// SPDX-License-Identifier: GPL-2.0
/*
 * Device driver for regulators in MAX5970 and MAX5978 IC
 *
 * Copyright (c) 2022 9elements GmbH
 *
 * Author: Patrick Rudolph <patrick.rudolph@9elements.com>
 */

#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/i2c.h>
#include <linux/regmap.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/of_regulator.h>
#include <linux/platform_device.h>

#include <linux/mfd/max5970.h>

struct max5970_regulator {
        int num_switches, mon_rng, irng, shunt_micro_ohms, lim_uA;
        struct regmap *regmap;
};

enum max597x_regulator_id {
        MAX597X_sw0,
        MAX597X_sw1,
};

static int max5970_read_adc(struct regmap *regmap, int reg, long *val)
{
        u8 reg_data[2];
        int ret;

        ret = regmap_bulk_read(regmap, reg, &reg_data[0], 2);
        if (ret < 0)
                return ret;

        *val = (reg_data[0] << 2) | (reg_data[1] & 3);

        return 0;
}

static int max5970_read(struct device *dev, enum hwmon_sensor_types type,
                        u32 attr, int channel, long *val)
{
        struct regulator_dev **rdevs = dev_get_drvdata(dev);
        struct max5970_regulator *ddata = rdev_get_drvdata(rdevs[channel]);
        struct regmap *regmap = ddata->regmap;
        int ret;

        switch (type) {
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_input:
                        ret = max5970_read_adc(regmap, MAX5970_REG_CURRENT_H(channel), val);
                        if (ret < 0)
                                return ret;
                        /*
                         * Calculate current from ADC value, IRNG range & shunt resistor value.
                         * ddata->irng holds the voltage corresponding to the maximum value the
                         * 10-bit ADC can measure.
                         * To obtain the output, multiply the ADC value by the IRNG range (in
                         * millivolts) and then divide it by the maximum value of the 10-bit ADC.
                         */
                        *val = (*val * ddata->irng) >> 10;
                        /* Convert the voltage measurement across shunt resistor to current */
                        *val = (*val * 1000) / ddata->shunt_micro_ohms;
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }

        case hwmon_in:
                switch (attr) {
                case hwmon_in_input:
                        ret = max5970_read_adc(regmap, MAX5970_REG_VOLTAGE_H(channel), val);
                        if (ret < 0)
                                return ret;
                        /*
                         * Calculate voltage from ADC value and MON range.
                         * ddata->mon_rng holds the voltage corresponding to the maximum value the
                         * 10-bit ADC can measure.
                         * To obtain the output, multiply the ADC value by the MON range (in
                         * microvolts) and then divide it by the maximum value of the 10-bit ADC.
                         */
                        *val = mul_u64_u32_shr(*val, ddata->mon_rng, 10);
                        /* uV to mV */
                        *val = *val / 1000;
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t max5970_is_visible(const void *data,
                                  enum hwmon_sensor_types type,
                                  u32 attr, int channel)
{
        struct regulator_dev **rdevs = (struct regulator_dev **)data;
        struct max5970_regulator *ddata;

        if (channel >= MAX5970_NUM_SWITCHES || !rdevs[channel])
                return 0;

        ddata = rdev_get_drvdata(rdevs[channel]);

        if (channel >= ddata->num_switches)
                return 0;

        switch (type) {
        case hwmon_in:
                switch (attr) {
                case hwmon_in_input:
                        return 0444;
                default:
                        break;
                }
                break;
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_input:
                        /* Current measurement requires knowledge of the shunt resistor value. */
                        if (ddata->shunt_micro_ohms)
                                return 0444;
                        break;
                default:
                        break;
                }
                break;
        default:
                break;
        }
        return 0;
}

static const struct hwmon_ops max5970_hwmon_ops = {
        .is_visible = max5970_is_visible,
        .read = max5970_read,
};

static const struct hwmon_channel_info *max5970_info[] = {
        HWMON_CHANNEL_INFO(in, HWMON_I_INPUT, HWMON_I_INPUT),
        HWMON_CHANNEL_INFO(curr, HWMON_C_INPUT, HWMON_C_INPUT),
        NULL
};

static const struct hwmon_chip_info max5970_chip_info = {
        .ops = &max5970_hwmon_ops,
        .info = max5970_info,
};

static int max597x_uvp_ovp_check_mode(struct regulator_dev *rdev, int severity)
{
        int ret, reg;

