// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Support for the FTS Systemmonitoring Chip "Teutates"
 *
 * Copyright (C) 2016 Fujitsu Technology Solutions GmbH,
 *                Thilo Cestonaro <thilo.cestonaro@ts.fujitsu.com>
 */
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/math.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/watchdog.h>

#define FTS_DEVICE_ID_REG               0x0000
#define FTS_DEVICE_REVISION_REG         0x0001
#define FTS_DEVICE_STATUS_REG           0x0004
#define FTS_SATELLITE_STATUS_REG        0x0005
#define FTS_EVENT_STATUS_REG            0x0006
#define FTS_GLOBAL_CONTROL_REG          0x0007

#define FTS_DEVICE_DETECT_REG_1         0x0C
#define FTS_DEVICE_DETECT_REG_2         0x0D
#define FTS_DEVICE_DETECT_REG_3         0x0E

#define FTS_SENSOR_EVENT_REG            0x0010

#define FTS_FAN_EVENT_REG               0x0014
#define FTS_FAN_PRESENT_REG             0x0015

#define FTS_POWER_ON_TIME_COUNTER_A     0x007A
#define FTS_POWER_ON_TIME_COUNTER_B     0x007B
#define FTS_POWER_ON_TIME_COUNTER_C     0x007C

#define FTS_PAGE_SELECT_REG             0x007F

#define FTS_WATCHDOG_TIME_PRESET        0x000B
#define FTS_WATCHDOG_CONTROL            0x5081

#define FTS_NO_FAN_SENSORS              0x08
#define FTS_NO_TEMP_SENSORS             0x10
#define FTS_NO_VOLT_SENSORS             0x04

#define FTS_FAN_SOURCE_INVALID          0xff

static const unsigned short normal_i2c[] = { 0x73, I2C_CLIENT_END };

static const struct i2c_device_id fts_id[] = {
        { .name = "ftsteutates" },
        { }
};
MODULE_DEVICE_TABLE(i2c, fts_id);

enum WATCHDOG_RESOLUTION {
        seconds = 1,
        minutes = 60
};

struct fts_data {
        struct i2c_client *client;
        unsigned long last_updated; /* in jiffies */
        struct watchdog_device wdd;
        enum WATCHDOG_RESOLUTION resolution;
        bool valid; /* false until following fields are valid */

        u8 volt[FTS_NO_VOLT_SENSORS];

        u8 temp_input[FTS_NO_TEMP_SENSORS];
        u8 temp_alarm;

        u8 fan_present;
        u8 fan_input[FTS_NO_FAN_SENSORS]; /* in rps */
        u8 fan_source[FTS_NO_FAN_SENSORS];
        u8 fan_alarm;
};

#define FTS_REG_FAN_INPUT(idx) ((idx) + 0x20)
#define FTS_REG_FAN_SOURCE(idx) ((idx) + 0x30)
#define FTS_REG_FAN_CONTROL(idx) (((idx) << 16) + 0x4881)

#define FTS_REG_TEMP_INPUT(idx) ((idx) + 0x40)
#define FTS_REG_TEMP_CONTROL(idx) (((idx) << 16) + 0x0681)

#define FTS_REG_VOLT(idx) ((idx) + 0x18)

/*****************************************************************************/
/* I2C Helper functions                                                      */
/*****************************************************************************/
static int fts_read_byte(struct i2c_client *client, unsigned short reg)
{
        int ret;
        unsigned char page = reg >> 8;

        dev_dbg(&client->dev, "page select - page: 0x%.02x\n", page);
        ret = i2c_smbus_write_byte_data(client, FTS_PAGE_SELECT_REG, page);
        if (ret < 0)
                return ret;

        reg &= 0xFF;
        ret = i2c_smbus_read_byte_data(client, reg);
        dev_dbg(&client->dev, "read - reg: 0x%.02x: val: 0x%.02x\n", reg, ret);
        return ret;
}

static int fts_write_byte(struct i2c_client *client, unsigned short reg,
                          unsigned char value)
{
        int ret;
        unsigned char page = reg >> 8;

        dev_dbg(&client->dev, "page select - page: 0x%.02x\n", page);
        ret = i2c_smbus_write_byte_data(client, FTS_PAGE_SELECT_REG, page);
        if (ret < 0)
                return ret;

        reg &= 0xFF;
        dev_dbg(&client->dev,
                "write - reg: 0x%.02x: val: 0x%.02x\n", reg, value);
        ret = i2c_smbus_write_byte_data(client, reg, value);
        return ret;
}

