drivers/iio/light/cm32181.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2013 Capella Microsystems Inc.
  * Author: Kevin Tsai <ktsai@capellamicro.com>
  */

 #include <linux/acpi.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/mutex.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/interrupt.h>
 #include <linux/regulator/consumer.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/iio/events.h>
 #include <linux/init.h>

 /* Registers Address */
 #define CM32181_REG_ADDR_CMD		0x00
 #define CM32181_REG_ADDR_WH		0x01
 #define CM32181_REG_ADDR_WL		0x02
 #define CM32181_REG_ADDR_TEST		0x03
 #define CM32181_REG_ADDR_ALS		0x04
 #define CM32181_REG_ADDR_STATUS		0x06
 #define CM32181_REG_ADDR_ID		0x07

 /* Number of Configurable Registers */
 #define CM32181_CONF_REG_NUM		4

 /* CMD register */
 #define CM32181_CMD_ALS_DISABLE		BIT(0)
 #define CM32181_CMD_ALS_INT_EN		BIT(1)
 #define CM32181_CMD_ALS_THRES_WINDOW	BIT(2)

 #define CM32181_CMD_ALS_PERS_SHIFT	4
 #define CM32181_CMD_ALS_PERS_MASK	(0x03 << CM32181_CMD_ALS_PERS_SHIFT)
 #define CM32181_CMD_ALS_PERS_DEFAULT	(0x01 << CM32181_CMD_ALS_PERS_SHIFT)

 #define CM32181_CMD_ALS_IT_SHIFT	6
 #define CM32181_CMD_ALS_IT_MASK		(0x0F << CM32181_CMD_ALS_IT_SHIFT)
 #define CM32181_CMD_ALS_IT_DEFAULT	(0x00 << CM32181_CMD_ALS_IT_SHIFT)

 #define CM32181_CMD_ALS_SM_SHIFT	11
 #define CM32181_CMD_ALS_SM_MASK		(0x03 << CM32181_CMD_ALS_SM_SHIFT)
 #define CM32181_CMD_ALS_SM_DEFAULT	(0x01 << CM32181_CMD_ALS_SM_SHIFT)

 #define CM32181_LUX_PER_BIT		500	/* ALS_SM=01 IT=800ms */
 #define CM32181_LUX_PER_BIT_RESOLUTION	100000
 #define CM32181_LUX_PER_BIT_BASE_IT	800000	/* Based on IT=800ms */
 #define CM32181_CALIBSCALE_DEFAULT	100000
 #define CM32181_CALIBSCALE_RESOLUTION	100000

 #define SMBUS_ALERT_RESPONSE_ADDRESS	0x0c

 /* CPM0 Index 0: device-id (3218 or 32181), 1: Unknown, 2: init_regs_bitmap */
 #define CPM0_REGS_BITMAP		2
 #define CPM0_HEADER_SIZE		3

 /* CPM1 Index 0: lux_per_bit, 1: calibscale, 2: resolution (100000) */
 #define CPM1_LUX_PER_BIT		0
 #define CPM1_CALIBSCALE			1
 #define CPM1_SIZE			3

 /* CM3218 Family */
 static const int cm3218_als_it_bits[] = { 0, 1, 2, 3 };
 static const int cm3218_als_it_values[] = { 100000, 200000, 400000, 800000 };

 /* CM32181 Family */
 static const int cm32181_als_it_bits[] = { 12, 8, 0, 1, 2, 3 };
 static const int cm32181_als_it_values[] = {
 	25000, 50000, 100000, 200000, 400000, 800000
 };

 struct cm32181_chip {
 	struct i2c_client *client;
 	struct device *dev;
 	struct mutex lock;
 	u16 conf_regs[CM32181_CONF_REG_NUM];
 	unsigned long init_regs_bitmap;
 	int calibscale;
 	int lux_per_bit;
 	int lux_per_bit_base_it;
 	int num_als_it;
 	const int *als_it_bits;
 	const int *als_it_values;
 };

 static int cm32181_read_als_it(struct cm32181_chip *cm32181, int *val2);

 #ifdef CONFIG_ACPI
 /**
  * cm32181_acpi_get_cpm() - Get CPM object from ACPI
  * @dev:	pointer of struct device.
  * @obj_name:	pointer of ACPI object name.
  * @values:	pointer of array for return elements.
  * @count:	maximum size of return array.
  *
  * Convert ACPI CPM table to array.
  *
  * Return: -ENODEV for fail.  Otherwise is number of elements.
  */
 static int cm32181_acpi_get_cpm(struct device *dev, char *obj_name,
 				u64 *values, int count)
 {
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object *cpm, *elem;
 	acpi_handle handle;
 	acpi_status status;
 	int i;

 	handle = ACPI_HANDLE(dev);
 	if (!handle)
 		return -ENODEV;

