// SPDX-License-Identifier: GPL-2.0-only

/*
 * Driver for hwmon elements found on QNAP-MCU devices
 *
 * Copyright (C) 2024 Heiko Stuebner <heiko@sntech.de>
 */

#include <linux/hwmon.h>
#include <linux/mfd/qnap-mcu.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/thermal.h>

struct qnap_mcu_hwmon {
        struct qnap_mcu *mcu;
        struct device *dev;

        unsigned int pwm_min;
        unsigned int pwm_max;

        struct fwnode_handle *fan_node;
        unsigned int fan_state;
        unsigned int fan_max_state;
        unsigned int *fan_cooling_levels;

        struct thermal_cooling_device *cdev;
        struct hwmon_chip_info info;
};

static int qnap_mcu_hwmon_get_rpm(struct qnap_mcu_hwmon *hwm)
{
        static const u8 cmd[] = { '@', 'F', 'A' };
        u8 reply[6];
        int ret;

        /* poll the fan rpm */
        ret = qnap_mcu_exec(hwm->mcu, cmd, sizeof(cmd), reply, sizeof(reply));
        if (ret)
                return ret;

        /* First 2 bytes must mirror the sent command */
        if (memcmp(cmd, reply, 2))
                return -EIO;

        return reply[4] * 30;
}

static int qnap_mcu_hwmon_get_pwm(struct qnap_mcu_hwmon *hwm)
{
        static const u8 cmd[] = { '@', 'F', 'Z', '0' }; /* 0 = fan-id? */
        u8 reply[4];
        int ret;

        /* poll the fan pwm */
        ret = qnap_mcu_exec(hwm->mcu, cmd, sizeof(cmd), reply, sizeof(reply));
        if (ret)
                return ret;

        /* First 3 bytes must mirror the sent command */
        if (memcmp(cmd, reply, 3))
                return -EIO;

        return reply[3];
}

static int qnap_mcu_hwmon_set_pwm(struct qnap_mcu_hwmon *hwm, u8 pwm)
{
        const u8 cmd[] = { '@', 'F', 'W', '0', pwm }; /* 0 = fan-id?, pwm 0-255 */

        /* set the fan pwm */
        return qnap_mcu_exec_with_ack(hwm->mcu, cmd, sizeof(cmd));
}

static int qnap_mcu_hwmon_get_temp(struct qnap_mcu_hwmon *hwm)
{
        static const u8 cmd[] = { '@', 'T', '3' };
        u8 reply[4];
        int ret;

        /* poll the fan rpm */
        ret = qnap_mcu_exec(hwm->mcu, cmd, sizeof(cmd), reply, sizeof(reply));
        if (ret)
                return ret;

        /* First bytes must mirror the sent command */
        if (memcmp(cmd, reply, sizeof(cmd)))
                return -EIO;

        /*
         * There is an unknown bit set in bit7.
         * Bits [6:0] report the actual temperature as returned by the
         * original qnap firmware-tools, so just drop bit7 for now.
         */
        return (reply[3] & 0x7f) * 1000;
}

static int qnap_mcu_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
                                u32 attr, int channel, long val)
{
        struct qnap_mcu_hwmon *hwm = dev_get_drvdata(dev);

        switch (attr) {
        case hwmon_pwm_input:
                if (val < 0 || val > 255)
                        return -EINVAL;

                if (val != 0)
                        val = clamp_val(val, hwm->pwm_min, hwm->pwm_max);

                return qnap_mcu_hwmon_set_pwm(hwm, val);
        default:
                return -EOPNOTSUPP;
        }

        return 0;
}

static int qnap_mcu_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
                               u32 attr, int channel, long *val)
{
        struct qnap_mcu_hwmon *hwm = dev_get_drvdata(dev);
        int ret;

        switch (type) {
        case hwmon_pwm:
                switch (attr) {
                case hwmon_pwm_input:
                        ret = qnap_mcu_hwmon_get_pwm(hwm);
                        if (ret < 0)
                                return ret;

                        *val = ret;
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }
        case hwmon_fan:
                ret = qnap_mcu_hwmon_get_rpm(hwm);
                if (ret < 0)
                        return ret;

                *val = ret;
                return 0;
        case hwmon_temp:
                ret = qnap_mcu_hwmon_get_temp(hwm);
                if (ret < 0)
                        return ret;

                *val = ret;
                return 0;
        default:
                return -EOPNOTSUPP;
        }
}

static umode_t qnap_mcu_hwmon_is_visible(const void *data,
                                         enum hwmon_sensor_types type,
                                         u32 attr, int channel)
{
        switch (type) {
        case hwmon_temp:
                return 0444;

        case hwmon_pwm:
                return 0644;

        case hwmon_fan:
                return 0444;

        default:
                return 0;
        }
}

static const struct hwmon_ops qnap_mcu_hwmon_hwmon_ops = {
        .is_visible = qnap_mcu_hwmon_is_visible,
        .read = qnap_mcu_hwmon_read,
        .write = qnap_mcu_hwmon_write,
};

/* thermal cooling device callbacks */
static int qnap_mcu_hwmon_get_max_state(struct thermal_cooling_device *cdev,
                                        unsigned long *state)
{
        struct qnap_mcu_hwmon *hwm = cdev->devdata;

        if (!hwm)
                return -EINVAL;

        *state = hwm->fan_max_state;

        return 0;
}

static int qnap_mcu_hwmon_get_cur_state(struct thermal_cooling_device *cdev,
                                        unsigned long *state)
{
        struct qnap_mcu_hwmon *hwm = cdev->devdata;

        if (!hwm)
                return -EINVAL;

