// SPDX-License-Identifier: GPL-2.0
/*
 * ROHM BH1710/BH1715/BH1721/BH1750/BH1751 ambient light sensor driver
 *
 * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
 *
 * Data sheets:
 *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1710fvc-e.pdf
 *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1715fvc-e.pdf
 *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1721fvc-e.pdf
 *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1750fvi-e.pdf
 *  http://rohmfs.rohm.com/en/products/databook/datasheet/ic/sensor/light/bh1751fvi-e.pdf
 *
 * 7-bit I2C slave addresses:
 *  0x23 (ADDR pin low)
 *  0x5C (ADDR pin high)
 *
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/module.h>
#include <linux/gpio/consumer.h>

#define BH1750_POWER_DOWN               0x00
#define BH1750_ONE_TIME_H_RES_MODE      0x20 /* auto-mode for BH1721 */
#define BH1750_CHANGE_INT_TIME_H_BIT    0x40
#define BH1750_CHANGE_INT_TIME_L_BIT    0x60

/* Define the reset delay time in microseconds */
#define BH1750_RESET_DELAY_US 10000 /* 10ms */

enum {
        BH1710,
        BH1721,
        BH1750,
};

struct bh1750_chip_info;
struct bh1750_data {
        struct i2c_client *client;
        struct mutex lock;
        const struct bh1750_chip_info *chip_info;
        u16 mtreg;
        struct gpio_desc *reset_gpio;
};

struct bh1750_chip_info {
        u16 mtreg_min;
        u16 mtreg_max;
        u16 mtreg_default;
        int mtreg_to_usec;
        int mtreg_to_scale;

        /*
         * For BH1710/BH1721 all possible integration time values won't fit
         * into one page so displaying is limited to every second one.
         * Note, that user can still write proper values which were not
         * listed.
         */
        int inc;

        u16 int_time_low_mask;
        u16 int_time_high_mask;
};

static const struct bh1750_chip_info bh1750_chip_info_tbl[] = {
        [BH1710] = { 140, 1022, 300, 400,  250000000, 2, 0x001F, 0x03E0 },
        [BH1721] = { 140, 1020, 300, 400,  250000000, 2, 0x0010, 0x03E0 },
        [BH1750] = { 31,  254,  69,  1740, 57500000,  1, 0x001F, 0x00E0 },
};

static int bh1750_change_int_time(struct bh1750_data *data, int usec)
{
        int ret;
        u16 val;
        u8 regval;
        const struct bh1750_chip_info *chip_info = data->chip_info;

        if ((usec % chip_info->mtreg_to_usec) != 0)
                return -EINVAL;

        val = usec / chip_info->mtreg_to_usec;
        if (val < chip_info->mtreg_min || val > chip_info->mtreg_max)
                return -EINVAL;

        ret = i2c_smbus_write_byte(data->client, BH1750_POWER_DOWN);
        if (ret < 0)
                return ret;

        regval = (val & chip_info->int_time_high_mask) >> 5;
        ret = i2c_smbus_write_byte(data->client,
                                   BH1750_CHANGE_INT_TIME_H_BIT | regval);
        if (ret < 0)
                return ret;

        regval = val & chip_info->int_time_low_mask;
        ret = i2c_smbus_write_byte(data->client,
                                   BH1750_CHANGE_INT_TIME_L_BIT | regval);
        if (ret < 0)
                return ret;

        data->mtreg = val;

        return 0;
}

static int bh1750_read(struct bh1750_data *data, int *val)
{
        int ret;
        __be16 result;
        const struct bh1750_chip_info *chip_info = data->chip_info;
        unsigned long delay = chip_info->mtreg_to_usec * data->mtreg;

        /*
         * BH1721 will enter continuous mode on receiving this command.
         * Note, that this eliminates need for bh1750_resume().
         */
        ret = i2c_smbus_write_byte(data->client, BH1750_ONE_TIME_H_RES_MODE);
        if (ret < 0)
                return ret;

        usleep_range(delay + 15000, delay + 40000);

        ret = i2c_master_recv(data->client, (char *)&result, 2);
        if (ret < 0)
                return ret;

        *val = be16_to_cpu(result);

        return 0;
}

static int bh1750_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val, int *val2, long mask)
{
        int ret, tmp;
        struct bh1750_data *data = iio_priv(indio_dev);
        const struct bh1750_chip_info *chip_info = data->chip_info;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                switch (chan->type) {
                case IIO_LIGHT:
                        mutex_lock(&data->lock);
                        ret = bh1750_read(data, val);
                        mutex_unlock(&data->lock);
                        if (ret < 0)
                                return ret;