 	status = acpi_evaluate_object(handle, obj_name, NULL, &buffer);
 	if (ACPI_FAILURE(status)) {
 		dev_err(dev, "object %s not found\n", obj_name);
 		return -ENODEV;
 	}

 	cpm = buffer.pointer;
 	if (cpm->package.count > count)
 		dev_warn(dev, "%s table contains %u values, only using first %d values\n",
 			 obj_name, cpm->package.count, count);

 	count = min_t(int, cpm->package.count, count);
 	for (i = 0; i < count; i++) {
 		elem = &(cpm->package.elements[i]);
 		values[i] = elem->integer.value;
 	}

 	kfree(buffer.pointer);

 	return count;
 }

 static void cm32181_acpi_parse_cpm_tables(struct cm32181_chip *cm32181)
 {
 	u64 vals[CPM0_HEADER_SIZE + CM32181_CONF_REG_NUM];
 	struct device *dev = cm32181->dev;
 	int i, count;

 	count = cm32181_acpi_get_cpm(dev, "CPM0", vals, ARRAY_SIZE(vals));
 	if (count <= CPM0_HEADER_SIZE)
 		return;

 	count -= CPM0_HEADER_SIZE;

 	cm32181->init_regs_bitmap = vals[CPM0_REGS_BITMAP];
 	cm32181->init_regs_bitmap &= GENMASK(count - 1, 0);
 	for_each_set_bit(i, &cm32181->init_regs_bitmap, count)
 		cm32181->conf_regs[i] =	vals[CPM0_HEADER_SIZE + i];

 	count = cm32181_acpi_get_cpm(dev, "CPM1", vals, ARRAY_SIZE(vals));
 	if (count != CPM1_SIZE)
 		return;

 	cm32181->lux_per_bit = vals[CPM1_LUX_PER_BIT];

 	/* Check for uncalibrated devices */
 	if (vals[CPM1_CALIBSCALE] == CM32181_CALIBSCALE_DEFAULT)
 		return;

 	cm32181->calibscale = vals[CPM1_CALIBSCALE];
 	/* CPM1 lux_per_bit is for the current it value */
 	cm32181_read_als_it(cm32181, &cm32181->lux_per_bit_base_it);
 }
 #else
 static void cm32181_acpi_parse_cpm_tables(struct cm32181_chip *cm32181)
 {
 }
 #endif /* CONFIG_ACPI */

 /**
  * cm32181_reg_init() - Initialize CM32181 registers
  * @cm32181:	pointer of struct cm32181.
  *
  * Initialize CM32181 ambient light sensor register to default values.
  *
  * Return: 0 for success; otherwise for error code.
  */
 static int cm32181_reg_init(struct cm32181_chip *cm32181)
 {
 	struct i2c_client *client = cm32181->client;
 	int i;
 	s32 ret;

 	ret = i2c_smbus_read_word_data(client, CM32181_REG_ADDR_ID);
 	if (ret < 0)
 		return ret;

 	/* check device ID */
 	switch (ret & 0xFF) {
 	case 0x18: /* CM3218 */
 		cm32181->num_als_it = ARRAY_SIZE(cm3218_als_it_bits);
 		cm32181->als_it_bits = cm3218_als_it_bits;
 		cm32181->als_it_values = cm3218_als_it_values;
 		break;
 	case 0x81: /* CM32181 */
 	case 0x82: /* CM32182, fully compat. with CM32181 */
 		cm32181->num_als_it = ARRAY_SIZE(cm32181_als_it_bits);
 		cm32181->als_it_bits = cm32181_als_it_bits;
 		cm32181->als_it_values = cm32181_als_it_values;
 		break;
 	default:
 		return -ENODEV;
 	}

 	/* Default Values */
 	cm32181->conf_regs[CM32181_REG_ADDR_CMD] =
 			CM32181_CMD_ALS_IT_DEFAULT | CM32181_CMD_ALS_SM_DEFAULT;
 	cm32181->init_regs_bitmap = BIT(CM32181_REG_ADDR_CMD);
 	cm32181->calibscale = CM32181_CALIBSCALE_DEFAULT;
 	cm32181->lux_per_bit = CM32181_LUX_PER_BIT;
 	cm32181->lux_per_bit_base_it = CM32181_LUX_PER_BIT_BASE_IT;

 	if (ACPI_HANDLE(cm32181->dev))
 		cm32181_acpi_parse_cpm_tables(cm32181);