/*****************************************************************************/
/* Data Updater Helper function                                              */
/*****************************************************************************/
static int fts_update_device(struct fts_data *data)
{
        int i, err;

        if (!time_after(jiffies, data->last_updated + 2 * HZ) && data->valid)
                return 0;

        err = fts_read_byte(data->client, FTS_DEVICE_STATUS_REG);
        if (err < 0)
                return err;

        data->valid = !!(err & 0x02); /* Data not ready yet */
        if (unlikely(!data->valid))
                return -EAGAIN;

        err = fts_read_byte(data->client, FTS_FAN_PRESENT_REG);
        if (err < 0)
                return err;
        data->fan_present = err;

        err = fts_read_byte(data->client, FTS_FAN_EVENT_REG);
        if (err < 0)
                return err;
        data->fan_alarm = err;

        for (i = 0; i < FTS_NO_FAN_SENSORS; i++) {
                if (data->fan_present & BIT(i)) {
                        err = fts_read_byte(data->client, FTS_REG_FAN_INPUT(i));
                        if (err < 0)
                                return err;
                        data->fan_input[i] = err;

                        err = fts_read_byte(data->client,
                                            FTS_REG_FAN_SOURCE(i));
                        if (err < 0)
                                return err;
                        data->fan_source[i] = err;
                } else {
                        data->fan_input[i] = 0;
                        data->fan_source[i] = FTS_FAN_SOURCE_INVALID;
                }
        }

        err = fts_read_byte(data->client, FTS_SENSOR_EVENT_REG);
        if (err < 0)
                return err;
        data->temp_alarm = err;

        for (i = 0; i < FTS_NO_TEMP_SENSORS; i++) {
                err = fts_read_byte(data->client, FTS_REG_TEMP_INPUT(i));
                if (err < 0)
                        return err;
                data->temp_input[i] = err;
        }

        for (i = 0; i < FTS_NO_VOLT_SENSORS; i++) {
                err = fts_read_byte(data->client, FTS_REG_VOLT(i));
                if (err < 0)
                        return err;
                data->volt[i] = err;
        }
        data->last_updated = jiffies;
        return 0;
}

/*****************************************************************************/
/* Watchdog functions                                                        */
/*****************************************************************************/
static int fts_wd_set_resolution(struct fts_data *data,
                                 enum WATCHDOG_RESOLUTION resolution)
{
        int ret;

        if (data->resolution == resolution)
                return 0;

        ret = fts_read_byte(data->client, FTS_WATCHDOG_CONTROL);
        if (ret < 0)
                return ret;

        if ((resolution == seconds && ret & BIT(1)) ||
            (resolution == minutes && (ret & BIT(1)) == 0)) {
                data->resolution = resolution;
                return 0;
        }

        if (resolution == seconds)
                ret |= BIT(1);
        else
                ret &= ~BIT(1);

        ret = fts_write_byte(data->client, FTS_WATCHDOG_CONTROL, ret);
        if (ret < 0)
                return ret;

        data->resolution = resolution;
        return ret;
}

static int fts_wd_set_timeout(struct watchdog_device *wdd, unsigned int timeout)
{
        struct fts_data *data;
        enum WATCHDOG_RESOLUTION resolution = seconds;
        int ret;

        data = watchdog_get_drvdata(wdd);
        /* switch watchdog resolution to minutes if timeout does not fit
         * into a byte
         */
        if (timeout > 0xFF) {
                timeout = DIV_ROUND_UP(timeout, 60) * 60;
                resolution = minutes;
        }

        ret = fts_wd_set_resolution(data, resolution);
        if (ret < 0)
                return ret;

        wdd->timeout = timeout;
        return 0;
}

static int fts_wd_start(struct watchdog_device *wdd)
{
        struct fts_data *data = watchdog_get_drvdata(wdd);

        return fts_write_byte(data->client, FTS_WATCHDOG_TIME_PRESET,
                              wdd->timeout / (u8)data->resolution);
}

static int fts_wd_stop(struct watchdog_device *wdd)
{
        struct fts_data *data;

        data = watchdog_get_drvdata(wdd);
        return fts_write_byte(data->client, FTS_WATCHDOG_TIME_PRESET, 0);
}

static const struct watchdog_info fts_wd_info = {
        .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .identity = "FTS Teutates Hardware Watchdog",
};

static const struct watchdog_ops fts_wd_ops = {
        .owner = THIS_MODULE,
        .start = fts_wd_start,
        .stop = fts_wd_stop,
        .set_timeout = fts_wd_set_timeout,
};

static int fts_watchdog_init(struct fts_data *data)
{
        int timeout, ret;

        watchdog_set_drvdata(&data->wdd, data);

        timeout = fts_read_byte(data->client, FTS_WATCHDOG_TIME_PRESET);
        if (timeout < 0)
                return timeout;

