// SPDX-License-Identifier: GPL-2.0
/*
 * Sensirion SCD30 carbon dioxide sensor core driver
 *
 * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
 */
#include <linux/bits.h>
#include <linux/cleanup.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/types.h>
#include <linux/interrupt.h>
#include <linux/irqreturn.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regulator/consumer.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/types.h>
#include <asm/byteorder.h>

#include "scd30.h"

#define SCD30_PRESSURE_COMP_MIN_MBAR 700
#define SCD30_PRESSURE_COMP_MAX_MBAR 1400
#define SCD30_PRESSURE_COMP_DEFAULT 1013
#define SCD30_MEAS_INTERVAL_MIN_S 2
#define SCD30_MEAS_INTERVAL_MAX_S 1800
#define SCD30_MEAS_INTERVAL_DEFAULT SCD30_MEAS_INTERVAL_MIN_S
#define SCD30_FRC_MIN_PPM 400
#define SCD30_FRC_MAX_PPM 2000
#define SCD30_TEMP_OFFSET_MAX 655360
#define SCD30_EXTRA_TIMEOUT_PER_S 250

enum {
        SCD30_CONC,
        SCD30_TEMP,
        SCD30_HR,
};

static int scd30_command_write(struct scd30_state *state, enum scd30_cmd cmd, u16 arg)
{
        return state->command(state, cmd, arg, NULL, 0);
}

static int scd30_command_read(struct scd30_state *state, enum scd30_cmd cmd, u16 *val)
{
        __be16 tmp;
        int ret;

        ret = state->command(state, cmd, 0, &tmp, sizeof(tmp));
        *val = be16_to_cpup(&tmp);

        return ret;
}

static int scd30_reset(struct scd30_state *state)
{
        int ret;
        u16 val;

        ret = scd30_command_write(state, CMD_RESET, 0);
        if (ret)
                return ret;

        /* sensor boots up within 2 secs */
        msleep(2000);
        /*
         * Power-on-reset causes sensor to produce some glitch on i2c bus and
         * some controllers end up in error state. Try to recover by placing
         * any data on the bus.
         */
        scd30_command_read(state, CMD_MEAS_READY, &val);

        return 0;
}

/* simplified float to fixed point conversion with a scaling factor of 0.01 */
static int scd30_float_to_fp(int float32)
{
        int fraction, shift,
            mantissa = float32 & GENMASK(22, 0),
            sign = (float32 & BIT(31)) ? -1 : 1,
            exp = (float32 & ~BIT(31)) >> 23;

        /* special case 0 */
        if (!exp && !mantissa)
                return 0;

        exp -= 127;
        if (exp < 0) {
                exp = -exp;
                /* return values ranging from 1 to 99 */
                return sign * ((((BIT(23) + mantissa) * 100) >> 23) >> exp);
        }

        /* return values starting at 100 */
        shift = 23 - exp;
        float32 = BIT(exp) + (mantissa >> shift);
        fraction = mantissa & GENMASK(shift - 1, 0);

        return sign * (float32 * 100 + ((fraction * 100) >> shift));
}

static int scd30_read_meas(struct scd30_state *state)
{
        int i, ret;

        ret = state->command(state, CMD_READ_MEAS, 0, state->meas, sizeof(state->meas));
        if (ret)
                return ret;

        be32_to_cpu_array(state->meas, (__be32 *)state->meas, ARRAY_SIZE(state->meas));

        for (i = 0; i < ARRAY_SIZE(state->meas); i++)
                state->meas[i] = scd30_float_to_fp(state->meas[i]);

        /*
         * co2 is left unprocessed while temperature and humidity are scaled
         * to milli deg C and milli percent respectively.
         */
        state->meas[SCD30_TEMP] *= 10;
        state->meas[SCD30_HR] *= 10;

        return 0;
}

static int scd30_wait_meas_irq(struct scd30_state *state)
{
        int ret, timeout;

        reinit_completion(&state->meas_ready);
        enable_irq(state->irq);
        timeout = msecs_to_jiffies(state->meas_interval * (1000 + SCD30_EXTRA_TIMEOUT_PER_S));
        ret = wait_for_completion_interruptible_timeout(&state->meas_ready, timeout);
        if (ret > 0)
                ret = 0;
        else if (!ret)
                ret = -ETIMEDOUT;

        disable_irq(state->irq);

        return ret;
}

static int scd30_wait_meas_poll(struct scd30_state *state)
{
        int timeout = state->meas_interval * SCD30_EXTRA_TIMEOUT_PER_S, tries = 5;

        do {
                int ret;
                u16 val;

                ret = scd30_command_read(state, CMD_MEAS_READY, &val);
                if (ret)
                        return -EIO;

