// SPDX-License-Identifier: GPL-2.0-only

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/hwmon.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/platform_device.h>
#include <linux/polynomial.h>
#include <linux/regmap.h>

/*
 * The original translation formulae of the temperature (in degrees of Celsius)
 * are as follows:
 *
 *   T = -3.4627e-11*(N^4) + 1.1023e-7*(N^3) + -1.9165e-4*(N^2) +
 *       3.0604e-1*(N^1) + -5.6197e1
 *
 * where [-56.197, 136.402]C and N = [0, 1023].
 *
 * They must be accordingly altered to be suitable for the integer arithmetics.
 * The technique is called 'factor redistribution', which just makes sure the
 * multiplications and divisions are made so to have a result of the operations
 * within the integer numbers limit. In addition we need to translate the
 * formulae to accept millidegrees of Celsius. Here what it looks like after
 * the alterations:
 *
 *   T = -34627e-12*(N^4) + 110230e-9*(N^3) + -191650e-6*(N^2) +
 *       306040e-3*(N^1) + -56197
 *
 * where T = [-56197, 136402]mC and N = [0, 1023].
 */

static const struct polynomial poly_N_to_temp = {
        .terms = {
                {4,  -34627, 1000, 1},
                {3,  110230, 1000, 1},
                {2, -191650, 1000, 1},
                {1,  306040, 1000, 1},
                {0,  -56197,    1, 1}
        }
};

#define PVT_SENSOR_CTRL         0x0 /* unused */
#define PVT_SENSOR_CFG          0x4
#define   SENSOR_CFG_CLK_CFG            GENMASK(27, 20)
#define   SENSOR_CFG_TRIM_VAL           GENMASK(13, 9)
#define   SENSOR_CFG_SAMPLE_ENA         BIT(8)
#define   SENSOR_CFG_START_CAPTURE      BIT(7)
#define   SENSOR_CFG_CONTINIOUS_MODE    BIT(6)
#define   SENSOR_CFG_PSAMPLE_ENA        GENMASK(1, 0)
#define PVT_SENSOR_STAT         0x8
#define   SENSOR_STAT_DATA_VALID        BIT(10)
#define   SENSOR_STAT_DATA              GENMASK(9, 0)

#define FAN_CFG                 0x0
#define   FAN_CFG_DUTY_CYCLE            GENMASK(23, 16)
#define   INV_POL                       BIT(3)
#define   GATE_ENA                      BIT(2)
#define   PWM_OPEN_COL_ENA              BIT(1)
#define   FAN_STAT_CFG                  BIT(0)
#define FAN_PWM_FREQ            0x4
#define   FAN_PWM_CYC_10US              GENMASK(25, 15)
#define   FAN_PWM_FREQ_FREQ             GENMASK(14, 0)
#define FAN_CNT                 0xc
#define   FAN_CNT_DATA                  GENMASK(15, 0)

#define LAN966X_PVT_CLK         1200000 /* 1.2 MHz */

struct lan966x_hwmon {
        struct regmap *regmap_pvt;
        struct regmap *regmap_fan;
        struct clk *clk;
        unsigned long clk_rate;
};

static int lan966x_hwmon_read_temp(struct device *dev, long *val)
{
        struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
        unsigned int data;
        int ret;

        ret = regmap_read(hwmon->regmap_pvt, PVT_SENSOR_STAT, &data);
        if (ret < 0)
                return ret;

        if (!(data & SENSOR_STAT_DATA_VALID))
                return -ENODATA;

        *val = polynomial_calc(&poly_N_to_temp,
                               FIELD_GET(SENSOR_STAT_DATA, data));

        return 0;
}

static int lan966x_hwmon_read_fan(struct device *dev, long *val)
{
        struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
        unsigned int data;
        int ret;

        ret = regmap_read(hwmon->regmap_fan, FAN_CNT, &data);
        if (ret < 0)
                return ret;

