// SPDX-License-Identifier: GPL-2.0
/*
 * Sensirion SPS30 particulate matter sensor driver
 *
 * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
 */

#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/kernel.h>
#include <linux/module.h>

#include "sps30.h"

/* sensor measures reliably up to 3000 ug / m3 */
#define SPS30_MAX_PM 3000
/* minimum and maximum self cleaning periods in seconds */
#define SPS30_AUTO_CLEANING_PERIOD_MIN 0
#define SPS30_AUTO_CLEANING_PERIOD_MAX 604800

enum {
        PM1,
        PM2P5,
        PM4,
        PM10,
};

enum {
        RESET,
        MEASURING,
};

static s32 sps30_float_to_int_clamped(__be32 *fp)
{
        int val = be32_to_cpup(fp);
        int mantissa = val & GENMASK(22, 0);
        /* this is fine since passed float is always non-negative */
        int exp = val >> 23;
        int fraction, shift;

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

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

        /* return values ranging from 100 to 300000 */
        shift = 23 - exp;
        val = (1 << exp) + (mantissa >> shift);
        if (val >= SPS30_MAX_PM)
                return SPS30_MAX_PM * 100;

        fraction = mantissa & GENMASK(shift - 1, 0);

        return val * 100 + ((fraction * 100) >> shift);
}

static int sps30_do_meas(struct sps30_state *state, s32 *data, int size)
{
        int i, ret;

        if (state->state == RESET) {
                ret = state->ops->start_meas(state);
                if (ret)
                        return ret;

                state->state = MEASURING;
        }

        ret = state->ops->read_meas(state, (__be32 *)data, size);
        if (ret)
                return ret;

        for (i = 0; i < size; i++)
                data[i] = sps30_float_to_int_clamped((__be32 *)&data[i]);

        return 0;
}

static int sps30_do_reset(struct sps30_state *state)
{
        int ret;

        ret = state->ops->reset(state);
        if (ret)
                return ret;

        state->state = RESET;

        return 0;
}

static irqreturn_t sps30_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct sps30_state *state = iio_priv(indio_dev);
        int ret;
        struct {
                s32 data[4]; /* PM1, PM2P5, PM4, PM10 */
                aligned_s64 ts;
        } scan;

        mutex_lock(&state->lock);
        ret = sps30_do_meas(state, scan.data, ARRAY_SIZE(scan.data));
        mutex_unlock(&state->lock);
        if (ret)
                goto err;

        iio_push_to_buffers_with_ts(indio_dev, &scan, sizeof(scan),
                                    iio_get_time_ns(indio_dev));
err:
        iio_trigger_notify_done(indio_dev->trig);

        return IRQ_HANDLED;
}

static int sps30_read_raw(struct iio_dev *indio_dev,
                          struct iio_chan_spec const *chan,
                          int *val, int *val2, long mask)
{
        struct sps30_state *state = iio_priv(indio_dev);
        int data[4], ret = -EINVAL;

        switch (mask) {
        case IIO_CHAN_INFO_PROCESSED:
                switch (chan->type) {
                case IIO_MASSCONCENTRATION:
                        mutex_lock(&state->lock);
                        /* read up to the number of bytes actually needed */
                        switch (chan->channel2) {
                        case IIO_MOD_PM1:
                                ret = sps30_do_meas(state, data, 1);
                                break;
                        case IIO_MOD_PM2P5:
                                ret = sps30_do_meas(state, data, 2);
                                break;
                        case IIO_MOD_PM4:
                                ret = sps30_do_meas(state, data, 3);
                                break;
                        case IIO_MOD_PM10:
                                ret = sps30_do_meas(state, data, 4);
                                break;
                        }
                        mutex_unlock(&state->lock);
                        if (ret)
                                return ret;

                        *val = data[chan->address] / 100;
                        *val2 = (data[chan->address] % 100) * 10000;

                        return IIO_VAL_INT_PLUS_MICRO;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_MASSCONCENTRATION:
                        switch (chan->channel2) {
                        case IIO_MOD_PM1:
                        case IIO_MOD_PM2P5:
                        case IIO_MOD_PM4:
                        case IIO_MOD_PM10:
                                *val = 0;
                                *val2 = 10000;

