// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Hardware monitoring driver for Maxim MAX6620
 *
 * Originally from L. Grunenberg.
 * (C) 2012 by L. Grunenberg <contact@lgrunenberg.de>
 *
 * Copyright (c) 2021 Dell Inc. or its subsidiaries. All Rights Reserved.
 *
 * based on code written by :
 * 2007 by Hans J. Koch <hjk@hansjkoch.de>
 * John Morris <john.morris@spirentcom.com>
 * Copyright (c) 2003 Spirent Communications
 * and Claus Gindhart <claus.gindhart@kontron.com>
 *
 * This module has only been tested with the MAX6620 chip.
 *
 * The datasheet was last seen at:
 *
 *        http://pdfserv.maxim-ic.com/en/ds/MAX6620.pdf
 *
 */

#include <linux/bits.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/slab.h>

/*
 * MAX 6620 registers
 */

#define MAX6620_REG_CONFIG      0x00
#define MAX6620_REG_FAULT       0x01
#define MAX6620_REG_CONF_FAN0   0x02
#define MAX6620_REG_CONF_FAN1   0x03
#define MAX6620_REG_CONF_FAN2   0x04
#define MAX6620_REG_CONF_FAN3   0x05
#define MAX6620_REG_DYN_FAN0    0x06
#define MAX6620_REG_DYN_FAN1    0x07
#define MAX6620_REG_DYN_FAN2    0x08
#define MAX6620_REG_DYN_FAN3    0x09
#define MAX6620_REG_TACH0       0x10
#define MAX6620_REG_TACH1       0x12
#define MAX6620_REG_TACH2       0x14
#define MAX6620_REG_TACH3       0x16
#define MAX6620_REG_VOLT0       0x18
#define MAX6620_REG_VOLT1       0x1A
#define MAX6620_REG_VOLT2       0x1C
#define MAX6620_REG_VOLT3       0x1E
#define MAX6620_REG_TAR0        0x20
#define MAX6620_REG_TAR1        0x22
#define MAX6620_REG_TAR2        0x24
#define MAX6620_REG_TAR3        0x26
#define MAX6620_REG_DAC0        0x28
#define MAX6620_REG_DAC1        0x2A
#define MAX6620_REG_DAC2        0x2C
#define MAX6620_REG_DAC3        0x2E

/*
 * Config register bits
 */

#define MAX6620_CFG_RUN         BIT(7)
#define MAX6620_CFG_POR         BIT(6)
#define MAX6620_CFG_TIMEOUT     BIT(5)
#define MAX6620_CFG_FULLFAN     BIT(4)
#define MAX6620_CFG_OSC         BIT(3)
#define MAX6620_CFG_WD_MASK     (BIT(2) | BIT(1))
#define MAX6620_CFG_WD_2        BIT(1)
#define MAX6620_CFG_WD_6        BIT(2)
#define MAX6620_CFG_WD10        (BIT(2) | BIT(1))
#define MAX6620_CFG_WD          BIT(0)

/*
 * Failure status register bits
 */

#define MAX6620_FAIL_TACH0      BIT(4)
#define MAX6620_FAIL_TACH1      BIT(5)
#define MAX6620_FAIL_TACH2      BIT(6)
#define MAX6620_FAIL_TACH3      BIT(7)
#define MAX6620_FAIL_MASK0      BIT(0)
#define MAX6620_FAIL_MASK1      BIT(1)
#define MAX6620_FAIL_MASK2      BIT(2)
#define MAX6620_FAIL_MASK3      BIT(3)

#define MAX6620_CLOCK_FREQ      8192 /* Clock frequency in Hz */
#define MAX6620_PULSE_PER_REV   2 /* Tachometer pulses per revolution */

/* Minimum and maximum values of the FAN-RPM */
#define FAN_RPM_MIN     240
#define FAN_RPM_MAX     30000

static const u8 config_reg[] = {
        MAX6620_REG_CONF_FAN0,
        MAX6620_REG_CONF_FAN1,
        MAX6620_REG_CONF_FAN2,
        MAX6620_REG_CONF_FAN3,
};

static const u8 dyn_reg[] = {
        MAX6620_REG_DYN_FAN0,
        MAX6620_REG_DYN_FAN1,
        MAX6620_REG_DYN_FAN2,
        MAX6620_REG_DYN_FAN3,
};

static const u8 tach_reg[] = {
        MAX6620_REG_TACH0,
        MAX6620_REG_TACH1,
        MAX6620_REG_TACH2,
        MAX6620_REG_TACH3,
};

static const u8 target_reg[] = {
        MAX6620_REG_TAR0,
        MAX6620_REG_TAR1,
        MAX6620_REG_TAR2,
        MAX6620_REG_TAR3,
};