 	/* Initialize registers*/
 	for_each_set_bit(i, &cm32181->init_regs_bitmap, CM32181_CONF_REG_NUM) {
 		ret = i2c_smbus_write_word_data(client, i,
 						cm32181->conf_regs[i]);
 		if (ret < 0)
 			return ret;
 	}

 	return 0;
 }

 /**
  *  cm32181_read_als_it() - Get sensor integration time (ms)
  *  @cm32181:	pointer of struct cm32181
  *  @val2:	pointer of int to load the als_it value.
  *
  *  Report the current integration time in milliseconds.
  *
  *  Return: IIO_VAL_INT_PLUS_MICRO for success, otherwise -EINVAL.
  */
 static int cm32181_read_als_it(struct cm32181_chip *cm32181, int *val2)
 {
 	u16 als_it;
 	int i;

 	als_it = cm32181->conf_regs[CM32181_REG_ADDR_CMD];
 	als_it &= CM32181_CMD_ALS_IT_MASK;
 	als_it >>= CM32181_CMD_ALS_IT_SHIFT;
 	for (i = 0; i < cm32181->num_als_it; i++) {
 		if (als_it == cm32181->als_it_bits[i]) {
 			*val2 = cm32181->als_it_values[i];
 			return IIO_VAL_INT_PLUS_MICRO;
 		}
 	}

 	return -EINVAL;
 }

 /**
  * cm32181_write_als_it() - Write sensor integration time
  * @cm32181:	pointer of struct cm32181.
  * @val:	integration time by millisecond.
  *
  * Convert integration time (ms) to sensor value.
  *
  * Return: i2c_smbus_write_word_data command return value.
  */
 static int cm32181_write_als_it(struct cm32181_chip *cm32181, int val)
 {
 	struct i2c_client *client = cm32181->client;
 	u16 als_it;
 	int ret, i, n;

 	n = cm32181->num_als_it;
 	for (i = 0; i < n; i++)
 		if (val <= cm32181->als_it_values[i])
 			break;
 	if (i >= n)
 		i = n - 1;

 	als_it = cm32181->als_it_bits[i];
 	als_it <<= CM32181_CMD_ALS_IT_SHIFT;

 	mutex_lock(&cm32181->lock);
 	cm32181->conf_regs[CM32181_REG_ADDR_CMD] &=
 		~CM32181_CMD_ALS_IT_MASK;
 	cm32181->conf_regs[CM32181_REG_ADDR_CMD] |=
 		als_it;
 	ret = i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD,
 			cm32181->conf_regs[CM32181_REG_ADDR_CMD]);
 	mutex_unlock(&cm32181->lock);

 	return ret;
 }

 /**
  * cm32181_get_lux() - report current lux value
  * @cm32181:	pointer of struct cm32181.
  *
  * Convert sensor raw data to lux.  It depends on integration
  * time and calibscale variable.
  *
  * Return: Positive value is lux, otherwise is error code.
  */
 static int cm32181_get_lux(struct cm32181_chip *cm32181)
 {
 	struct i2c_client *client = cm32181->client;
 	int ret;
 	int als_it;
 	u64 lux;

 	ret = cm32181_read_als_it(cm32181, &als_it);
 	if (ret < 0)
 		return -EINVAL;

 	lux = cm32181->lux_per_bit;
 	lux *= cm32181->lux_per_bit_base_it;
 	lux = div_u64(lux, als_it);

 	ret = i2c_smbus_read_word_data(client, CM32181_REG_ADDR_ALS);
 	if (ret < 0)
 		return ret;

 	lux *= ret;
 	lux *= cm32181->calibscale;
 	lux = div_u64(lux, CM32181_CALIBSCALE_RESOLUTION);
 	lux = div_u64(lux, CM32181_LUX_PER_BIT_RESOLUTION);

 	if (lux > 0xFFFF)
 		lux = 0xFFFF;

 	return lux;
 }

 static int cm32181_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int *val, int *val2, long mask)
 {
 	struct cm32181_chip *cm32181 = iio_priv(indio_dev);
 	int ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_PROCESSED:
 		ret = cm32181_get_lux(cm32181);
 		if (ret < 0)
 			return ret;
 		*val = ret;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_CALIBSCALE:
 		*val = cm32181->calibscale;
 		return IIO_VAL_INT;
 	case IIO_CHAN_INFO_INT_TIME:
 		*val = 0;
 		ret = cm32181_read_als_it(cm32181, val2);
 		return ret;
 	}

 	return -EINVAL;
 }

 static int cm32181_write_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     int val, int val2, long mask)
 {
 	struct cm32181_chip *cm32181 = iio_priv(indio_dev);
 	int ret;

 	switch (mask) {
 	case IIO_CHAN_INFO_CALIBSCALE:
 		cm32181->calibscale = val;
 		return val;
 	case IIO_CHAN_INFO_INT_TIME:
 		ret = cm32181_write_als_it(cm32181, val2);
 		return ret;
 	}

