// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2020 Invensense, Inc.
 */

#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/minmax.h>
#include <linux/mutex.h>
#include <linux/pm_runtime.h>
#include <linux/regmap.h>
#include <linux/delay.h>

#include <linux/iio/buffer.h>
#include <linux/iio/common/inv_sensors_timestamp.h>
#include <linux/iio/iio.h>

#include "inv_icm42600.h"
#include "inv_icm42600_buffer.h"

/* FIFO header: 1 byte */
#define INV_ICM42600_FIFO_HEADER_MSG            BIT(7)
#define INV_ICM42600_FIFO_HEADER_ACCEL          BIT(6)
#define INV_ICM42600_FIFO_HEADER_GYRO           BIT(5)
#define INV_ICM42600_FIFO_HEADER_TMST_FSYNC     GENMASK(3, 2)
#define INV_ICM42600_FIFO_HEADER_ODR_ACCEL      BIT(1)
#define INV_ICM42600_FIFO_HEADER_ODR_GYRO       BIT(0)

struct inv_icm42600_fifo_1sensor_packet {
        u8 header;
        struct inv_icm42600_fifo_sensor_data data;
        s8 temp;
} __packed;
#define INV_ICM42600_FIFO_1SENSOR_PACKET_SIZE           8

struct inv_icm42600_fifo_2sensors_packet {
        u8 header;
        struct inv_icm42600_fifo_sensor_data accel;
        struct inv_icm42600_fifo_sensor_data gyro;
        s8 temp;
        __be16 timestamp;
} __packed;
#define INV_ICM42600_FIFO_2SENSORS_PACKET_SIZE          16

ssize_t inv_icm42600_fifo_decode_packet(const void *packet, const void **accel,
                                        const void **gyro, const s8 **temp,
                                        const void **timestamp, unsigned int *odr)
{
        const struct inv_icm42600_fifo_1sensor_packet *pack1 = packet;
        const struct inv_icm42600_fifo_2sensors_packet *pack2 = packet;
        u8 header = *((const u8 *)packet);

        /* FIFO empty */
        if (header & INV_ICM42600_FIFO_HEADER_MSG) {
                *accel = NULL;
                *gyro = NULL;
                *temp = NULL;
                *timestamp = NULL;
                *odr = 0;
                return 0;
        }

        /* handle odr flags */
        *odr = 0;
        if (header & INV_ICM42600_FIFO_HEADER_ODR_GYRO)
                *odr |= INV_ICM42600_SENSOR_GYRO;
        if (header & INV_ICM42600_FIFO_HEADER_ODR_ACCEL)
                *odr |= INV_ICM42600_SENSOR_ACCEL;

        /* accel + gyro */
        if ((header & INV_ICM42600_FIFO_HEADER_ACCEL) &&
            (header & INV_ICM42600_FIFO_HEADER_GYRO)) {
                *accel = &pack2->accel;
                *gyro = &pack2->gyro;
                *temp = &pack2->temp;
                *timestamp = &pack2->timestamp;
                return INV_ICM42600_FIFO_2SENSORS_PACKET_SIZE;
        }

        /* accel only */
        if (header & INV_ICM42600_FIFO_HEADER_ACCEL) {
                *accel = &pack1->data;
                *gyro = NULL;
                *temp = &pack1->temp;
                *timestamp = NULL;
                return INV_ICM42600_FIFO_1SENSOR_PACKET_SIZE;
        }

        /* gyro only */
        if (header & INV_ICM42600_FIFO_HEADER_GYRO) {
                *accel = NULL;
                *gyro = &pack1->data;
                *temp = &pack1->temp;
                *timestamp = NULL;
                return INV_ICM42600_FIFO_1SENSOR_PACKET_SIZE;
        }

        /* invalid packet if here */
        return -EINVAL;
}

void inv_icm42600_buffer_update_fifo_period(struct inv_icm42600_state *st)
{
        u32 period_gyro, period_accel;

        if (st->fifo.en & INV_ICM42600_SENSOR_GYRO)
                period_gyro = inv_icm42600_odr_to_period(st->conf.gyro.odr);
        else
                period_gyro = U32_MAX;

        if (st->fifo.en & INV_ICM42600_SENSOR_ACCEL)
                period_accel = inv_icm42600_odr_to_period(st->conf.accel.odr);
        else
                period_accel = U32_MAX;

        st->fifo.period = min(period_gyro, period_accel);
}

int inv_icm42600_buffer_set_fifo_en(struct inv_icm42600_state *st,
                                    unsigned int fifo_en)
{
        unsigned int mask, val;
        int ret;