        /*
         * Data is given in pulses per second. Assume two pulses
         * per revolution.
         */
        *val = FIELD_GET(FAN_CNT_DATA, data) * 60 / 2;

        return 0;
}

static int lan966x_hwmon_read_pwm(struct device *dev, long *val)
{
        struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
        unsigned int data;
        int ret;

        ret = regmap_read(hwmon->regmap_fan, FAN_CFG, &data);
        if (ret < 0)
                return ret;

        *val = FIELD_GET(FAN_CFG_DUTY_CYCLE, data);

        return 0;
}

static int lan966x_hwmon_read_pwm_freq(struct device *dev, long *val)
{
        struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);
        unsigned long tmp;
        unsigned int data;
        int ret;

        ret = regmap_read(hwmon->regmap_fan, FAN_PWM_FREQ, &data);
        if (ret < 0)
                return ret;

        /*
         * Datasheet says it is sys_clk / 256 / pwm_freq. But in reality
         * it is sys_clk / 256 / (pwm_freq + 1).
         */
        data = FIELD_GET(FAN_PWM_FREQ_FREQ, data) + 1;
        tmp = DIV_ROUND_CLOSEST(hwmon->clk_rate, 256);
        *val = DIV_ROUND_CLOSEST(tmp, data);

        return 0;
}

static int lan966x_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
                              u32 attr, int channel, long *val)
{
        switch (type) {
        case hwmon_temp:
                return lan966x_hwmon_read_temp(dev, val);
        case hwmon_fan:
                return lan966x_hwmon_read_fan(dev, val);
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        return lan966x_hwmon_read_pwm(dev, val);
                case hwmon_pwm_freq:
                        return lan966x_hwmon_read_pwm_freq(dev, val);
                default:
                        return -EOPNOTSUPP;
                }
        default:
                return -EOPNOTSUPP;
        }
}

static int lan966x_hwmon_write_pwm(struct device *dev, long val)
{
        struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);

        if (val < 0 || val > 255)
                return -EINVAL;

        return regmap_update_bits(hwmon->regmap_fan, FAN_CFG,
                                  FAN_CFG_DUTY_CYCLE,
                                  FIELD_PREP(FAN_CFG_DUTY_CYCLE, val));
}

static int lan966x_hwmon_write_pwm_freq(struct device *dev, long val)
{
        struct lan966x_hwmon *hwmon = dev_get_drvdata(dev);

        if (val <= 0)
                return -EINVAL;

        val = DIV_ROUND_CLOSEST(hwmon->clk_rate, val);
        val = DIV_ROUND_CLOSEST(val, 256) - 1;
        val = clamp_val(val, 0, FAN_PWM_FREQ_FREQ);

        return regmap_update_bits(hwmon->regmap_fan, FAN_PWM_FREQ,
                                  FAN_PWM_FREQ_FREQ,
                                  FIELD_PREP(FAN_PWM_FREQ_FREQ, val));
}

static int lan966x_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
                               u32 attr, int channel, long val)
{
        switch (type) {
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        return lan966x_hwmon_write_pwm(dev, val);
                case hwmon_pwm_freq:
                        return lan966x_hwmon_write_pwm_freq(dev, val);
                default:
                        return -EOPNOTSUPP;
                }
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t lan966x_hwmon_is_visible(const void *data,
                                        enum hwmon_sensor_types type,
                                        u32 attr, int channel)
{
        umode_t mode = 0;

        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_input:
                        mode = 0444;
                        break;
                default:
                        break;
                }
                break;
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_input:
                        mode = 0444;
                        break;
                default:
                        break;
                }
                break;
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                case hwmon_pwm_freq:
                        mode = 0644;
                        break;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return mode;
}

static const struct hwmon_channel_info * const lan966x_hwmon_info[] = {
        HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
        HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
        HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_FREQ),
        NULL
};

static const struct hwmon_ops lan966x_hwmon_ops = {
        .is_visible = lan966x_hwmon_is_visible,
        .read = lan966x_hwmon_read,
        .write = lan966x_hwmon_write,
};

static const struct hwmon_chip_info lan966x_hwmon_chip_info = {
        .ops = &lan966x_hwmon_ops,
        .info = lan966x_hwmon_info,
};