        /* watchdog not running, set timeout to a default of 60 sec. */
        if (timeout == 0) {
                ret = fts_wd_set_resolution(data, seconds);
                if (ret < 0)
                        return ret;
                data->wdd.timeout = 60;
        } else {
                ret = fts_read_byte(data->client, FTS_WATCHDOG_CONTROL);
                if (ret < 0)
                        return ret;

                data->resolution = ret & BIT(1) ? seconds : minutes;
                data->wdd.timeout = timeout * (u8)data->resolution;
                set_bit(WDOG_HW_RUNNING, &data->wdd.status);
        }

        /* Register our watchdog part */
        data->wdd.info = &fts_wd_info;
        data->wdd.ops = &fts_wd_ops;
        data->wdd.parent = &data->client->dev;
        data->wdd.min_timeout = 1;

        /* max timeout 255 minutes. */
        data->wdd.max_hw_heartbeat_ms = 0xFF * 60 * MSEC_PER_SEC;

        return devm_watchdog_register_device(&data->client->dev, &data->wdd);
}

static umode_t fts_is_visible(const void *devdata, enum hwmon_sensor_types type, u32 attr,
                              int channel)
{
        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_input:
                case hwmon_temp_fault:
                        return 0444;
                case hwmon_temp_alarm:
                        return 0644;
                default:
                        break;
                }
                break;
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_input:
                case hwmon_fan_fault:
                        return 0444;
                case hwmon_fan_alarm:
                        return 0644;
                default:
                        break;
                }
                break;
        case hwmon_pwm:
        case hwmon_in:
                return 0444;
        default:
                break;
        }

        return 0;
}

static int fts_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
                    long *val)
{
        struct fts_data *data = dev_get_drvdata(dev);
        int ret = fts_update_device(data);

        if (ret < 0)
                return ret;

        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_input:
                        *val = (data->temp_input[channel] - 64) * 1000;

                        return 0;
                case hwmon_temp_alarm:
                        *val = !!(data->temp_alarm & BIT(channel));

                        return 0;
                case hwmon_temp_fault:
                        /* 00h Temperature = Sensor Error */;
                        *val = (data->temp_input[channel] == 0);

                        return 0;
                default:
                        break;
                }
                break;
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_input:
                        *val = data->fan_input[channel] * 60;

                        return 0;
                case hwmon_fan_alarm:
                        *val = !!(data->fan_alarm & BIT(channel));

                        return 0;
                case hwmon_fan_fault:
                        *val = !(data->fan_present & BIT(channel));

                        return 0;
                default:
                        break;
                }
                break;
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_auto_channels_temp: {
                        u8 fan_source = data->fan_source[channel];

                        if (fan_source == FTS_FAN_SOURCE_INVALID || fan_source >= BITS_PER_LONG)
                                *val = 0;
                        else
                                *val = BIT(fan_source);

                        return 0;
                }
                default:
                        break;
                }
                break;
        case hwmon_in:
                switch (attr) {
                case hwmon_in_input:
                        *val = DIV_ROUND_CLOSEST(data->volt[channel] * 3300, 255);

                        return 0;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return -EOPNOTSUPP;
}

static int fts_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
                     long val)
{
        struct fts_data *data = dev_get_drvdata(dev);
        int ret = fts_update_device(data);

        if (ret < 0)
                return ret;

        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_alarm:
                        if (val)
                                return -EINVAL;

                        ret = fts_read_byte(data->client, FTS_REG_TEMP_CONTROL(channel));
                        if (ret < 0)
                                return ret;
                        ret = fts_write_byte(data->client, FTS_REG_TEMP_CONTROL(channel),
                                             ret | 0x1);
                        if (ret < 0)
                                return ret;
                        data->valid = false;
                        return 0;
                default:
                        break;
                }
                break;
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_alarm:
                        if (val)
                                return -EINVAL;

                        ret = fts_read_byte(data->client, FTS_REG_FAN_CONTROL(channel));
                        if (ret < 0)
                                return ret;
                        ret = fts_write_byte(data->client, FTS_REG_FAN_CONTROL(channel),
                                             ret | 0x1);
                        if (ret < 0)
                                return ret;
                        data->valid = false;
                        return 0;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return -EOPNOTSUPP;
}

static const struct hwmon_ops fts_ops = {
        .is_visible = fts_is_visible,
        .read = fts_read,
        .write = fts_write,
};