 	return -EINVAL;
 }

 /**
  * cm32181_get_it_available() - Get available ALS IT value
  * @dev:	pointer of struct device.
  * @attr:	pointer of struct device_attribute.
  * @buf:	pointer of return string buffer.
  *
  * Display the available integration time values by millisecond.
  *
  * Return: string length.
  */
 static ssize_t cm32181_get_it_available(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {
 	struct cm32181_chip *cm32181 = iio_priv(dev_to_iio_dev(dev));
 	int i, n, len;

 	n = cm32181->num_als_it;
 	for (i = 0, len = 0; i < n; i++)
 		len += sprintf(buf + len, "0.%06u ", cm32181->als_it_values[i]);
 	return len + sprintf(buf + len, "\n");
 }

 static const struct iio_chan_spec cm32181_channels[] = {
 	{
 		.type = IIO_LIGHT,
 		.info_mask_separate =
 			BIT(IIO_CHAN_INFO_PROCESSED) |
 			BIT(IIO_CHAN_INFO_CALIBSCALE) |
 			BIT(IIO_CHAN_INFO_INT_TIME),
 	}
 };

 static IIO_DEVICE_ATTR(in_illuminance_integration_time_available,
 			S_IRUGO, cm32181_get_it_available, NULL, 0);

 static struct attribute *cm32181_attributes[] = {
 	&iio_dev_attr_in_illuminance_integration_time_available.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group cm32181_attribute_group = {
 	.attrs = cm32181_attributes
 };

 static const struct iio_info cm32181_info = {
 	.read_raw		= &cm32181_read_raw,
 	.write_raw		= &cm32181_write_raw,
 	.attrs			= &cm32181_attribute_group,
 };

 static int cm32181_probe(struct i2c_client *client)
 {
 	struct device *dev = &client->dev;
 	struct cm32181_chip *cm32181;
 	struct iio_dev *indio_dev;
 	int ret;

 	indio_dev = devm_iio_device_alloc(dev, sizeof(*cm32181));
 	if (!indio_dev)
 		return -ENOMEM;

 	/*
 	 * Some ACPI systems list 2 I2C resources for the CM3218 sensor, the
 	 * SMBus Alert Response Address (ARA, 0x0c) and the actual I2C address.
 	 * Detect this and take the following step to deal with it:
 	 * 1. When a SMBus Alert capable sensor has an Alert asserted, it will
 	 *    not respond on its actual I2C address. Read a byte from the ARA
 	 *    to clear any pending Alerts.
 	 * 2. Create a "dummy" client for the actual I2C address and
 	 *    use that client to communicate with the sensor.
 	 */
 	if (ACPI_HANDLE(dev) && client->addr == SMBUS_ALERT_RESPONSE_ADDRESS) {
 		struct i2c_board_info board_info = { .type = "dummy" };

 		i2c_smbus_read_byte(client);

 		client = i2c_acpi_new_device(dev, 1, &board_info);
 		if (IS_ERR(client))
 			return PTR_ERR(client);
 	}

 	i2c_set_clientdata(client, indio_dev);

 	cm32181 = iio_priv(indio_dev);
 	cm32181->client = client;
 	cm32181->dev = dev;

 	mutex_init(&cm32181->lock);
 	indio_dev->channels = cm32181_channels;
 	indio_dev->num_channels = ARRAY_SIZE(cm32181_channels);
 	indio_dev->info = &cm32181_info;
 	indio_dev->name = dev_name(dev);
 	indio_dev->modes = INDIO_DIRECT_MODE;

 	ret = cm32181_reg_init(cm32181);
 	if (ret) {
 		dev_err(dev, "%s: register init failed\n", __func__);
 		return ret;
 	}

 	ret = devm_iio_device_register(dev, indio_dev);
 	if (ret) {
 		dev_err(dev, "%s: regist device failed\n", __func__);
 		return ret;
 	}

 	return 0;
 }

 static int cm32181_suspend(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);

 	return i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD,
 					 CM32181_CMD_ALS_DISABLE);
 }

 static int cm32181_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
 	struct cm32181_chip *cm32181 = iio_priv(dev_get_drvdata(dev));

 	return i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD,
 					 cm32181->conf_regs[CM32181_REG_ADDR_CMD]);
 }

 static DEFINE_SIMPLE_DEV_PM_OPS(cm32181_pm_ops, cm32181_suspend, cm32181_resume);

 static const struct of_device_id cm32181_of_match[] = {
 	{ .compatible = "capella,cm3218" },
 	{ .compatible = "capella,cm32181" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, cm32181_of_match);

 #ifdef CONFIG_ACPI
 static const struct acpi_device_id cm32181_acpi_match[] = {
 	{ "CPLM3218", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, cm32181_acpi_match);
 #endif

 static struct i2c_driver cm32181_driver = {
 	.driver = {
 		.name	= "cm32181",
 		.acpi_match_table = ACPI_PTR(cm32181_acpi_match),
 		.of_match_table = cm32181_of_match,
 		.pm = pm_sleep_ptr(&cm32181_pm_ops),
 	},
 	.probe_new	= cm32181_probe,
 };

 module_i2c_driver(cm32181_driver);