static void lan966x_hwmon_disable(void *data)
{
        struct lan966x_hwmon *hwmon = data;

        regmap_update_bits(hwmon->regmap_pvt, PVT_SENSOR_CFG,
                           SENSOR_CFG_SAMPLE_ENA | SENSOR_CFG_CONTINIOUS_MODE,
                           0);
}

static int lan966x_hwmon_enable(struct device *dev,
                                struct lan966x_hwmon *hwmon)
{
        unsigned int mask = SENSOR_CFG_CLK_CFG |
                            SENSOR_CFG_SAMPLE_ENA |
                            SENSOR_CFG_START_CAPTURE |
                            SENSOR_CFG_CONTINIOUS_MODE |
                            SENSOR_CFG_PSAMPLE_ENA;
        unsigned int val;
        unsigned int div;
        int ret;

        /* enable continuous mode */
        val = SENSOR_CFG_SAMPLE_ENA | SENSOR_CFG_CONTINIOUS_MODE;

        /* set PVT clock to be between 1.15 and 1.25 MHz */
        div = DIV_ROUND_CLOSEST(hwmon->clk_rate, LAN966X_PVT_CLK);
        val |= FIELD_PREP(SENSOR_CFG_CLK_CFG, div);

        ret = regmap_update_bits(hwmon->regmap_pvt, PVT_SENSOR_CFG,
                                 mask, val);
        if (ret)
                return ret;

        return devm_add_action_or_reset(dev, lan966x_hwmon_disable, hwmon);
}

static struct regmap *lan966x_init_regmap(struct platform_device *pdev,
                                          const char *name)
{
        struct regmap_config regmap_config = {
                .reg_bits = 32,
                .reg_stride = 4,
                .val_bits = 32,
        };
        void __iomem *base;

        base = devm_platform_ioremap_resource_byname(pdev, name);
        if (IS_ERR(base))
                return ERR_CAST(base);

        regmap_config.name = name;

        return devm_regmap_init_mmio(&pdev->dev, base, &regmap_config);
}

static int lan966x_hwmon_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct lan966x_hwmon *hwmon;
        struct device *hwmon_dev;
        int ret;

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

        hwmon->clk = devm_clk_get_enabled(dev, NULL);
        if (IS_ERR(hwmon->clk))
                return dev_err_probe(dev, PTR_ERR(hwmon->clk),
                                     "failed to get clock\n");

        hwmon->clk_rate = clk_get_rate(hwmon->clk);

        hwmon->regmap_pvt = lan966x_init_regmap(pdev, "pvt");
        if (IS_ERR(hwmon->regmap_pvt))
                return dev_err_probe(dev, PTR_ERR(hwmon->regmap_pvt),
                                     "failed to get regmap for PVT registers\n");

        hwmon->regmap_fan = lan966x_init_regmap(pdev, "fan");
        if (IS_ERR(hwmon->regmap_fan))
                return dev_err_probe(dev, PTR_ERR(hwmon->regmap_fan),
                                     "failed to get regmap for fan registers\n");

        ret = lan966x_hwmon_enable(dev, hwmon);
        if (ret)
                return dev_err_probe(dev, ret, "failed to enable sensor\n");

        hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
                                "lan966x_hwmon", hwmon,
                                &lan966x_hwmon_chip_info, NULL);
        if (IS_ERR(hwmon_dev))
                return dev_err_probe(dev, PTR_ERR(hwmon_dev),
                                     "failed to register hwmon device\n");

        return 0;
}

static const struct of_device_id lan966x_hwmon_of_match[] = {
        { .compatible = "microchip,lan9668-hwmon" },
        {}
};
MODULE_DEVICE_TABLE(of, lan966x_hwmon_of_match);

static struct platform_driver lan966x_hwmon_driver = {
        .probe = lan966x_hwmon_probe,
        .driver = {
                .name = "lan966x-hwmon",
                .of_match_table = lan966x_hwmon_of_match,
        },
};
module_platform_driver(lan966x_hwmon_driver);

MODULE_DESCRIPTION("LAN966x Hardware Monitoring Driver");
MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
MODULE_LICENSE("GPL");