/*
 * Measurements Specialties driver common i2c functions
 *
 * Copyright (c) 2015 Measurement-Specialties
 *
 * Licensed under the GPL-2.
 */

#include <linux/module.h>
#include <linux/iio/iio.h>
#include <linux/device.h>
#include <linux/delay.h>

#include "ms_sensors_i2c.h"

/* Conversion times in us */
static const u16 ms_sensors_ht_t_conversion_time[] = { 50000, 25000,
                                                       13000, 7000 };
static const u16 ms_sensors_ht_h_conversion_time[] = { 16000, 3000,
                                                       5000, 8000 };
static const u16 ms_sensors_tp_conversion_time[] = { 500, 1100, 2100,
                                                     4100, 8220, 16440 };

#define MS_SENSORS_SERIAL_READ_MSB              0xFA0F
#define MS_SENSORS_SERIAL_READ_LSB              0xFCC9
#define MS_SENSORS_CONFIG_REG_WRITE             0xE6
#define MS_SENSORS_CONFIG_REG_READ              0xE7
#define MS_SENSORS_HT_T_CONVERSION_START        0xF3
#define MS_SENSORS_HT_H_CONVERSION_START        0xF5

#define MS_SENSORS_TP_PROM_READ                 0xA0
#define MS_SENSORS_TP_T_CONVERSION_START        0x50
#define MS_SENSORS_TP_P_CONVERSION_START        0x40
#define MS_SENSORS_TP_ADC_READ                  0x00

#define MS_SENSORS_NO_READ_CMD                  0xFF

/**
 * ms_sensors_reset() - Reset function
 * @cli:        pointer to device client
 * @cmd:        reset cmd. Depends on device in use
 * @delay:      usleep minimal delay after reset command is issued
 *
 * Generic I2C reset function for Measurement Specialties devices.
 *
 * Return: 0 on success, negative errno otherwise.
 */
int ms_sensors_reset(void *cli, u8 cmd, unsigned int delay)
{
        int ret;
        struct i2c_client *client = cli;

        ret = i2c_smbus_write_byte(client, cmd);
        if (ret) {
                dev_err(&client->dev, "Failed to reset device\n");
                return ret;
        }
        usleep_range(delay, delay + 1000);

        return 0;
}
EXPORT_SYMBOL(ms_sensors_reset);

/**
 * ms_sensors_read_prom_word() - PROM word read function
 * @cli:        pointer to device client
 * @cmd:        PROM read cmd. Depends on device and prom id
 * @word:       pointer to word destination value
 *
 * Generic i2c prom word read function for Measurement Specialties devices.
 *
 * Return: 0 on success, negative errno otherwise.
 */
int ms_sensors_read_prom_word(void *cli, int cmd, u16 *word)
{
        int ret;
        struct i2c_client *client = cli;

        ret = i2c_smbus_read_word_swapped(client, cmd);
        if (ret < 0) {
                dev_err(&client->dev, "Failed to read prom word\n");
                return ret;
        }
        *word = ret;

        return 0;
}
EXPORT_SYMBOL(ms_sensors_read_prom_word);

/**
 * ms_sensors_convert_and_read() - ADC conversion & read function
 * @cli:        pointer to device client
 * @conv:       ADC conversion command. Depends on device in use
 * @rd:         ADC read command. Depends on device in use
 * @delay:      usleep minimal delay after conversion command is issued
 * @adc:        pointer to ADC destination value
 *
 * Generic ADC conversion & read function for Measurement Specialties
 * devices.
 * The function will issue conversion command, sleep appopriate delay, and
 * issue command to read ADC.
 *
 * Return: 0 on success, negative errno otherwise.
 */
int ms_sensors_convert_and_read(void *cli, u8 conv, u8 rd,
                                unsigned int delay, u32 *adc)
{
        int ret;
        __be32 buf = 0;
        struct i2c_client *client = cli;

        /* Trigger conversion */
        ret = i2c_smbus_write_byte(client, conv);
        if (ret)
                goto err;
        usleep_range(delay, delay + 1000);