        /* update only FIFO EN bits */
        mask = INV_ICM42600_FIFO_CONFIG1_TMST_FSYNC_EN |
                INV_ICM42600_FIFO_CONFIG1_TEMP_EN |
                INV_ICM42600_FIFO_CONFIG1_GYRO_EN |
                INV_ICM42600_FIFO_CONFIG1_ACCEL_EN;

        val = 0;
        if (fifo_en & INV_ICM42600_SENSOR_GYRO)
                val |= INV_ICM42600_FIFO_CONFIG1_GYRO_EN;
        if (fifo_en & INV_ICM42600_SENSOR_ACCEL)
                val |= INV_ICM42600_FIFO_CONFIG1_ACCEL_EN;
        if (fifo_en & INV_ICM42600_SENSOR_TEMP)
                val |= INV_ICM42600_FIFO_CONFIG1_TEMP_EN;

        ret = regmap_update_bits(st->map, INV_ICM42600_REG_FIFO_CONFIG1, mask, val);
        if (ret)
                return ret;

        st->fifo.en = fifo_en;
        inv_icm42600_buffer_update_fifo_period(st);

        return 0;
}

static size_t inv_icm42600_get_packet_size(unsigned int fifo_en)
{
        size_t packet_size;

        if ((fifo_en & INV_ICM42600_SENSOR_GYRO) &&
            (fifo_en & INV_ICM42600_SENSOR_ACCEL))
                packet_size = INV_ICM42600_FIFO_2SENSORS_PACKET_SIZE;
        else
                packet_size = INV_ICM42600_FIFO_1SENSOR_PACKET_SIZE;

        return packet_size;
}

static unsigned int inv_icm42600_wm_truncate(unsigned int watermark,
                                             size_t packet_size)
{
        size_t wm_size;
        unsigned int wm;

        wm_size = watermark * packet_size;
        if (wm_size > INV_ICM42600_FIFO_WATERMARK_MAX)
                wm_size = INV_ICM42600_FIFO_WATERMARK_MAX;

        wm = wm_size / packet_size;

        return wm;
}

/**
 * inv_icm42600_buffer_update_watermark - update watermark FIFO threshold
 * @st: driver internal state
 *
 * Returns 0 on success, a negative error code otherwise.
 *
 * FIFO watermark threshold is computed based on the required watermark values
 * set for gyro and accel sensors. Since watermark is all about acceptable data
 * latency, use the smallest setting between the 2. It means choosing the
 * smallest latency but this is not as simple as choosing the smallest watermark
 * value. Latency depends on watermark and ODR. It requires several steps:
 * 1) compute gyro and accel latencies and choose the smallest value.
 * 2) adapt the choosen latency so that it is a multiple of both gyro and accel
 *    ones. Otherwise it is possible that you don't meet a requirement. (for
 *    example with gyro @100Hz wm 4 and accel @100Hz with wm 6, choosing the
 *    value of 4 will not meet accel latency requirement because 6 is not a
 *    multiple of 4. You need to use the value 2.)
 * 3) Since all periods are multiple of each others, watermark is computed by
 *    dividing this computed latency by the smallest period, which corresponds
 *    to the FIFO frequency. Beware that this is only true because we are not
 *    using 500Hz frequency which is not a multiple of the others.
 */
int inv_icm42600_buffer_update_watermark(struct inv_icm42600_state *st)
{
        size_t packet_size, wm_size;
        unsigned int wm_gyro, wm_accel, watermark;
        u32 period_gyro, period_accel;
        u32 latency_gyro, latency_accel, latency;
        bool restore;
        __le16 raw_wm;
        int ret;

        packet_size = inv_icm42600_get_packet_size(st->fifo.en);

        /* compute sensors latency, depending on sensor watermark and odr */
        wm_gyro = inv_icm42600_wm_truncate(st->fifo.watermark.gyro, packet_size);
        wm_accel = inv_icm42600_wm_truncate(st->fifo.watermark.accel, packet_size);
        /* use us for odr to avoid overflow using 32 bits values */
        period_gyro = inv_icm42600_odr_to_period(st->conf.gyro.odr) / 1000UL;
        period_accel = inv_icm42600_odr_to_period(st->conf.accel.odr) / 1000UL;
        latency_gyro = period_gyro * wm_gyro;
        latency_accel = period_accel * wm_accel;