        /* Status1 register contains the soft strap values sampled at POR */
        ret = regmap_read(rdev->regmap, MAX5970_REG_STATUS1, &reg);
        if (ret)
                return ret;

        /* Check soft straps match requested mode */
        if (severity == REGULATOR_SEVERITY_PROT) {
                if (STATUS1_PROT(reg) != STATUS1_PROT_SHUTDOWN)
                        return -EOPNOTSUPP;

                return 0;
        }
        if (STATUS1_PROT(reg) == STATUS1_PROT_SHUTDOWN)
                return -EOPNOTSUPP;

        return 0;
}

static int max597x_set_vp(struct regulator_dev *rdev, int lim_uV, int severity,
                          bool enable, bool overvoltage)
{
        int off_h, off_l, reg, ret;
        struct max5970_regulator *data = rdev_get_drvdata(rdev);
        int channel = rdev_get_id(rdev);

        if (overvoltage) {
                if (severity == REGULATOR_SEVERITY_WARN) {
                        off_h = MAX5970_REG_CH_OV_WARN_H(channel);
                        off_l = MAX5970_REG_CH_OV_WARN_L(channel);
                } else {
                        off_h = MAX5970_REG_CH_OV_CRIT_H(channel);
                        off_l = MAX5970_REG_CH_OV_CRIT_L(channel);
                }
        } else {
                if (severity == REGULATOR_SEVERITY_WARN) {
                        off_h = MAX5970_REG_CH_UV_WARN_H(channel);
                        off_l = MAX5970_REG_CH_UV_WARN_L(channel);
                } else {
                        off_h = MAX5970_REG_CH_UV_CRIT_H(channel);
                        off_l = MAX5970_REG_CH_UV_CRIT_L(channel);
                }
        }

        if (enable)
                /* reg = ADC_MASK * (lim_uV / 1000000) / (data->mon_rng / 1000000) */
                reg = ADC_MASK * lim_uV / data->mon_rng;
        else
                reg = 0;

        ret = regmap_write(rdev->regmap, off_h, MAX5970_VAL2REG_H(reg));
        if (ret)
                return ret;

        ret = regmap_write(rdev->regmap, off_l, MAX5970_VAL2REG_L(reg));
        if (ret)
                return ret;

        return 0;
}

static int max597x_set_uvp(struct regulator_dev *rdev, int lim_uV, int severity,
                           bool enable)
{
        int ret;

        /*
         * MAX5970 has enable control as a special value in limit reg. Can't
         * set limit but keep feature disabled or enable W/O given limit.
         */
        if ((lim_uV && !enable) || (!lim_uV && enable))
                return -EINVAL;

        ret = max597x_uvp_ovp_check_mode(rdev, severity);
        if (ret)
                return ret;

        return max597x_set_vp(rdev, lim_uV, severity, enable, false);
}

static int max597x_set_ovp(struct regulator_dev *rdev, int lim_uV, int severity,
                           bool enable)
{
        int ret;

        /*
         * MAX5970 has enable control as a special value in limit reg. Can't
         * set limit but keep feature disabled or enable W/O given limit.
         */
        if ((lim_uV && !enable) || (!lim_uV && enable))
                return -EINVAL;

        ret = max597x_uvp_ovp_check_mode(rdev, severity);
        if (ret)
                return ret;

        return max597x_set_vp(rdev, lim_uV, severity, enable, true);
}

static int max597x_set_ocp(struct regulator_dev *rdev, int lim_uA,
                           int severity, bool enable)
{
        int val, reg;
        unsigned int vthst, vthfst;

        struct max5970_regulator *data = rdev_get_drvdata(rdev);
        int rdev_id = rdev_get_id(rdev);
        /*
         * MAX5970 doesn't has enable control for ocp.
         * If limit is specified but enable is not set then hold the value in
         * variable & later use it when ocp needs to be enabled.
         */
        if (lim_uA != 0 && lim_uA != data->lim_uA)
                data->lim_uA = lim_uA;

        if (severity != REGULATOR_SEVERITY_PROT)
                return -EINVAL;

        if (enable) {

                /* Calc Vtrip threshold in uV. */
                vthst =
                    div_u64(mul_u32_u32(data->shunt_micro_ohms, data->lim_uA),
                            1000000);

