// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * max31790.c - Part of lm_sensors, Linux kernel modules for hardware
 *             monitoring.
 *
 * (C) 2015 by Il Han <corone.il.han@gmail.com>
 */

#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>

/* MAX31790 registers */
#define MAX31790_REG_GLOBAL_CONFIG      0x00
#define MAX31790_REG_FAN_CONFIG(ch)     (0x02 + (ch))
#define MAX31790_REG_FAN_DYNAMICS(ch)   (0x08 + (ch))
#define MAX31790_REG_FAN_FAULT_STATUS2  0x10
#define MAX31790_REG_FAN_FAULT_STATUS1  0x11
#define MAX31790_REG_TACH_COUNT(ch)     (0x18 + (ch) * 2)
#define MAX31790_REG_PWM_DUTY_CYCLE(ch) (0x30 + (ch) * 2)
#define MAX31790_REG_PWMOUT(ch)         (0x40 + (ch) * 2)
#define MAX31790_REG_TARGET_COUNT(ch)   (0x50 + (ch) * 2)

/* Fan Config register bits */
#define MAX31790_FAN_CFG_RPM_MODE       0x80
#define MAX31790_FAN_CFG_CTRL_MON       0x10
#define MAX31790_FAN_CFG_TACH_INPUT_EN  0x08
#define MAX31790_FAN_CFG_TACH_INPUT     0x01

/* Fan Dynamics register bits */
#define MAX31790_FAN_DYN_SR_SHIFT       5
#define MAX31790_FAN_DYN_SR_MASK        0xE0
#define SR_FROM_REG(reg)                (((reg) & MAX31790_FAN_DYN_SR_MASK) \
                                         >> MAX31790_FAN_DYN_SR_SHIFT)

#define FAN_RPM_MIN                     120
#define FAN_RPM_MAX                     7864320

#define FAN_COUNT_REG_MAX               0xffe0

#define RPM_FROM_REG(reg, sr)           (((reg) >> 4) ? \
                                         ((60 * (sr) * 8192) / ((reg) >> 4)) : \
                                         FAN_RPM_MAX)
#define RPM_TO_REG(rpm, sr)             ((60 * (sr) * 8192) / ((rpm) * 2))

#define NR_CHANNEL                      6

#define PWM_INPUT_SCALE 255
#define MAX31790_REG_PWMOUT_SCALE       511

/*
 * Client data (each client gets its own)
 */
struct max31790_data {
        struct i2c_client *client;
        bool valid; /* zero until following fields are valid */
        unsigned long last_updated; /* in jiffies */

        /* register values */
        u8 fan_config[NR_CHANNEL];
        u8 fan_dynamics[NR_CHANNEL];
        u16 fault_status;
        u16 tach[NR_CHANNEL * 2];
        u16 pwm[NR_CHANNEL];
        u16 target_count[NR_CHANNEL];
};

static struct max31790_data *max31790_update_device(struct device *dev)
{
        struct max31790_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int i, rv;

        if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
                data->valid = false;
                rv = i2c_smbus_read_byte_data(client,
                                MAX31790_REG_FAN_FAULT_STATUS1);
                if (rv < 0)
                        return ERR_PTR(rv);
                data->fault_status |= rv & 0x3F;

                rv = i2c_smbus_read_byte_data(client,
                                MAX31790_REG_FAN_FAULT_STATUS2);
                if (rv < 0)
                        return ERR_PTR(rv);
                data->fault_status |= (rv & 0x3F) << 6;

                for (i = 0; i < NR_CHANNEL; i++) {
                        rv = i2c_smbus_read_word_swapped(client,
                                        MAX31790_REG_TACH_COUNT(i));
                        if (rv < 0)
                                return ERR_PTR(rv);
                        data->tach[i] = rv;