                /* new measurement available */
                if (val)
                        break;

                msleep_interruptible(timeout);
        } while (--tries);

        return tries ? 0 : -ETIMEDOUT;
}

static int scd30_read_poll(struct scd30_state *state)
{
        int ret;

        ret = scd30_wait_meas_poll(state);
        if (ret)
                return ret;

        return scd30_read_meas(state);
}

static int scd30_read(struct scd30_state *state)
{
        if (state->irq > 0)
                return scd30_wait_meas_irq(state);

        return scd30_read_poll(state);
}

static int scd30_read_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
                          int *val, int *val2, long mask)
{
        struct scd30_state *state = iio_priv(indio_dev);
        int ret;
        u16 tmp;

        guard(mutex)(&state->lock);
        switch (mask) {
        case IIO_CHAN_INFO_RAW:
        case IIO_CHAN_INFO_PROCESSED:
                if (chan->output) {
                        *val = state->pressure_comp;
                        return IIO_VAL_INT;
                }

                if (!iio_device_claim_direct(indio_dev))
                        return -EBUSY;

                ret = scd30_read(state);
                if (ret) {
                        iio_device_release_direct(indio_dev);
                        return ret;
                }

                *val = state->meas[chan->address];
                iio_device_release_direct(indio_dev);
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                *val2 = 1;
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_SAMP_FREQ:
                ret = scd30_command_read(state, CMD_MEAS_INTERVAL, &tmp);
                if (ret)
                        return ret;

                *val = 0;
                *val2 = 1000000000 / tmp;
                return IIO_VAL_INT_PLUS_NANO;
        case IIO_CHAN_INFO_CALIBBIAS:
                ret = scd30_command_read(state, CMD_TEMP_OFFSET, &tmp);
                if (ret)
                        return ret;

                *val = tmp;
                return IIO_VAL_INT;
        default:
                return -EINVAL;
        }
}

static int scd30_write_raw(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
                           int val, int val2, long mask)
{
        struct scd30_state *state = iio_priv(indio_dev);
        int ret;

        guard(mutex)(&state->lock);
        switch (mask) {
        case IIO_CHAN_INFO_SAMP_FREQ:
                if (val)
                        return -EINVAL;

                val = 1000000000 / val2;
                if (val < SCD30_MEAS_INTERVAL_MIN_S || val > SCD30_MEAS_INTERVAL_MAX_S)
                        return -EINVAL;

                ret = scd30_command_write(state, CMD_MEAS_INTERVAL, val);
                if (ret)
                        return ret;

                state->meas_interval = val;
                return 0;
        case IIO_CHAN_INFO_RAW:
                switch (chan->type) {
                case IIO_PRESSURE:
                        if (val < SCD30_PRESSURE_COMP_MIN_MBAR ||
                            val > SCD30_PRESSURE_COMP_MAX_MBAR)
                                return -EINVAL;

                        ret = scd30_command_write(state, CMD_START_MEAS, val);
                        if (ret)
                                return ret;

                        state->pressure_comp = val;
                        return 0;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_CALIBBIAS:
                if (val < 0 || val > SCD30_TEMP_OFFSET_MAX)
                        return -EINVAL;
                /*
                 * Manufacturer does not explicitly specify min/max sensible
                 * values hence check is omitted for simplicity.
                 */
                return scd30_command_write(state, CMD_TEMP_OFFSET / 10, val);
        default:
                return -EINVAL;
        }
}

static int scd30_write_raw_get_fmt(struct iio_dev *indio_dev, struct iio_chan_spec const *chan,
                                   long mask)
{
        switch (mask) {
        case IIO_CHAN_INFO_SAMP_FREQ:
                return IIO_VAL_INT_PLUS_NANO;
        case IIO_CHAN_INFO_RAW:
        case IIO_CHAN_INFO_CALIBBIAS:
                return IIO_VAL_INT;
        }