 MODULE_AUTHOR("Kevin Tsai <ktsai@capellamicro.com>");
 MODULE_DESCRIPTION("CM32181 ambient light sensor driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2013 Capella Microsystems Inc.
	* Author: Kevin Tsai <ktsai@capellamicro.com>
	*/

	#include <linux/acpi.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/mutex.h>
	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/interrupt.h>
	#include <linux/regulator/consumer.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>
	#include <linux/iio/events.h>
	#include <linux/init.h>

	/* Registers Address */
	#define CM32181_REG_ADDR_CMD 0x00
	#define CM32181_REG_ADDR_WH 0x01
	#define CM32181_REG_ADDR_WL 0x02
	#define CM32181_REG_ADDR_TEST 0x03
	#define CM32181_REG_ADDR_ALS 0x04
	#define CM32181_REG_ADDR_STATUS 0x06
	#define CM32181_REG_ADDR_ID 0x07

	/* Number of Configurable Registers */
	#define CM32181_CONF_REG_NUM 4

	/* CMD register */
	#define CM32181_CMD_ALS_DISABLE BIT(0)
	#define CM32181_CMD_ALS_INT_EN BIT(1)
	#define CM32181_CMD_ALS_THRES_WINDOW BIT(2)

	#define CM32181_CMD_ALS_PERS_SHIFT 4
	#define CM32181_CMD_ALS_PERS_MASK (0x03 << CM32181_CMD_ALS_PERS_SHIFT)
	#define CM32181_CMD_ALS_PERS_DEFAULT (0x01 << CM32181_CMD_ALS_PERS_SHIFT)

	#define CM32181_CMD_ALS_IT_SHIFT 6
	#define CM32181_CMD_ALS_IT_MASK (0x0F << CM32181_CMD_ALS_IT_SHIFT)
	#define CM32181_CMD_ALS_IT_DEFAULT (0x00 << CM32181_CMD_ALS_IT_SHIFT)

	#define CM32181_CMD_ALS_SM_SHIFT 11
	#define CM32181_CMD_ALS_SM_MASK (0x03 << CM32181_CMD_ALS_SM_SHIFT)
	#define CM32181_CMD_ALS_SM_DEFAULT (0x01 << CM32181_CMD_ALS_SM_SHIFT)

	#define CM32181_LUX_PER_BIT 500 /* ALS_SM=01 IT=800ms */
	#define CM32181_LUX_PER_BIT_RESOLUTION 100000
	#define CM32181_LUX_PER_BIT_BASE_IT 800000 /* Based on IT=800ms */
	#define CM32181_CALIBSCALE_DEFAULT 100000
	#define CM32181_CALIBSCALE_RESOLUTION 100000

	#define SMBUS_ALERT_RESPONSE_ADDRESS 0x0c

	/* CPM0 Index 0: device-id (3218 or 32181), 1: Unknown, 2: init_regs_bitmap */
	#define CPM0_REGS_BITMAP 2
	#define CPM0_HEADER_SIZE 3

	/* CPM1 Index 0: lux_per_bit, 1: calibscale, 2: resolution (100000) */
	#define CPM1_LUX_PER_BIT 0
	#define CPM1_CALIBSCALE 1
	#define CPM1_SIZE 3

	/* CM3218 Family */
	static const int cm3218_als_it_bits[] = { 0, 1, 2, 3 };
	static const int cm3218_als_it_values[] = { 100000, 200000, 400000, 800000 };

	/* CM32181 Family */
	static const int cm32181_als_it_bits[] = { 12, 8, 0, 1, 2, 3 };
	static const int cm32181_als_it_values[] = {
	25000, 50000, 100000, 200000, 400000, 800000
	};

	struct cm32181_chip {
	struct i2c_client *client;
	struct device *dev;
	struct mutex lock;
	u16 conf_regs[CM32181_CONF_REG_NUM];
	unsigned long init_regs_bitmap;
	int calibscale;
	int lux_per_bit;
	int lux_per_bit_base_it;
	int num_als_it;
	const int *als_it_bits;
	const int *als_it_values;
	};

	static int cm32181_read_als_it(struct cm32181_chip cm32181, int val2);

