// SPDX-License-Identifier: GPL-2.0
/*
 * Sensirion SPS30 particulate matter sensor i2c driver
 *
 * Copyright (c) 2020 Tomasz Duszynski <tomasz.duszynski@octakon.com>
 *
 * I2C slave address: 0x69
 */
#include <linux/unaligned.h>
#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/types.h>

#include "sps30.h"

#define SPS30_I2C_CRC8_POLYNOMIAL 0x31
/* max number of bytes needed to store PM measurements or serial string */
#define SPS30_I2C_MAX_BUF_SIZE 48

DECLARE_CRC8_TABLE(sps30_i2c_crc8_table);

#define SPS30_I2C_START_MEAS 0x0010
#define SPS30_I2C_STOP_MEAS 0x0104
#define SPS30_I2C_READ_MEAS 0x0300
#define SPS30_I2C_MEAS_READY 0x0202
#define SPS30_I2C_RESET 0xd304
#define SPS30_I2C_CLEAN_FAN 0x5607
#define SPS30_I2C_PERIOD 0x8004
#define SPS30_I2C_READ_SERIAL 0xd033
#define SPS30_I2C_READ_VERSION 0xd100

static int sps30_i2c_xfer(struct sps30_state *state, unsigned char *txbuf, size_t txsize,
                          unsigned char *rxbuf, size_t rxsize)
{
        struct i2c_client *client = to_i2c_client(state->dev);
        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(client, txbuf, txsize);
        if (ret < 0)
                return ret;
        if (ret != txsize)
                return -EIO;

        if (!rxsize)
                return 0;

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

        return 0;
}

static int sps30_i2c_command(struct sps30_state *state, u16 cmd, void *arg, size_t arg_size,
                             void *rsp, size_t rsp_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.
         */
        unsigned char buf[SPS30_I2C_MAX_BUF_SIZE];
        unsigned char *tmp;
        unsigned char crc;
        size_t i;
        int ret;

        put_unaligned_be16(cmd, buf);
        i = 2;

        if (rsp) {
                /* each two bytes are followed by a crc8 */
                rsp_size += rsp_size / 2;
        } else {
                tmp = arg;

                while (arg_size) {
                        buf[i] = *tmp++;
                        buf[i + 1] = *tmp++;
                        buf[i + 2] = crc8(sps30_i2c_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
                        arg_size -= 2;
                        i += 3;
                }
        }

        ret = sps30_i2c_xfer(state, buf, i, buf, rsp_size);
        if (ret)
                return ret;

        /* validate received data and strip off crc bytes */
        tmp = rsp;
        for (i = 0; i < rsp_size; i += 3) {
                crc = crc8(sps30_i2c_crc8_table, buf + i, 2, CRC8_INIT_VALUE);
                if (crc != buf[i + 2]) {
                        dev_err(state->dev, "data integrity check failed\n");
                        return -EIO;
                }

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

        return 0;
}

static int sps30_i2c_start_meas(struct sps30_state *state)
{
        /* request BE IEEE754 formatted data */
        unsigned char buf[] = { 0x03, 0x00 };

        return sps30_i2c_command(state, SPS30_I2C_START_MEAS, buf, sizeof(buf), NULL, 0);
}

static int sps30_i2c_stop_meas(struct sps30_state *state)
{
        return sps30_i2c_command(state, SPS30_I2C_STOP_MEAS, NULL, 0, NULL, 0);
}

static int sps30_i2c_reset(struct sps30_state *state)
{
        int ret;

        ret = sps30_i2c_command(state, SPS30_I2C_RESET, NULL, 0, NULL, 0);
        msleep(500);
        /*
         * 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_i2c_stop_meas(state);

        return ret;
}

static bool sps30_i2c_meas_ready(struct sps30_state *state)
{
        unsigned char buf[2];
        int ret;

        ret = sps30_i2c_command(state, SPS30_I2C_MEAS_READY, NULL, 0, buf, sizeof(buf));
        if (ret)
                return false;

        return buf[1];
}

static int sps30_i2c_read_meas(struct sps30_state *state, __be32 *meas, size_t num)
{
        /* measurements are ready within a second */
        if (msleep_interruptible(1000))
                return -EINTR;

        if (!sps30_i2c_meas_ready(state))
                return -ETIMEDOUT;

        return sps30_i2c_command(state, SPS30_I2C_READ_MEAS, NULL, 0, meas, sizeof(*meas) * num);
}

static int sps30_i2c_clean_fan(struct sps30_state *state)
{
        return sps30_i2c_command(state, SPS30_I2C_CLEAN_FAN, NULL, 0, NULL, 0);
}

static int sps30_i2c_read_cleaning_period(struct sps30_state *state, __be32 *period)
{
        return sps30_i2c_command(state, SPS30_I2C_PERIOD, NULL, 0, period, sizeof(*period));
}

static int sps30_i2c_write_cleaning_period(struct sps30_state *state, __be32 period)
{
        return sps30_i2c_command(state, SPS30_I2C_PERIOD, &period, sizeof(period), NULL, 0);
}

static int sps30_i2c_show_info(struct sps30_state *state)
{
        /* extra nul just in case */
        unsigned char buf[32 + 1] = { 0x00 };
        int ret;

        ret = sps30_i2c_command(state, SPS30_I2C_READ_SERIAL, NULL, 0, buf, sizeof(buf) - 1);
        if (ret)
                return ret;

        dev_info(state->dev, "serial number: %s\n", buf);

        ret = sps30_i2c_command(state, SPS30_I2C_READ_VERSION, NULL, 0, buf, 2);
        if (ret)
                return ret;

        dev_info(state->dev, "fw version: %u.%u\n", buf[0], buf[1]);

        return 0;
}

static const struct sps30_ops sps30_i2c_ops = {
        .start_meas = sps30_i2c_start_meas,
        .stop_meas = sps30_i2c_stop_meas,
        .read_meas = sps30_i2c_read_meas,
        .reset = sps30_i2c_reset,
        .clean_fan = sps30_i2c_clean_fan,
        .read_cleaning_period = sps30_i2c_read_cleaning_period,
        .write_cleaning_period = sps30_i2c_write_cleaning_period,
        .show_info = sps30_i2c_show_info,
};

static int sps30_i2c_probe(struct i2c_client *client)
{
        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
                return -EOPNOTSUPP;

        crc8_populate_msb(sps30_i2c_crc8_table, SPS30_I2C_CRC8_POLYNOMIAL);

        return sps30_probe(&client->dev, client->name, NULL, &sps30_i2c_ops);
}

static const struct i2c_device_id sps30_i2c_id[] = {
        { "sps30" },
        { }
};
MODULE_DEVICE_TABLE(i2c, sps30_i2c_id);

static const struct of_device_id sps30_i2c_of_match[] = {
        { .compatible = "sensirion,sps30" },
        { }
};
MODULE_DEVICE_TABLE(of, sps30_i2c_of_match);

static struct i2c_driver sps30_i2c_driver = {
        .driver = {
                .name = KBUILD_MODNAME,
                .of_match_table = sps30_i2c_of_match,
        },
        .id_table = sps30_i2c_id,
        .probe = sps30_i2c_probe,
};
module_i2c_driver(sps30_i2c_driver);

MODULE_AUTHOR("Tomasz Duszynski <tomasz.duszynski@octakon.com>");
MODULE_DESCRIPTION("Sensirion SPS30 particulate matter sensor i2c driver");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS("IIO_SPS30");