                                return IIO_VAL_INT_PLUS_MICRO;
                        default:
                                return -EINVAL;
                        }
                default:
                        return -EINVAL;
                }
        }

        return -EINVAL;
}

static ssize_t start_cleaning_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 sps30_state *state = iio_priv(indio_dev);
        int val, ret;

        if (kstrtoint(buf, 0, &val) || val != 1)
                return -EINVAL;

        mutex_lock(&state->lock);
        ret = state->ops->clean_fan(state);
        mutex_unlock(&state->lock);
        if (ret)
                return ret;

        return len;
}

static ssize_t cleaning_period_show(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct sps30_state *state = iio_priv(indio_dev);
        __be32 val;
        int ret;

        mutex_lock(&state->lock);
        ret = state->ops->read_cleaning_period(state, &val);
        mutex_unlock(&state->lock);
        if (ret)
                return ret;

        return sysfs_emit(buf, "%d\n", be32_to_cpu(val));
}

static ssize_t cleaning_period_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 sps30_state *state = iio_priv(indio_dev);
        int val, ret;

        if (kstrtoint(buf, 0, &val))
                return -EINVAL;

        if ((val < SPS30_AUTO_CLEANING_PERIOD_MIN) ||
            (val > SPS30_AUTO_CLEANING_PERIOD_MAX))
                return -EINVAL;

        mutex_lock(&state->lock);
        ret = state->ops->write_cleaning_period(state, cpu_to_be32(val));
        if (ret) {
                mutex_unlock(&state->lock);
                return ret;
        }

        msleep(20);

        /*
         * sensor requires reset in order to return up to date self cleaning
         * period
         */
        ret = sps30_do_reset(state);
        if (ret)
                dev_warn(dev,
                         "period changed but reads will return the old value\n");

        mutex_unlock(&state->lock);

        return len;
}

static ssize_t cleaning_period_available_show(struct device *dev,
                                              struct device_attribute *attr,
                                              char *buf)
{
        return sysfs_emit(buf, "[%d %d %d]\n",
                          SPS30_AUTO_CLEANING_PERIOD_MIN, 1,
                          SPS30_AUTO_CLEANING_PERIOD_MAX);
}

static IIO_DEVICE_ATTR_WO(start_cleaning, 0);
static IIO_DEVICE_ATTR_RW(cleaning_period, 0);
static IIO_DEVICE_ATTR_RO(cleaning_period_available, 0);

static struct attribute *sps30_attrs[] = {
        &iio_dev_attr_start_cleaning.dev_attr.attr,
        &iio_dev_attr_cleaning_period.dev_attr.attr,
        &iio_dev_attr_cleaning_period_available.dev_attr.attr,
        NULL
};

static const struct attribute_group sps30_attr_group = {
        .attrs = sps30_attrs,
};

static const struct iio_info sps30_info = {
        .attrs = &sps30_attr_group,
        .read_raw = sps30_read_raw,
};

#define SPS30_CHAN(_index, _mod) { \
        .type = IIO_MASSCONCENTRATION, \
        .modified = 1, \
        .channel2 = IIO_MOD_ ## _mod, \
        .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
        .address = _mod, \
        .scan_index = _index, \
        .scan_type = { \
                .sign = 'u', \
                .realbits = 19, \
                .storagebits = 32, \
                .endianness = IIO_CPU, \
        }, \
}

static const struct iio_chan_spec sps30_channels[] = {
        SPS30_CHAN(0, PM1),
        SPS30_CHAN(1, PM2P5),
        SPS30_CHAN(2, PM4),
        SPS30_CHAN(3, PM10),
        IIO_CHAN_SOFT_TIMESTAMP(4),
};

static void sps30_devm_stop_meas(void *data)
{
        struct sps30_state *state = data;

        if (state->state == MEASURING)
                state->ops->stop_meas(state);
}

static const unsigned long sps30_scan_masks[] = { 0x0f, 0x00 };

int sps30_probe(struct device *dev, const char *name, void *priv, const struct sps30_ops *ops)
{
        struct iio_dev *indio_dev;
        struct sps30_state *state;
        int ret;

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

        dev_set_drvdata(dev, indio_dev);

        state = iio_priv(indio_dev);
        state->dev = dev;
        state->priv = priv;
        state->ops = ops;
        mutex_init(&state->lock);

        indio_dev->info = &sps30_info;
        indio_dev->name = name;
        indio_dev->channels = sps30_channels;
        indio_dev->num_channels = ARRAY_SIZE(sps30_channels);
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->available_scan_masks = sps30_scan_masks;

        ret = sps30_do_reset(state);
        if (ret) {
                dev_err(dev, "failed to reset device\n");
                return ret;
        }

        ret = state->ops->show_info(state);
        if (ret) {
                dev_err(dev, "failed to read device info\n");
                return ret;
        }

        ret = devm_add_action_or_reset(dev, sps30_devm_stop_meas, state);
        if (ret)
                return ret;

        ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
                                              sps30_trigger_handler, NULL);
        if (ret)
                return ret;

        return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_NS_GPL(sps30_probe, "IIO_SPS30");

MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor driver");
MODULE_LICENSE("GPL v2");