        /* 0 value for watermark means that the sensor is turned off */
        if (wm_gyro == 0 && wm_accel == 0)
                return 0;

        if (latency_gyro == 0) {
                watermark = wm_accel;
                st->fifo.watermark.eff_accel = wm_accel;
        } else if (latency_accel == 0) {
                watermark = wm_gyro;
                st->fifo.watermark.eff_gyro = wm_gyro;
        } else {
                /* compute the smallest latency that is a multiple of both */
                if (latency_gyro <= latency_accel)
                        latency = latency_gyro - (latency_accel % latency_gyro);
                else
                        latency = latency_accel - (latency_gyro % latency_accel);
                /* all this works because periods are multiple of each others */
                watermark = latency / min(period_gyro, period_accel);
                if (watermark < 1)
                        watermark = 1;
                /* update effective watermark */
                st->fifo.watermark.eff_gyro = latency / period_gyro;
                if (st->fifo.watermark.eff_gyro < 1)
                        st->fifo.watermark.eff_gyro = 1;
                st->fifo.watermark.eff_accel = latency / period_accel;
                if (st->fifo.watermark.eff_accel < 1)
                        st->fifo.watermark.eff_accel = 1;
        }

        /* compute watermark value in bytes */
        wm_size = watermark * packet_size;

        /* changing FIFO watermark requires to turn off watermark interrupt */
        ret = regmap_update_bits_check(st->map, INV_ICM42600_REG_INT_SOURCE0,
                                       INV_ICM42600_INT_SOURCE0_FIFO_THS_INT1_EN,
                                       0, &restore);
        if (ret)
                return ret;

        raw_wm = INV_ICM42600_FIFO_WATERMARK_VAL(wm_size);
        memcpy(st->buffer, &raw_wm, sizeof(raw_wm));
        ret = regmap_bulk_write(st->map, INV_ICM42600_REG_FIFO_WATERMARK,
                                st->buffer, sizeof(raw_wm));
        if (ret)
                return ret;

        /* restore watermark interrupt */
        if (restore) {
                ret = regmap_set_bits(st->map, INV_ICM42600_REG_INT_SOURCE0,
                                      INV_ICM42600_INT_SOURCE0_FIFO_THS_INT1_EN);
                if (ret)
                        return ret;
        }

        return 0;
}

static int inv_icm42600_buffer_preenable(struct iio_dev *indio_dev)
{
        struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
        struct device *dev = regmap_get_device(st->map);
        struct inv_icm42600_sensor_state *sensor_st = iio_priv(indio_dev);
        struct inv_sensors_timestamp *ts = &sensor_st->ts;

        pm_runtime_get_sync(dev);

        guard(mutex)(&st->lock);
        inv_sensors_timestamp_reset(ts);

        return 0;
}

/*
 * update_scan_mode callback is turning sensors on and setting data FIFO enable
 * bits.
 */
static int inv_icm42600_buffer_postenable(struct iio_dev *indio_dev)
{
        struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
        int ret;

        guard(mutex)(&st->lock);

        if (st->fifo.on) {
                st->fifo.on++;
                return 0;
        }

        /* set FIFO threshold interrupt */
        ret = regmap_set_bits(st->map, INV_ICM42600_REG_INT_SOURCE0,
                              INV_ICM42600_INT_SOURCE0_FIFO_THS_INT1_EN);
        if (ret)
                return ret;

        /* flush FIFO data */
        ret = regmap_write(st->map, INV_ICM42600_REG_SIGNAL_PATH_RESET,
                           INV_ICM42600_SIGNAL_PATH_RESET_FIFO_FLUSH);
        if (ret)
                return ret;

        /* set FIFO in streaming mode */
        ret = regmap_write(st->map, INV_ICM42600_REG_FIFO_CONFIG,
                           INV_ICM42600_FIFO_CONFIG_STREAM);
        if (ret)
                return ret;

        /* workaround: first read of FIFO count after reset is always 0 */
        ret = regmap_bulk_read(st->map, INV_ICM42600_REG_FIFO_COUNT, st->buffer, 2);
        if (ret)
                return ret;

        st->fifo.on++;

        return 0;
}

static int inv_icm42600_buffer_predisable(struct iio_dev *indio_dev)
{
        struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
        int ret;

        guard(mutex)(&st->lock);

        if (st->fifo.on > 1) {
                st->fifo.on--;
                return 0;
        }

        /* set FIFO in bypass mode */
        ret = regmap_write(st->map, INV_ICM42600_REG_FIFO_CONFIG,
                           INV_ICM42600_FIFO_CONFIG_BYPASS);
        if (ret)
                return ret;