	#ifdef CONFIG_ACPI
	/**
	* cm32181_acpi_get_cpm() - Get CPM object from ACPI
	* @dev: pointer of struct device.
	* @obj_name: pointer of ACPI object name.
	* @values: pointer of array for return elements.
	* @count: maximum size of return array.
	*
	* Convert ACPI CPM table to array.
	*
	* Return: -ENODEV for fail. Otherwise is number of elements.
	*/
	static int cm32181_acpi_get_cpm(struct device dev, char obj_name,
	u64 *values, int count)
	{
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object cpm, elem;
	acpi_handle handle;
	acpi_status status;
	int i;

	handle = ACPI_HANDLE(dev);
	if (!handle)
	return -ENODEV;

	status = acpi_evaluate_object(handle, obj_name, NULL, &buffer);
	if (ACPI_FAILURE(status)) {
	dev_err(dev, "object %s not found\n", obj_name);
	return -ENODEV;
	}

	cpm = buffer.pointer;
	if (cpm->package.count > count)
	dev_warn(dev, "%s table contains %u values, only using first %d values\n",
	obj_name, cpm->package.count, count);

	count = min_t(int, cpm->package.count, count);
	for (i = 0; i < count; i++) {
	elem = &(cpm->package.elements[i]);
	values[i] = elem->integer.value;
	}

	kfree(buffer.pointer);

	return count;
	}

	static void cm32181_acpi_parse_cpm_tables(struct cm32181_chip *cm32181)
	{
	u64 vals[CPM0_HEADER_SIZE + CM32181_CONF_REG_NUM];
	struct device *dev = cm32181->dev;
	int i, count;

	count = cm32181_acpi_get_cpm(dev, "CPM0", vals, ARRAY_SIZE(vals));
	if (count <= CPM0_HEADER_SIZE)
	return;

	count -= CPM0_HEADER_SIZE;

	cm32181->init_regs_bitmap = vals[CPM0_REGS_BITMAP];
	cm32181->init_regs_bitmap &= GENMASK(count - 1, 0);
	for_each_set_bit(i, &cm32181->init_regs_bitmap, count)
	cm32181->conf_regs[i] = vals[CPM0_HEADER_SIZE + i];

	count = cm32181_acpi_get_cpm(dev, "CPM1", vals, ARRAY_SIZE(vals));
	if (count != CPM1_SIZE)
	return;

	cm32181->lux_per_bit = vals[CPM1_LUX_PER_BIT];

	/* Check for uncalibrated devices */
	if (vals[CPM1_CALIBSCALE] == CM32181_CALIBSCALE_DEFAULT)
	return;

	cm32181->calibscale = vals[CPM1_CALIBSCALE];
	/* CPM1 lux_per_bit is for the current it value */
	cm32181_read_als_it(cm32181, &cm32181->lux_per_bit_base_it);
	}
	#else
	static void cm32181_acpi_parse_cpm_tables(struct cm32181_chip *cm32181)
	{
	}
	#endif /* CONFIG_ACPI */

	/**
	* cm32181_reg_init() - Initialize CM32181 registers
	* @cm32181: pointer of struct cm32181.
	*
	* Initialize CM32181 ambient light sensor register to default values.
	*
	* Return: 0 for success; otherwise for error code.
	*/
	static int cm32181_reg_init(struct cm32181_chip *cm32181)
	{
	struct i2c_client *client = cm32181->client;
	int i;
	s32 ret;

	ret = i2c_smbus_read_word_data(client, CM32181_REG_ADDR_ID);
	if (ret < 0)
	return ret;

	/* check device ID */
	switch (ret & 0xFF) {
	case 0x18: /* CM3218 */
	cm32181->num_als_it = ARRAY_SIZE(cm3218_als_it_bits);
	cm32181->als_it_bits = cm3218_als_it_bits;
	cm32181->als_it_values = cm3218_als_it_values;
	break;
	case 0x81: /* CM32181 */
	case 0x82: /* CM32182, fully compat. with CM32181 */
	cm32181->num_als_it = ARRAY_SIZE(cm32181_als_it_bits);
	cm32181->als_it_bits = cm32181_als_it_bits;
	cm32181->als_it_values = cm32181_als_it_values;
	break;
	default:
	return -ENODEV;
	}

	/* Default Values */
	cm32181->conf_regs[CM32181_REG_ADDR_CMD] =
	CM32181_CMD_ALS_IT_DEFAULT \| CM32181_CMD_ALS_SM_DEFAULT;
	cm32181->init_regs_bitmap = BIT(CM32181_REG_ADDR_CMD);
	cm32181->calibscale = CM32181_CALIBSCALE_DEFAULT;
	cm32181->lux_per_bit = CM32181_LUX_PER_BIT;
	cm32181->lux_per_bit_base_it = CM32181_LUX_PER_BIT_BASE_IT;

	if (ACPI_HANDLE(cm32181->dev))
	cm32181_acpi_parse_cpm_tables(cm32181);

