// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
//
// Copyright (c) 2018 Mellanox Technologies. All rights reserved.
// Copyright (c) 2018 Vadim Pasternak <vadimp@mellanox.com>

#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/platform_data/mlxreg.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/thermal.h>

#define MLXREG_FAN_MAX_TACHO            24
#define MLXREG_FAN_MAX_PWM              4
#define MLXREG_FAN_PWM_NOT_CONNECTED    0xff
#define MLXREG_FAN_MAX_STATE            10
#define MLXREG_FAN_MIN_DUTY             51      /* 20% */
#define MLXREG_FAN_MAX_DUTY             255     /* 100% */
#define MLXREG_FAN_SPEED_MIN_LEVEL              2       /* 20 percent */
#define MLXREG_FAN_TACHO_SAMPLES_PER_PULSE_DEF  44
#define MLXREG_FAN_TACHO_DIV_MIN                283
#define MLXREG_FAN_TACHO_DIV_DEF                (MLXREG_FAN_TACHO_DIV_MIN * 4)
#define MLXREG_FAN_TACHO_DIV_SCALE_MAX  64
/*
 * FAN datasheet defines the formula for RPM calculations as RPM = 15/t-high.
 * The logic in a programmable device measures the time t-high by sampling the
 * tachometer every t-sample (with the default value 11.32 uS) and increment
 * a counter (N) as long as the pulse has not change:
 * RPM = 15 / (t-sample * (K + Regval)), where:
 * Regval: is the value read from the programmable device register;
 *  - 0xff - represents tachometer fault;
 *  - 0xfe - represents tachometer minimum value , which is 4444 RPM;
 *  - 0x00 - represents tachometer maximum value , which is 300000 RPM;
 * K: is 44 and it represents the minimum allowed samples per pulse;
 * N: is equal K + Regval;
 * In order to calculate RPM from the register value the following formula is
 * used: RPM = 15 / ((Regval + K) * 11.32) * 10^(-6)), which in  the
 * default case is modified to:
 * RPM = 15000000 * 100 / ((Regval + 44) * 1132);
 * - for Regval 0x00, RPM will be 15000000 * 100 / (44 * 1132) = 30115;
 * - for Regval 0xfe, RPM will be 15000000 * 100 / ((254 + 44) * 1132) = 4446;
 * In common case the formula is modified to:
 * RPM = 15000000 * 100 / ((Regval + samples) * divider).
 */
#define MLXREG_FAN_GET_RPM(rval, d, s)  (DIV_ROUND_CLOSEST(15000000 * 100, \
                                         ((rval) + (s)) * (d)))
#define MLXREG_FAN_GET_FAULT(val, mask) ((val) == (mask))
#define MLXREG_FAN_PWM_DUTY2STATE(duty) (DIV_ROUND_CLOSEST((duty) *     \
                                         MLXREG_FAN_MAX_STATE,          \
                                         MLXREG_FAN_MAX_DUTY))
#define MLXREG_FAN_PWM_STATE2DUTY(stat) (DIV_ROUND_CLOSEST((stat) *     \
                                         MLXREG_FAN_MAX_DUTY,           \
                                         MLXREG_FAN_MAX_STATE))

struct mlxreg_fan;

/*
 * struct mlxreg_fan_tacho - tachometer data (internal use):
 *
 * @connected: indicates if tachometer is connected;
 * @reg: register offset;
 * @mask: fault mask;
 * @prsnt: present register offset;
 * @shift: tacho presence bit shift;
 */
struct mlxreg_fan_tacho {
        bool connected;
        u32 reg;
        u32 mask;
        u32 prsnt;
        u32 shift;
};

/*
 * struct mlxreg_fan_pwm - PWM data (internal use):
 *
 * @fan: private data;
 * @connected: indicates if PWM is connected;
 * @reg: register offset;
 * @cooling: cooling device levels;
 * @last_hwmon_state: last cooling state set by hwmon subsystem;
 * @last_thermal_state: last cooling state set by thermal subsystem;
 * @cdev: cooling device;
 */
struct mlxreg_fan_pwm {
        struct mlxreg_fan *fan;
        bool connected;
        u32 reg;
        unsigned long last_hwmon_state;
        unsigned long last_thermal_state;
        struct thermal_cooling_device *cdev;
};