        /* Retrieve ADC value */
        if (rd != MS_SENSORS_NO_READ_CMD)
                ret = i2c_smbus_read_i2c_block_data(client, rd, 3, (u8 *)&buf);
        else
                ret = i2c_master_recv(client, (u8 *)&buf, 3);
        if (ret < 0)
                goto err;

        dev_dbg(&client->dev, "ADC raw value : %x\n", be32_to_cpu(buf) >> 8);
        *adc = be32_to_cpu(buf) >> 8;

        return 0;
err:
        dev_err(&client->dev, "Unable to make sensor adc conversion\n");
        return ret;
}
EXPORT_SYMBOL(ms_sensors_convert_and_read);

/**
 * ms_sensors_crc_valid() - CRC check function
 * @value:      input and CRC compare value
 *
 * Cyclic Redundancy Check function used in TSYS02D, HTU21, MS8607.
 * This function performs a x^8 + x^5 + x^4 + 1 polynomial CRC.
 * The argument contains CRC value in LSB byte while the bytes 1 and 2
 * are used for CRC computation.
 *
 * Return: 1 if CRC is valid, 0 otherwise.
 */
static bool ms_sensors_crc_valid(u32 value)
{
        u32 polynom = 0x988000; /* x^8 + x^5 + x^4 + 1 */
        u32 msb = 0x800000;
        u32 mask = 0xFF8000;
        u32 result = value & 0xFFFF00;
        u8 crc = value & 0xFF;

        while (msb != 0x80) {
                if (result & msb)
                        result = ((result ^ polynom) & mask)
                                | (result & ~mask);
                msb >>= 1;
                mask >>= 1;
                polynom >>= 1;
        }

        return result == crc;
}

/**
 * ms_sensors_read_serial() - Serial number read function
 * @cli:        pointer to i2c client
 * @sn:         pointer to 64-bits destination value
 *
 * Generic i2c serial number read function for Measurement Specialties devices.
 * This function is used for TSYS02d, HTU21, MS8607 chipset.
 * Refer to datasheet:
 *      http://www.meas-spec.com/downloads/HTU2X_Serial_Number_Reading.pdf
 *
 * Sensor raw MSB serial number format is the following :
 *      [ SNB3, CRC, SNB2, CRC, SNB1, CRC, SNB0, CRC]
 * Sensor raw LSB serial number format is the following :
 *      [ X, X, SNC1, SNC0, CRC, SNA1, SNA0, CRC]
 * The resulting serial number is following :
 *      [ SNA1, SNA0, SNB3, SNB2, SNB1, SNB0, SNC1, SNC0]
 *
 * Return: 0 on success, negative errno otherwise.
 */
int ms_sensors_read_serial(struct i2c_client *client, u64 *sn)
{
        u8 i;
        __be64 rcv_buf = 0;
        u64 rcv_val;
        __be16 send_buf;
        int ret;

        struct i2c_msg msg[2] = {
                {
                 .addr = client->addr,
                 .flags = client->flags,
                 .len = 2,
                 .buf = (__u8 *)&send_buf,
                 },
                {
                 .addr = client->addr,
                 .flags = client->flags | I2C_M_RD,
                 .buf = (__u8 *)&rcv_buf,
                 },
        };

        /* Read MSB part of serial number */
        send_buf = cpu_to_be16(MS_SENSORS_SERIAL_READ_MSB);
        msg[1].len = 8;
        ret = i2c_transfer(client->adapter, msg, 2);
        if (ret < 0) {
                dev_err(&client->dev, "Unable to read device serial number");
                return ret;
        }

        rcv_val = be64_to_cpu(rcv_buf);
        dev_dbg(&client->dev, "Serial MSB raw : %llx\n", rcv_val);

        for (i = 0; i < 64; i += 16) {
                if (!ms_sensors_crc_valid((rcv_val >> i) & 0xFFFF))
                        return -ENODEV;
        }

        *sn = (((rcv_val >> 32) & 0xFF000000) |
               ((rcv_val >> 24) & 0x00FF0000) |
               ((rcv_val >> 16) & 0x0000FF00) |
               ((rcv_val >> 8) & 0x000000FF)) << 16;

        /* Read LSB part of serial number */
        send_buf = cpu_to_be16(MS_SENSORS_SERIAL_READ_LSB);
        msg[1].len = 6;
        rcv_buf = 0;
        ret = i2c_transfer(client->adapter, msg, 2);
        if (ret < 0) {
                dev_err(&client->dev, "Unable to read device serial number");
                return ret;
        }

        rcv_val = be64_to_cpu(rcv_buf) >> 16;
        dev_dbg(&client->dev, "Serial MSB raw : %llx\n", rcv_val);

        for (i = 0; i < 48; i += 24) {
                if (!ms_sensors_crc_valid((rcv_val >> i) & 0xFFFFFF))
                        return -ENODEV;
        }