/*
 * Client data (each client gets its own)
 */

struct max6620_data {
        struct i2c_client *client;
        bool valid; /* false until following fields are valid */
        unsigned long last_updated; /* in jiffies */

        /* register values */
        u8 fancfg[4];
        u8 fandyn[4];
        u8 fault;
        u16 tach[4];
        u16 target[4];
};

static u8 max6620_fan_div_from_reg(u8 val)
{
        return BIT((val & 0xE0) >> 5);
}

static u16 max6620_fan_rpm_to_tach(u8 div, int rpm)
{
        return (60 * div * MAX6620_CLOCK_FREQ) / (rpm * MAX6620_PULSE_PER_REV);
}

static int max6620_fan_tach_to_rpm(u8 div, u16 tach)
{
        return (60 * div * MAX6620_CLOCK_FREQ) / (tach * MAX6620_PULSE_PER_REV);
}

static int max6620_update_device(struct device *dev)
{
        struct max6620_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int i, ret;

        if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
                for (i = 0; i < 4; i++) {
                        ret = i2c_smbus_read_byte_data(client, config_reg[i]);
                        if (ret < 0)
                                return ret;
                        data->fancfg[i] = ret;

                        ret = i2c_smbus_read_byte_data(client, dyn_reg[i]);
                        if (ret < 0)
                                return ret;
                        data->fandyn[i] = ret;

                        ret = i2c_smbus_read_byte_data(client, tach_reg[i]);
                        if (ret < 0)
                                return ret;
                        data->tach[i] = (ret << 3) & 0x7f8;
                        ret = i2c_smbus_read_byte_data(client, tach_reg[i] + 1);
                        if (ret < 0)
                                return ret;
                        data->tach[i] |= (ret >> 5) & 0x7;

                        ret = i2c_smbus_read_byte_data(client, target_reg[i]);
                        if (ret < 0)
                                return ret;
                        data->target[i] = (ret << 3) & 0x7f8;
                        ret = i2c_smbus_read_byte_data(client, target_reg[i] + 1);
                        if (ret < 0)
                                return ret;
                        data->target[i] |= (ret >> 5) & 0x7;
                }

                /*
                 * Alarms are cleared on read in case the condition that
                 * caused the alarm is removed. Keep the value latched here
                 * for providing the register through different alarm files.
                 */
                ret = i2c_smbus_read_byte_data(client, MAX6620_REG_FAULT);
                if (ret < 0)
                        return ret;
                data->fault |= (ret >> 4) & (ret & 0x0F);

                data->last_updated = jiffies;
                data->valid = true;
        }
        return 0;
}

static umode_t
max6620_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr,
                   int channel)
{
        switch (type) {
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_alarm:
                case hwmon_fan_input:
                        return 0444;
                case hwmon_fan_div:
                case hwmon_fan_target:
                        return 0644;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return 0;
}

static int
max6620_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
             int channel, long *val)
{
        struct max6620_data *data;
        struct i2c_client *client;
        int ret;
        u8 div;
        u8 val1;
        u8 val2;

        ret = max6620_update_device(dev);
        if (ret < 0)
                return ret;
        data = dev_get_drvdata(dev);
        client = data->client;

        switch (type) {
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_alarm:
                        *val = !!(data->fault & BIT(channel));

                        /* Setting TACH count to re-enable fan fault detection */
                        if (*val == 1) {
                                val1 = (data->target[channel] >> 3) & 0xff;
                                val2 = (data->target[channel] << 5) & 0xe0;
                                ret = i2c_smbus_write_byte_data(client,
                                                                target_reg[channel], val1);
                                if (ret < 0)
                                        return ret;
                                ret = i2c_smbus_write_byte_data(client,
                                                                target_reg[channel] + 1, val2);
                                if (ret < 0)
                                        return ret;

                                data->fault &= ~BIT(channel);
                        }
                        break;
                case hwmon_fan_div:
                        *val = max6620_fan_div_from_reg(data->fandyn[channel]);
                        break;
                case hwmon_fan_input:
                        if (data->tach[channel] == 0) {
                                *val = 0;
                        } else {
                                div = max6620_fan_div_from_reg(data->fandyn[channel]);
                                *val = max6620_fan_tach_to_rpm(div, data->tach[channel]);
                        }
                        break;
                case hwmon_fan_target:
                        if (data->target[channel] == 0) {
                                *val = 0;
                        } else {
                                div = max6620_fan_div_from_reg(data->fandyn[channel]);
                                *val = max6620_fan_tach_to_rpm(div, data->target[channel]);
                        }
                        break;
                default:
                        return -EOPNOTSUPP;
                }
                break;