        return -EINVAL;
}

static const int scd30_pressure_raw_available[] = {
        SCD30_PRESSURE_COMP_MIN_MBAR, 1, SCD30_PRESSURE_COMP_MAX_MBAR,
};

static const int scd30_temp_calibbias_available[] = {
        0, 10, SCD30_TEMP_OFFSET_MAX,
};

static int scd30_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_RAW:
                *vals = scd30_pressure_raw_available;
                *type = IIO_VAL_INT;

                return IIO_AVAIL_RANGE;
        case IIO_CHAN_INFO_CALIBBIAS:
                *vals = scd30_temp_calibbias_available;
                *type = IIO_VAL_INT;

                return IIO_AVAIL_RANGE;
        }

        return -EINVAL;
}

static ssize_t sampling_frequency_available_show(struct device *dev, struct device_attribute *attr,
                                                 char *buf)
{
        int i = SCD30_MEAS_INTERVAL_MIN_S;
        ssize_t len = 0;

        do {
                len += sysfs_emit_at(buf, len, "0.%09u ", 1000000000 / i);
                /*
                 * Not all values fit PAGE_SIZE buffer hence print every 6th
                 * (each frequency differs by 6s in time domain from the
                 * adjacent). Unlisted but valid ones are still accepted.
                 */
                i += 6;
        } while (i <= SCD30_MEAS_INTERVAL_MAX_S);

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

        return len;
}

static ssize_t calibration_auto_enable_show(struct device *dev, struct device_attribute *attr,
                                            char *buf)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct scd30_state *state = iio_priv(indio_dev);
        int ret;
        u16 val;

        mutex_lock(&state->lock);
        ret = scd30_command_read(state, CMD_ASC, &val);
        mutex_unlock(&state->lock);

        return ret ?: sysfs_emit(buf, "%d\n", val);
}

static ssize_t calibration_auto_enable_store(struct device *dev, struct device_attribute *attr,
                                             const char *buf, size_t len)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct scd30_state *state = iio_priv(indio_dev);
        bool val;
        int ret;

        ret = kstrtobool(buf, &val);
        if (ret)
                return ret;

        mutex_lock(&state->lock);
        ret = scd30_command_write(state, CMD_ASC, val);
        mutex_unlock(&state->lock);

        return ret ?: len;
}

static ssize_t calibration_forced_value_show(struct device *dev, struct device_attribute *attr,
                                             char *buf)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct scd30_state *state = iio_priv(indio_dev);
        int ret;
        u16 val;

        mutex_lock(&state->lock);
        ret = scd30_command_read(state, CMD_FRC, &val);
        mutex_unlock(&state->lock);

        return ret ?: sysfs_emit(buf, "%d\n", val);
}

static ssize_t calibration_forced_value_store(struct device *dev, struct device_attribute *attr,
                                              const char *buf, size_t len)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct scd30_state *state = iio_priv(indio_dev);
        int ret;
        u16 val;

        ret = kstrtou16(buf, 0, &val);
        if (ret)
                return ret;

        if (val < SCD30_FRC_MIN_PPM || val > SCD30_FRC_MAX_PPM)
                return -EINVAL;

        mutex_lock(&state->lock);
        ret = scd30_command_write(state, CMD_FRC, val);
        mutex_unlock(&state->lock);

        return ret ?: len;
}

static IIO_DEVICE_ATTR_RO(sampling_frequency_available, 0);
static IIO_DEVICE_ATTR_RW(calibration_auto_enable, 0);
static IIO_DEVICE_ATTR_RW(calibration_forced_value, 0);

static struct attribute *scd30_attrs[] = {
        &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
        &iio_dev_attr_calibration_auto_enable.dev_attr.attr,
        &iio_dev_attr_calibration_forced_value.dev_attr.attr,
        NULL
};

static const struct attribute_group scd30_attr_group = {
        .attrs = scd30_attrs,
};

static const struct iio_info scd30_info = {
        .attrs = &scd30_attr_group,
        .read_raw = scd30_read_raw,
        .write_raw = scd30_write_raw,
        .write_raw_get_fmt = scd30_write_raw_get_fmt,
        .read_avail = scd30_read_avail,
};

