret;
 	}
 	if (test_bit(MAX44000_SCAN_INDEX_PRX, indio_dev->active_scan_mask)) {
 		ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, &regval);
 		if (ret < 0)
 			goto out_unlock;
 		data->scan.channels[index] = regval;
 	}
 	mutex_unlock(&data->lock);

 	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
 					   iio_get_time_ns(indio_dev));
 	iio_trigger_notify_done(indio_dev->trig);
 	return IRQ_HANDLED;

 out_unlock:
 	mutex_unlock(&data->lock);
 	iio_trigger_notify_done(indio_dev->trig);
 	return IRQ_HANDLED;
 }

 static int max44000_probe(struct i2c_client *client,
 			  const struct i2c_device_id *id)
 {
 	struct max44000_data *data;
 	struct iio_dev *indio_dev;
 	int ret, reg;

 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 	if (!indio_dev)
 		return -ENOMEM;
 	data = iio_priv(indio_dev);
 	data->regmap = devm_regmap_init_i2c(client, &max44000_regmap_config);
 	if (IS_ERR(data->regmap)) {
 		dev_err(&client->dev, "regmap_init failed!\n");
 		return PTR_ERR(data->regmap);
 	}

 	mutex_init(&data->lock);
 	indio_dev->info = &max44000_info;
 	indio_dev->name = MAX44000_DRV_NAME;
 	indio_dev->channels = max44000_channels;
 	indio_dev->num_channels = ARRAY_SIZE(max44000_channels);

 	/*
 	 * The device doesn't have a reset function so we just clear some
 	 * important bits at probe time to ensure sane operation.
 	 *
 	 * Since we don't support interrupts/events the threshold values are
 	 * not important. We also don't touch trim values.
 	 */

 	/* Reset ALS scaling bits */
 	ret = regmap_write(data->regmap, MAX44000_REG_CFG_RX,
 			   MAX44000_REG_CFG_RX_DEFAULT);
 	if (ret < 0) {
 		dev_err(&client->dev, "failed to write default CFG_RX: %d\n",
 			ret);
 		return ret;
 	}

 	/*
 	 * By default the LED pulse used for the proximity sensor is disabled.
 	 * Set a middle value so that we get some sort of valid data by default.
 	 */
 	ret = max44000_write_led_current_raw(data, MAX44000_LED_CURRENT_DEFAULT);
 	if (ret < 0) {
 		dev_err(&client->dev, "failed to write init config: %d\n", ret);
 		return ret;
 	}

 	/* Reset CFG bits to ALS_PRX mode which allows easy reading of both values. */
 	reg = MAX44000_CFG_TRIM | MAX44000_CFG_MODE_ALS_PRX;
 	ret = regmap_write(data->regmap, MAX44000_REG_CFG_MAIN, reg);
 	if (ret < 0) {
 		dev_err(&client->dev, "failed to write init config: %d\n", ret);
 		return ret;
 	}

 	/* Read status at least once to clear any stale interrupt bits. */
 	ret = regmap_read(data->regmap, MAX44000_REG_STATUS, &reg);
 	if (ret < 0) {
 		dev_err(&client->dev, "failed to read init status: %d\n", ret);
 		return ret;
 	}

 	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev, NULL,
 					      max44000_trigger_handler, NULL);
 	if (ret < 0) {
 		dev_err(&client->dev, "iio triggered buffer setup failed\n");
 		return ret;
 	}

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

 static const struct i2c_device_id max44000_id[] = {
 	{"max44000", 0},
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, max44000_id);

 #ifdef CONFIG_ACPI
 static const struct acpi_device_id max44000_acpi_match[] = {
 	{"MAX44000", 0},
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, max44000_acpi_match);
 #endif

 static struct i2c_driver max44000_driver = {
 	.driver = {
 		.name	= MAX44000_DRV_NAME,
 		.acpi_match_table = ACPI_PTR(max44000_acpi_match),
 	},
 	.probe		= max44000_probe,
 	.id_table	= max44000_id,
 };

 module_i2c_driver(max44000_driver);

