// SPDX-License-Identifier: GPL-2.0+
/*
 * nzxt-kraken2.c - hwmon driver for NZXT Kraken X42/X52/X62/X72 coolers
 *
 * The device asynchronously sends HID reports (with id 0x04) twice a second to
 * communicate current fan speed, pump speed and coolant temperature.  The
 * device does not respond to Get_Report requests for this status report.
 *
 * Copyright 2019-2021  Jonas Malaco <jonas@protocubo.io>
 */

#include <linux/unaligned.h>
#include <linux/hid.h>
#include <linux/hwmon.h>
#include <linux/jiffies.h>
#include <linux/module.h>

#define STATUS_REPORT_ID        0x04
#define STATUS_VALIDITY         2 /* seconds; equivalent to 4 missed updates */

static const char *const kraken2_temp_label[] = {
        "Coolant",
};

static const char *const kraken2_fan_label[] = {
        "Fan",
        "Pump",
};

struct kraken2_priv_data {
        struct hid_device *hid_dev;
        struct device *hwmon_dev;
        s32 temp_input[1];
        u16 fan_input[2];
        unsigned long updated; /* jiffies */
};

static int kraken2_read(struct device *dev, enum hwmon_sensor_types type,
                        u32 attr, int channel, long *val)
{
        struct kraken2_priv_data *priv = dev_get_drvdata(dev);

        if (time_after(jiffies, priv->updated + STATUS_VALIDITY * HZ))
                return -ENODATA;

        switch (type) {
        case hwmon_temp:
                *val = priv->temp_input[channel];
                break;
        case hwmon_fan:
                *val = priv->fan_input[channel];
                break;
        default:
                return -EOPNOTSUPP; /* unreachable */
        }

        return 0;
}

static int kraken2_read_string(struct device *dev, enum hwmon_sensor_types type,
                               u32 attr, int channel, const char **str)
{
        switch (type) {
        case hwmon_temp:
                *str = kraken2_temp_label[channel];
                break;
        case hwmon_fan:
                *str = kraken2_fan_label[channel];
                break;
        default:
                return -EOPNOTSUPP; /* unreachable */
        }
        return 0;
}

static const struct hwmon_ops kraken2_hwmon_ops = {
        .visible = 0444,
        .read = kraken2_read,
        .read_string = kraken2_read_string,
};

static const struct hwmon_channel_info * const kraken2_info[] = {
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT | HWMON_T_LABEL),
        HWMON_CHANNEL_INFO(fan,
                           HWMON_F_INPUT | HWMON_F_LABEL,
                           HWMON_F_INPUT | HWMON_F_LABEL),
        NULL
};

static const struct hwmon_chip_info kraken2_chip_info = {
        .ops = &kraken2_hwmon_ops,
        .info = kraken2_info,
};

static int kraken2_raw_event(struct hid_device *hdev,
                             struct hid_report *report, u8 *data, int size)
{
        struct kraken2_priv_data *priv;

        if (size < 7 || report->id != STATUS_REPORT_ID)
                return 0;

        priv = hid_get_drvdata(hdev);

        /*
         * The fractional byte of the coolant temperature has been observed to
         * be in the interval [1,9], but some of these steps are also
         * consistently skipped for certain integer parts.
         *
         * For the lack of a better idea, assume that the resolution is 0.1°C,
         * and that the missing steps are artifacts of how the firmware
         * processes the raw sensor data.
         */
        priv->temp_input[0] = data[1] * 1000 + data[2] * 100;

        priv->fan_input[0] = get_unaligned_be16(data + 3);
        priv->fan_input[1] = get_unaligned_be16(data + 5);

        priv->updated = jiffies;

        return 0;
}

static int kraken2_probe(struct hid_device *hdev,
                         const struct hid_device_id *id)
{
        struct kraken2_priv_data *priv;
        int ret;

        priv = devm_kzalloc(&hdev->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->hid_dev = hdev;
        hid_set_drvdata(hdev, priv);

        /*
         * Initialize ->updated to STATUS_VALIDITY seconds in the past, making
         * the initial empty data invalid for kraken2_read without the need for
         * a special case there.
         */
        priv->updated = jiffies - STATUS_VALIDITY * HZ;

        ret = hid_parse(hdev);
        if (ret) {
                hid_err(hdev, "hid parse failed with %d\n", ret);
                return ret;
        }

        /*
         * Enable hidraw so existing user-space tools can continue to work.
         */
        ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
        if (ret) {
                hid_err(hdev, "hid hw start failed with %d\n", ret);
                return ret;
        }

        ret = hid_hw_open(hdev);
        if (ret) {
                hid_err(hdev, "hid hw open failed with %d\n", ret);
                goto fail_and_stop;
        }

        priv->hwmon_dev = hwmon_device_register_with_info(&hdev->dev, "kraken2",
                                                          priv, &kraken2_chip_info,
                                                          NULL);
        if (IS_ERR(priv->hwmon_dev)) {
                ret = PTR_ERR(priv->hwmon_dev);
                hid_err(hdev, "hwmon registration failed with %d\n", ret);
                goto fail_and_close;
        }

        return 0;

fail_and_close:
        hid_hw_close(hdev);
fail_and_stop:
        hid_hw_stop(hdev);
        return ret;
}

static void kraken2_remove(struct hid_device *hdev)
{
        struct kraken2_priv_data *priv = hid_get_drvdata(hdev);

        hwmon_device_unregister(priv->hwmon_dev);

        hid_hw_close(hdev);
        hid_hw_stop(hdev);
}

static const struct hid_device_id kraken2_table[] = {
        { HID_USB_DEVICE(0x1e71, 0x170e) }, /* NZXT Kraken X42/X52/X62/X72 */
        { }
};

MODULE_DEVICE_TABLE(hid, kraken2_table);

static struct hid_driver kraken2_driver = {
        .name = "nzxt-kraken2",
        .id_table = kraken2_table,
        .probe = kraken2_probe,
        .remove = kraken2_remove,
        .raw_event = kraken2_raw_event,
};

static int __init kraken2_init(void)
{
        return hid_register_driver(&kraken2_driver);
}

static void __exit kraken2_exit(void)
{
        hid_unregister_driver(&kraken2_driver);
}

/*
 * When compiled into the kernel, initialize after the hid bus.
 */
late_initcall(kraken2_init);
module_exit(kraken2_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jonas Malaco <jonas@protocubo.io>");
MODULE_DESCRIPTION("Hwmon driver for NZXT Kraken X42/X52/X62/X72 coolers");