        *sn |= (rcv_val & 0xFFFF00) << 40 | (rcv_val >> 32);

        return 0;
}
EXPORT_SYMBOL(ms_sensors_read_serial);

static int ms_sensors_read_config_reg(struct i2c_client *client,
                                      u8 *config_reg)
{
        int ret;

        ret = i2c_smbus_write_byte(client, MS_SENSORS_CONFIG_REG_READ);
        if (ret) {
                dev_err(&client->dev, "Unable to read config register");
                return ret;
        }

        ret = i2c_master_recv(client, config_reg, 1);
        if (ret < 0) {
                dev_err(&client->dev, "Unable to read config register");
                return ret;
        }
        dev_dbg(&client->dev, "Config register :%x\n", *config_reg);

        return 0;
}

/**
 * ms_sensors_write_resolution() - Set resolution function
 * @dev_data:   pointer to temperature/humidity device data
 * @i:          resolution index to set
 *
 * This function will program the appropriate resolution based on the index
 * provided when user space will set samp_freq channel.
 * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
 *
 * Return: 0 on success, negative errno otherwise.
 */
ssize_t ms_sensors_write_resolution(struct ms_ht_dev *dev_data,
                                    u8 i)
{
        u8 config_reg;
        int ret;

        ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
        if (ret)
                return ret;

        config_reg &= 0x7E;
        config_reg |= ((i & 1) << 7) + ((i & 2) >> 1);

        return i2c_smbus_write_byte_data(dev_data->client,
                                         MS_SENSORS_CONFIG_REG_WRITE,
                                         config_reg);
}
EXPORT_SYMBOL(ms_sensors_write_resolution);

/**
 * ms_sensors_show_battery_low() - Show device battery low indicator
 * @dev_data:   pointer to temperature/humidity device data
 * @buf:        pointer to char buffer to write result
 *
 * This function will read battery indicator value in the device and
 * return 1 if the device voltage is below 2.25V.
 * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
 *
 * Return: length of sprintf on success, negative errno otherwise.
 */
ssize_t ms_sensors_show_battery_low(struct ms_ht_dev *dev_data,
                                    char *buf)
{
        int ret;
        u8 config_reg;

        mutex_lock(&dev_data->lock);
        ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
        mutex_unlock(&dev_data->lock);
        if (ret)
                return ret;

        return sprintf(buf, "%d\n", (config_reg & 0x40) >> 6);
}
EXPORT_SYMBOL(ms_sensors_show_battery_low);

/**
 * ms_sensors_show_heater() - Show device heater
 * @dev_data:   pointer to temperature/humidity device data
 * @buf:        pointer to char buffer to write result
 *
 * This function will read heater enable value in the device and
 * return 1 if the heater is enabled.
 * This function is used for HTU21 and MS8607 chipsets.
 *
 * Return: length of sprintf on success, negative errno otherwise.
 */
ssize_t ms_sensors_show_heater(struct ms_ht_dev *dev_data,
                               char *buf)
{
        u8 config_reg;
        int ret;

        mutex_lock(&dev_data->lock);
        ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
        mutex_unlock(&dev_data->lock);
        if (ret)
                return ret;

        return sprintf(buf, "%d\n", (config_reg & 0x4) >> 2);
}
EXPORT_SYMBOL(ms_sensors_show_heater);

/**
 * ms_sensors_write_heater() - Write device heater
 * @dev_data:   pointer to temperature/humidity device data
 * @buf:        pointer to char buffer from user space
 * @len:        length of buf
 *
 * This function will write 1 or 0 value in the device
 * to enable or disable heater.
 * This function is used for HTU21 and MS8607 chipsets.
 *
 * Return: length of buffer, negative errno otherwise.
 */
ssize_t ms_sensors_write_heater(struct ms_ht_dev *dev_data,
                                const char *buf, size_t len)
{
        u8 val, config_reg;
        int ret;

        ret = kstrtou8(buf, 10, &val);
        if (ret)
                return ret;

        if (val > 1)
                return -EINVAL;

        mutex_lock(&dev_data->lock);
        ret = ms_sensors_read_config_reg(dev_data->client, &config_reg);
        if (ret) {
                mutex_unlock(&dev_data->lock);
                return ret;
        }

        config_reg &= 0xFB;
        config_reg |= val << 2;

        ret = i2c_smbus_write_byte_data(dev_data->client,
                                        MS_SENSORS_CONFIG_REG_WRITE,
                                        config_reg);
        mutex_unlock(&dev_data->lock);
        if (ret) {
                dev_err(&dev_data->client->dev, "Unable to write config register\n");
                return ret;
        }

        return len;
}
EXPORT_SYMBOL(ms_sensors_write_heater);