                        return IIO_VAL_INT;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_SCALE:
                tmp = chip_info->mtreg_to_scale / data->mtreg;
                *val = tmp / 1000000;
                *val2 = tmp % 1000000;
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_INT_TIME:
                *val = 0;
                *val2 = chip_info->mtreg_to_usec * data->mtreg;
                return IIO_VAL_INT_PLUS_MICRO;
        default:
                return -EINVAL;
        }
}

static int bh1750_write_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int val, int val2, long mask)
{
        int ret;
        struct bh1750_data *data = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_INT_TIME:
                if (val != 0)
                        return -EINVAL;

                mutex_lock(&data->lock);
                ret = bh1750_change_int_time(data, val2);
                mutex_unlock(&data->lock);
                return ret;
        default:
                return -EINVAL;
        }
}

static ssize_t bh1750_show_int_time_available(struct device *dev,
                struct device_attribute *attr, char *buf)
{
        int i;
        size_t len = 0;
        struct bh1750_data *data = iio_priv(dev_to_iio_dev(dev));
        const struct bh1750_chip_info *chip_info = data->chip_info;

        for (i = chip_info->mtreg_min; i <= chip_info->mtreg_max; i += chip_info->inc)
                len += scnprintf(buf + len, PAGE_SIZE - len, "0.%06d ",
                                 chip_info->mtreg_to_usec * i);

        buf[len - 1] = '\n';

        return len;
}

static IIO_DEV_ATTR_INT_TIME_AVAIL(bh1750_show_int_time_available);

static struct attribute *bh1750_attributes[] = {
        &iio_dev_attr_integration_time_available.dev_attr.attr,
        NULL,
};

static const struct attribute_group bh1750_attribute_group = {
        .attrs = bh1750_attributes,
};

static const struct iio_info bh1750_info = {
        .attrs = &bh1750_attribute_group,
        .read_raw = bh1750_read_raw,
        .write_raw = bh1750_write_raw,
};

static const struct iio_chan_spec bh1750_channels[] = {
        {
                .type = IIO_LIGHT,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_SCALE) |
                                      BIT(IIO_CHAN_INFO_INT_TIME)
        }
};

static int bh1750_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        int ret, usec;
        struct bh1750_data *data;
        struct iio_dev *indio_dev;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
                                I2C_FUNC_SMBUS_WRITE_BYTE))
                return -EOPNOTSUPP;

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

        data = iio_priv(indio_dev);
        i2c_set_clientdata(client, indio_dev);
        data->client = client;
        data->chip_info = &bh1750_chip_info_tbl[id->driver_data];

        /* Get reset GPIO from device tree */
        data->reset_gpio = devm_gpiod_get_optional(&client->dev,
                                                   "reset", GPIOD_OUT_HIGH);

        if (IS_ERR(data->reset_gpio))
                return dev_err_probe(&client->dev, PTR_ERR(data->reset_gpio),
                                     "Failed to get reset GPIO\n");

        /* Perform hardware reset if GPIO is provided */
        if (data->reset_gpio) {
                /* Perform reset sequence: low-high */
                gpiod_set_value_cansleep(data->reset_gpio, 1);
                fsleep(BH1750_RESET_DELAY_US);
                gpiod_set_value_cansleep(data->reset_gpio, 0);
                fsleep(BH1750_RESET_DELAY_US);

                dev_dbg(&client->dev, "BH1750 reset completed via GPIO\n");
        }

        usec = data->chip_info->mtreg_to_usec * data->chip_info->mtreg_default;
        ret = bh1750_change_int_time(data, usec);
        if (ret < 0)
                return ret;

        mutex_init(&data->lock);
        indio_dev->info = &bh1750_info;
        indio_dev->name = id->name;
        indio_dev->channels = bh1750_channels;
        indio_dev->num_channels = ARRAY_SIZE(bh1750_channels);
        indio_dev->modes = INDIO_DIRECT_MODE;

        return iio_device_register(indio_dev);
}

static void bh1750_remove(struct i2c_client *client)
{
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
        struct bh1750_data *data = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);

        mutex_lock(&data->lock);
        i2c_smbus_write_byte(client, BH1750_POWER_DOWN);
        mutex_unlock(&data->lock);
}

static int bh1750_suspend(struct device *dev)
{
        int ret;
        struct bh1750_data *data =
                iio_priv(i2c_get_clientdata(to_i2c_client(dev)));

        /*
         * This is mainly for BH1721 which doesn't enter power down
         * mode automatically.
         */
        mutex_lock(&data->lock);
        ret = i2c_smbus_write_byte(data->client, BH1750_POWER_DOWN);
        mutex_unlock(&data->lock);

        return ret;
}

static DEFINE_SIMPLE_DEV_PM_OPS(bh1750_pm_ops, bh1750_suspend, NULL);

static const struct i2c_device_id bh1750_id[] = {
        { "bh1710", BH1710 },
        { "bh1715", BH1750 },
        { "bh1721", BH1721 },
        { "bh1750", BH1750 },
        { "bh1751", BH1750 },
        { }
};
MODULE_DEVICE_TABLE(i2c, bh1750_id);

static const struct of_device_id bh1750_of_match[] = {
        { .compatible = "rohm,bh1710", },
        { .compatible = "rohm,bh1715", },
        { .compatible = "rohm,bh1721", },
        { .compatible = "rohm,bh1750", },
        { .compatible = "rohm,bh1751", },
        { }
};
MODULE_DEVICE_TABLE(of, bh1750_of_match);

static struct i2c_driver bh1750_driver = {
        .driver = {
                .name = "bh1750",
                .of_match_table = bh1750_of_match,
                .pm = pm_sleep_ptr(&bh1750_pm_ops),
        },
        .probe = bh1750_probe,
        .remove = bh1750_remove,
        .id_table = bh1750_id,

};
module_i2c_driver(bh1750_driver);

MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
MODULE_DESCRIPTION("ROHM BH1710/BH1715/BH1721/BH1750/BH1751 als driver");
MODULE_LICENSE("GPL v2");