// SPDX-License-Identifier: GPL-2.0
/*
 * Lochnagar hardware monitoring features
 *
 * Copyright (c) 2016-2019 Cirrus Logic, Inc. and
 *                         Cirrus Logic International Semiconductor Ltd.
 *
 * Author: Lucas Tanure <tanureal@opensource.cirrus.com>
 */

#include <linux/delay.h>
#include <linux/hwmon.h>
#include <linux/math64.h>
#include <linux/mfd/lochnagar.h>
#include <linux/mfd/lochnagar2_regs.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

#define LN2_MAX_NSAMPLE 1023
#define LN2_SAMPLE_US   1670

#define LN2_CURR_UNITS  1000
#define LN2_VOLT_UNITS  1000
#define LN2_TEMP_UNITS  1000
#define LN2_PWR_UNITS   1000000

static const char * const lochnagar_chan_names[] = {
        "DBVDD1",
        "1V8 DSP",
        "1V8 CDC",
        "VDDCORE DSP",
        "AVDD 1V8",
        "SYSVDD",
        "VDDCORE CDC",
        "MICVDD",
};

struct lochnagar_hwmon {
        struct regmap *regmap;

        long power_nsamples[ARRAY_SIZE(lochnagar_chan_names)];
};

enum lochnagar_measure_mode {
        LN2_CURR = 0,
        LN2_VOLT,
        LN2_TEMP,
};

/**
 * float_to_long - Convert ieee754 reading from hardware to an integer
 *
 * @data: Value read from the hardware
 * @precision: Units to multiply up to eg. 1000 = milli, 1000000 = micro
 *
 * Return: Converted integer reading
 *
 * Depending on the measurement type the hardware returns an ieee754
 * floating point value in either volts, amps or celsius. This function
 * will convert that into an integer in a smaller unit such as micro-amps
 * or milli-celsius. The hardware does not return NaN, so consideration of
 * that is not required.
 */
static long float_to_long(u32 data, u32 precision)
{
        u64 man = data & 0x007FFFFF;
        int exp = ((data & 0x7F800000) >> 23) - 127 - 23;
        bool negative = data & 0x80000000;
        long result;

        man = (man + (1 << 23)) * precision;

        if (fls64(man) + exp > (int)sizeof(long) * 8 - 1)
                result = LONG_MAX;
        else if (exp < 0)
                result = (man + (1ull << (-exp - 1))) >> -exp;
        else
                result = man << exp;

        return negative ? -result : result;
}

static int do_measurement(struct regmap *regmap, int chan,
                          enum lochnagar_measure_mode mode, int nsamples)
{
        unsigned int val;
        int ret;

        chan = 1 << (chan + LOCHNAGAR2_IMON_MEASURED_CHANNELS_SHIFT);

        ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL1,
                           LOCHNAGAR2_IMON_ENA_MASK | chan | mode);
        if (ret < 0)
                return ret;

        ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL2, nsamples);
        if (ret < 0)
                return ret;

        ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3,
                           LOCHNAGAR2_IMON_CONFIGURE_MASK);
        if (ret < 0)
                return ret;

        ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL3, val,
                                        val & LOCHNAGAR2_IMON_DONE_MASK,
                                        1000, 10000);
        if (ret < 0)
                return ret;

        ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3,
                           LOCHNAGAR2_IMON_MEASURE_MASK);
        if (ret < 0)
                return ret;

        /*
         * Actual measurement time is ~1.67mS per sample, approximate this
         * with a 1.5mS per sample msleep and then poll for success up to
         * ~0.17mS * 1023 (LN2_MAX_NSAMPLES). Normally for smaller values
         * of nsamples the poll will complete on the first loop due to
         * other latency in the system.
         */
        msleep((nsamples * 3) / 2);

        ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL3, val,
                                        val & LOCHNAGAR2_IMON_DONE_MASK,
                                        5000, 200000);
        if (ret < 0)
                return ret;

        return regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3, 0);
}

static int request_data(struct regmap *regmap, int chan, u32 *data)
{
        unsigned int val;
        int ret;

        ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL4,
                           LOCHNAGAR2_IMON_DATA_REQ_MASK |
                           chan << LOCHNAGAR2_IMON_CH_SEL_SHIFT);
        if (ret < 0)
                return ret;

        ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL4, val,
                                        val & LOCHNAGAR2_IMON_DATA_RDY_MASK,
                                        1000, 10000);
        if (ret < 0)
                return ret;

        ret = regmap_read(regmap, LOCHNAGAR2_IMON_DATA1, &val);
        if (ret < 0)
                return ret;

        *data = val << 16;

        ret = regmap_read(regmap, LOCHNAGAR2_IMON_DATA2, &val);
        if (ret < 0)
                return ret;

        *data |= val;

        return regmap_write(regmap, LOCHNAGAR2_IMON_CTRL4, 0);
}

static int read_sensor(struct device *dev, int chan,
                       enum lochnagar_measure_mode mode, int nsamples,
                       unsigned int precision, long *val)
{
        struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
        struct regmap *regmap = priv->regmap;
        u32 data;
        int ret;

        ret = do_measurement(regmap, chan, mode, nsamples);
        if (ret < 0) {
                dev_err(dev, "Failed to perform measurement: %d\n", ret);
                return ret;
        }

        ret = request_data(regmap, chan, &data);
        if (ret < 0) {
                dev_err(dev, "Failed to read measurement: %d\n", ret);
                return ret;
        }

        *val = float_to_long(data, precision);
        return 0;
}

static int read_power(struct device *dev, int chan, long *val)
{
        struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
        int nsamples = priv->power_nsamples[chan];
        u64 power;
        int ret;

        if (!strcmp("SYSVDD", lochnagar_chan_names[chan])) {
                power = 5 * LN2_PWR_UNITS;
        } else {
                ret = read_sensor(dev, chan, LN2_VOLT, 1, LN2_PWR_UNITS, val);
                if (ret < 0)
                        return ret;

                power = abs(*val);
        }

        ret = read_sensor(dev, chan, LN2_CURR, nsamples, LN2_PWR_UNITS, val);
        if (ret < 0)
                return ret;

        power *= abs(*val);
        power = DIV_ROUND_CLOSEST_ULL(power, LN2_PWR_UNITS);

        if (power > LONG_MAX)
                *val = LONG_MAX;
        else
                *val = power;

        return 0;
}

static umode_t lochnagar_is_visible(const void *drvdata,
                                    enum hwmon_sensor_types type,
                                    u32 attr, int chan)
{
        switch (type) {
        case hwmon_in:
                if (!strcmp("SYSVDD", lochnagar_chan_names[chan]))
                        return 0;
                break;
        case hwmon_power:
                if (attr == hwmon_power_average_interval)
                        return 0644;
                break;
        default:
                break;
        }

        return 0444;
}

static int lochnagar_read(struct device *dev, enum hwmon_sensor_types type,
                          u32 attr, int chan, long *val)
{
        struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
        int interval;

        switch (type) {
        case hwmon_in:
                return read_sensor(dev, chan, LN2_VOLT, 1, LN2_VOLT_UNITS, val);
        case hwmon_curr:
                return read_sensor(dev, chan, LN2_CURR, 1, LN2_CURR_UNITS, val);
        case hwmon_temp:
                return read_sensor(dev, chan, LN2_TEMP, 1, LN2_TEMP_UNITS, val);
        case hwmon_power:
                switch (attr) {
                case hwmon_power_average:
                        return read_power(dev, chan, val);
                case hwmon_power_average_interval:
                        interval = priv->power_nsamples[chan] * LN2_SAMPLE_US;
                        *val = DIV_ROUND_CLOSEST(interval, 1000);
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }
        default:
                return -EOPNOTSUPP;
        }
}

static int lochnagar_read_string(struct device *dev,
                                 enum hwmon_sensor_types type, u32 attr,
                                 int chan, const char **str)
{
        switch (type) {
        case hwmon_in:
        case hwmon_curr:
        case hwmon_power:
                *str = lochnagar_chan_names[chan];
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static int lochnagar_write(struct device *dev, enum hwmon_sensor_types type,
                           u32 attr, int chan, long val)
{
        struct lochnagar_hwmon *priv = dev_get_drvdata(dev);