        /* flush FIFO data */
        ret = regmap_write(st->map, INV_ICM42600_REG_SIGNAL_PATH_RESET,
                           INV_ICM42600_SIGNAL_PATH_RESET_FIFO_FLUSH);
        if (ret)
                return ret;

        /* disable FIFO threshold interrupt */
        ret = regmap_clear_bits(st->map, INV_ICM42600_REG_INT_SOURCE0,
                                INV_ICM42600_INT_SOURCE0_FIFO_THS_INT1_EN);
        if (ret)
                return ret;

        st->fifo.on--;

        return 0;
}

static int inv_icm42600_buffer_postdisable(struct iio_dev *indio_dev)
{
        struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
        struct inv_icm42600_sensor_state *sensor_st = iio_priv(indio_dev);
        struct inv_sensors_timestamp *ts = &sensor_st->ts;
        struct device *dev = regmap_get_device(st->map);
        unsigned int sensor;
        unsigned int *watermark;
        struct inv_icm42600_sensor_conf conf = INV_ICM42600_SENSOR_CONF_INIT;
        unsigned int sleep_temp = 0;
        unsigned int sleep_sensor = 0;
        unsigned int sleep;
        int ret;

        if (indio_dev == st->indio_gyro) {
                sensor = INV_ICM42600_SENSOR_GYRO;
                watermark = &st->fifo.watermark.gyro;
        } else if (indio_dev == st->indio_accel) {
                sensor = INV_ICM42600_SENSOR_ACCEL;
                watermark = &st->fifo.watermark.accel;
        } else {
                return -EINVAL;
        }

        mutex_lock(&st->lock);

        inv_sensors_timestamp_apply_odr(ts, 0, 0, 0);

        ret = inv_icm42600_buffer_set_fifo_en(st, st->fifo.en & ~sensor);
        if (ret)
                goto out_unlock;

        *watermark = 0;
        ret = inv_icm42600_buffer_update_watermark(st);
        if (ret)
                goto out_unlock;

        conf.mode = INV_ICM42600_SENSOR_MODE_OFF;
        if (sensor == INV_ICM42600_SENSOR_GYRO)
                ret = inv_icm42600_set_gyro_conf(st, &conf, &sleep_sensor);
        else if (!st->apex.on)
                ret = inv_icm42600_set_accel_conf(st, &conf, &sleep_sensor);
        if (ret)
                goto out_unlock;

        /* if FIFO is off, turn temperature off */
        if (!st->fifo.on)
                ret = inv_icm42600_set_temp_conf(st, false, &sleep_temp);

out_unlock:
        mutex_unlock(&st->lock);

        /* sleep maximum required time */
        sleep = max(sleep_sensor, sleep_temp);
        if (sleep)
                msleep(sleep);

        pm_runtime_put_autosuspend(dev);

        return ret;
}

const struct iio_buffer_setup_ops inv_icm42600_buffer_ops = {
        .preenable = inv_icm42600_buffer_preenable,
        .postenable = inv_icm42600_buffer_postenable,
        .predisable = inv_icm42600_buffer_predisable,
        .postdisable = inv_icm42600_buffer_postdisable,
};

int inv_icm42600_buffer_fifo_read(struct inv_icm42600_state *st,
                                  unsigned int max)
{
        size_t max_count;
        __be16 *raw_fifo_count;
        ssize_t i, size;
        const void *accel, *gyro, *timestamp;
        const s8 *temp;
        unsigned int odr;
        int ret;

        /* reset all samples counters */
        st->fifo.count = 0;
        st->fifo.nb.gyro = 0;
        st->fifo.nb.accel = 0;
        st->fifo.nb.total = 0;

        /* compute maximum FIFO read size */
        if (max == 0)
                max_count = sizeof(st->fifo.data);
        else
                max_count = max * inv_icm42600_get_packet_size(st->fifo.en);

        /* read FIFO count value */
        raw_fifo_count = (__be16 *)st->buffer;
        ret = regmap_bulk_read(st->map, INV_ICM42600_REG_FIFO_COUNT,
                               raw_fifo_count, sizeof(*raw_fifo_count));
        if (ret)
                return ret;
        st->fifo.count = be16_to_cpup(raw_fifo_count);

        /* check and clamp FIFO count value */
        if (st->fifo.count == 0)
                return 0;
        if (st->fifo.count > max_count)
                st->fifo.count = max_count;