#define SCD30_CHAN_SCAN_TYPE(_sign, _realbits) .scan_type = { \
        .sign = _sign, \
        .realbits = _realbits, \
        .storagebits = 32, \
        .endianness = IIO_CPU, \
}

static const struct iio_chan_spec scd30_channels[] = {
        {
                /*
                 * this channel is special in a sense we are pretending that
                 * sensor is able to change measurement chamber pressure but in
                 * fact we're just setting pressure compensation value
                 */
                .type = IIO_PRESSURE,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
                .output = 1,
                .scan_index = -1,
        },
        {
                .type = IIO_CONCENTRATION,
                .channel2 = IIO_MOD_CO2,
                .address = SCD30_CONC,
                .scan_index = SCD30_CONC,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                                      BIT(IIO_CHAN_INFO_SCALE),
                .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .modified = 1,

                SCD30_CHAN_SCAN_TYPE('u', 20),
        },
        {
                .type = IIO_TEMP,
                .address = SCD30_TEMP,
                .scan_index = SCD30_TEMP,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
                                      BIT(IIO_CHAN_INFO_CALIBBIAS),
                .info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBBIAS),
                .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),

                SCD30_CHAN_SCAN_TYPE('s', 18),
        },
        {
                .type = IIO_HUMIDITYRELATIVE,
                .address = SCD30_HR,
                .scan_index = SCD30_HR,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
                .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),

                SCD30_CHAN_SCAN_TYPE('u', 17),
        },
        IIO_CHAN_SOFT_TIMESTAMP(3),
};

static int scd30_suspend(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct scd30_state *state  = iio_priv(indio_dev);
        int ret;

        ret = scd30_command_write(state, CMD_STOP_MEAS, 0);
        if (ret)
                return ret;

        return regulator_disable(state->vdd);
}

static int scd30_resume(struct device *dev)
{
        struct iio_dev *indio_dev = dev_get_drvdata(dev);
        struct scd30_state *state = iio_priv(indio_dev);
        int ret;

        ret = regulator_enable(state->vdd);
        if (ret)
                return ret;

        return scd30_command_write(state, CMD_START_MEAS, state->pressure_comp);
}

EXPORT_NS_SIMPLE_DEV_PM_OPS(scd30_pm_ops, scd30_suspend, scd30_resume, IIO_SCD30);

static void scd30_stop_meas(void *data)
{
        struct scd30_state *state = data;

        scd30_command_write(state, CMD_STOP_MEAS, 0);
}

static void scd30_disable_regulator(void *data)
{
        struct scd30_state *state = data;

        regulator_disable(state->vdd);
}

static irqreturn_t scd30_irq_handler(int irq, void *priv)
{
        struct iio_dev *indio_dev = priv;

        if (iio_buffer_enabled(indio_dev)) {
                iio_trigger_poll(indio_dev->trig);

                return IRQ_HANDLED;
        }

        return IRQ_WAKE_THREAD;
}

static irqreturn_t scd30_irq_thread_handler(int irq, void *priv)
{
        struct iio_dev *indio_dev = priv;
        struct scd30_state *state = iio_priv(indio_dev);
        int ret;

        ret = scd30_read_meas(state);
        if (ret)
                goto out;

        complete_all(&state->meas_ready);
out:
        return IRQ_HANDLED;
}

static irqreturn_t scd30_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct scd30_state *state = iio_priv(indio_dev);
        struct {
                int data[SCD30_MEAS_COUNT];
                aligned_s64 ts;
        } scan = { };
        int ret;

        mutex_lock(&state->lock);
        if (!iio_trigger_using_own(indio_dev))
                ret = scd30_read_poll(state);
        else
                ret = scd30_read_meas(state);
        memcpy(scan.data, state->meas, sizeof(state->meas));
        mutex_unlock(&state->lock);
        if (ret)
                goto out;

        iio_push_to_buffers_with_ts(indio_dev, &scan, sizeof(scan),
                                    iio_get_time_ns(indio_dev));
out:
        iio_trigger_notify_done(indio_dev->trig);
        return IRQ_HANDLED;
}

static int scd30_set_trigger_state(struct iio_trigger *trig, bool state)
{
        struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
        struct scd30_state *st = iio_priv(indio_dev);

        if (state)
                enable_irq(st->irq);
        else
                disable_irq(st->irq);

