// SPDX-License-Identifier: GPL-2.0+
/*
 * Support for ON Semiconductor NOA1305 ambient light sensor
 *
 * Copyright (C) 2016 Emcraft Systems
 * Copyright (C) 2019 Collabora Ltd.
 */

#include <linux/delay.h>
#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>

#define NOA1305_REG_POWER_CONTROL       0x0
#define   NOA1305_POWER_CONTROL_DOWN    0x00
#define   NOA1305_POWER_CONTROL_ON      0x08
#define NOA1305_REG_RESET               0x1
#define   NOA1305_RESET_RESET           0x10
#define NOA1305_REG_INTEGRATION_TIME    0x2
#define   NOA1305_INTEGR_TIME_800MS     0x00
#define   NOA1305_INTEGR_TIME_400MS     0x01
#define   NOA1305_INTEGR_TIME_200MS     0x02
#define   NOA1305_INTEGR_TIME_100MS     0x03
#define   NOA1305_INTEGR_TIME_50MS      0x04
#define   NOA1305_INTEGR_TIME_25MS      0x05
#define   NOA1305_INTEGR_TIME_12_5MS    0x06
#define   NOA1305_INTEGR_TIME_6_25MS    0x07
#define   NOA1305_INTEGR_TIME_MASK      0x07
#define NOA1305_REG_INT_SELECT          0x3
#define   NOA1305_INT_SEL_ACTIVE_HIGH   0x01
#define   NOA1305_INT_SEL_ACTIVE_LOW    0x02
#define   NOA1305_INT_SEL_INACTIVE      0x03
#define NOA1305_REG_INT_THRESH_LSB      0x4
#define NOA1305_REG_INT_THRESH_MSB      0x5
#define NOA1305_REG_ALS_DATA_LSB        0x6
#define NOA1305_REG_ALS_DATA_MSB        0x7
#define NOA1305_REG_DEVICE_ID_LSB       0x8
#define NOA1305_REG_DEVICE_ID_MSB       0x9

#define NOA1305_DEVICE_ID       0x0519
#define NOA1305_DRIVER_NAME     "noa1305"

static int noa1305_scale_available[] = {
        100, 8 * 77,            /* 800 ms */
        100, 4 * 77,            /* 400 ms */
        100, 2 * 77,            /* 200 ms */
        100, 1 * 77,            /* 100 ms */
        1000, 5 * 77,           /* 50 ms */
        10000, 25 * 77,         /* 25 ms */
        100000, 125 * 77,       /* 12.5 ms */
        1000000, 625 * 77,      /* 6.25 ms */
};

static int noa1305_int_time_available[] = {
        0, 800000,              /* 800 ms */
        0, 400000,              /* 400 ms */
        0, 200000,              /* 200 ms */
        0, 100000,              /* 100 ms */
        0, 50000,               /* 50 ms */
        0, 25000,               /* 25 ms */
        0, 12500,               /* 12.5 ms */
        0, 6250,                /* 6.25 ms */
};

struct noa1305_priv {
        struct i2c_client *client;
        struct regmap *regmap;
};

static int noa1305_measure(struct noa1305_priv *priv, int *val)
{
        __le16 data;
        int ret;

        ret = regmap_bulk_read(priv->regmap, NOA1305_REG_ALS_DATA_LSB, &data,
                               2);
        if (ret < 0)
                return ret;

        *val = le16_to_cpu(data);

        return IIO_VAL_INT;
}

static int noa1305_scale(struct noa1305_priv *priv, int *val, int *val2)
{
        int data;
        int ret;

        ret = regmap_read(priv->regmap, NOA1305_REG_INTEGRATION_TIME, &data);
        if (ret < 0)
                return ret;

        /*
         * Lux = count / (<Integration Constant> * <Integration Time>)
         *
         * Integration Constant = 7.7
         * Integration Time in Seconds
         */
        data &= NOA1305_INTEGR_TIME_MASK;
        *val = noa1305_scale_available[2 * data + 0];
        *val2 = noa1305_scale_available[2 * data + 1];

        return IIO_VAL_FRACTIONAL;
}

static int noa1305_int_time(struct noa1305_priv *priv, int *val, int *val2)
{
        int data;
        int ret;

        ret = regmap_read(priv->regmap, NOA1305_REG_INTEGRATION_TIME, &data);
        if (ret < 0)
                return ret;

        data &= NOA1305_INTEGR_TIME_MASK;
        *val = noa1305_int_time_available[2 * data + 0];
        *val2 = noa1305_int_time_available[2 * data + 1];

        return IIO_VAL_INT_PLUS_MICRO;
}

static const struct iio_chan_spec noa1305_channels[] = {
        {
                .type = IIO_LIGHT,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = 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),
                .info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_INT_TIME),
        }
};

static int noa1305_read_avail(struct iio_dev *indio_dev,
                              struct iio_chan_spec const *chan,
                              const int **vals, int *type,
                              int *length, long mask)
{
        if (chan->type != IIO_LIGHT)
                return -EINVAL;

        switch (mask) {
        case IIO_CHAN_INFO_SCALE:
                *vals = noa1305_scale_available;
                *length = ARRAY_SIZE(noa1305_scale_available);
                *type = IIO_VAL_FRACTIONAL;
                return IIO_AVAIL_LIST;
        case IIO_CHAN_INFO_INT_TIME:
                *vals = noa1305_int_time_available;
                *length = ARRAY_SIZE(noa1305_int_time_available);
                *type = IIO_VAL_INT_PLUS_MICRO;
                return IIO_AVAIL_LIST;
        default:
                return -EINVAL;
        }
}

