// SPDX-License-Identifier: GPL-2.0
/*
 * Sensirion SPS30 particulate matter sensor driver
 *
 * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
 *
 * I2C slave address: 0x69
 */

#include <asm/unaligned.h>
#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>

#define SPS30_CRC8_POLYNOMIAL 0x31
/* max number of bytes needed to store PM measurements or serial string */
#define SPS30_MAX_READ_SIZE 48
/* 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

/* SPS30 commands */
#define SPS30_START_MEAS 0x0010
#define SPS30_STOP_MEAS 0x0104
#define SPS30_RESET 0xd304
#define SPS30_READ_DATA_READY_FLAG 0x0202
#define SPS30_READ_DATA 0x0300
#define SPS30_READ_SERIAL 0xd033
#define SPS30_START_FAN_CLEANING 0x5607
#define SPS30_AUTO_CLEANING_PERIOD 0x8004
/* not a sensor command per se, used only to distinguish write from read */
#define SPS30_READ_AUTO_CLEANING_PERIOD 0x8005

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

enum {
        RESET,
        MEASURING,
};

struct sps30_state {
        struct i2c_client *client;
        /*
         * Guards against concurrent access to sensor registers.
         * Must be held whenever sequence of commands is to be executed.
         */
        struct mutex lock;
        int state;
};

DECLARE_CRC8_TABLE(sps30_crc8_table);

static int sps30_write_then_read(struct sps30_state *state, u8 *txbuf,
                                 int txsize, u8 *rxbuf, int rxsize)
{
        int ret;

        /*
         * Sensor does not support repeated start so instead of
         * sending two i2c messages in a row we just send one by one.
         */
        ret = i2c_master_send(state->client, txbuf, txsize);
        if (ret != txsize)
                return ret < 0 ? ret : -EIO;

        if (!rxbuf)
                return 0;

        ret = i2c_master_recv(state->client, rxbuf, rxsize);
        if (ret != rxsize)
                return ret < 0 ? ret : -EIO;

        return 0;
}

static int sps30_do_cmd(struct sps30_state *state, u16 cmd, u8 *data, int size)
{
        /*
         * Internally sensor stores measurements in a following manner:
         *
         * PM1: upper two bytes, crc8, lower two bytes, crc8
         * PM2P5: upper two bytes, crc8, lower two bytes, crc8
         * PM4: upper two bytes, crc8, lower two bytes, crc8
         * PM10: upper two bytes, crc8, lower two bytes, crc8
         *
         * What follows next are number concentration measurements and
         * typical particle size measurement which we omit.
         */
        u8 buf[SPS30_MAX_READ_SIZE] = { cmd >> 8, cmd };
        int i, ret = 0;

        switch (cmd) {
        case SPS30_START_MEAS:
                buf[2] = 0x03;
                buf[3] = 0x00;
                buf[4] = crc8(sps30_crc8_table, &buf[2], 2, CRC8_INIT_VALUE);
                ret = sps30_write_then_read(state, buf, 5, NULL, 0);
                break;
        case SPS30_STOP_MEAS:
        case SPS30_RESET:
        case SPS30_START_FAN_CLEANING:
                ret = sps30_write_then_read(state, buf, 2, NULL, 0);
                break;
        case SPS30_READ_AUTO_CLEANING_PERIOD:
                buf[0] = SPS30_AUTO_CLEANING_PERIOD >> 8;
                buf[1] = (u8)(SPS30_AUTO_CLEANING_PERIOD & 0xff);
                fallthrough;
        case SPS30_READ_DATA_READY_FLAG:
        case SPS30_READ_DATA:
        case SPS30_READ_SERIAL:
                /* every two data bytes are checksummed */
                size += size / 2;
                ret = sps30_write_then_read(state, buf, 2, buf, size);
                break;
        case SPS30_AUTO_CLEANING_PERIOD:
                buf[2] = data[0];
                buf[3] = data[1];
                buf[4] = crc8(sps30_crc8_table, &buf[2], 2, CRC8_INIT_VALUE);
                buf[5] = data[2];
                buf[6] = data[3];
                buf[7] = crc8(sps30_crc8_table, &buf[5], 2, CRC8_INIT_VALUE);
                ret = sps30_write_then_read(state, buf, 8, NULL, 0);
                break;
        }

        if (ret)
                return ret;

        /* validate received data and strip off crc bytes */
        for (i = 0; i < size; i += 3) {
                u8 crc = crc8(sps30_crc8_table, &buf[i], 2, CRC8_INIT_VALUE);

                if (crc != buf[i + 2]) {
                        dev_err(&state->client->dev,
                                "data integrity check failed\n");
                        return -EIO;
                }