 MODULE_AUTHOR("Crestez Dan Leonard <leonard.crestez@intel.com>");
 MODULE_DESCRIPTION("MAX44000 Ambient and Infrared Proximity Sensor");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* MAX44000 Ambient and Infrared Proximity Sensor
	*
	* Copyright (c) 2016, Intel Corporation.
	*
	* Data sheet: https://datasheets.maximintegrated.com/en/ds/MAX44000.pdf
	*
	* 7-bit I2C slave address 0x4a
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/i2c.h>
	#include <linux/regmap.h>
	#include <linux/util_macros.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/iio/buffer.h>
	#include <linux/iio/trigger_consumer.h>
	#include <linux/iio/triggered_buffer.h>
	#include <linux/acpi.h>

	#define MAX44000_DRV_NAME "max44000"

	/* Registers in datasheet order */
	#define MAX44000_REG_STATUS 0x00
	#define MAX44000_REG_CFG_MAIN 0x01
	#define MAX44000_REG_CFG_RX 0x02
	#define MAX44000_REG_CFG_TX 0x03
	#define MAX44000_REG_ALS_DATA_HI 0x04
	#define MAX44000_REG_ALS_DATA_LO 0x05
	#define MAX44000_REG_PRX_DATA 0x16
	#define MAX44000_REG_ALS_UPTHR_HI 0x06
	#define MAX44000_REG_ALS_UPTHR_LO 0x07
	#define MAX44000_REG_ALS_LOTHR_HI 0x08
	#define MAX44000_REG_ALS_LOTHR_LO 0x09
	#define MAX44000_REG_PST 0x0a
	#define MAX44000_REG_PRX_IND 0x0b
	#define MAX44000_REG_PRX_THR 0x0c
	#define MAX44000_REG_TRIM_GAIN_GREEN 0x0f
	#define MAX44000_REG_TRIM_GAIN_IR 0x10

	/* REG_CFG bits */
	#define MAX44000_CFG_ALSINTE 0x01
	#define MAX44000_CFG_PRXINTE 0x02
	#define MAX44000_CFG_MASK 0x1c
	#define MAX44000_CFG_MODE_SHUTDOWN 0x00
	#define MAX44000_CFG_MODE_ALS_GIR 0x04
	#define MAX44000_CFG_MODE_ALS_G 0x08
	#define MAX44000_CFG_MODE_ALS_IR 0x0c
	#define MAX44000_CFG_MODE_ALS_PRX 0x10
	#define MAX44000_CFG_MODE_PRX 0x14
	#define MAX44000_CFG_TRIM 0x20

	/*
	* Upper 4 bits are not documented but start as 1 on powerup
	* Setting them to 0 causes proximity to misbehave so set them to 1
	*/
	#define MAX44000_REG_CFG_RX_DEFAULT 0xf0

	/* REG_RX bits */
	#define MAX44000_CFG_RX_ALSTIM_MASK 0x0c
	#define MAX44000_CFG_RX_ALSTIM_SHIFT 2
	#define MAX44000_CFG_RX_ALSPGA_MASK 0x03
	#define MAX44000_CFG_RX_ALSPGA_SHIFT 0

	/* REG_TX bits */
	#define MAX44000_LED_CURRENT_MASK 0xf
	#define MAX44000_LED_CURRENT_MAX 11
	#define MAX44000_LED_CURRENT_DEFAULT 6

	#define MAX44000_ALSDATA_OVERFLOW 0x4000

	struct max44000_data {
	struct mutex lock;
	struct regmap *regmap;
	/* Ensure naturally aligned timestamp */
	struct {
	u16 channels[2];
	s64 ts __aligned(8);
	} scan;
	};

	/* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */
	#define MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2 5

	/* Scale can be multiplied by up to 128x via ALSPGA for measurement gain */
	static const int max44000_alspga_shift[] = {0, 2, 4, 7};
	#define MAX44000_ALSPGA_MAX_SHIFT 7

	/*
	* Scale can be multiplied by up to 64x via ALSTIM because of lost resolution
	*
	* This scaling factor is hidden from userspace and instead accounted for when
	* reading raw values from the device.
	*
	* This makes it possible to cleanly expose ALSPGA as IIO_CHAN_INFO_SCALE and
	* ALSTIM as IIO_CHAN_INFO_INT_TIME without the values affecting each other.
	*
	* Handling this internally is also required for buffer support because the
	* channel's scan_type can't be modified dynamically.
	*/
	#define MAX44000_ALSTIM_SHIFT(alstim) (2 * (alstim))