/**
 * ms_sensors_ht_read_temperature() - Read temperature
 * @dev_data:   pointer to temperature/humidity device data
 * @temperature:pointer to temperature destination value
 *
 * This function will get temperature ADC value from the device,
 * check the CRC and compute the temperature value.
 * This function is used for TSYS02D, HTU21 and MS8607 chipsets.
 *
 * Return: 0 on success, negative errno otherwise.
 */
int ms_sensors_ht_read_temperature(struct ms_ht_dev *dev_data,
                                   s32 *temperature)
{
        int ret;
        u32 adc;
        u16 delay;

        mutex_lock(&dev_data->lock);
        delay = ms_sensors_ht_t_conversion_time[dev_data->res_index];
        ret = ms_sensors_convert_and_read(dev_data->client,
                                          MS_SENSORS_HT_T_CONVERSION_START,
                                          MS_SENSORS_NO_READ_CMD,
                                          delay, &adc);
        mutex_unlock(&dev_data->lock);
        if (ret)
                return ret;

        if (!ms_sensors_crc_valid(adc)) {
                dev_err(&dev_data->client->dev,
                        "Temperature read crc check error\n");
                return -ENODEV;
        }

        /* Temperature algorithm */
        *temperature = (((s64)(adc >> 8) * 175720) >> 16) - 46850;

        return 0;
}
EXPORT_SYMBOL(ms_sensors_ht_read_temperature);

/**
 * ms_sensors_ht_read_humidity() - Read humidity
 * @dev_data:   pointer to temperature/humidity device data
 * @humidity:   pointer to humidity destination value
 *
 * This function will get humidity ADC value from the device,
 * check the CRC and compute the temperature value.
 * This function is used for HTU21 and MS8607 chipsets.
 *
 * Return: 0 on success, negative errno otherwise.
 */
int ms_sensors_ht_read_humidity(struct ms_ht_dev *dev_data,
                                u32 *humidity)
{
        int ret;
        u32 adc;
        u16 delay;

        mutex_lock(&dev_data->lock);
        delay = ms_sensors_ht_h_conversion_time[dev_data->res_index];
        ret = ms_sensors_convert_and_read(dev_data->client,
                                          MS_SENSORS_HT_H_CONVERSION_START,
                                          MS_SENSORS_NO_READ_CMD,
                                          delay, &adc);
        mutex_unlock(&dev_data->lock);
        if (ret)
                return ret;

        if (!ms_sensors_crc_valid(adc)) {
                dev_err(&dev_data->client->dev,
                        "Humidity read crc check error\n");
                return -ENODEV;
        }

        /* Humidity algorithm */
        *humidity = (((s32)(adc >> 8) * 12500) >> 16) * 10 - 6000;
        if (*humidity >= 100000)
                *humidity = 100000;

        return 0;
}
EXPORT_SYMBOL(ms_sensors_ht_read_humidity);

/**
 * ms_sensors_tp_crc_valid() - CRC check function for
 *     Temperature and pressure devices.
 *     This function is only used when reading PROM coefficients
 *
 * @prom:       pointer to PROM coefficients array
 * @len:        length of PROM coefficients array
 *
 * Return: True if CRC is ok.
 */
static bool ms_sensors_tp_crc_valid(u16 *prom, u8 len)
{
        unsigned int cnt, n_bit;
        u16 n_rem = 0x0000, crc_read = prom[0], crc = (*prom & 0xF000) >> 12;

        prom[len - 1] = 0;
        prom[0] &= 0x0FFF;      /* Clear the CRC computation part */