                *data++ = buf[i];
                *data++ = buf[i + 1];
        }

        return 0;
}

static s32 sps30_float_to_int_clamped(const u8 *fp)
{
        int val = get_unaligned_be32(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, tries = 5;
        u8 tmp[16];

        if (state->state == RESET) {
                ret = sps30_do_cmd(state, SPS30_START_MEAS, NULL, 0);
                if (ret)
                        return ret;

                state->state = MEASURING;
        }

        while (tries--) {
                ret = sps30_do_cmd(state, SPS30_READ_DATA_READY_FLAG, tmp, 2);
                if (ret)
                        return -EIO;

                /* new measurements ready to be read */
                if (tmp[1] == 1)
                        break;

                msleep_interruptible(300);
        }

        if (tries == -1)
                return -ETIMEDOUT;

        ret = sps30_do_cmd(state, SPS30_READ_DATA, tmp, sizeof(int) * size);
        if (ret)
                return ret;

        for (i = 0; i < size; i++)
                data[i] = sps30_float_to_int_clamped(&tmp[4 * i]);

        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 */
                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_timestamp(indio_dev, &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 int sps30_do_cmd_reset(struct sps30_state *state)
{
        int ret;

        ret = sps30_do_cmd(state, SPS30_RESET, NULL, 0);
        msleep(300);
        /*
         * Power-on-reset causes sensor to produce some glitch on i2c bus and
         * some controllers end up in error state. Recover simply by placing
         * some data on the bus, for example STOP_MEAS command, which
         * is NOP in this case.
         */
        sps30_do_cmd(state, SPS30_STOP_MEAS, NULL, 0);
        state->state = RESET;

        return ret;
}

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 = sps30_do_cmd(state, SPS30_START_FAN_CLEANING, NULL, 0);
        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);
        u8 tmp[4];
        int ret;

        mutex_lock(&state->lock);
        ret = sps30_do_cmd(state, SPS30_READ_AUTO_CLEANING_PERIOD, tmp, 4);
        mutex_unlock(&state->lock);
        if (ret)
                return ret;

        return sprintf(buf, "%d\n", get_unaligned_be32(tmp));
}

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;
        u8 tmp[4];

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

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

        put_unaligned_be32(val, tmp);

        mutex_lock(&state->lock);
        ret = sps30_do_cmd(state, SPS30_AUTO_CLEANING_PERIOD, tmp, 0);
        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_cmd_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 snprintf(buf, PAGE_SIZE, "[%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_stop_meas(void *data)
{
        struct sps30_state *state = data;

        sps30_do_cmd(state, SPS30_STOP_MEAS, NULL, 0);
}

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

static int sps30_probe(struct i2c_client *client)
{
        struct iio_dev *indio_dev;
        struct sps30_state *state;
        u8 buf[32];
        int ret;

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

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

        state = iio_priv(indio_dev);
        i2c_set_clientdata(client, indio_dev);
        state->client = client;
        state->state = RESET;
        indio_dev->info = &sps30_info;
        indio_dev->name = client->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;

        mutex_init(&state->lock);
        crc8_populate_msb(sps30_crc8_table, SPS30_CRC8_POLYNOMIAL);

        ret = sps30_do_cmd_reset(state);
        if (ret) {
                dev_err(&client->dev, "failed to reset device\n");
                return ret;
        }

        ret = sps30_do_cmd(state, SPS30_READ_SERIAL, buf, sizeof(buf));
        if (ret) {
                dev_err(&client->dev, "failed to read serial number\n");
                return ret;
        }
        /* returned serial number is already NUL terminated */
        dev_info(&client->dev, "serial number: %s\n", buf);

        ret = devm_add_action_or_reset(&client->dev, sps30_stop_meas, state);
        if (ret)
                return ret;

        ret = devm_iio_triggered_buffer_setup(&client->dev, indio_dev, NULL,
                                              sps30_trigger_handler, NULL);
        if (ret)
                return ret;

        return devm_iio_device_register(&client->dev, indio_dev);
}

static const struct i2c_device_id sps30_id[] = {
        { "sps30" },
        { }
};
MODULE_DEVICE_TABLE(i2c, sps30_id);

static const struct of_device_id sps30_of_match[] = {
        { .compatible = "sensirion,sps30" },
        { }
};
MODULE_DEVICE_TABLE(of, sps30_of_match);

static struct i2c_driver sps30_driver = {
        .driver = {
                .name = "sps30",
                .of_match_table = sps30_of_match,
        },
        .id_table = sps30_id,
        .probe_new = sps30_probe,
};
module_i2c_driver(sps30_driver);

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