/*
 * struct mlxreg_fan - private data (internal use):
 *
 * @dev: basic device;
 * @regmap: register map of parent device;
 * @tacho: tachometer data;
 * @pwm: PWM data;
 * @tachos_per_drwr - number of tachometers per drawer;
 * @samples: minimum allowed samples per pulse;
 * @divider: divider value for tachometer RPM calculation;
 */
struct mlxreg_fan {
        struct device *dev;
        void *regmap;
        struct mlxreg_core_platform_data *pdata;
        struct mlxreg_fan_tacho tacho[MLXREG_FAN_MAX_TACHO];
        struct mlxreg_fan_pwm pwm[MLXREG_FAN_MAX_PWM];
        int tachos_per_drwr;
        int samples;
        int divider;
};

static int _mlxreg_fan_set_cur_state(struct thermal_cooling_device *cdev,
                                     unsigned long state, bool thermal);

static int
mlxreg_fan_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
                int channel, long *val)
{
        struct mlxreg_fan *fan = dev_get_drvdata(dev);
        struct mlxreg_fan_tacho *tacho;
        struct mlxreg_fan_pwm *pwm;
        u32 regval;
        int err;

        switch (type) {
        case hwmon_fan:
                tacho = &fan->tacho[channel];
                switch (attr) {
                case hwmon_fan_input:
                        /*
                         * Check FAN presence: FAN related bit in presence register is one,
                         * if FAN is physically connected, zero - otherwise.
                         */
                        if (tacho->prsnt && fan->tachos_per_drwr) {
                                err = regmap_read(fan->regmap, tacho->prsnt, &regval);
                                if (err)
                                        return err;

                                /*
                                 * Map channel to presence bit - drawer can be equipped with
                                 * one or few FANs, while presence is indicated per drawer.
                                 * Shift channel value if necessary to align with register value.
                                 */
                                if (BIT(rol32(channel, tacho->shift) / fan->tachos_per_drwr) &
                                        regval) {
                                        /* FAN is not connected - return zero for FAN speed. */
                                        *val = 0;
                                        return 0;
                                }
                        }

                        err = regmap_read(fan->regmap, tacho->reg, &regval);
                        if (err)
                                return err;

                        if (MLXREG_FAN_GET_FAULT(regval, tacho->mask)) {
                                /* FAN is broken - return zero for FAN speed. */
                                *val = 0;
                                return 0;
                        }

                        *val = MLXREG_FAN_GET_RPM(regval, fan->divider,
                                                  fan->samples);
                        break;

                case hwmon_fan_fault:
                        err = regmap_read(fan->regmap, tacho->reg, &regval);
                        if (err)
                                return err;

                        *val = MLXREG_FAN_GET_FAULT(regval, tacho->mask);
                        break;

                default:
                        return -EOPNOTSUPP;
                }
                break;

        case hwmon_pwm:
                pwm = &fan->pwm[channel];
                switch (attr) {
                case hwmon_pwm_input:
                        err = regmap_read(fan->regmap, pwm->reg, &regval);
                        if (err)
                                return err;

                        *val = regval;
                        break;

                default:
                        return -EOPNOTSUPP;
                }
                break;

