// SPDX-License-Identifier: GPL-2.0+
/*
 * hwmon driver for Gigabyte AORUS Waterforce AIO CPU coolers: X240, X280 and X360.
 *
 * Copyright 2023 Aleksa Savic <savicaleksa83@gmail.com>
 */

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

#define DRIVER_NAME     "gigabyte_waterforce"

#define USB_VENDOR_ID_GIGABYTE          0x1044
#define USB_PRODUCT_ID_WATERFORCE       0x7a4d  /* Gigabyte AORUS WATERFORCE X240, X280 and X360 */

#define STATUS_VALIDITY         (2 * 1000)      /* ms */
#define MAX_REPORT_LENGTH       6144

#define WATERFORCE_TEMP_SENSOR  0xD
#define WATERFORCE_FAN_SPEED    0x02
#define WATERFORCE_PUMP_SPEED   0x05
#define WATERFORCE_FAN_DUTY     0x08
#define WATERFORCE_PUMP_DUTY    0x09

/* Control commands, inner offsets and lengths */
static const u8 get_status_cmd[] = { 0x99, 0xDA };

#define FIRMWARE_VER_START_OFFSET_1     2
#define FIRMWARE_VER_START_OFFSET_2     3
static const u8 get_firmware_ver_cmd[] = { 0x99, 0xD6 };

/* Command lengths */
#define GET_STATUS_CMD_LENGTH           2
#define GET_FIRMWARE_VER_CMD_LENGTH     2

static const char *const waterforce_temp_label[] = {
        "Coolant temp"
};

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

struct waterforce_data {
        struct hid_device *hdev;
        struct device *hwmon_dev;
        struct dentry *debugfs;
        /* For locking access to buffer */
        struct mutex buffer_lock;
        /* For queueing multiple readers */
        struct mutex status_report_request_mutex;
        /* For reinitializing the completion below */
        spinlock_t status_report_request_lock;
        struct completion status_report_received;
        struct completion fw_version_processed;

        /* Sensor data */
        s32 temp_input[1];
        u16 speed_input[2];     /* Fan and pump speed in RPM */
        u8 duty_input[2];       /* Fan and pump duty in 0-100% */

        u8 *buffer;
        int firmware_version;
        unsigned long updated;  /* jiffies */
};

static umode_t waterforce_is_visible(const void *data,
                                     enum hwmon_sensor_types type, u32 attr, int channel)
{
        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_label:
                case hwmon_temp_input:
                        return 0444;
                default:
                        break;
                }
                break;
        case hwmon_fan:
                switch (attr) {
                case hwmon_fan_label:
                case hwmon_fan_input:
                        return 0444;
                default:
                        break;
                }
                break;
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        return 0444;
                default:
                        break;
                }
                break;
        default:
                break;
        }

        return 0;
}

/* Writes the command to the device with the rest of the report filled with zeroes */
static int waterforce_write_expanded(struct waterforce_data *priv, const u8 *cmd, int cmd_length)
{
        int ret;

        mutex_lock(&priv->buffer_lock);

        memcpy_and_pad(priv->buffer, MAX_REPORT_LENGTH, cmd, cmd_length, 0x00);
        ret = hid_hw_output_report(priv->hdev, priv->buffer, MAX_REPORT_LENGTH);

        mutex_unlock(&priv->buffer_lock);
        return ret;
}

static int waterforce_get_status(struct waterforce_data *priv)
{
        int ret = mutex_lock_interruptible(&priv->status_report_request_mutex);

        if (ret < 0)
                return ret;

        if (!time_after(jiffies, priv->updated + msecs_to_jiffies(STATUS_VALIDITY))) {
                /* Data is up to date */
                goto unlock_and_return;
        }

        /*
         * Disable raw event parsing for a moment to safely reinitialize the
         * completion. Reinit is done because hidraw could have triggered
         * the raw event parsing and marked the priv->status_report_received
         * completion as done.
         */
        spin_lock_bh(&priv->status_report_request_lock);
        reinit_completion(&priv->status_report_received);
        spin_unlock_bh(&priv->status_report_request_lock);

        /* Send command for getting status */
        ret = waterforce_write_expanded(priv, get_status_cmd, GET_STATUS_CMD_LENGTH);
        if (ret < 0)
                goto unlock_and_return;

        ret = wait_for_completion_interruptible_timeout(&priv->status_report_received,
                                                        msecs_to_jiffies(STATUS_VALIDITY));
        if (ret == 0)
                ret = -ETIMEDOUT;

unlock_and_return:
        mutex_unlock(&priv->status_report_request_mutex);
        if (ret < 0)
                return ret;

        return 0;
}

static int waterforce_read(struct device *dev, enum hwmon_sensor_types type,
                           u32 attr, int channel, long *val)
{
        struct waterforce_data *priv = dev_get_drvdata(dev);
        int ret = waterforce_get_status(priv);

        if (ret < 0)
                return ret;

        switch (type) {
        case hwmon_temp:
                *val = priv->temp_input[channel];
                break;
        case hwmon_fan:
                *val = priv->speed_input[channel];
                break;
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        *val = DIV_ROUND_CLOSEST(priv->duty_input[channel] * 255, 100);
                        break;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        default:
                return -EOPNOTSUPP;     /* unreachable */
        }

        return 0;
}

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

        return 0;
}

static int waterforce_get_fw_ver(struct hid_device *hdev)
{
        struct waterforce_data *priv = hid_get_drvdata(hdev);
        int ret;