        /* read all FIFO data in internal buffer */
        ret = regmap_noinc_read(st->map, INV_ICM42600_REG_FIFO_DATA,
                                st->fifo.data, st->fifo.count);
        if (ret)
                return ret;

        /* compute number of samples for each sensor */
        for (i = 0; i < st->fifo.count; i += size) {
                size = inv_icm42600_fifo_decode_packet(&st->fifo.data[i],
                                &accel, &gyro, &temp, &timestamp, &odr);
                if (size <= 0)
                        break;
                if (gyro != NULL && inv_icm42600_fifo_is_data_valid(gyro))
                        st->fifo.nb.gyro++;
                if (accel != NULL && inv_icm42600_fifo_is_data_valid(accel))
                        st->fifo.nb.accel++;
                st->fifo.nb.total++;
        }

        return 0;
}

int inv_icm42600_buffer_fifo_parse(struct inv_icm42600_state *st)
{
        struct inv_icm42600_sensor_state *gyro_st = iio_priv(st->indio_gyro);
        struct inv_icm42600_sensor_state *accel_st = iio_priv(st->indio_accel);
        struct inv_sensors_timestamp *ts;
        int ret;

        if (st->fifo.nb.total == 0)
                return 0;

        /* handle gyroscope timestamp and FIFO data parsing */
        if (st->fifo.nb.gyro > 0) {
                ts = &gyro_st->ts;
                inv_sensors_timestamp_interrupt(ts, st->fifo.watermark.eff_gyro,
                                                st->timestamp.gyro);
                ret = inv_icm42600_gyro_parse_fifo(st->indio_gyro);
                if (ret)
                        return ret;
        }

        /* handle accelerometer timestamp and FIFO data parsing */
        if (st->fifo.nb.accel > 0) {
                ts = &accel_st->ts;
                inv_sensors_timestamp_interrupt(ts, st->fifo.watermark.eff_accel,
                                                st->timestamp.accel);
                ret = inv_icm42600_accel_parse_fifo(st->indio_accel);
                if (ret)
                        return ret;
        }

        return 0;
}

int inv_icm42600_buffer_hwfifo_flush(struct inv_icm42600_state *st,
                                     unsigned int count)
{
        struct inv_icm42600_sensor_state *gyro_st = iio_priv(st->indio_gyro);
        struct inv_icm42600_sensor_state *accel_st = iio_priv(st->indio_accel);
        struct inv_sensors_timestamp *ts;
        s64 gyro_ts, accel_ts;
        int ret;

        gyro_ts = iio_get_time_ns(st->indio_gyro);
        accel_ts = iio_get_time_ns(st->indio_accel);

        ret = inv_icm42600_buffer_fifo_read(st, count);
        if (ret)
                return ret;

        if (st->fifo.nb.total == 0)
                return 0;

        if (st->fifo.nb.gyro > 0) {
                ts = &gyro_st->ts;
                inv_sensors_timestamp_interrupt(ts, st->fifo.nb.gyro, gyro_ts);
                ret = inv_icm42600_gyro_parse_fifo(st->indio_gyro);
                if (ret)
                        return ret;
        }

        if (st->fifo.nb.accel > 0) {
                ts = &accel_st->ts;
                inv_sensors_timestamp_interrupt(ts, st->fifo.nb.accel, accel_ts);
                ret = inv_icm42600_accel_parse_fifo(st->indio_accel);
                if (ret)
                        return ret;
        }

        return 0;
}

int inv_icm42600_buffer_init(struct inv_icm42600_state *st)
{
        unsigned int val;
        int ret;

        st->fifo.watermark.eff_gyro = 1;
        st->fifo.watermark.eff_accel = 1;

        /*
         * Default FIFO configuration (bits 7 to 5)
         * - use invalid value
         * - FIFO count in bytes
         * - FIFO count in big endian
         */
        val = INV_ICM42600_INTF_CONFIG0_FIFO_COUNT_ENDIAN;
        ret = regmap_update_bits(st->map, INV_ICM42600_REG_INTF_CONFIG0,
                                 GENMASK(7, 5), val);
        if (ret)
                return ret;

        /*
         * Enable FIFO partial read and continuous watermark interrupt.
         * Disable all FIFO EN bits.
         */
        val = INV_ICM42600_FIFO_CONFIG1_RESUME_PARTIAL_RD |
              INV_ICM42600_FIFO_CONFIG1_WM_GT_TH;
        return regmap_update_bits(st->map, INV_ICM42600_REG_FIFO_CONFIG1,
                                  GENMASK(6, 5) | GENMASK(3, 0), val);
}