        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int
mlxreg_fan_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
                 int channel, long val)
{
        struct mlxreg_fan *fan = dev_get_drvdata(dev);
        struct mlxreg_fan_pwm *pwm;

        switch (type) {
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        if (val < MLXREG_FAN_MIN_DUTY ||
                            val > MLXREG_FAN_MAX_DUTY)
                                return -EINVAL;
                        pwm = &fan->pwm[channel];
                        /* If thermal is configured - handle PWM limit setting. */
                        if (IS_REACHABLE(CONFIG_THERMAL)) {
                                pwm->last_hwmon_state = MLXREG_FAN_PWM_DUTY2STATE(val);
                                /*
                                 * Update PWM only in case requested state is not less than the
                                 * last thermal state.
                                 */
                                if (pwm->last_hwmon_state >= pwm->last_thermal_state)
                                        return _mlxreg_fan_set_cur_state(pwm->cdev,
                                                                         pwm->last_hwmon_state,
                                                                         false);
                                return 0;
                        }
                        return regmap_write(fan->regmap, pwm->reg, val);
                default:
                        return -EOPNOTSUPP;
                }
                break;

        default:
                return -EOPNOTSUPP;
        }

        return -EOPNOTSUPP;
}

static umode_t
mlxreg_fan_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
                      int channel)
{
        switch (type) {
        case hwmon_fan:
                if (!(((struct mlxreg_fan *)data)->tacho[channel].connected))
                        return 0;

                switch (attr) {
                case hwmon_fan_input:
                case hwmon_fan_fault:
                        return 0444;
                default:
                        break;
                }
                break;

        case hwmon_pwm:
                if (!(((struct mlxreg_fan *)data)->pwm[channel].connected))
                        return 0;

                switch (attr) {
                case hwmon_pwm_input:
                        return 0644;
                default:
                        break;
                }
                break;

        default:
                break;
        }

        return 0;
}

static char *mlxreg_fan_name[] = {
        "mlxreg_fan",
        "mlxreg_fan1",
        "mlxreg_fan2",
        "mlxreg_fan3",
};

static const struct hwmon_channel_info * const mlxreg_fan_hwmon_info[] = {
        HWMON_CHANNEL_INFO(fan,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_FAULT),
        HWMON_CHANNEL_INFO(pwm,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT),
        NULL
};

static const struct hwmon_ops mlxreg_fan_hwmon_hwmon_ops = {
        .is_visible = mlxreg_fan_is_visible,
        .read = mlxreg_fan_read,
        .write = mlxreg_fan_write,
};

static const struct hwmon_chip_info mlxreg_fan_hwmon_chip_info = {
        .ops = &mlxreg_fan_hwmon_hwmon_ops,
        .info = mlxreg_fan_hwmon_info,
};

static int mlxreg_fan_get_max_state(struct thermal_cooling_device *cdev,
                                    unsigned long *state)
{
        *state = MLXREG_FAN_MAX_STATE;
        return 0;
}

static int mlxreg_fan_get_cur_state(struct thermal_cooling_device *cdev,
                                    unsigned long *state)

{
        struct mlxreg_fan_pwm *pwm = cdev->devdata;
        struct mlxreg_fan *fan = pwm->fan;
        u32 regval;
        int err;

        err = regmap_read(fan->regmap, pwm->reg, &regval);
        if (err) {
                dev_err(fan->dev, "Failed to query PWM duty\n");
                return err;
        }

        *state = MLXREG_FAN_PWM_DUTY2STATE(regval);

        return 0;
}

static int _mlxreg_fan_set_cur_state(struct thermal_cooling_device *cdev,
                                     unsigned long state, bool thermal)
{
        struct mlxreg_fan_pwm *pwm = cdev->devdata;
        struct mlxreg_fan *fan = pwm->fan;
        int err;

        if (state > MLXREG_FAN_MAX_STATE)
                return -EINVAL;

        /* Save thermal state. */
        if (thermal)
                pwm->last_thermal_state = state;

        state = max_t(unsigned long, state, pwm->last_hwmon_state);
        err = regmap_write(fan->regmap, pwm->reg,
                           MLXREG_FAN_PWM_STATE2DUTY(state));
        if (err) {
                dev_err(fan->dev, "Failed to write PWM duty\n");
                return err;
        }
        return 0;
}

static int mlxreg_fan_set_cur_state(struct thermal_cooling_device *cdev,
                                    unsigned long state)

