root/drivers/iio/pressure/ms5611_core.c
// SPDX-License-Identifier: GPL-2.0
/*
 * MS5611 pressure and temperature sensor driver
 *
 * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
 *
 * Data sheet:
 *  http://www.meas-spec.com/downloads/MS5611-01BA03.pdf
 *  http://www.meas-spec.com/downloads/MS5607-02BA03.pdf
 *
 */

#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/delay.h>
#include <linux/regulator/consumer.h>

#include <linux/iio/sysfs.h>
#include <linux/iio/buffer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
#include "ms5611.h"

#define MS5611_INIT_OSR(_cmd, _conv_usec, _rate) \
        { .cmd = _cmd, .conv_usec = _conv_usec, .rate = _rate }

static const struct ms5611_osr ms5611_avail_pressure_osr[] = {
        MS5611_INIT_OSR(0x40, 600,  256),
        MS5611_INIT_OSR(0x42, 1170, 512),
        MS5611_INIT_OSR(0x44, 2280, 1024),
        MS5611_INIT_OSR(0x46, 4540, 2048),
        MS5611_INIT_OSR(0x48, 9040, 4096)
};

static const struct ms5611_osr ms5611_avail_temp_osr[] = {
        MS5611_INIT_OSR(0x50, 600,  256),
        MS5611_INIT_OSR(0x52, 1170, 512),
        MS5611_INIT_OSR(0x54, 2280, 1024),
        MS5611_INIT_OSR(0x56, 4540, 2048),
        MS5611_INIT_OSR(0x58, 9040, 4096)
};

static const char ms5611_show_osr[] = "256 512 1024 2048 4096";

static IIO_CONST_ATTR(oversampling_ratio_available, ms5611_show_osr);

static struct attribute *ms5611_attributes[] = {
        &iio_const_attr_oversampling_ratio_available.dev_attr.attr,
        NULL,
};

static const struct attribute_group ms5611_attribute_group = {
        .attrs = ms5611_attributes,
};

static bool ms5611_prom_is_valid(u16 *prom, size_t len)
{
        int i, j;
        uint16_t crc = 0, crc_orig = prom[7] & 0x000F;

        prom[7] &= 0xFF00;

        for (i = 0; i < len * 2; i++) {
                if (i % 2 == 1)
                        crc ^= prom[i >> 1] & 0x00FF;
                else
                        crc ^= prom[i >> 1] >> 8;

                for (j = 0; j < 8; j++) {
                        if (crc & 0x8000)
                                crc = (crc << 1) ^ 0x3000;
                        else
                                crc <<= 1;
                }
        }

        crc = (crc >> 12) & 0x000F;

        return crc == crc_orig;
}

static int ms5611_read_prom(struct iio_dev *indio_dev)
{
        int ret, i;
        struct ms5611_state *st = iio_priv(indio_dev);

        for (i = 0; i < MS5611_PROM_WORDS_NB; i++) {
                ret = st->read_prom_word(st, i, &st->prom[i]);
                if (ret < 0) {
                        dev_err(&indio_dev->dev,
                                "failed to read prom at %d\n", i);
                        return ret;
                }
        }

        if (!ms5611_prom_is_valid(st->prom, MS5611_PROM_WORDS_NB)) {
                dev_err(&indio_dev->dev, "PROM integrity check failed\n");
                return -ENODEV;
        }

        return 0;
}

static int ms5611_read_temp_and_pressure(struct iio_dev *indio_dev,
                                         s32 *temp, s32 *pressure)
{
        int ret;
        struct ms5611_state *st = iio_priv(indio_dev);

        ret = st->read_adc_temp_and_pressure(st, temp, pressure);
        if (ret < 0) {
                dev_err(&indio_dev->dev,
                        "failed to read temperature and pressure\n");
                return ret;
        }

        return st->compensate_temp_and_pressure(st, temp, pressure);
}

static int ms5611_temp_and_pressure_compensate(struct ms5611_state *st,
                                               s32 *temp, s32 *pressure)
{
        s32 t = *temp, p = *pressure;
        s64 off, sens, dt;

        dt = t - (st->prom[5] << 8);
        off = ((s64)st->prom[2] << 16) + ((st->prom[4] * dt) >> 7);
        sens = ((s64)st->prom[1] << 15) + ((st->prom[3] * dt) >> 8);

        t = 2000 + ((st->prom[6] * dt) >> 23);
        if (t < 2000) {
                s64 off2, sens2, t2;

                t2 = (dt * dt) >> 31;
                off2 = (5 * (t - 2000) * (t - 2000)) >> 1;
                sens2 = off2 >> 1;

                if (t < -1500) {
                        s64 tmp = (t + 1500) * (t + 1500);