	/* Available integration times with pretty manual alignment: */
	static const int max44000_int_time_avail_ns_array[] = {
	100000000,
	25000000,
	6250000,
	1562500,
	};
	static const char max44000_int_time_avail_str[] =
	"0.100 "
	"0.025 "
	"0.00625 "
	"0.0015625";

	/* Available scales (internal to ulux) with pretty manual alignment: */
	static const int max44000_scale_avail_ulux_array[] = {
	31250,
	125000,
	500000,
	4000000,
	};
	static const char max44000_scale_avail_str[] =
	"0.03125 "
	"0.125 "
	"0.5 "
	"4";

	#define MAX44000_SCAN_INDEX_ALS 0
	#define MAX44000_SCAN_INDEX_PRX 1

	static const struct iio_chan_spec max44000_channels[] = {
	{
	.type = IIO_LIGHT,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \|
	BIT(IIO_CHAN_INFO_INT_TIME),
	.scan_index = MAX44000_SCAN_INDEX_ALS,
	.scan_type = {
	.sign = 'u',
	.realbits = 14,
	.storagebits = 16,
	}
	},
	{
	.type = IIO_PROXIMITY,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
	.scan_index = MAX44000_SCAN_INDEX_PRX,
	.scan_type = {
	.sign = 'u',
	.realbits = 8,
	.storagebits = 16,
	}
	},
	IIO_CHAN_SOFT_TIMESTAMP(2),
	{
	.type = IIO_CURRENT,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
	BIT(IIO_CHAN_INFO_SCALE),
	.extend_name = "led",
	.output = 1,
	.scan_index = -1,
	},
	};

	static int max44000_read_alstim(struct max44000_data *data)
	{
	unsigned int val;
	int ret;

	ret = regmap_read(data->regmap, MAX44000_REG_CFG_RX, &val);
	if (ret < 0)
	return ret;
	return (val & MAX44000_CFG_RX_ALSTIM_MASK) >> MAX44000_CFG_RX_ALSTIM_SHIFT;
	}

	static int max44000_write_alstim(struct max44000_data *data, int val)
	{
	return regmap_write_bits(data->regmap, MAX44000_REG_CFG_RX,
	MAX44000_CFG_RX_ALSTIM_MASK,
	val << MAX44000_CFG_RX_ALSTIM_SHIFT);
	}

	static int max44000_read_alspga(struct max44000_data *data)
	{
	unsigned int val;
	int ret;

	ret = regmap_read(data->regmap, MAX44000_REG_CFG_RX, &val);
	if (ret < 0)
	return ret;
	return (val & MAX44000_CFG_RX_ALSPGA_MASK) >> MAX44000_CFG_RX_ALSPGA_SHIFT;
	}

	static int max44000_write_alspga(struct max44000_data *data, int val)
	{
	return regmap_write_bits(data->regmap, MAX44000_REG_CFG_RX,
	MAX44000_CFG_RX_ALSPGA_MASK,
	val << MAX44000_CFG_RX_ALSPGA_SHIFT);
	}

	static int max44000_read_alsval(struct max44000_data *data)
	{
	u16 regval;
	__be16 val;
	int alstim, ret;

	ret = regmap_bulk_read(data->regmap, MAX44000_REG_ALS_DATA_HI,
	&val, sizeof(val));
	if (ret < 0)
	return ret;
	alstim = ret = max44000_read_alstim(data);
	if (ret < 0)
	return ret;

	regval = be16_to_cpu(val);