static const struct hwmon_channel_info * const fts_info[] = {
        HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT,
                           HWMON_T_INPUT | HWMON_T_ALARM | HWMON_T_FAULT
                           ),
        HWMON_CHANNEL_INFO(fan,
                           HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT,
                           HWMON_F_INPUT | HWMON_F_ALARM | HWMON_F_FAULT
                           ),
        HWMON_CHANNEL_INFO(pwm,
                           HWMON_PWM_AUTO_CHANNELS_TEMP,
                           HWMON_PWM_AUTO_CHANNELS_TEMP,
                           HWMON_PWM_AUTO_CHANNELS_TEMP,
                           HWMON_PWM_AUTO_CHANNELS_TEMP,
                           HWMON_PWM_AUTO_CHANNELS_TEMP,
                           HWMON_PWM_AUTO_CHANNELS_TEMP,
                           HWMON_PWM_AUTO_CHANNELS_TEMP,
                           HWMON_PWM_AUTO_CHANNELS_TEMP
                           ),
        HWMON_CHANNEL_INFO(in,
                           HWMON_I_INPUT,
                           HWMON_I_INPUT,
                           HWMON_I_INPUT,
                           HWMON_I_INPUT
                           ),
        NULL
};

static const struct hwmon_chip_info fts_chip_info = {
        .ops = &fts_ops,
        .info = fts_info,
};

/*****************************************************************************/
/* Module initialization / remove functions                                  */
/*****************************************************************************/
static int fts_detect(struct i2c_client *client,
                      struct i2c_board_info *info)
{
        int val;

        /* detection works with revision greater or equal to 0x2b */
        val = i2c_smbus_read_byte_data(client, FTS_DEVICE_REVISION_REG);
        if (val < 0x2b)
                return -ENODEV;

        /* Device Detect Regs must have 0x17 0x34 and 0x54 */
        val = i2c_smbus_read_byte_data(client, FTS_DEVICE_DETECT_REG_1);
        if (val != 0x17)
                return -ENODEV;

        val = i2c_smbus_read_byte_data(client, FTS_DEVICE_DETECT_REG_2);
        if (val != 0x34)
                return -ENODEV;

        val = i2c_smbus_read_byte_data(client, FTS_DEVICE_DETECT_REG_3);
        if (val != 0x54)
                return -ENODEV;

        /*
         * 0x10 == Baseboard Management Controller, 0x01 == Teutates
         * Device ID Reg needs to be 0x11
         */
        val = i2c_smbus_read_byte_data(client, FTS_DEVICE_ID_REG);
        if (val != 0x11)
                return -ENODEV;

        strscpy(info->type, fts_id[0].name, I2C_NAME_SIZE);
        info->flags = 0;
        return 0;
}

static int fts_probe(struct i2c_client *client)
{
        u8 revision;
        struct fts_data *data;
        int err;
        s8 deviceid;
        struct device *hwmon_dev;

        if (client->addr != 0x73)
                return -ENODEV;

        /* Baseboard Management Controller check */
        deviceid = i2c_smbus_read_byte_data(client, FTS_DEVICE_ID_REG);
        if (deviceid > 0 && (deviceid & 0xF0) == 0x10) {
                switch (deviceid & 0x0F) {
                case 0x01:
                        break;
                default:
                        dev_dbg(&client->dev,
                                "No Baseboard Management Controller\n");
                        return -ENODEV;
                }
        } else {
                dev_dbg(&client->dev, "No fujitsu board\n");
                return -ENODEV;
        }

        data = devm_kzalloc(&client->dev, sizeof(struct fts_data),
                            GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->client = client;
        dev_set_drvdata(&client->dev, data);

        err = i2c_smbus_read_byte_data(client, FTS_DEVICE_REVISION_REG);
        if (err < 0)
                return err;
        revision = err;

        hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, "ftsteutates", data,
                                                         &fts_chip_info, NULL);
        if (IS_ERR(hwmon_dev))
                return PTR_ERR(hwmon_dev);

        err = fts_watchdog_init(data);
        if (err)
                return err;

        dev_info(&client->dev, "Detected FTS Teutates chip, revision: %d.%d\n",
                 (revision & 0xF0) >> 4, revision & 0x0F);
        return 0;
}

/*****************************************************************************/
/* Module Details                                                            */
/*****************************************************************************/
static struct i2c_driver fts_driver = {
        .class = I2C_CLASS_HWMON,
        .driver = {
                .name = "ftsteutates",
        },
        .id_table = fts_id,
        .probe = fts_probe,
        .detect = fts_detect,
        .address_list = normal_i2c,
};

module_i2c_driver(fts_driver);

MODULE_AUTHOR("Thilo Cestonaro <thilo.cestonaro@ts.fujitsu.com>");
MODULE_DESCRIPTION("FTS Teutates driver");
MODULE_LICENSE("GPL");