// SPDX-License-Identifier: GPL-2.0-only
/*
 * IIO driver for the light sensor ISL76682.
 * ISL76682 is Ambient Light Sensor
 *
 * Copyright (c) 2023 Marek Vasut <marex@denx.de>
 */

#include <linux/array_size.h>
#include <linux/bits.h>
#include <linux/cleanup.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regmap.h>
#include <linux/types.h>

#include <linux/iio/iio.h>

#define ISL76682_REG_COMMAND                    0x00

#define ISL76682_COMMAND_EN                     BIT(7)
#define ISL76682_COMMAND_MODE_CONTINUOUS        BIT(6)
#define ISL76682_COMMAND_LIGHT_IR               BIT(5)

#define ISL76682_COMMAND_RANGE_LUX_1K           0x0
#define ISL76682_COMMAND_RANGE_LUX_4K           0x1
#define ISL76682_COMMAND_RANGE_LUX_16K          0x2
#define ISL76682_COMMAND_RANGE_LUX_64K          0x3
#define ISL76682_COMMAND_RANGE_LUX_MASK         GENMASK(1, 0)

#define ISL76682_REG_ALSIR_L                    0x01

#define ISL76682_REG_ALSIR_U                    0x02

#define ISL76682_NUM_REGS                       (ISL76682_REG_ALSIR_U + 1)

#define ISL76682_CONV_TIME_MS                   100
#define ISL76682_INT_TIME_US                    90000

#define ISL76682_ADC_MAX                        (BIT(16) - 1)

struct isl76682_chip {
        /*
         * Lock to synchronize access to device command register
         * and the content of range variable below.
         */
        struct mutex                    lock;
        struct regmap                   *regmap;
        u8                              range;
        u8                              command;
};

struct isl76682_range {
        u8                              range;
        u32                             als;
        u32                             ir;
};

static const struct isl76682_range isl76682_range_table[] = {
        { ISL76682_COMMAND_RANGE_LUX_1K, 15000, 10500 },
        { ISL76682_COMMAND_RANGE_LUX_4K, 60000, 42000 },
        { ISL76682_COMMAND_RANGE_LUX_16K, 240000, 168000 },
        { ISL76682_COMMAND_RANGE_LUX_64K, 960000, 673000 }
};

static int isl76682_get(struct isl76682_chip *chip, bool mode_ir, int *data)
{
        u8 command;
        int ret;

        command = ISL76682_COMMAND_EN | ISL76682_COMMAND_MODE_CONTINUOUS |
                  chip->range;

        if (mode_ir)
                command |= ISL76682_COMMAND_LIGHT_IR;

        if (command != chip->command) {
                ret = regmap_write(chip->regmap, ISL76682_REG_COMMAND, command);
                if (ret)
                        return ret;

                /* Need to wait for conversion time if ALS/IR mode enabled */
                msleep(ISL76682_CONV_TIME_MS);

                chip->command = command;
        }

        ret = regmap_bulk_read(chip->regmap, ISL76682_REG_ALSIR_L, data, 2);
        *data &= ISL76682_ADC_MAX;
        return ret;
}

static int isl76682_write_raw(struct iio_dev *indio_dev,
                              struct iio_chan_spec const *chan,
                              int val, int val2, long mask)
{
        struct isl76682_chip *chip = iio_priv(indio_dev);
        int i;

        if (mask != IIO_CHAN_INFO_SCALE)
                return -EINVAL;

        if (val != 0)
                return -EINVAL;

        for (i = 0; i < ARRAY_SIZE(isl76682_range_table); i++) {
                if (chan->type == IIO_LIGHT && val2 != isl76682_range_table[i].als)
                        continue;
                if (chan->type == IIO_INTENSITY && val2 != isl76682_range_table[i].ir)
                        continue;

                scoped_guard(mutex, &chip->lock)
                        chip->range = isl76682_range_table[i].range;
                return 0;
        }

        return -EINVAL;
}

static int isl76682_read_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int *val, int *val2, long mask)
{
        struct isl76682_chip *chip = iio_priv(indio_dev);
        int ret;
        int i;

        guard(mutex)(&chip->lock);

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                switch (chan->type) {
                case IIO_LIGHT:
                        ret = isl76682_get(chip, false, val);
                        return (ret < 0) ? ret : IIO_VAL_INT;
                case IIO_INTENSITY:
                        ret = isl76682_get(chip, true, val);
                        return (ret < 0) ? ret : IIO_VAL_INT;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_SCALE:
                for (i = 0; i < ARRAY_SIZE(isl76682_range_table); i++) {
                        if (chip->range != isl76682_range_table[i].range)
                                continue;