{
        return _mlxreg_fan_set_cur_state(cdev, state, true);
}

static const struct thermal_cooling_device_ops mlxreg_fan_cooling_ops = {
        .get_max_state  = mlxreg_fan_get_max_state,
        .get_cur_state  = mlxreg_fan_get_cur_state,
        .set_cur_state  = mlxreg_fan_set_cur_state,
};

static int mlxreg_fan_connect_verify(struct mlxreg_fan *fan,
                                     struct mlxreg_core_data *data)
{
        u32 regval;
        int err;

        err = regmap_read(fan->regmap, data->capability, &regval);
        if (err) {
                dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
                        data->capability);
                return err;
        }

        return data->slot ? (data->slot <= regval ? 1 : 0) : !!(regval & data->bit);
}

static int mlxreg_pwm_connect_verify(struct mlxreg_fan *fan,
                                     struct mlxreg_core_data *data)
{
        u32 regval;
        int err;

        err = regmap_read(fan->regmap, data->reg, &regval);
        if (err) {
                dev_err(fan->dev, "Failed to query pwm register 0x%08x\n",
                        data->reg);
                return err;
        }

        return regval != MLXREG_FAN_PWM_NOT_CONNECTED;
}

static int mlxreg_fan_speed_divider_get(struct mlxreg_fan *fan,
                                        struct mlxreg_core_data *data)
{
        u32 regval;
        int err;

        err = regmap_read(fan->regmap, data->capability, &regval);
        if (err) {
                dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
                        data->capability);
                return err;
        }

        /*
         * Set divider value according to the capability register, in case it
         * contains valid value. Otherwise use default value. The purpose of
         * this validation is to protect against the old hardware, in which
         * this register can return zero.
         */
        if (regval > 0 && regval <= MLXREG_FAN_TACHO_DIV_SCALE_MAX)
                fan->divider = regval * MLXREG_FAN_TACHO_DIV_MIN;

        return 0;
}

static int mlxreg_fan_config(struct mlxreg_fan *fan,
                             struct mlxreg_core_platform_data *pdata)
{
        int tacho_num = 0, tacho_avail = 0, pwm_num = 0, i;
        struct mlxreg_core_data *data = pdata->data;
        bool configured = false;
        int err;

        fan->samples = MLXREG_FAN_TACHO_SAMPLES_PER_PULSE_DEF;
        fan->divider = MLXREG_FAN_TACHO_DIV_DEF;
        for (i = 0; i < pdata->counter; i++, data++) {
                if (strnstr(data->label, "tacho", sizeof(data->label))) {
                        if (tacho_num == MLXREG_FAN_MAX_TACHO) {
                                dev_err(fan->dev, "too many tacho entries: %s\n",
                                        data->label);
                                return -EINVAL;
                        }

                        if (data->capability) {
                                err = mlxreg_fan_connect_verify(fan, data);
                                if (err < 0)
                                        return err;
                                else if (!err) {
                                        tacho_num++;
                                        continue;
                                }
                        }

                        fan->tacho[tacho_num].reg = data->reg;
                        fan->tacho[tacho_num].mask = data->mask;
                        fan->tacho[tacho_num].prsnt = data->reg_prsnt;
                        fan->tacho[tacho_num++].connected = true;
                        tacho_avail++;
                } else if (strnstr(data->label, "pwm", sizeof(data->label))) {
                        if (pwm_num == MLXREG_FAN_MAX_TACHO) {
                                dev_err(fan->dev, "too many pwm entries: %s\n",
                                        data->label);
                                return -EINVAL;
                        }

                        /* Validate if more then one PWM is connected. */
                        if (pwm_num) {
                                err = mlxreg_pwm_connect_verify(fan, data);
                                if (err < 0)
                                        return err;
                                else if (!err)
                                        continue;
                        }