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

                for (n_bit = 8; n_bit > 0; n_bit--) {
                        if (n_rem & 0x8000)
                                n_rem = (n_rem << 1) ^ 0x3000;
                        else
                                n_rem <<= 1;
                }
        }
        n_rem >>= 12;
        prom[0] = crc_read;

        return n_rem == crc;
}

/**
 * ms_sensors_tp_read_prom() - prom coeff read function
 * @dev_data:   pointer to temperature/pressure device data
 *
 * This function will read prom coefficients and check CRC.
 * This function is used for MS5637 and MS8607 chipsets.
 *
 * Return: 0 on success, negative errno otherwise.
 */
int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data)
{
        int i, ret;

        for (i = 0; i < MS_SENSORS_TP_PROM_WORDS_NB; i++) {
                ret = ms_sensors_read_prom_word(
                        dev_data->client,
                        MS_SENSORS_TP_PROM_READ + (i << 1),
                        &dev_data->prom[i]);

                if (ret)
                        return ret;
        }

        if (!ms_sensors_tp_crc_valid(dev_data->prom,
                                     MS_SENSORS_TP_PROM_WORDS_NB + 1)) {
                dev_err(&dev_data->client->dev,
                        "Calibration coefficients crc check error\n");
                return -ENODEV;
        }

        return 0;
}
EXPORT_SYMBOL(ms_sensors_tp_read_prom);

/**
 * ms_sensors_read_temp_and_pressure() - read temp and pressure
 * @dev_data:   pointer to temperature/pressure device data
 * @temperature:pointer to temperature destination value
 * @pressure:   pointer to pressure destination value
 *
 * This function will read ADC and compute pressure and temperature value.
 * This function is used for MS5637 and MS8607 chipsets.
 *
 * Return: 0 on success, negative errno otherwise.
 */
int ms_sensors_read_temp_and_pressure(struct ms_tp_dev *dev_data,
                                      int *temperature,
                                      unsigned int *pressure)
{
        int ret;
        u32 t_adc, p_adc;
        s32 dt, temp;
        s64 off, sens, t2, off2, sens2;
        u16 *prom = dev_data->prom, delay;

        mutex_lock(&dev_data->lock);
        delay = ms_sensors_tp_conversion_time[dev_data->res_index];

        ret = ms_sensors_convert_and_read(
                                        dev_data->client,
                                        MS_SENSORS_TP_T_CONVERSION_START +
                                                dev_data->res_index * 2,
                                        MS_SENSORS_TP_ADC_READ,
                                        delay, &t_adc);
        if (ret) {
                mutex_unlock(&dev_data->lock);
                return ret;
        }

        ret = ms_sensors_convert_and_read(
                                        dev_data->client,
                                        MS_SENSORS_TP_P_CONVERSION_START +
                                                dev_data->res_index * 2,
                                        MS_SENSORS_TP_ADC_READ,
                                        delay, &p_adc);
        mutex_unlock(&dev_data->lock);
        if (ret)
                return ret;

        dt = (s32)t_adc - (prom[5] << 8);

        /* Actual temperature = 2000 + dT * TEMPSENS */
        temp = 2000 + (((s64)dt * prom[6]) >> 23);

        /* Second order temperature compensation */
        if (temp < 2000) {
                s64 tmp = (s64)temp - 2000;

                t2 = (3 * ((s64)dt * (s64)dt)) >> 33;
                off2 = (61 * tmp * tmp) >> 4;
                sens2 = (29 * tmp * tmp) >> 4;

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

                        off2 += 17 * tmp * tmp;
                        sens2 += 9 * tmp * tmp;
                }
        } else {
                t2 = (5 * ((s64)dt * (s64)dt)) >> 38;
                off2 = 0;
                sens2 = 0;
        }

        /* OFF = OFF_T1 + TCO * dT */
        off = (((s64)prom[2]) << 17) + ((((s64)prom[4]) * (s64)dt) >> 6);
        off -= off2;

        /* Sensitivity at actual temperature = SENS_T1 + TCS * dT */
        sens = (((s64)prom[1]) << 16) + (((s64)prom[3] * dt) >> 7);
        sens -= sens2;

        /* Temperature compensated pressure = D1 * SENS - OFF */
        *temperature = (temp - t2) * 10;
        *pressure = (u32)(((((s64)p_adc * sens) >> 21) - off) >> 15);

        return 0;
}
EXPORT_SYMBOL(ms_sensors_read_temp_and_pressure);

MODULE_DESCRIPTION("Measurement-Specialties common i2c driver");
MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
MODULE_AUTHOR("Ludovic Tancerel <ludovic.tancerel@maplehightech.com>");
MODULE_LICENSE("GPL v2");