                        if (data->fan_config[i]
                            & MAX31790_FAN_CFG_TACH_INPUT) {
                                rv = i2c_smbus_read_word_swapped(client,
                                        MAX31790_REG_TACH_COUNT(NR_CHANNEL
                                                                + i));
                                if (rv < 0)
                                        return ERR_PTR(rv);
                                data->tach[NR_CHANNEL + i] = rv;
                        } else {
                                rv = i2c_smbus_read_word_swapped(client,
                                                MAX31790_REG_PWM_DUTY_CYCLE(i));
                                if (rv < 0)
                                        return ERR_PTR(rv);
                                data->pwm[i] = rv;

                                rv = i2c_smbus_read_word_swapped(client,
                                                MAX31790_REG_TARGET_COUNT(i));
                                if (rv < 0)
                                        return ERR_PTR(rv);
                                data->target_count[i] = rv;
                        }
                }

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

static const u8 tach_period[8] = { 1, 2, 4, 8, 16, 32, 32, 32 };

static u8 get_tach_period(u8 fan_dynamics)
{
        return tach_period[SR_FROM_REG(fan_dynamics)];
}

static u8 bits_for_tach_period(int rpm)
{
        u8 bits;

        if (rpm < 500)
                bits = 0x0;
        else if (rpm < 1000)
                bits = 0x1;
        else if (rpm < 2000)
                bits = 0x2;
        else if (rpm < 4000)
                bits = 0x3;
        else if (rpm < 8000)
                bits = 0x4;
        else
                bits = 0x5;

        return bits;
}

static int max31790_read_fan(struct device *dev, u32 attr, int channel,
                             long *val)
{
        struct max31790_data *data = max31790_update_device(dev);
        int sr, rpm;

        if (IS_ERR(data))
                return PTR_ERR(data);

        switch (attr) {
        case hwmon_fan_input:
                sr = get_tach_period(data->fan_dynamics[channel % NR_CHANNEL]);
                if (data->tach[channel] == FAN_COUNT_REG_MAX)
                        rpm = 0;
                else
                        rpm = RPM_FROM_REG(data->tach[channel], sr);
                *val = rpm;
                return 0;
        case hwmon_fan_target:
                sr = get_tach_period(data->fan_dynamics[channel]);
                rpm = RPM_FROM_REG(data->target_count[channel], sr);
                *val = rpm;
                return 0;
        case hwmon_fan_fault:
                *val = !!(data->fault_status & (1 << channel));
                data->fault_status &= ~(1 << channel);
                /*
                 * If a fault bit is set, we need to write into one of the fan
                 * configuration registers to clear it. Note that this also
                 * clears the fault for the companion channel if enabled.
                 */
                if (*val) {
                        int reg = MAX31790_REG_TARGET_COUNT(channel % NR_CHANNEL);

                        return i2c_smbus_write_byte_data(data->client, reg,
                                                data->target_count[channel % NR_CHANNEL] >> 8);
                }
                return 0;
        case hwmon_fan_enable:
                *val = !!(data->fan_config[channel] & MAX31790_FAN_CFG_TACH_INPUT_EN);
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static int max31790_write_fan(struct device *dev, u32 attr, int channel,
                              long val)
{
        struct max31790_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        int target_count;
        int err = 0;
        u8 bits, fan_config;
        int sr;

        switch (attr) {
        case hwmon_fan_target:
                val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
                bits = bits_for_tach_period(val);
                data->fan_dynamics[channel] =
                        ((data->fan_dynamics[channel] &
                          ~MAX31790_FAN_DYN_SR_MASK) |
                         (bits << MAX31790_FAN_DYN_SR_SHIFT));
                err = i2c_smbus_write_byte_data(client,
                                        MAX31790_REG_FAN_DYNAMICS(channel),
                                        data->fan_dynamics[channel]);
                if (err < 0)
                        break;

                sr = get_tach_period(data->fan_dynamics[channel]);
                target_count = RPM_TO_REG(val, sr);
                target_count = clamp_val(target_count, 0x1, 0x7FF);

                data->target_count[channel] = target_count << 5;