        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int
max6620_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
              int channel, long val)
{
        struct max6620_data *data;
        struct i2c_client *client;
        int ret;
        u8 div;
        u16 tach;
        u8 val1;
        u8 val2;

        ret = max6620_update_device(dev);
        if (ret < 0)
                return ret;
        data = dev_get_drvdata(dev);
        client = data->client;

        switch (type) {
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_div:
                        switch (val) {
                        case 1:
                                div = 0;
                                break;
                        case 2:
                                div = 1;
                                break;
                        case 4:
                                div = 2;
                                break;
                        case 8:
                                div = 3;
                                break;
                        case 16:
                                div = 4;
                                break;
                        case 32:
                                div = 5;
                                break;
                        default:
                                return -EINVAL;
                        }
                        data->fandyn[channel] &= 0x1F;
                        data->fandyn[channel] |= div << 5;
                        ret = i2c_smbus_write_byte_data(client, dyn_reg[channel],
                                                        data->fandyn[channel]);
                        break;
                case hwmon_fan_target:
                        val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
                        div = max6620_fan_div_from_reg(data->fandyn[channel]);
                        tach = max6620_fan_rpm_to_tach(div, val);
                        val1 = (tach >> 3) & 0xff;
                        val2 = (tach << 5) & 0xe0;
                        ret = i2c_smbus_write_byte_data(client, target_reg[channel], val1);
                        if (ret < 0)
                                break;
                        ret = i2c_smbus_write_byte_data(client, target_reg[channel] + 1, val2);
                        if (ret < 0)
                                break;

                        /* Setting TACH count re-enables fan fault detection */
                        data->fault &= ~BIT(channel);

                        break;
                default:
                        ret = -EOPNOTSUPP;
                        break;
                }
                break;

        default:
                ret = -EOPNOTSUPP;
                break;
        }

        return ret;
}

static const struct hwmon_channel_info * const max6620_info[] = {
        HWMON_CHANNEL_INFO(fan,
                           HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
                           HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
                           HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM,
                           HWMON_F_INPUT | HWMON_F_DIV | HWMON_F_TARGET | HWMON_F_ALARM),
        NULL
};

static const struct hwmon_ops max6620_hwmon_ops = {
        .read = max6620_read,
        .write = max6620_write,
        .is_visible = max6620_is_visible,
};

static const struct hwmon_chip_info max6620_chip_info = {
        .ops = &max6620_hwmon_ops,
        .info = max6620_info,
};

static int max6620_init_client(struct max6620_data *data)
{
        struct i2c_client *client = data->client;
        int config;
        int err;
        int i;
        int reg;

        config = i2c_smbus_read_byte_data(client, MAX6620_REG_CONFIG);
        if (config < 0) {
                dev_err(&client->dev, "Error reading config, aborting.\n");
                return config;
        }

        /*
         * Set bit 4, disable other fans from going full speed on a fail
         * failure.
         */
        err = i2c_smbus_write_byte_data(client, MAX6620_REG_CONFIG, config | 0x10);
        if (err < 0) {
                dev_err(&client->dev, "Config write error, aborting.\n");
                return err;
        }

        for (i = 0; i < 4; i++) {
                reg = i2c_smbus_read_byte_data(client, config_reg[i]);
                if (reg < 0)
                        return reg;
                data->fancfg[i] = reg;

                /* Enable RPM mode */
                data->fancfg[i] |= 0xa8;
                err = i2c_smbus_write_byte_data(client, config_reg[i], data->fancfg[i]);
                if (err < 0)
                        return err;

                /* 2 counts (001) and Rate change 100 (0.125 secs) */
                data->fandyn[i] = 0x30;
                err = i2c_smbus_write_byte_data(client, dyn_reg[i], data->fandyn[i]);
                if (err < 0)
                        return err;
        }
        return 0;
}

static int max6620_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct max6620_data *data;
        struct device *hwmon_dev;
        int err;

        data = devm_kzalloc(dev, sizeof(struct max6620_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->client = client;

        err = max6620_init_client(data);
        if (err)
                return err;

        hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
                                                         data,
                                                         &max6620_chip_info,
                                                         NULL);

        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id max6620_id[] = {
        { "max6620" },
        { }
};
MODULE_DEVICE_TABLE(i2c, max6620_id);

static struct i2c_driver max6620_driver = {
        .class          = I2C_CLASS_HWMON,
        .driver = {
                .name   = "max6620",
        },
        .probe          = max6620_probe,
        .id_table       = max6620_id,
};

module_i2c_driver(max6620_driver);

MODULE_AUTHOR("Lucas Grunenberg");
MODULE_DESCRIPTION("MAX6620 sensor driver");
MODULE_LICENSE("GPL");