                /*
                 * As recommended in datasheed, add 20% margin to avoid
                 * spurious event & passive component tolerance.
                 */
                vthst = div_u64(mul_u32_u32(vthst, 120), 100);

                /* Calc fast Vtrip threshold in uV */
                vthfst = vthst * (MAX5970_FAST2SLOW_RATIO / 100);

                if (vthfst > data->irng) {
                        dev_err(&rdev->dev, "Current limit out of range\n");
                        return -EINVAL;
                }
                /* Fast trip threshold to be programmed */
                val = div_u64(mul_u32_u32(0xFF, vthfst), data->irng);
        } else
                /*
                 * Since there is no option to disable ocp, set limit to max
                 * value
                 */
                val = 0xFF;

        reg = MAX5970_REG_DAC_FAST(rdev_id);

        return regmap_write(rdev->regmap, reg, val);
}

static int max597x_get_status(struct regulator_dev *rdev)
{
        int val, ret;

        ret = regmap_read(rdev->regmap, MAX5970_REG_STATUS3, &val);
        if (ret)
                return ret;

        if (val & MAX5970_STATUS3_ALERT)
                return REGULATOR_STATUS_ERROR;

        ret = regulator_is_enabled_regmap(rdev);
        if (ret < 0)
                return ret;

        if (ret)
                return REGULATOR_STATUS_ON;

        return REGULATOR_STATUS_OFF;
}

static const struct regulator_ops max597x_switch_ops = {
        .enable = regulator_enable_regmap,
        .disable = regulator_disable_regmap,
        .is_enabled = regulator_is_enabled_regmap,
        .get_status = max597x_get_status,
        .set_over_voltage_protection = max597x_set_ovp,
        .set_under_voltage_protection = max597x_set_uvp,
        .set_over_current_protection = max597x_set_ocp,
};

static int max597x_dt_parse(struct device_node *np,
                            const struct regulator_desc *desc,
                            struct regulator_config *cfg)
{
        struct max5970_regulator *data = cfg->driver_data;
        int ret = 0;

        ret =
            of_property_read_u32(np, "shunt-resistor-micro-ohms",
                                 &data->shunt_micro_ohms);
        if (ret < 0)
                dev_err(cfg->dev,
                        "property 'shunt-resistor-micro-ohms' not found, err %d\n",
                        ret);
        return ret;

}

#define MAX597X_SWITCH(_ID, _ereg, _chan, _supply) {     \
        .name            = #_ID,                         \
        .of_match        = of_match_ptr(#_ID),           \
        .ops             = &max597x_switch_ops,          \
        .regulators_node = of_match_ptr("regulators"),   \
        .type            = REGULATOR_VOLTAGE,            \
        .id              = MAX597X_##_ID,                \
        .owner           = THIS_MODULE,                  \
        .supply_name     = _supply,                      \
        .enable_reg      = _ereg,                        \
        .enable_mask     = CHXEN((_chan)),               \
        .of_parse_cb     = max597x_dt_parse,             \
}

static const struct regulator_desc regulators[] = {
        MAX597X_SWITCH(sw0, MAX5970_REG_CHXEN, 0, "vss1"),
        MAX597X_SWITCH(sw1, MAX5970_REG_CHXEN, 1, "vss2"),
};

static int max597x_regmap_read_clear(struct regmap *map, unsigned int reg,
                                     unsigned int *val)
{
        int ret;

        ret = regmap_read(map, reg, val);
        if (ret)
                return ret;

        if (*val)
                return regmap_write(map, reg, 0);

        return 0;
}

static int max597x_irq_handler(int irq, struct regulator_irq_data *rid,
                               unsigned long *dev_mask)
{
        struct regulator_err_state *stat;
        struct max5970_regulator *d = (struct max5970_regulator *)rid->data;
        int val, ret, i;

        ret = max597x_regmap_read_clear(d->regmap, MAX5970_REG_FAULT0, &val);
        if (ret)
                return REGULATOR_FAILED_RETRY;

