// 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);
        }

        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 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,
        },
        .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");