	/*
	* Overflow is explained on datasheet page 17.
	*
	* It's a warning that either the G or IR channel has become saturated
	* and that the value in the register is likely incorrect.
	*
	* The recommendation is to change the scale (ALSPGA).
	* The driver just returns the max representable value.
	*/
	if (regval & MAX44000_ALSDATA_OVERFLOW)
	return 0x3FFF;

	return regval << MAX44000_ALSTIM_SHIFT(alstim);
	}

	static int max44000_write_led_current_raw(struct max44000_data *data, int val)
	{
	/* Maybe we should clamp the value instead? */
	if (val < 0 \|\| val > MAX44000_LED_CURRENT_MAX)
	return -ERANGE;
	if (val >= 8)
	val += 4;
	return regmap_write_bits(data->regmap, MAX44000_REG_CFG_TX,
	MAX44000_LED_CURRENT_MASK, val);
	}

	static int max44000_read_led_current_raw(struct max44000_data *data)
	{
	unsigned int regval;
	int ret;

	ret = regmap_read(data->regmap, MAX44000_REG_CFG_TX, &regval);
	if (ret < 0)
	return ret;
	regval &= MAX44000_LED_CURRENT_MASK;
	if (regval >= 8)
	regval -= 4;
	return regval;
	}

	static int max44000_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct max44000_data *data = iio_priv(indio_dev);
	int alstim, alspga;
	unsigned int regval;
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	switch (chan->type) {
	case IIO_LIGHT:
	mutex_lock(&data->lock);
	ret = max44000_read_alsval(data);
	mutex_unlock(&data->lock);
	if (ret < 0)
	return ret;
	*val = ret;
	return IIO_VAL_INT;

	case IIO_PROXIMITY:
	mutex_lock(&data->lock);
	ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, &regval);
	mutex_unlock(&data->lock);
	if (ret < 0)
	return ret;
	*val = regval;
	return IIO_VAL_INT;

	case IIO_CURRENT:
	mutex_lock(&data->lock);
	ret = max44000_read_led_current_raw(data);
	mutex_unlock(&data->lock);
	if (ret < 0)
	return ret;
	*val = ret;
	return IIO_VAL_INT;

	default:
	return -EINVAL;
	}

	case IIO_CHAN_INFO_SCALE:
	switch (chan->type) {
	case IIO_CURRENT:
	/* Output register is in 10s of miliamps */
	*val = 10;
	return IIO_VAL_INT;

	case IIO_LIGHT:
	mutex_lock(&data->lock);
	alspga = ret = max44000_read_alspga(data);
	mutex_unlock(&data->lock);
	if (ret < 0)
	return ret;

	/* Avoid negative shifts */
	*val = (1 << MAX44000_ALSPGA_MAX_SHIFT);
	*val2 = MAX44000_ALS_TO_LUX_DEFAULT_FRACTION_LOG2
	+ MAX44000_ALSPGA_MAX_SHIFT
	- max44000_alspga_shift[alspga];
	return IIO_VAL_FRACTIONAL_LOG2;

	default:
	return -EINVAL;
	}

	case IIO_CHAN_INFO_INT_TIME:
	mutex_lock(&data->lock);
	alstim = ret = max44000_read_alstim(data);
	mutex_unlock(&data->lock);

	if (ret < 0)
	return ret;
	*val = 0;
	*val2 = max44000_int_time_avail_ns_array[alstim];
	return IIO_VAL_INT_PLUS_NANO;

	default:
	return -EINVAL;
	}
	}

	static int max44000_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct max44000_data *data = iio_priv(indio_dev);
	int ret;

	if (mask == IIO_CHAN_INFO_RAW && chan->type == IIO_CURRENT) {
	mutex_lock(&data->lock);
	ret = max44000_write_led_current_raw(data, val);
	mutex_unlock(&data->lock);
	return ret;
	} else if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT) {
	s64 valns = val * NSEC_PER_SEC + val2;
	int alstim = find_closest_descending(valns,
	max44000_int_time_avail_ns_array,
	ARRAY_SIZE(max44000_int_time_avail_ns_array));
	mutex_lock(&data->lock);
	ret = max44000_write_alstim(data, alstim);
	mutex_unlock(&data->lock);
	return ret;
	} else if (mask == IIO_CHAN_INFO_SCALE && chan->type == IIO_LIGHT) {
	s64 valus = val * USEC_PER_SEC + val2;
	int alspga = find_closest(valus,
	max44000_scale_avail_ulux_array,
	ARRAY_SIZE(max44000_scale_avail_ulux_array));
	mutex_lock(&data->lock);
	ret = max44000_write_alspga(data, alspga);
	mutex_unlock(&data->lock);
	return ret;
	}