                        off2 += 7 * tmp;
                        sens2 += (11 * tmp) >> 1;
                }

                t -= t2;
                off -= off2;
                sens -= sens2;
        }

        *temp = t;
        *pressure = (((p * sens) >> 21) - off) >> 15;

        return 0;
}

static int ms5607_temp_and_pressure_compensate(struct ms5611_state *st,
                                               s32 *temp, s32 *pressure)
{
        s32 t = *temp, p = *pressure;
        s64 off, sens, dt;

        dt = t - (st->prom[5] << 8);
        off = ((s64)st->prom[2] << 17) + ((st->prom[4] * dt) >> 6);
        sens = ((s64)st->prom[1] << 16) + ((st->prom[3] * dt) >> 7);

        t = 2000 + ((st->prom[6] * dt) >> 23);
        if (t < 2000) {
                s64 off2, sens2, t2, tmp;

                t2 = (dt * dt) >> 31;
                tmp = (t - 2000) * (t - 2000);
                off2 = (61 * tmp) >> 4;
                sens2 = tmp << 1;

                if (t < -1500) {
                        tmp = (t + 1500) * (t + 1500);
                        off2 += 15 * tmp;
                        sens2 += 8 * tmp;
                }

                t -= t2;
                off -= off2;
                sens -= sens2;
        }

        *temp = t;
        *pressure = (((p * sens) >> 21) - off) >> 15;

        return 0;
}

static int ms5611_reset(struct iio_dev *indio_dev)
{
        int ret;
        struct ms5611_state *st = iio_priv(indio_dev);

        ret = st->reset(st);
        if (ret < 0) {
                dev_err(&indio_dev->dev, "failed to reset device\n");
                return ret;
        }

        usleep_range(3000, 4000);

        return 0;
}

static irqreturn_t ms5611_trigger_handler(int irq, void *p)
{
        struct iio_poll_func *pf = p;
        struct iio_dev *indio_dev = pf->indio_dev;
        struct ms5611_state *st = iio_priv(indio_dev);
        /* Ensure buffer elements are naturally aligned */
        struct {
                s32 channels[2];
                aligned_s64 ts;
        } scan;
        int ret;

        mutex_lock(&st->lock);
        ret = ms5611_read_temp_and_pressure(indio_dev, &scan.channels[1],
                                            &scan.channels[0]);
        mutex_unlock(&st->lock);
        if (ret < 0)
                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 ms5611_read_raw(struct iio_dev *indio_dev,
                           struct iio_chan_spec const *chan,
                           int *val, int *val2, long mask)
{
        int ret;
        s32 temp, pressure;
        struct ms5611_state *st = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_PROCESSED:
                mutex_lock(&st->lock);
                ret = ms5611_read_temp_and_pressure(indio_dev,
                                                    &temp, &pressure);
                mutex_unlock(&st->lock);
                if (ret < 0)
                        return ret;

                switch (chan->type) {
                case IIO_TEMP:
                        *val = temp * 10;
                        return IIO_VAL_INT;
                case IIO_PRESSURE:
                        *val = pressure / 1000;
                        *val2 = (pressure % 1000) * 1000;
                        return IIO_VAL_INT_PLUS_MICRO;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_TEMP:
                        *val = 10;
                        return IIO_VAL_INT;
                case IIO_PRESSURE:
                        *val = 0;
                        *val2 = 1000;
                        return IIO_VAL_INT_PLUS_MICRO;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                if (chan->type != IIO_TEMP && chan->type != IIO_PRESSURE)
                        break;
                mutex_lock(&st->lock);
                if (chan->type == IIO_TEMP)
                        *val = (int)st->temp_osr->rate;
                else
                        *val = (int)st->pressure_osr->rate;
                mutex_unlock(&st->lock);
                return IIO_VAL_INT;
        }

        return -EINVAL;
}

static const struct ms5611_osr *ms5611_find_osr(int rate,
                                                const struct ms5611_osr *osr,
                                                size_t count)
{
        unsigned int r;

