// SPDX-License-Identifier: GPL-2.0
/*
 * ADM1177 Hot Swap Controller and Digital Power Monitor with Soft Start Pin
 *
 * Copyright 2015-2019 Analog Devices Inc.
 */

#include <linux/bits.h>
#include <linux/device.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/math64.h>
#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>

/*  Command Byte Operations */
#define ADM1177_CMD_V_CONT      BIT(0)
#define ADM1177_CMD_I_CONT      BIT(2)
#define ADM1177_CMD_VRANGE      BIT(4)

/* Extended Register */
#define ADM1177_REG_ALERT_TH    2

#define ADM1177_BITS            12

/**
 * struct adm1177_state - driver instance specific data
 * @client:             pointer to i2c client
 * @r_sense_uohm:       current sense resistor value
 * @alert_threshold_ua: current limit for shutdown
 * @vrange_high:        internal voltage divider
 */
struct adm1177_state {
        struct i2c_client       *client;
        u32                     r_sense_uohm;
        u64                     alert_threshold_ua;
        bool                    vrange_high;
};

static int adm1177_read_raw(struct adm1177_state *st, u8 num, u8 *data)
{
        return i2c_master_recv(st->client, data, num);
}

static int adm1177_write_cmd(struct adm1177_state *st, u8 cmd)
{
        return i2c_smbus_write_byte(st->client, cmd);
}

static int adm1177_write_alert_thr(struct adm1177_state *st,
                                   u64 alert_threshold_ua)
{
        u64 val;
        int ret;

        val = 0xFFULL * alert_threshold_ua * st->r_sense_uohm;
        val = div_u64(val, 105840000U);
        val = div_u64(val, 1000U);
        if (val > 0xFF)
                val = 0xFF;

        ret = i2c_smbus_write_byte_data(st->client, ADM1177_REG_ALERT_TH,
                                        val);
        if (ret)
                return ret;

        st->alert_threshold_ua = alert_threshold_ua;
        return 0;
}

static int adm1177_read(struct device *dev, enum hwmon_sensor_types type,
                        u32 attr, int channel, long *val)
{
        struct adm1177_state *st = dev_get_drvdata(dev);
        u8 data[3];
        long dummy;
        int ret;

        switch (type) {
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_input:
                        ret = adm1177_read_raw(st, 3, data);
                        if (ret < 0)
                                return ret;
                        dummy = (data[1] << 4) | (data[2] & 0xF);
                        /*
                         * convert to milliamperes
                         * ((105.84mV / 4096) x raw) / senseResistor(ohm)
                         */
                        *val = div_u64((105840000ull * dummy),
                                       4096 * st->r_sense_uohm);
                        return 0;
                case hwmon_curr_max:
                        *val = div_u64(st->alert_threshold_ua, 1000);
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }
        case hwmon_in:
                ret = adm1177_read_raw(st, 3, data);
                if (ret < 0)
                        return ret;
                dummy = (data[0] << 4) | (data[2] >> 4);
                /*
                 * convert to millivolts based on resistor devision
                 * (V_fullscale / 4096) * raw
                 */
                if (st->vrange_high)
                        dummy *= 26350;
                else
                        dummy *= 6650;

                *val = DIV_ROUND_CLOSEST(dummy, 4096);
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static int adm1177_write(struct device *dev, enum hwmon_sensor_types type,
                         u32 attr, int channel, long val)
{
        struct adm1177_state *st = dev_get_drvdata(dev);

        switch (type) {
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_max:
                        val = clamp_val(val, 0,
                                        div_u64(105840000ULL, st->r_sense_uohm));
                        return adm1177_write_alert_thr(st, (u64)val * 1000);
                default:
                        return -EOPNOTSUPP;
                }
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t adm1177_is_visible(const void *data,
                                  enum hwmon_sensor_types type,
                                  u32 attr, int channel)
{
        const struct adm1177_state *st = data;

        switch (type) {
        case hwmon_in:
                switch (attr) {
                case hwmon_in_input:
                        return 0444;
                }
                break;
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_input:
                        if (st->r_sense_uohm)
                                return 0444;
                        return 0;
                case hwmon_curr_max:
                        if (st->r_sense_uohm)
                                return 0644;
                        return 0;
                }
                break;
        default:
                break;
        }
        return 0;
}

static const struct hwmon_channel_info * const adm1177_info[] = {
        HWMON_CHANNEL_INFO(curr,
                           HWMON_C_INPUT | HWMON_C_MAX),
        HWMON_CHANNEL_INFO(in,
                           HWMON_I_INPUT),
        NULL
};

static const struct hwmon_ops adm1177_hwmon_ops = {
        .is_visible = adm1177_is_visible,
        .read = adm1177_read,
        .write = adm1177_write,
};

static const struct hwmon_chip_info adm1177_chip_info = {
        .ops = &adm1177_hwmon_ops,
        .info = adm1177_info,
};

static int adm1177_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct adm1177_state *st;
        u64 alert_threshold_ua;
        u32 prop;
        int ret;

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

        st->client = client;

        ret = devm_regulator_get_enable_optional(&client->dev, "vref");
        if (ret == -EPROBE_DEFER)
                return -EPROBE_DEFER;

        if (device_property_read_u32(dev, "shunt-resistor-micro-ohms",
                                     &st->r_sense_uohm))
                st->r_sense_uohm = 0;
        if (!device_property_read_u32(dev, "adi,shutdown-threshold-microamp",
                                      &prop)) {
                alert_threshold_ua = prop;
        } else if (st->r_sense_uohm) {
                /*
                 * set maximum default value from datasheet based on
                 * shunt-resistor
                 */
                alert_threshold_ua = div_u64(105840000000ULL,
                                             st->r_sense_uohm);
        } else {
                alert_threshold_ua = 0;
        }
        st->vrange_high = device_property_read_bool(dev,
                                                    "adi,vrange-high-enable");
        if (alert_threshold_ua && st->r_sense_uohm) {
                ret = adm1177_write_alert_thr(st, alert_threshold_ua);
                if (ret)
                        return ret;
        }

        ret = adm1177_write_cmd(st, ADM1177_CMD_V_CONT |
                                    ADM1177_CMD_I_CONT |
                                    (st->vrange_high ? 0 : ADM1177_CMD_VRANGE));
        if (ret)
                return ret;

        hwmon_dev =
                devm_hwmon_device_register_with_info(dev, client->name, st,
                                                     &adm1177_chip_info, NULL);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id adm1177_id[] = {
        {"adm1177"},
        {}
};
MODULE_DEVICE_TABLE(i2c, adm1177_id);

static const struct of_device_id adm1177_dt_ids[] = {
        { .compatible = "adi,adm1177" },
        {},
};
MODULE_DEVICE_TABLE(of, adm1177_dt_ids);

static struct i2c_driver adm1177_driver = {
        .driver = {
                .name = "adm1177",
                .of_match_table = adm1177_dt_ids,
        },
        .probe = adm1177_probe,
        .id_table = adm1177_id,
};
module_i2c_driver(adm1177_driver);

MODULE_AUTHOR("Beniamin Bia <beniamin.bia@analog.com>");
MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices ADM1177 ADC driver");
MODULE_LICENSE("GPL v2");