	return -EINVAL;
	}

	static int max44000_write_raw_get_fmt(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	long mask)
	{
	if (mask == IIO_CHAN_INFO_INT_TIME && chan->type == IIO_LIGHT)
	return IIO_VAL_INT_PLUS_NANO;
	else if (mask == IIO_CHAN_INFO_SCALE && chan->type == IIO_LIGHT)
	return IIO_VAL_INT_PLUS_MICRO;
	else
	return IIO_VAL_INT;
	}

	static IIO_CONST_ATTR(illuminance_integration_time_available, max44000_int_time_avail_str);
	static IIO_CONST_ATTR(illuminance_scale_available, max44000_scale_avail_str);

	static struct attribute *max44000_attributes[] = {
	&iio_const_attr_illuminance_integration_time_available.dev_attr.attr,
	&iio_const_attr_illuminance_scale_available.dev_attr.attr,
	NULL
	};

	static const struct attribute_group max44000_attribute_group = {
	.attrs = max44000_attributes,
	};

	static const struct iio_info max44000_info = {
	.read_raw = max44000_read_raw,
	.write_raw = max44000_write_raw,
	.write_raw_get_fmt = max44000_write_raw_get_fmt,
	.attrs = &max44000_attribute_group,
	};

	static bool max44000_readable_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MAX44000_REG_STATUS:
	case MAX44000_REG_CFG_MAIN:
	case MAX44000_REG_CFG_RX:
	case MAX44000_REG_CFG_TX:
	case MAX44000_REG_ALS_DATA_HI:
	case MAX44000_REG_ALS_DATA_LO:
	case MAX44000_REG_PRX_DATA:
	case MAX44000_REG_ALS_UPTHR_HI:
	case MAX44000_REG_ALS_UPTHR_LO:
	case MAX44000_REG_ALS_LOTHR_HI:
	case MAX44000_REG_ALS_LOTHR_LO:
	case MAX44000_REG_PST:
	case MAX44000_REG_PRX_IND:
	case MAX44000_REG_PRX_THR:
	case MAX44000_REG_TRIM_GAIN_GREEN:
	case MAX44000_REG_TRIM_GAIN_IR:
	return true;
	default:
	return false;
	}
	}

	static bool max44000_writeable_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MAX44000_REG_CFG_MAIN:
	case MAX44000_REG_CFG_RX:
	case MAX44000_REG_CFG_TX:
	case MAX44000_REG_ALS_UPTHR_HI:
	case MAX44000_REG_ALS_UPTHR_LO:
	case MAX44000_REG_ALS_LOTHR_HI:
	case MAX44000_REG_ALS_LOTHR_LO:
	case MAX44000_REG_PST:
	case MAX44000_REG_PRX_IND:
	case MAX44000_REG_PRX_THR:
	case MAX44000_REG_TRIM_GAIN_GREEN:
	case MAX44000_REG_TRIM_GAIN_IR:
	return true;
	default:
	return false;
	}
	}

	static bool max44000_volatile_reg(struct device *dev, unsigned int reg)
	{
	switch (reg) {
	case MAX44000_REG_STATUS:
	case MAX44000_REG_ALS_DATA_HI:
	case MAX44000_REG_ALS_DATA_LO:
	case MAX44000_REG_PRX_DATA:
	return true;
	default:
	return false;
	}
	}

	static bool max44000_precious_reg(struct device *dev, unsigned int reg)
	{
	return reg == MAX44000_REG_STATUS;
	}

	static const struct regmap_config max44000_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,

	.max_register = MAX44000_REG_PRX_DATA,
	.readable_reg = max44000_readable_reg,
	.writeable_reg = max44000_writeable_reg,
	.volatile_reg = max44000_volatile_reg,
	.precious_reg = max44000_precious_reg,