                err = i2c_smbus_write_word_swapped(client,
                                        MAX31790_REG_TARGET_COUNT(channel),
                                        data->target_count[channel]);
                break;
        case hwmon_fan_enable:
                fan_config = data->fan_config[channel];
                if (val == 0) {
                        fan_config &= ~MAX31790_FAN_CFG_TACH_INPUT_EN;
                } else if (val == 1) {
                        fan_config |= MAX31790_FAN_CFG_TACH_INPUT_EN;
                } else {
                        err = -EINVAL;
                        break;
                }
                if (fan_config != data->fan_config[channel]) {
                        err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
                                                        fan_config);
                        if (!err)
                                data->fan_config[channel] = fan_config;
                }
                break;
        default:
                err = -EOPNOTSUPP;
                break;
        }
        return err;
}

static umode_t max31790_fan_is_visible(const void *_data, u32 attr, int channel)
{
        const struct max31790_data *data = _data;
        u8 fan_config = data->fan_config[channel % NR_CHANNEL];

        switch (attr) {
        case hwmon_fan_input:
        case hwmon_fan_fault:
                if (channel < NR_CHANNEL ||
                    (fan_config & MAX31790_FAN_CFG_TACH_INPUT))
                        return 0444;
                return 0;
        case hwmon_fan_target:
                if (channel < NR_CHANNEL &&
                    !(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
                        return 0644;
                return 0;
        case hwmon_fan_enable:
                if (channel < NR_CHANNEL)
                        return 0644;
                return 0;
        default:
                return 0;
        }
}

static int max31790_read_pwm(struct device *dev, u32 attr, int channel,
                             long *val)
{
        struct max31790_data *data = max31790_update_device(dev);
        u8 fan_config;

        if (IS_ERR(data))
                return PTR_ERR(data);

        fan_config = data->fan_config[channel];

        switch (attr) {
        case hwmon_pwm_input:
                *val = data->pwm[channel] >> 8;
                return 0;
        case hwmon_pwm_enable:
                if (fan_config & MAX31790_FAN_CFG_CTRL_MON)
                        *val = 0;
                else if (fan_config & MAX31790_FAN_CFG_RPM_MODE)
                        *val = 2;
                else
                        *val = 1;
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static int max31790_write_pwm(struct device *dev, u32 attr, int channel,
                              long val)
{
        struct max31790_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        u8 fan_config;
        int err = 0;

        switch (attr) {
        case hwmon_pwm_input:
                if (val < 0 || val > 255) {
                        err = -EINVAL;
                        break;
                }

                val = DIV_ROUND_CLOSEST(val * MAX31790_REG_PWMOUT_SCALE,
                                        PWM_INPUT_SCALE);
                data->valid = false;
                err = i2c_smbus_write_word_swapped(client,
                                                   MAX31790_REG_PWMOUT(channel),
                                                   val << 7);
                break;
        case hwmon_pwm_enable:
                fan_config = data->fan_config[channel];
                if (val == 0) {
                        fan_config |= MAX31790_FAN_CFG_CTRL_MON;
                        /*
                         * Disable RPM mode; otherwise disabling fan speed
                         * monitoring is not possible.
                         */
                        fan_config &= ~MAX31790_FAN_CFG_RPM_MODE;
                } else if (val == 1) {
                        fan_config &= ~(MAX31790_FAN_CFG_CTRL_MON | MAX31790_FAN_CFG_RPM_MODE);
                } else if (val == 2) {
                        fan_config &= ~MAX31790_FAN_CFG_CTRL_MON;
                        /*
                         * The chip sets MAX31790_FAN_CFG_TACH_INPUT_EN on its
                         * own if MAX31790_FAN_CFG_RPM_MODE is set.
                         * Do it here as well to reflect the actual register
                         * value in the cache.
                         */
                        fan_config |= (MAX31790_FAN_CFG_RPM_MODE | MAX31790_FAN_CFG_TACH_INPUT_EN);
                } else {
                        err = -EINVAL;
                        break;
                }
                if (fan_config != data->fan_config[channel]) {
                        err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
                                                        fan_config);
                        if (!err)
                                data->fan_config[channel] = fan_config;
                }
                break;
        default:
                err = -EOPNOTSUPP;
                break;
        }
        return err;
}