        *state = hwm->fan_state;

        return 0;
}

static int qnap_mcu_hwmon_set_cur_state(struct thermal_cooling_device *cdev,
                                        unsigned long state)
{
        struct qnap_mcu_hwmon *hwm = cdev->devdata;
        int ret;

        if (!hwm || state > hwm->fan_max_state)
                return -EINVAL;

        if (state == hwm->fan_state)
                return 0;

        ret = qnap_mcu_hwmon_set_pwm(hwm, hwm->fan_cooling_levels[state]);
        if (ret)
                return ret;

        hwm->fan_state = state;

        return ret;
}

static const struct thermal_cooling_device_ops qnap_mcu_hwmon_cooling_ops = {
        .get_max_state = qnap_mcu_hwmon_get_max_state,
        .get_cur_state = qnap_mcu_hwmon_get_cur_state,
        .set_cur_state = qnap_mcu_hwmon_set_cur_state,
};

static void devm_fan_node_release(void *data)
{
        struct qnap_mcu_hwmon *hwm = data;

        fwnode_handle_put(hwm->fan_node);
}

static int qnap_mcu_hwmon_get_cooling_data(struct device *dev, struct qnap_mcu_hwmon *hwm)
{
        struct fwnode_handle *fwnode;
        int num, i, ret;

        fwnode = device_get_named_child_node(dev->parent, "fan-0");
        if (!fwnode)
                return 0;

        /* if we found the fan-node, we're keeping it until device-unbind */
        hwm->fan_node = fwnode;
        ret = devm_add_action_or_reset(dev, devm_fan_node_release, hwm);
        if (ret)
                return ret;

        num = fwnode_property_count_u32(fwnode, "cooling-levels");
        if (num <= 0)
                return dev_err_probe(dev, num ? : -EINVAL,
                                     "Failed to count elements in 'cooling-levels'\n");

        hwm->fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
                                               GFP_KERNEL);
        if (!hwm->fan_cooling_levels)
                return -ENOMEM;

        ret = fwnode_property_read_u32_array(fwnode, "cooling-levels",
                                             hwm->fan_cooling_levels, num);
        if (ret)
                return dev_err_probe(dev, ret, "Failed to read 'cooling-levels'\n");

        for (i = 0; i < num; i++) {
                if (hwm->fan_cooling_levels[i] > hwm->pwm_max)
                        return dev_err_probe(dev, -EINVAL, "fan state[%d]:%d > %d\n", i,
                                             hwm->fan_cooling_levels[i], hwm->pwm_max);
        }

        hwm->fan_max_state = num - 1;

        return 0;
}

static const struct hwmon_channel_info * const qnap_mcu_hwmon_channels[] = {
        HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT),
        HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
        HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
        NULL
};

static int qnap_mcu_hwmon_probe(struct platform_device *pdev)
{
        struct qnap_mcu *mcu = dev_get_drvdata(pdev->dev.parent);
        const struct qnap_mcu_variant *variant = pdev->dev.platform_data;
        struct qnap_mcu_hwmon *hwm;
        struct thermal_cooling_device *cdev;
        struct device *dev = &pdev->dev;
        struct device *hwmon;
        int ret;

        hwm = devm_kzalloc(dev, sizeof(*hwm), GFP_KERNEL);
        if (!hwm)
                return -ENOMEM;

        hwm->mcu = mcu;
        hwm->dev = &pdev->dev;
        hwm->pwm_min = variant->fan_pwm_min;
        hwm->pwm_max = variant->fan_pwm_max;

        platform_set_drvdata(pdev, hwm);

        /*
         * Set duty cycle to maximum allowed.
         */
        ret = qnap_mcu_hwmon_set_pwm(hwm, hwm->pwm_max);
        if (ret)
                return ret;

        hwm->info.ops = &qnap_mcu_hwmon_hwmon_ops;
        hwm->info.info = qnap_mcu_hwmon_channels;

        ret = qnap_mcu_hwmon_get_cooling_data(dev, hwm);
        if (ret)
                return ret;

        hwm->fan_state = hwm->fan_max_state;

        hwmon = devm_hwmon_device_register_with_info(dev, "qnapmcu",
                                                     hwm, &hwm->info, NULL);
        if (IS_ERR(hwmon))
                return dev_err_probe(dev, PTR_ERR(hwmon), "Failed to register hwmon device\n");

        /*
         * Only register cooling device when we found cooling-levels.
         * qnap_mcu_hwmon_get_cooling_data() will fail when reading malformed
         * levels and only succeed with either no or correct cooling levels.
         */
        if (IS_ENABLED(CONFIG_THERMAL) && hwm->fan_cooling_levels) {
                cdev = devm_thermal_of_cooling_device_register(dev,
                                        to_of_node(hwm->fan_node), "qnap-mcu-hwmon",
                                        hwm, &qnap_mcu_hwmon_cooling_ops);
                if (IS_ERR(cdev))
                        return dev_err_probe(dev, PTR_ERR(cdev),
                                "Failed to register qnap-mcu-hwmon as cooling device\n");
                hwm->cdev = cdev;
        }

        return 0;
}

static struct platform_driver qnap_mcu_hwmon_driver = {
        .probe = qnap_mcu_hwmon_probe,
        .driver = {
                .name = "qnap-mcu-hwmon",
        },
};
module_platform_driver(qnap_mcu_hwmon_driver);

MODULE_ALIAS("platform:qnap-mcu-hwmon");
MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
MODULE_DESCRIPTION("QNAP MCU hwmon driver");
MODULE_LICENSE("GPL");