        ret = waterforce_write_expanded(priv, get_firmware_ver_cmd, GET_FIRMWARE_VER_CMD_LENGTH);
        if (ret < 0)
                return ret;

        ret = wait_for_completion_interruptible_timeout(&priv->fw_version_processed,
                                                        msecs_to_jiffies(STATUS_VALIDITY));
        if (ret == 0)
                return -ETIMEDOUT;
        else if (ret < 0)
                return ret;

        return 0;
}

static const struct hwmon_ops waterforce_hwmon_ops = {
        .is_visible = waterforce_is_visible,
        .read = waterforce_read,
        .read_string = waterforce_read_string
};

static const struct hwmon_channel_info *waterforce_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),
        HWMON_CHANNEL_INFO(pwm,
                           HWMON_PWM_INPUT,
                           HWMON_PWM_INPUT),
        NULL
};

static const struct hwmon_chip_info waterforce_chip_info = {
        .ops = &waterforce_hwmon_ops,
        .info = waterforce_info,
};

static int waterforce_raw_event(struct hid_device *hdev, struct hid_report *report, u8 *data,
                                int size)
{
        struct waterforce_data *priv = hid_get_drvdata(hdev);

        if (data[0] == get_firmware_ver_cmd[0] && data[1] == get_firmware_ver_cmd[1]) {
                /* Received a firmware version report */
                priv->firmware_version =
                    data[FIRMWARE_VER_START_OFFSET_1] * 10 + data[FIRMWARE_VER_START_OFFSET_2];

                if (!completion_done(&priv->fw_version_processed))
                        complete_all(&priv->fw_version_processed);
                return 0;
        }

        if (data[0] != get_status_cmd[0] || data[1] != get_status_cmd[1])
                return 0;

        priv->temp_input[0] = data[WATERFORCE_TEMP_SENSOR] * 1000;
        priv->speed_input[0] = get_unaligned_le16(data + WATERFORCE_FAN_SPEED);
        priv->speed_input[1] = get_unaligned_le16(data + WATERFORCE_PUMP_SPEED);
        priv->duty_input[0] = data[WATERFORCE_FAN_DUTY];
        priv->duty_input[1] = data[WATERFORCE_PUMP_DUTY];

        spin_lock(&priv->status_report_request_lock);
        if (!completion_done(&priv->status_report_received))
                complete_all(&priv->status_report_received);
        spin_unlock(&priv->status_report_request_lock);

        priv->updated = jiffies;

        return 0;
}

static int firmware_version_show(struct seq_file *seqf, void *unused)
{
        struct waterforce_data *priv = seqf->private;

        seq_printf(seqf, "%u\n", priv->firmware_version);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(firmware_version);

static void waterforce_debugfs_init(struct waterforce_data *priv)
{
        char name[64];

        if (!priv->firmware_version)
                return; /* There's nothing to show in debugfs */

        scnprintf(name, sizeof(name), "%s-%s", DRIVER_NAME, dev_name(&priv->hdev->dev));

        priv->debugfs = debugfs_create_dir(name, NULL);
        debugfs_create_file("firmware_version", 0444, priv->debugfs, priv, &firmware_version_fops);
}

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

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

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

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

        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->buffer = devm_kzalloc(&hdev->dev, MAX_REPORT_LENGTH, GFP_KERNEL);
        if (!priv->buffer) {
                ret = -ENOMEM;
                goto fail_and_close;
        }

        mutex_init(&priv->status_report_request_mutex);
        mutex_init(&priv->buffer_lock);
        spin_lock_init(&priv->status_report_request_lock);
        init_completion(&priv->status_report_received);
        init_completion(&priv->fw_version_processed);

        hid_device_io_start(hdev);
        ret = waterforce_get_fw_ver(hdev);
        if (ret < 0)
                hid_warn(hdev, "fw version request failed with %d\n", ret);

        priv->hwmon_dev = hwmon_device_register_with_info(&hdev->dev, "waterforce",
                                                          priv, &waterforce_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;
        }

        waterforce_debugfs_init(priv);

        return 0;

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

static void waterforce_remove(struct hid_device *hdev)
{
        struct waterforce_data *priv = hid_get_drvdata(hdev);

        debugfs_remove_recursive(priv->debugfs);
        hwmon_device_unregister(priv->hwmon_dev);

        hid_hw_close(hdev);
        hid_hw_stop(hdev);
}

static const struct hid_device_id waterforce_table[] = {
        { HID_USB_DEVICE(USB_VENDOR_ID_GIGABYTE, USB_PRODUCT_ID_WATERFORCE) },
        { }
};

MODULE_DEVICE_TABLE(hid, waterforce_table);

static struct hid_driver waterforce_driver = {
        .name = "waterforce",
        .id_table = waterforce_table,
        .probe = waterforce_probe,
        .remove = waterforce_remove,
        .raw_event = waterforce_raw_event,
};

static int __init waterforce_init(void)
{
        return hid_register_driver(&waterforce_driver);
}

static void __exit waterforce_exit(void)
{
        hid_unregister_driver(&waterforce_driver);
}

/* When compiled into the kernel, initialize after the HID bus */
late_initcall(waterforce_init);
module_exit(waterforce_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Aleksa Savic <savicaleksa83@gmail.com>");
MODULE_DESCRIPTION("Hwmon driver for Gigabyte AORUS Waterforce AIO coolers");