	/* Initialize registers*/
	for_each_set_bit(i, &cm32181->init_regs_bitmap, CM32181_CONF_REG_NUM) {
	ret = i2c_smbus_write_word_data(client, i,
	cm32181->conf_regs[i]);
	if (ret < 0)
	return ret;
	}

	return 0;
	}

	/**
	* cm32181_read_als_it() - Get sensor integration time (ms)
	* @cm32181: pointer of struct cm32181
	* @val2: pointer of int to load the als_it value.
	*
	* Report the current integration time in milliseconds.
	*
	* Return: IIO_VAL_INT_PLUS_MICRO for success, otherwise -EINVAL.
	*/
	static int cm32181_read_als_it(struct cm32181_chip cm32181, int val2)
	{
	u16 als_it;
	int i;

	als_it = cm32181->conf_regs[CM32181_REG_ADDR_CMD];
	als_it &= CM32181_CMD_ALS_IT_MASK;
	als_it >>= CM32181_CMD_ALS_IT_SHIFT;
	for (i = 0; i < cm32181->num_als_it; i++) {
	if (als_it == cm32181->als_it_bits[i]) {
	*val2 = cm32181->als_it_values[i];
	return IIO_VAL_INT_PLUS_MICRO;
	}
	}

	return -EINVAL;
	}

	/**
	* cm32181_write_als_it() - Write sensor integration time
	* @cm32181: pointer of struct cm32181.
	* @val: integration time by millisecond.
	*
	* Convert integration time (ms) to sensor value.
	*
	* Return: i2c_smbus_write_word_data command return value.
	*/
	static int cm32181_write_als_it(struct cm32181_chip *cm32181, int val)
	{
	struct i2c_client *client = cm32181->client;
	u16 als_it;
	int ret, i, n;

	n = cm32181->num_als_it;
	for (i = 0; i < n; i++)
	if (val <= cm32181->als_it_values[i])
	break;
	if (i >= n)
	i = n - 1;

	als_it = cm32181->als_it_bits[i];
	als_it <<= CM32181_CMD_ALS_IT_SHIFT;

	mutex_lock(&cm32181->lock);
	cm32181->conf_regs[CM32181_REG_ADDR_CMD] &=
	~CM32181_CMD_ALS_IT_MASK;
	cm32181->conf_regs[CM32181_REG_ADDR_CMD] \|=
	als_it;
	ret = i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD,
	cm32181->conf_regs[CM32181_REG_ADDR_CMD]);
	mutex_unlock(&cm32181->lock);

	return ret;
	}

	/**
	* cm32181_get_lux() - report current lux value
	* @cm32181: pointer of struct cm32181.
	*
	* Convert sensor raw data to lux. It depends on integration
	* time and calibscale variable.
	*
	* Return: Positive value is lux, otherwise is error code.
	*/
	static int cm32181_get_lux(struct cm32181_chip *cm32181)
	{
	struct i2c_client *client = cm32181->client;
	int ret;
	int als_it;
	u64 lux;

	ret = cm32181_read_als_it(cm32181, &als_it);
	if (ret < 0)
	return -EINVAL;

	lux = cm32181->lux_per_bit;
	lux *= cm32181->lux_per_bit_base_it;
	lux = div_u64(lux, als_it);

	ret = i2c_smbus_read_word_data(client, CM32181_REG_ADDR_ALS);
	if (ret < 0)
	return ret;

	lux *= ret;
	lux *= cm32181->calibscale;
	lux = div_u64(lux, CM32181_CALIBSCALE_RESOLUTION);
	lux = div_u64(lux, CM32181_LUX_PER_BIT_RESOLUTION);

	if (lux > 0xFFFF)
	lux = 0xFFFF;

	return lux;
	}

	static int cm32181_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct cm32181_chip *cm32181 = iio_priv(indio_dev);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_PROCESSED:
	ret = cm32181_get_lux(cm32181);
	if (ret < 0)
	return ret;
	*val = ret;
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_CALIBSCALE:
	*val = cm32181->calibscale;
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_INT_TIME:
	*val = 0;
	ret = cm32181_read_als_it(cm32181, val2);
	return ret;
	}

	return -EINVAL;
	}

	static int cm32181_write_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int val, int val2, long mask)
	{
	struct cm32181_chip *cm32181 = iio_priv(indio_dev);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_CALIBSCALE:
	cm32181->calibscale = val;
	return val;
	case IIO_CHAN_INFO_INT_TIME:
	ret = cm32181_write_als_it(cm32181, val2);
	return ret;
	}

	return -EINVAL;
	}

	/**
	* cm32181_get_it_available() - Get available ALS IT value
	* @dev: pointer of struct device.
	* @attr: pointer of struct device_attribute.
	* @buf: pointer of return string buffer.
	*
	* Display the available integration time values by millisecond.
	*
	* Return: string length.
	*/
	static ssize_t cm32181_get_it_available(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct cm32181_chip *cm32181 = iio_priv(dev_to_iio_dev(dev));
	int i, n, len;