        return 0;
}

static const struct iio_trigger_ops scd30_trigger_ops = {
        .set_trigger_state = scd30_set_trigger_state,
        .validate_device = iio_trigger_validate_own_device,
};

static int scd30_setup_trigger(struct iio_dev *indio_dev)
{
        struct scd30_state *state = iio_priv(indio_dev);
        struct device *dev = indio_dev->dev.parent;
        struct iio_trigger *trig;
        int ret;

        trig = devm_iio_trigger_alloc(dev, "%s-dev%d", indio_dev->name,
                                      iio_device_id(indio_dev));
        if (!trig)
                return -ENOMEM;

        trig->ops = &scd30_trigger_ops;
        iio_trigger_set_drvdata(trig, indio_dev);

        ret = devm_iio_trigger_register(dev, trig);
        if (ret)
                return ret;

        indio_dev->trig = iio_trigger_get(trig);

        /*
         * Interrupt is enabled just before taking a fresh measurement
         * and disabled afterwards. This means we need to ensure it is not
         * enabled here to keep calls to enable/disable balanced.
         */
        ret = devm_request_threaded_irq(dev, state->irq, scd30_irq_handler,
                                        scd30_irq_thread_handler,
                                        IRQF_TRIGGER_HIGH | IRQF_ONESHOT |
                                        IRQF_NO_AUTOEN,
                                        indio_dev->name, indio_dev);
        if (ret)
                return dev_err_probe(dev, ret, "failed to request irq\n");

        return 0;
}

int scd30_probe(struct device *dev, int irq, const char *name, void *priv,
                scd30_command_t command)
{
        static const unsigned long scd30_scan_masks[] = { 0x07, 0x00 };
        struct scd30_state *state;
        struct iio_dev *indio_dev;
        int ret;
        u16 val;

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

        state = iio_priv(indio_dev);
        state->dev = dev;
        state->priv = priv;
        state->irq = irq;
        state->pressure_comp = SCD30_PRESSURE_COMP_DEFAULT;
        state->meas_interval = SCD30_MEAS_INTERVAL_DEFAULT;
        state->command = command;
        mutex_init(&state->lock);
        init_completion(&state->meas_ready);

        dev_set_drvdata(dev, indio_dev);

        indio_dev->info = &scd30_info;
        indio_dev->name = name;
        indio_dev->channels = scd30_channels;
        indio_dev->num_channels = ARRAY_SIZE(scd30_channels);
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->available_scan_masks = scd30_scan_masks;

        state->vdd = devm_regulator_get(dev, "vdd");
        if (IS_ERR(state->vdd))
                return dev_err_probe(dev, PTR_ERR(state->vdd), "failed to get regulator\n");

        ret = regulator_enable(state->vdd);
        if (ret)
                return ret;

        ret = devm_add_action_or_reset(dev, scd30_disable_regulator, state);
        if (ret)
                return ret;

        ret = scd30_reset(state);
        if (ret)
                return dev_err_probe(dev, ret, "failed to reset device\n");

        if (state->irq > 0) {
                ret = scd30_setup_trigger(indio_dev);
                if (ret)
                        return dev_err_probe(dev, ret, "failed to setup trigger\n");
        }

        ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL, scd30_trigger_handler, NULL);
        if (ret)
                return ret;

        ret = scd30_command_read(state, CMD_FW_VERSION, &val);
        if (ret)
                return dev_err_probe(dev, ret, "failed to read firmware version\n");
        dev_info(dev, "firmware version: %d.%d\n", val >> 8, (char)val);

        ret = scd30_command_write(state, CMD_MEAS_INTERVAL, state->meas_interval);
        if (ret)
                return dev_err_probe(dev, ret, "failed to set measurement interval\n");

        ret = scd30_command_write(state, CMD_START_MEAS, state->pressure_comp);
        if (ret)
                return dev_err_probe(dev, ret, "failed to start measurement\n");

        ret = devm_add_action_or_reset(dev, scd30_stop_meas, state);
        if (ret)
                return ret;

        return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_NS(scd30_probe, "IIO_SCD30");

MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
MODULE_DESCRIPTION("Sensirion SCD30 carbon dioxide sensor core driver");
MODULE_LICENSE("GPL v2");