        for (r = 0; r < count; r++)
                if ((unsigned short)rate == osr[r].rate)
                        break;
        if (r >= count)
                return NULL;
        return &osr[r];
}

static int ms5611_write_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int val, int val2, long mask)
{
        struct ms5611_state *st = iio_priv(indio_dev);
        const struct ms5611_osr *osr = NULL;

        if (mask != IIO_CHAN_INFO_OVERSAMPLING_RATIO)
                return -EINVAL;

        if (chan->type == IIO_TEMP)
                osr = ms5611_find_osr(val, ms5611_avail_temp_osr,
                                      ARRAY_SIZE(ms5611_avail_temp_osr));
        else if (chan->type == IIO_PRESSURE)
                osr = ms5611_find_osr(val, ms5611_avail_pressure_osr,
                                      ARRAY_SIZE(ms5611_avail_pressure_osr));
        if (!osr)
                return -EINVAL;

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

        mutex_lock(&st->lock);

        if (chan->type == IIO_TEMP)
                st->temp_osr = osr;
        else
                st->pressure_osr = osr;

        mutex_unlock(&st->lock);
        iio_device_release_direct(indio_dev);

        return 0;
}

static const unsigned long ms5611_scan_masks[] = {0x3, 0};

static const struct iio_chan_spec ms5611_channels[] = {
        {
                .type = IIO_PRESSURE,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
                        BIT(IIO_CHAN_INFO_SCALE) |
                        BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
                .scan_index = 0,
                .scan_type = {
                        .sign = 's',
                        .realbits = 32,
                        .storagebits = 32,
                        .endianness = IIO_CPU,
                },
        },
        {
                .type = IIO_TEMP,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
                        BIT(IIO_CHAN_INFO_SCALE) |
                        BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
                .scan_index = 1,
                .scan_type = {
                        .sign = 's',
                        .realbits = 32,
                        .storagebits = 32,
                        .endianness = IIO_CPU,
                },
        },
        IIO_CHAN_SOFT_TIMESTAMP(2),
};

static const struct iio_info ms5611_info = {
        .read_raw = &ms5611_read_raw,
        .write_raw = &ms5611_write_raw,
        .attrs = &ms5611_attribute_group,
};

static int ms5611_init(struct iio_dev *indio_dev)
{
        int ret;

        /* Enable attached regulator if any. */
        ret = devm_regulator_get_enable(indio_dev->dev.parent, "vdd");
        if (ret)
                return ret;

        ret = ms5611_reset(indio_dev);
        if (ret < 0)
                return ret;

        ret = ms5611_read_prom(indio_dev);
        if (ret < 0)
                return ret;

        return 0;
}

int ms5611_probe(struct iio_dev *indio_dev, struct device *dev,
                 const char *name, int type)
{
        int ret;
        struct ms5611_state *st = iio_priv(indio_dev);

        mutex_init(&st->lock);

        switch (type) {
        case MS5611:
                st->compensate_temp_and_pressure =
                        ms5611_temp_and_pressure_compensate;
                break;
        case MS5607:
                st->compensate_temp_and_pressure =
                        ms5607_temp_and_pressure_compensate;
                break;
        default:
                return -EINVAL;
        }

        st->temp_osr =
                &ms5611_avail_temp_osr[ARRAY_SIZE(ms5611_avail_temp_osr) - 1];
        st->pressure_osr =
                &ms5611_avail_pressure_osr[ARRAY_SIZE(ms5611_avail_pressure_osr)
                                           - 1];
        indio_dev->name = name;
        indio_dev->info = &ms5611_info;
        indio_dev->channels = ms5611_channels;
        indio_dev->num_channels = ARRAY_SIZE(ms5611_channels);
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->available_scan_masks = ms5611_scan_masks;

        ret = ms5611_init(indio_dev);
        if (ret < 0)
                return ret;

        ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
                                         ms5611_trigger_handler, NULL);
        if (ret < 0) {
                dev_err(dev, "iio triggered buffer setup failed\n");
                return ret;
        }

        ret = devm_iio_device_register(dev, indio_dev);
        if (ret < 0) {
                dev_err(dev, "unable to register iio device\n");
                return ret;
        }

        return 0;
}
EXPORT_SYMBOL_NS(ms5611_probe, "IIO_MS5611");

MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
MODULE_DESCRIPTION("MS5611 core driver");
MODULE_LICENSE("GPL v2");