                        fan->pwm[pwm_num].reg = data->reg;
                        fan->pwm[pwm_num].connected = true;
                        pwm_num++;
                } else if (strnstr(data->label, "conf", sizeof(data->label))) {
                        if (configured) {
                                dev_err(fan->dev, "duplicate conf entry: %s\n",
                                        data->label);
                                return -EINVAL;
                        }
                        /* Validate that conf parameters are not zeros. */
                        if (!data->mask && !data->bit && !data->capability) {
                                dev_err(fan->dev, "invalid conf entry params: %s\n",
                                        data->label);
                                return -EINVAL;
                        }
                        if (data->capability) {
                                err = mlxreg_fan_speed_divider_get(fan, data);
                                if (err)
                                        return err;
                        } else {
                                if (data->mask)
                                        fan->samples = data->mask;
                                if (data->bit)
                                        fan->divider = data->bit;
                        }
                        configured = true;
                } else {
                        dev_err(fan->dev, "invalid label: %s\n", data->label);
                        return -EINVAL;
                }
        }

        if (pdata->capability) {
                int drwr_avail;
                u32 regval;

                /* Obtain the number of FAN drawers, supported by system. */
                err = regmap_read(fan->regmap, pdata->capability, &regval);
                if (err) {
                        dev_err(fan->dev, "Failed to query capability register 0x%08x\n",
                                pdata->capability);
                        return err;
                }

                /*
                 * The number of drawers could be specified in registers by counters for newer
                 * systems, or by bitmasks for older systems. In case the data is provided by
                 * counter, it is indicated through 'version' field.
                 */
                if (pdata->version)
                        drwr_avail = regval;
                else
                        drwr_avail = hweight32(regval);
                if (!tacho_avail || !drwr_avail || tacho_avail < drwr_avail) {
                        dev_err(fan->dev, "Configuration is invalid: drawers num %d tachos num %d\n",
                                drwr_avail, tacho_avail);
                        return -EINVAL;
                }

                /* Set the number of tachometers per one drawer. */
                fan->tachos_per_drwr = tacho_avail / drwr_avail;
        }

        return 0;
}

static int mlxreg_fan_cooling_config(struct device *dev, struct mlxreg_fan *fan)
{
        int i;

        for (i = 0; i < MLXREG_FAN_MAX_PWM; i++) {
                struct mlxreg_fan_pwm *pwm = &fan->pwm[i];

                if (!pwm->connected)
                        continue;
                pwm->fan = fan;
                /* Set minimal PWM speed. */
                pwm->last_hwmon_state = MLXREG_FAN_PWM_DUTY2STATE(MLXREG_FAN_MIN_DUTY);
                pwm->cdev = devm_thermal_of_cooling_device_register(dev, NULL, mlxreg_fan_name[i],
                                                                    pwm, &mlxreg_fan_cooling_ops);
                if (IS_ERR(pwm->cdev)) {
                        dev_err(dev, "Failed to register cooling device\n");
                        return PTR_ERR(pwm->cdev);
                }
        }

        return 0;
}

static int mlxreg_fan_probe(struct platform_device *pdev)
{
        struct mlxreg_core_platform_data *pdata;
        struct device *dev = &pdev->dev;
        struct mlxreg_fan *fan;
        struct device *hwm;
        int err;

        pdata = dev_get_platdata(dev);
        if (!pdata) {
                dev_err(dev, "Failed to get platform data.\n");
                return -EINVAL;
        }

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

        fan->dev = dev;
        fan->regmap = pdata->regmap;

        err = mlxreg_fan_config(fan, pdata);
        if (err)
                return err;

        hwm = devm_hwmon_device_register_with_info(dev, "mlxreg_fan",
                                                   fan,
                                                   &mlxreg_fan_hwmon_chip_info,
                                                   NULL);
        if (IS_ERR(hwm)) {
                dev_err(dev, "Failed to register hwmon device\n");
                return PTR_ERR(hwm);
        }

        if (IS_REACHABLE(CONFIG_THERMAL))
                err = mlxreg_fan_cooling_config(dev, fan);

        return err;
}

static struct platform_driver mlxreg_fan_driver = {
        .driver = {
            .name = "mlxreg-fan",
        },
        .probe = mlxreg_fan_probe,
};

module_platform_driver(mlxreg_fan_driver);

MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
MODULE_DESCRIPTION("Mellanox FAN driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:mlxreg-fan");