static umode_t max31790_pwm_is_visible(const void *_data, u32 attr, int channel)
{
        const struct max31790_data *data = _data;
        u8 fan_config = data->fan_config[channel];

        switch (attr) {
        case hwmon_pwm_input:
        case hwmon_pwm_enable:
                if (!(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
                        return 0644;
                return 0;
        default:
                return 0;
        }
}

static int max31790_read(struct device *dev, enum hwmon_sensor_types type,
                         u32 attr, int channel, long *val)
{
        switch (type) {
        case hwmon_fan:
                return max31790_read_fan(dev, attr, channel, val);
        case hwmon_pwm:
                return max31790_read_pwm(dev, attr, channel, val);
        default:
                return -EOPNOTSUPP;
        }
}

static int max31790_write(struct device *dev, enum hwmon_sensor_types type,
                          u32 attr, int channel, long val)
{
        switch (type) {
        case hwmon_fan:
                return max31790_write_fan(dev, attr, channel, val);
        case hwmon_pwm:
                return max31790_write_pwm(dev, attr, channel, val);
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t max31790_is_visible(const void *data,
                                   enum hwmon_sensor_types type,
                                   u32 attr, int channel)
{
        switch (type) {
        case hwmon_fan:
                return max31790_fan_is_visible(data, attr, channel);
        case hwmon_pwm:
                return max31790_pwm_is_visible(data, attr, channel);
        default:
                return 0;
        }
}

static const struct hwmon_channel_info * const max31790_info[] = {
        HWMON_CHANNEL_INFO(fan,
                           HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
                           HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
                           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_ENABLE,
                           HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
                           HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
                           HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
                           HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
                           HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
        NULL
};

static const struct hwmon_ops max31790_hwmon_ops = {
        .is_visible = max31790_is_visible,
        .read = max31790_read,
        .write = max31790_write,
};

static const struct hwmon_chip_info max31790_chip_info = {
        .ops = &max31790_hwmon_ops,
        .info = max31790_info,
};

static int max31790_init_client(struct i2c_client *client,
                                struct max31790_data *data)
{
        int i, rv;

        for (i = 0; i < NR_CHANNEL; i++) {
                rv = i2c_smbus_read_byte_data(client,
                                MAX31790_REG_FAN_CONFIG(i));
                if (rv < 0)
                        return rv;
                data->fan_config[i] = rv;

                rv = i2c_smbus_read_byte_data(client,
                                MAX31790_REG_FAN_DYNAMICS(i));
                if (rv < 0)
                        return rv;
                data->fan_dynamics[i] = rv;
        }

        return 0;
}

static int max31790_probe(struct i2c_client *client)
{
        struct i2c_adapter *adapter = client->adapter;
        struct device *dev = &client->dev;
        struct max31790_data *data;
        struct device *hwmon_dev;
        int err;

        if (!i2c_check_functionality(adapter,
                        I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
                return -ENODEV;

        data = devm_kzalloc(dev, sizeof(struct max31790_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->client = client;

        /*
         * Initialize the max31790 chip
         */
        err = max31790_init_client(client, data);
        if (err)
                return err;

        hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
                                                         data,
                                                         &max31790_chip_info,
                                                         NULL);

        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id max31790_id[] = {
        { "max31790" },
        { }
};
MODULE_DEVICE_TABLE(i2c, max31790_id);

static struct i2c_driver max31790_driver = {
        .probe          = max31790_probe,
        .driver = {
                .name   = "max31790",
        },
        .id_table       = max31790_id,
};

module_i2c_driver(max31790_driver);

MODULE_AUTHOR("Il Han <corone.il.han@gmail.com>");
MODULE_DESCRIPTION("MAX31790 sensor driver");
MODULE_LICENSE("GPL");