        *dev_mask = 0;
        for (i = 0; i < d->num_switches; i++) {
                stat = &rid->states[i];
                stat->notifs = 0;
                stat->errors = 0;
        }

        for (i = 0; i < d->num_switches; i++) {
                stat = &rid->states[i];

                if (val & UV_STATUS_CRIT(i)) {
                        *dev_mask |= 1 << i;
                        stat->notifs |= REGULATOR_EVENT_UNDER_VOLTAGE;
                        stat->errors |= REGULATOR_ERROR_UNDER_VOLTAGE;
                } else if (val & UV_STATUS_WARN(i)) {
                        *dev_mask |= 1 << i;
                        stat->notifs |= REGULATOR_EVENT_UNDER_VOLTAGE_WARN;
                        stat->errors |= REGULATOR_ERROR_UNDER_VOLTAGE_WARN;
                }
        }

        ret = max597x_regmap_read_clear(d->regmap, MAX5970_REG_FAULT1, &val);
        if (ret)
                return REGULATOR_FAILED_RETRY;

        for (i = 0; i < d->num_switches; i++) {
                stat = &rid->states[i];

                if (val & OV_STATUS_CRIT(i)) {
                        *dev_mask |= 1 << i;
                        stat->notifs |= REGULATOR_EVENT_REGULATION_OUT;
                        stat->errors |= REGULATOR_ERROR_REGULATION_OUT;
                } else if (val & OV_STATUS_WARN(i)) {
                        *dev_mask |= 1 << i;
                        stat->notifs |= REGULATOR_EVENT_OVER_VOLTAGE_WARN;
                        stat->errors |= REGULATOR_ERROR_OVER_VOLTAGE_WARN;
                }
        }

        ret = max597x_regmap_read_clear(d->regmap, MAX5970_REG_FAULT2, &val);
        if (ret)
                return REGULATOR_FAILED_RETRY;

        for (i = 0; i < d->num_switches; i++) {
                stat = &rid->states[i];

                if (val & OC_STATUS_WARN(i)) {
                        *dev_mask |= 1 << i;
                        stat->notifs |= REGULATOR_EVENT_OVER_CURRENT_WARN;
                        stat->errors |= REGULATOR_ERROR_OVER_CURRENT_WARN;
                }
        }

        ret = regmap_read(d->regmap, MAX5970_REG_STATUS0, &val);
        if (ret)
                return REGULATOR_FAILED_RETRY;

        for (i = 0; i < d->num_switches; i++) {
                stat = &rid->states[i];

                if ((val & MAX5970_CB_IFAULTF(i))
                    || (val & MAX5970_CB_IFAULTS(i))) {
                        *dev_mask |= 1 << i;
                        stat->notifs |=
                            REGULATOR_EVENT_OVER_CURRENT |
                            REGULATOR_EVENT_DISABLE;
                        stat->errors |=
                            REGULATOR_ERROR_OVER_CURRENT | REGULATOR_ERROR_FAIL;

                        /* Clear the sub-IRQ status */
                        regulator_disable_regmap(stat->rdev);
                }
        }
        return 0;
}

static int max597x_adc_range(struct regmap *regmap, const int ch,
                             int *irng, int *mon_rng)
{
        unsigned int reg;
        int ret;

        /* Decode current ADC range */
        ret = regmap_read(regmap, MAX5970_REG_STATUS2, &reg);
        if (ret)
                return ret;
        switch (MAX5970_IRNG(reg, ch)) {
        case 0:
                *irng = 100000; /* 100 mV */
                break;
        case 1:
                *irng = 50000;  /* 50 mV */
                break;
        case 2:
                *irng = 25000;  /* 25 mV */
                break;
        default:
                return -EINVAL;
        }

        /* Decode current voltage monitor range */
        ret = regmap_read(regmap, MAX5970_REG_MON_RANGE, &reg);
        if (ret)
                return ret;