                        *val = 0;
                        switch (chan->type) {
                        case IIO_LIGHT:
                                *val2 = isl76682_range_table[i].als;
                                return IIO_VAL_INT_PLUS_MICRO;
                        case IIO_INTENSITY:
                                *val2 = isl76682_range_table[i].ir;
                                return IIO_VAL_INT_PLUS_MICRO;
                        default:
                                return -EINVAL;
                        }
                }
                return -EINVAL;
        case IIO_CHAN_INFO_INT_TIME:
                *val = 0;
                *val2 = ISL76682_INT_TIME_US;
                return IIO_VAL_INT_PLUS_MICRO;
        default:
                return -EINVAL;
        }
}

static int illuminance_scale_available[] = {
        0, 15000,
        0, 60000,
        0, 240000,
        0, 960000,
};

static int intensity_scale_available[] = {
        0, 10500,
        0, 42000,
        0, 168000,
        0, 673000,
};

static int isl76682_read_avail(struct iio_dev *indio_dev,
                               struct iio_chan_spec const *chan,
                               const int **vals, int *type,
                               int *length, long mask)
{
        switch (mask) {
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_LIGHT:
                        *vals = illuminance_scale_available;
                        *length = ARRAY_SIZE(illuminance_scale_available);
                        *type = IIO_VAL_INT_PLUS_MICRO;
                        return IIO_AVAIL_LIST;
                case IIO_INTENSITY:
                        *vals = intensity_scale_available;
                        *length = ARRAY_SIZE(intensity_scale_available);
                        *type = IIO_VAL_INT_PLUS_MICRO;
                        return IIO_AVAIL_LIST;
                default:
                        return -EINVAL;
                }
        default:
                return -EINVAL;
        }
}

static const struct iio_chan_spec isl76682_channels[] = {
        {
                .type = IIO_LIGHT,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_SCALE),
                .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),
                .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
        }, {
                .type = IIO_INTENSITY,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_SCALE),
                .info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),
                .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_INT_TIME),
        }
};

static const struct iio_info isl76682_info = {
        .read_avail     = isl76682_read_avail,
        .read_raw       = isl76682_read_raw,
        .write_raw      = isl76682_write_raw,
};

static int isl76682_clear_configure_reg(struct isl76682_chip *chip)
{
        struct device *dev = regmap_get_device(chip->regmap);
        int ret;

        ret = regmap_write(chip->regmap, ISL76682_REG_COMMAND, 0x0);
        if (ret < 0)
                dev_err(dev, "Error %d clearing the CONFIGURE register\n", ret);

        /*
         * In the success case, the command register was zeroed out.
         *
         * In the error case, we do not know in which state the command
         * register is, so we assume it is zeroed out, so that it would
         * be reprogrammed at the next data read out, and at that time
         * we hope it would be reprogrammed successfully. That is very
         * much a best effort approach.
         */
        chip->command = 0;

        return ret;
}

static void isl76682_reset_action(void *chip)
{
        isl76682_clear_configure_reg(chip);
}

static bool isl76682_is_volatile_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case ISL76682_REG_ALSIR_L:
        case ISL76682_REG_ALSIR_U:
                return true;
        default:
                return false;
        }
}

static const struct regmap_config isl76682_regmap_config = {
        .reg_bits               = 8,
        .val_bits               = 8,
        .volatile_reg           = isl76682_is_volatile_reg,
        .max_register           = ISL76682_NUM_REGS - 1,
        .num_reg_defaults_raw   = ISL76682_NUM_REGS,
        .cache_type             = REGCACHE_FLAT,
};

static int isl76682_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct isl76682_chip *chip;
        struct iio_dev *indio_dev;
        int ret;

        indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
        if (!indio_dev)
                return -ENOMEM;

        chip = iio_priv(indio_dev);

        mutex_init(&chip->lock);

        chip->regmap = devm_regmap_init_i2c(client, &isl76682_regmap_config);
        ret = PTR_ERR_OR_ZERO(chip->regmap);
        if (ret)
                return dev_err_probe(dev, ret, "Error initializing regmap\n");

        chip->range = ISL76682_COMMAND_RANGE_LUX_1K;

        ret = isl76682_clear_configure_reg(chip);
        if (ret < 0)
                return ret;

        ret = devm_add_action_or_reset(dev, isl76682_reset_action, chip);
        if (ret)
                return ret;

        indio_dev->info = &isl76682_info;
        indio_dev->channels = isl76682_channels;
        indio_dev->num_channels = ARRAY_SIZE(isl76682_channels);
        indio_dev->name = "isl76682";
        indio_dev->modes = INDIO_DIRECT_MODE;

        return devm_iio_device_register(dev, indio_dev);
}

static const struct i2c_device_id isl76682_id[] = {
        { "isl76682" },
        { }
};
MODULE_DEVICE_TABLE(i2c, isl76682_id);

static const struct of_device_id isl76682_of_match[] = {
        { .compatible = "isil,isl76682" },
        { }
};
MODULE_DEVICE_TABLE(of, isl76682_of_match);

static struct i2c_driver isl76682_driver = {
        .driver  = {
                .name           = "isl76682",
                .of_match_table = isl76682_of_match,
        },
        .probe          = isl76682_probe,
        .id_table       = isl76682_id,
};
module_i2c_driver(isl76682_driver);

MODULE_DESCRIPTION("ISL76682 Ambient Light Sensor driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marek Vasut <marex@denx.de>");