static int noa1305_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long mask)
{
        struct noa1305_priv *priv = iio_priv(indio_dev);

        if (chan->type != IIO_LIGHT)
                return -EINVAL;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                return noa1305_measure(priv, val);
        case IIO_CHAN_INFO_SCALE:
                return noa1305_scale(priv, val, val2);
        case IIO_CHAN_INFO_INT_TIME:
                return noa1305_int_time(priv, val, val2);
        default:
                return -EINVAL;
        }
}

static int noa1305_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int val, int val2, long mask)
{
        struct noa1305_priv *priv = iio_priv(indio_dev);
        int i;

        if (chan->type != IIO_LIGHT)
                return -EINVAL;

        if (mask != IIO_CHAN_INFO_INT_TIME)
                return -EINVAL;

        if (val)        /* >= 1s integration time not supported */
                return -EINVAL;

        /* Look up integration time register settings and write it if found. */
        for (i = 0; i < ARRAY_SIZE(noa1305_int_time_available) / 2; i++)
                if (noa1305_int_time_available[2 * i + 1] == val2)
                        return regmap_write(priv->regmap, NOA1305_REG_INTEGRATION_TIME, i);

        return -EINVAL;
}

static const struct iio_info noa1305_info = {
        .read_avail = noa1305_read_avail,
        .read_raw = noa1305_read_raw,
        .write_raw = noa1305_write_raw,
};

static bool noa1305_writable_reg(struct device *dev, unsigned int reg)
{
        switch (reg) {
        case NOA1305_REG_POWER_CONTROL:
        case NOA1305_REG_RESET:
        case NOA1305_REG_INTEGRATION_TIME:
        case NOA1305_REG_INT_SELECT:
        case NOA1305_REG_INT_THRESH_LSB:
        case NOA1305_REG_INT_THRESH_MSB:
                return true;
        default:
                return false;
        }
}

static const struct regmap_config noa1305_regmap_config = {
        .name = NOA1305_DRIVER_NAME,
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = NOA1305_REG_DEVICE_ID_MSB,
        .writeable_reg = noa1305_writable_reg,
};

static int noa1305_probe(struct i2c_client *client)
{
        struct noa1305_priv *priv;
        struct iio_dev *indio_dev;
        struct regmap *regmap;
        __le16 data;
        unsigned int dev_id;
        int ret;

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

        regmap = devm_regmap_init_i2c(client, &noa1305_regmap_config);
        if (IS_ERR(regmap)) {
                dev_err(&client->dev, "Regmap initialization failed.\n");
                return PTR_ERR(regmap);
        }

        priv = iio_priv(indio_dev);

        ret = devm_regulator_get_enable(&client->dev, "vin");
        if (ret)
                return dev_err_probe(&client->dev, ret,
                                     "get regulator vin failed\n");

        i2c_set_clientdata(client, indio_dev);
        priv->client = client;
        priv->regmap = regmap;

        ret = regmap_bulk_read(regmap, NOA1305_REG_DEVICE_ID_LSB, &data, 2);
        if (ret < 0) {
                dev_err(&client->dev, "ID reading failed: %d\n", ret);
                return ret;
        }

        dev_id = le16_to_cpu(data);
        if (dev_id != NOA1305_DEVICE_ID) {
                dev_err(&client->dev, "Unknown device ID: 0x%x\n", dev_id);
                return -ENODEV;
        }

        ret = regmap_write(regmap, NOA1305_REG_POWER_CONTROL,
                           NOA1305_POWER_CONTROL_ON);
        if (ret < 0) {
                dev_err(&client->dev, "Enabling power control failed\n");
                return ret;
        }

        ret = regmap_write(regmap, NOA1305_REG_RESET, NOA1305_RESET_RESET);
        if (ret < 0) {
                dev_err(&client->dev, "Device reset failed\n");
                return ret;
        }

        ret = regmap_write(regmap, NOA1305_REG_INTEGRATION_TIME,
                           NOA1305_INTEGR_TIME_800MS);
        if (ret < 0) {
                dev_err(&client->dev, "Setting integration time failed\n");
                return ret;
        }

        indio_dev->info = &noa1305_info;
        indio_dev->channels = noa1305_channels;
        indio_dev->num_channels = ARRAY_SIZE(noa1305_channels);
        indio_dev->name = NOA1305_DRIVER_NAME;
        indio_dev->modes = INDIO_DIRECT_MODE;

        ret = devm_iio_device_register(&client->dev, indio_dev);
        if (ret)
                dev_err(&client->dev, "registering device failed\n");

        return ret;
}

static const struct of_device_id noa1305_of_match[] = {
        { .compatible = "onnn,noa1305" },
        { }
};
MODULE_DEVICE_TABLE(of, noa1305_of_match);

static const struct i2c_device_id noa1305_ids[] = {
        { "noa1305" },
        { }
};
MODULE_DEVICE_TABLE(i2c, noa1305_ids);

static struct i2c_driver noa1305_driver = {
        .driver = {
                .name           = NOA1305_DRIVER_NAME,
                .of_match_table = noa1305_of_match,
        },
        .probe          = noa1305_probe,
        .id_table       = noa1305_ids,
};

module_i2c_driver(noa1305_driver);

MODULE_AUTHOR("Sergei Miroshnichenko <sergeimir@emcraft.com>");
MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.com");
MODULE_DESCRIPTION("ON Semiconductor NOA1305 ambient light sensor");
MODULE_LICENSE("GPL");