	n = cm32181->num_als_it;
	for (i = 0, len = 0; i < n; i++)
	len += sprintf(buf + len, "0.%06u ", cm32181->als_it_values[i]);
	return len + sprintf(buf + len, "\n");
	}

	static const struct iio_chan_spec cm32181_channels[] = {
	{
	.type = IIO_LIGHT,
	.info_mask_separate =
	BIT(IIO_CHAN_INFO_PROCESSED) \|
	BIT(IIO_CHAN_INFO_CALIBSCALE) \|
	BIT(IIO_CHAN_INFO_INT_TIME),
	}
	};

	static IIO_DEVICE_ATTR(in_illuminance_integration_time_available,
	S_IRUGO, cm32181_get_it_available, NULL, 0);

	static struct attribute *cm32181_attributes[] = {
	&iio_dev_attr_in_illuminance_integration_time_available.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group cm32181_attribute_group = {
	.attrs = cm32181_attributes
	};

	static const struct iio_info cm32181_info = {
	.read_raw = &cm32181_read_raw,
	.write_raw = &cm32181_write_raw,
	.attrs = &cm32181_attribute_group,
	};

	static int cm32181_probe(struct i2c_client *client)
	{
	struct device *dev = &client->dev;
	struct cm32181_chip *cm32181;
	struct iio_dev *indio_dev;
	int ret;

	indio_dev = devm_iio_device_alloc(dev, sizeof(*cm32181));
	if (!indio_dev)
	return -ENOMEM;

	/*
	* Some ACPI systems list 2 I2C resources for the CM3218 sensor, the
	* SMBus Alert Response Address (ARA, 0x0c) and the actual I2C address.
	* Detect this and take the following step to deal with it:
	* 1. When a SMBus Alert capable sensor has an Alert asserted, it will
	* not respond on its actual I2C address. Read a byte from the ARA
	* to clear any pending Alerts.
	* 2. Create a "dummy" client for the actual I2C address and
	* use that client to communicate with the sensor.
	*/
	if (ACPI_HANDLE(dev) && client->addr == SMBUS_ALERT_RESPONSE_ADDRESS) {
	struct i2c_board_info board_info = { .type = "dummy" };

	i2c_smbus_read_byte(client);

	client = i2c_acpi_new_device(dev, 1, &board_info);
	if (IS_ERR(client))
	return PTR_ERR(client);
	}

	i2c_set_clientdata(client, indio_dev);

	cm32181 = iio_priv(indio_dev);
	cm32181->client = client;
	cm32181->dev = dev;

	mutex_init(&cm32181->lock);
	indio_dev->channels = cm32181_channels;
	indio_dev->num_channels = ARRAY_SIZE(cm32181_channels);
	indio_dev->info = &cm32181_info;
	indio_dev->name = dev_name(dev);
	indio_dev->modes = INDIO_DIRECT_MODE;

	ret = cm32181_reg_init(cm32181);
	if (ret) {
	dev_err(dev, "%s: register init failed\n", __func__);
	return ret;
	}

	ret = devm_iio_device_register(dev, indio_dev);
	if (ret) {
	dev_err(dev, "%s: regist device failed\n", __func__);
	return ret;
	}

	return 0;
	}

	static int cm32181_suspend(struct device *dev)
	{
	struct i2c_client *client = to_i2c_client(dev);

	return i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD,
	CM32181_CMD_ALS_DISABLE);
	}

	static int cm32181_resume(struct device *dev)
	{
	struct i2c_client *client = to_i2c_client(dev);
	struct cm32181_chip *cm32181 = iio_priv(dev_get_drvdata(dev));

	return i2c_smbus_write_word_data(client, CM32181_REG_ADDR_CMD,
	cm32181->conf_regs[CM32181_REG_ADDR_CMD]);
	}

	static DEFINE_SIMPLE_DEV_PM_OPS(cm32181_pm_ops, cm32181_suspend, cm32181_resume);

	static const struct of_device_id cm32181_of_match[] = {
	{ .compatible = "capella,cm3218" },
	{ .compatible = "capella,cm32181" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, cm32181_of_match);

	#ifdef CONFIG_ACPI
	static const struct acpi_device_id cm32181_acpi_match[] = {
	{ "CPLM3218", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(acpi, cm32181_acpi_match);
	#endif

	static struct i2c_driver cm32181_driver = {
	.driver = {
	.name = "cm32181",
	.acpi_match_table = ACPI_PTR(cm32181_acpi_match),
	.of_match_table = cm32181_of_match,
	.pm = pm_sleep_ptr(&cm32181_pm_ops),
	},
	.probe_new = cm32181_probe,
	};

	module_i2c_driver(cm32181_driver);

	MODULE_AUTHOR("Kevin Tsai <ktsai@capellamicro.com>");
	MODULE_DESCRIPTION("CM32181 ambient light sensor driver");
	MODULE_LICENSE("GPL");