        *mon_rng = MAX5970_MON_MAX_RANGE_UV >> MAX5970_MON(reg, ch);

        return 0;
}

static int max597x_setup_irq(struct device *dev,
                             int irq,
                             struct regulator_dev *rdevs[MAX5970_NUM_SWITCHES],
                             int num_switches, struct max5970_regulator *data)
{
        struct regulator_irq_desc max597x_notif = {
                .name = "max597x-irq",
                .map_event = max597x_irq_handler,
                .data = data,
        };
        int errs = REGULATOR_ERROR_UNDER_VOLTAGE |
            REGULATOR_ERROR_UNDER_VOLTAGE_WARN |
            REGULATOR_ERROR_OVER_VOLTAGE_WARN |
            REGULATOR_ERROR_REGULATION_OUT |
            REGULATOR_ERROR_OVER_CURRENT |
            REGULATOR_ERROR_OVER_CURRENT_WARN | REGULATOR_ERROR_FAIL;
        void *irq_helper;

        /* Register notifiers - can fail if IRQ is not given */
        irq_helper = devm_regulator_irq_helper(dev, &max597x_notif,
                                               irq, 0, errs, NULL,
                                               &rdevs[0], num_switches);
        if (IS_ERR(irq_helper)) {
                if (PTR_ERR(irq_helper) == -EPROBE_DEFER)
                        return -EPROBE_DEFER;

                dev_warn(dev, "IRQ disabled %pe\n", irq_helper);
        }

        return 0;
}

static int max597x_regulator_probe(struct platform_device *pdev)
{
        struct regmap *regmap = dev_get_regmap(pdev->dev.parent, NULL);
        struct max5970_regulator *data;
        struct i2c_client *i2c = to_i2c_client(pdev->dev.parent);
        struct regulator_config config = { };
        struct regulator_dev *rdev;
        struct regulator_dev **rdevs = NULL;
        struct device *hwmon_dev;
        int num_switches;
        int ret, i;

        if (!regmap)
                return -EPROBE_DEFER;

        rdevs = devm_kcalloc(&i2c->dev, MAX5970_NUM_SWITCHES, sizeof(struct regulator_dev *),
                             GFP_KERNEL);
        if (!rdevs)
                return -ENOMEM;

        if (of_device_is_compatible(i2c->dev.of_node, "maxim,max5978"))
                num_switches = MAX5978_NUM_SWITCHES;
        else if (of_device_is_compatible(i2c->dev.of_node, "maxim,max5970"))
                num_switches = MAX5970_NUM_SWITCHES;
        else
                return -ENODEV;

        for (i = 0; i < num_switches; i++) {
                data =
                    devm_kzalloc(&i2c->dev, sizeof(struct max5970_regulator),
                                 GFP_KERNEL);
                if (!data)
                        return -ENOMEM;

                data->num_switches = num_switches;
                data->regmap = regmap;

                ret = max597x_adc_range(regmap, i, &data->irng, &data->mon_rng);
                if (ret < 0)
                        return ret;

                config.dev = &i2c->dev;
                config.driver_data = (void *)data;
                config.regmap = data->regmap;
                rdev = devm_regulator_register(&i2c->dev,
                                               &regulators[i], &config);
                if (IS_ERR(rdev)) {
                        dev_err(&i2c->dev, "failed to register regulator %s\n",
                                regulators[i].name);
                        return PTR_ERR(rdev);
                }
                rdevs[i] = rdev;
        }

        if (IS_REACHABLE(CONFIG_HWMON)) {
                hwmon_dev = devm_hwmon_device_register_with_info(&i2c->dev, "max5970", rdevs,
                                                                 &max5970_chip_info, NULL);
                if (IS_ERR(hwmon_dev)) {
                        return dev_err_probe(&i2c->dev, PTR_ERR(hwmon_dev),
                                             "Unable to register hwmon device\n");
                }
        }

        if (i2c->irq) {
                ret =
                    max597x_setup_irq(&i2c->dev, i2c->irq, rdevs, num_switches,
                                      data);
                if (ret) {
                        dev_err(&i2c->dev, "IRQ setup failed");
                        return ret;
                }
        }

        return ret;
}

static struct platform_driver max597x_regulator_driver = {
        .driver = {
                .name = "max5970-regulator",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
        },
        .probe = max597x_regulator_probe,
};

module_platform_driver(max597x_regulator_driver);


MODULE_AUTHOR("Patrick Rudolph <patrick.rudolph@9elements.com>");
MODULE_DESCRIPTION("MAX5970_hot-swap controller driver");
MODULE_LICENSE("GPL v2");