        if (type != hwmon_power || attr != hwmon_power_average_interval)
                return -EOPNOTSUPP;

        val = clamp_t(long, val, 1, (LN2_MAX_NSAMPLE * LN2_SAMPLE_US) / 1000);
        val = DIV_ROUND_CLOSEST(val * 1000, LN2_SAMPLE_US);

        priv->power_nsamples[chan] = val;

        return 0;
}

static const struct hwmon_ops lochnagar_ops = {
        .is_visible = lochnagar_is_visible,
        .read = lochnagar_read,
        .read_string = lochnagar_read_string,
        .write = lochnagar_write,
};

static const struct hwmon_channel_info * const lochnagar_info[] = {
        HWMON_CHANNEL_INFO(temp,  HWMON_T_INPUT),
        HWMON_CHANNEL_INFO(in,    HWMON_I_INPUT | HWMON_I_LABEL,
                                  HWMON_I_INPUT | HWMON_I_LABEL,
                                  HWMON_I_INPUT | HWMON_I_LABEL,
                                  HWMON_I_INPUT | HWMON_I_LABEL,
                                  HWMON_I_INPUT | HWMON_I_LABEL,
                                  HWMON_I_INPUT | HWMON_I_LABEL,
                                  HWMON_I_INPUT | HWMON_I_LABEL,
                                  HWMON_I_INPUT | HWMON_I_LABEL),
        HWMON_CHANNEL_INFO(curr,  HWMON_C_INPUT | HWMON_C_LABEL,
                                  HWMON_C_INPUT | HWMON_C_LABEL,
                                  HWMON_C_INPUT | HWMON_C_LABEL,
                                  HWMON_C_INPUT | HWMON_C_LABEL,
                                  HWMON_C_INPUT | HWMON_C_LABEL,
                                  HWMON_C_INPUT | HWMON_C_LABEL,
                                  HWMON_C_INPUT | HWMON_C_LABEL,
                                  HWMON_C_INPUT | HWMON_C_LABEL),
        HWMON_CHANNEL_INFO(power, HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
                                  HWMON_P_LABEL,
                                  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
                                  HWMON_P_LABEL,
                                  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
                                  HWMON_P_LABEL,
                                  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
                                  HWMON_P_LABEL,
                                  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
                                  HWMON_P_LABEL,
                                  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
                                  HWMON_P_LABEL,
                                  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
                                  HWMON_P_LABEL,
                                  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
                                  HWMON_P_LABEL),
        NULL
};

static const struct hwmon_chip_info lochnagar_chip_info = {
        .ops = &lochnagar_ops,
        .info = lochnagar_info,
};

static const struct of_device_id lochnagar_of_match[] = {
        { .compatible = "cirrus,lochnagar2-hwmon" },
        {}
};
MODULE_DEVICE_TABLE(of, lochnagar_of_match);

static int lochnagar_hwmon_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device *hwmon_dev;
        struct lochnagar_hwmon *priv;
        int i;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->regmap = dev_get_regmap(dev->parent, NULL);
        if (!priv->regmap) {
                dev_err(dev, "No register map found\n");
                return -EINVAL;
        }

        for (i = 0; i < ARRAY_SIZE(priv->power_nsamples); i++)
                priv->power_nsamples[i] = 96;

        hwmon_dev = devm_hwmon_device_register_with_info(dev, "Lochnagar", priv,
                                                         &lochnagar_chip_info,
                                                         NULL);

        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static struct platform_driver lochnagar_hwmon_driver = {
        .driver = {
                .name = "lochnagar-hwmon",
                .of_match_table = lochnagar_of_match,
        },
        .probe = lochnagar_hwmon_probe,
};
module_platform_driver(lochnagar_hwmon_driver);

MODULE_AUTHOR("Lucas Tanure <tanureal@opensource.cirrus.com>");
MODULE_DESCRIPTION("Lochnagar hardware monitoring features");
MODULE_LICENSE("GPL");