	.use_single_read = true,
	.use_single_write = true,
	.cache_type = REGCACHE_RBTREE,
	};

	static irqreturn_t max44000_trigger_handler(int irq, void *p)
	{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct max44000_data *data = iio_priv(indio_dev);
	int index = 0;
	unsigned int regval;
	int ret;

	mutex_lock(&data->lock);
	if (test_bit(MAX44000_SCAN_INDEX_ALS, indio_dev->active_scan_mask)) {
	ret = max44000_read_alsval(data);
	if (ret < 0)
	goto out_unlock;
	data->scan.channels[index++] = ret;
	}
	if (test_bit(MAX44000_SCAN_INDEX_PRX, indio_dev->active_scan_mask)) {
	ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, &regval);
	if (ret < 0)
	goto out_unlock;
	data->scan.channels[index] = regval;
	}
	mutex_unlock(&data->lock);

	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan,
	iio_get_time_ns(indio_dev));
	iio_trigger_notify_done(indio_dev->trig);
	return IRQ_HANDLED;

	out_unlock:
	mutex_unlock(&data->lock);
	iio_trigger_notify_done(indio_dev->trig);
	return IRQ_HANDLED;
	}

	static int max44000_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct max44000_data *data;
	struct iio_dev *indio_dev;
	int ret, reg;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (!indio_dev)
	return -ENOMEM;
	data = iio_priv(indio_dev);
	data->regmap = devm_regmap_init_i2c(client, &max44000_regmap_config);
	if (IS_ERR(data->regmap)) {
	dev_err(&client->dev, "regmap_init failed!\n");
	return PTR_ERR(data->regmap);
	}

	mutex_init(&data->lock);
	indio_dev->info = &max44000_info;
	indio_dev->name = MAX44000_DRV_NAME;
	indio_dev->channels = max44000_channels;
	indio_dev->num_channels = ARRAY_SIZE(max44000_channels);

	/*
	* The device doesn't have a reset function so we just clear some
	* important bits at probe time to ensure sane operation.
	*
	* Since we don't support interrupts/events the threshold values are
	* not important. We also don't touch trim values.
	*/

	/* Reset ALS scaling bits */
	ret = regmap_write(data->regmap, MAX44000_REG_CFG_RX,
	MAX44000_REG_CFG_RX_DEFAULT);
	if (ret < 0) {
	dev_err(&client->dev, "failed to write default CFG_RX: %d\n",
	ret);
	return ret;
	}

	/*
	* By default the LED pulse used for the proximity sensor is disabled.
	* Set a middle value so that we get some sort of valid data by default.
	*/
	ret = max44000_write_led_current_raw(data, MAX44000_LED_CURRENT_DEFAULT);
	if (ret < 0) {
	dev_err(&client->dev, "failed to write init config: %d\n", ret);
	return ret;
	}

	/* Reset CFG bits to ALS_PRX mode which allows easy reading of both values. */
	reg = MAX44000_CFG_TRIM \| MAX44000_CFG_MODE_ALS_PRX;
	ret = regmap_write(data->regmap, MAX44000_REG_CFG_MAIN, reg);
	if (ret < 0) {
	dev_err(&client->dev, "failed to write init config: %d\n", ret);
	return ret;
	}

	/* Read status at least once to clear any stale interrupt bits. */
	ret = regmap_read(data->regmap, MAX44000_REG_STATUS, &reg);
	if (ret < 0) {
	dev_err(&client->dev, "failed to read init status: %d\n", ret);
	return ret;
	}

	ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev, NULL,
	max44000_trigger_handler, NULL);
	if (ret < 0) {
	dev_err(&client->dev, "iio triggered buffer setup failed\n");
	return ret;
	}

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

	static const struct i2c_device_id max44000_id[] = {
	{"max44000", 0},
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, max44000_id);

	#ifdef CONFIG_ACPI
	static const struct acpi_device_id max44000_acpi_match[] = {
	{"MAX44000", 0},
	{ }
	};
	MODULE_DEVICE_TABLE(acpi, max44000_acpi_match);
	#endif

	static struct i2c_driver max44000_driver = {
	.driver = {
	.name = MAX44000_DRV_NAME,
	.acpi_match_table = ACPI_PTR(max44000_acpi_match),
	},
	.probe = max44000_probe,
	.id_table = max44000_id,
	};

	module_i2c_driver(max44000_driver);

	MODULE_AUTHOR("Crestez Dan Leonard <leonard.crestez@intel.com>");
	MODULE_DESCRIPTION("MAX44000 Ambient and Infrared Proximity Sensor");
	MODULE_LICENSE("GPL v2");