// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * corsair-psu.c - Linux driver for Corsair power supplies with HID sensors interface
 * Copyright (C) 2020 Wilken Gottwalt <wilken.gottwalt@posteo.net>
 */

#include <linux/completion.h>
#include <linux/debugfs.h>
#include <linux/errno.h>
#include <linux/hid.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/types.h>

/*
 * Corsair protocol for PSUs
 *
 * message size = 64 bytes (request and response, little endian)
 * request:
 *      [length][command][param0][param1][paramX]...
 * reply:
 *      [echo of length][echo of command][data0][data1][dataX]...
 *
 *      - commands are byte sized opcodes
 *      - length is the sum of all bytes of the commands/params
 *      - the micro-controller of most of these PSUs support concatenation in the request and reply,
 *        but it is better to not rely on this (it is also hard to parse)
 *      - the driver uses raw events to be accessible from userspace (though this is not really
 *        supported, it is just there for convenience, may be removed in the future)
 *      - a reply always start with the length and command in the same order the request used it
 *      - length of the reply data is specific to the command used
 *      - some of the commands work on a rail and can be switched to a specific rail (0 = 12v,
 *        1 = 5v, 2 = 3.3v)
 *      - the format of the init command 0xFE is swapped length/command bytes
 *      - parameter bytes amount and values are specific to the command (rail setting is the only
 *        for now that uses non-zero values)
 *      - there are much more commands, especially for configuring the device, but they are not
 *        supported because a wrong command/length can lockup the micro-controller
 *      - the driver supports debugfs for values not fitting into the hwmon class
 *      - not every device class (HXi, RMi or AXi) supports all commands
 *      - it is a pure sensors reading driver (will not support configuring)
 */

#define DRIVER_NAME             "corsair-psu"

#define REPLY_SIZE              16 /* max length of a reply to a single command */
#define CMD_BUFFER_SIZE         64
#define CMD_TIMEOUT_MS          250
#define SECONDS_PER_HOUR        (60 * 60)
#define SECONDS_PER_DAY         (SECONDS_PER_HOUR * 24)

#define PSU_CMD_SELECT_RAIL     0x00 /* expects length 2 */
#define PSU_CMD_IN_VOLTS        0x88 /* the rest of the commands expect length 3 */
#define PSU_CMD_IN_AMPS         0x89
#define PSU_CMD_RAIL_OUT_VOLTS  0x8B
#define PSU_CMD_RAIL_AMPS       0x8C
#define PSU_CMD_TEMP0           0x8D
#define PSU_CMD_TEMP1           0x8E
#define PSU_CMD_FAN             0x90
#define PSU_CMD_RAIL_WATTS      0x96
#define PSU_CMD_VEND_STR        0x99
#define PSU_CMD_PROD_STR        0x9A
#define PSU_CMD_TOTAL_WATTS     0xEE
#define PSU_CMD_TOTAL_UPTIME    0xD1
#define PSU_CMD_UPTIME          0xD2
#define PSU_CMD_INIT            0xFE

#define L_IN_VOLTS              "v_in"
#define L_OUT_VOLTS_12V         "v_out +12v"
#define L_OUT_VOLTS_5V          "v_out +5v"
#define L_OUT_VOLTS_3_3V        "v_out +3.3v"
#define L_IN_AMPS               "curr in"
#define L_AMPS_12V              "curr +12v"
#define L_AMPS_5V               "curr +5v"
#define L_AMPS_3_3V             "curr +3.3v"
#define L_FAN                   "psu fan"
#define L_TEMP0                 "vrm temp"
#define L_TEMP1                 "case temp"
#define L_WATTS                 "power total"
#define L_WATTS_12V             "power +12v"
#define L_WATTS_5V              "power +5v"
#define L_WATTS_3_3V            "power +3.3v"

static const char *const label_watts[] = {
        L_WATTS,
        L_WATTS_12V,
        L_WATTS_5V,
        L_WATTS_3_3V
};

static const char *const label_volts[] = {
        L_IN_VOLTS,
        L_OUT_VOLTS_12V,
        L_OUT_VOLTS_5V,
        L_OUT_VOLTS_3_3V
};

static const char *const label_amps[] = {
        L_IN_AMPS,
        L_AMPS_12V,
        L_AMPS_5V,
        L_AMPS_3_3V
};

struct corsairpsu_data {
        struct hid_device *hdev;
        struct device *hwmon_dev;
        struct dentry *debugfs;
        struct completion wait_completion;
        struct mutex lock; /* for locking access to cmd_buffer */
        u8 *cmd_buffer;
        char vendor[REPLY_SIZE];
        char product[REPLY_SIZE];
};

/* some values are SMBus LINEAR11 data which need a conversion */
static int corsairpsu_linear11_to_int(const int val)
{
        int exp = (val & 0xFFFF) >> 0x0B;
        int mant = val & 0x7FF;
        int i;

        if (exp > 0x0F)
                exp -= 0x20;
        if (mant > 0x3FF)
                mant -= 0x800;
        if ((mant & 0x01) == 1)
                ++mant;
        if (exp < 0) {
                for (i = 0; i < -exp; ++i)
                        mant /= 2;
        } else {
                for (i = 0; i < exp; ++i)
                        mant *= 2;
        }

        return mant;
}

static int corsairpsu_usb_cmd(struct corsairpsu_data *priv, u8 p0, u8 p1, u8 p2, void *data)
{
        unsigned long time;
        int ret;

        memset(priv->cmd_buffer, 0, CMD_BUFFER_SIZE);
        priv->cmd_buffer[0] = p0;
        priv->cmd_buffer[1] = p1;
        priv->cmd_buffer[2] = p2;

        reinit_completion(&priv->wait_completion);

        ret = hid_hw_output_report(priv->hdev, priv->cmd_buffer, CMD_BUFFER_SIZE);
        if (ret < 0)
                return ret;

        time = wait_for_completion_timeout(&priv->wait_completion,
                                           msecs_to_jiffies(CMD_TIMEOUT_MS));
        if (!time)
                return -ETIMEDOUT;

        /*
         * at the start of the reply is an echo of the send command/length in the same order it
         * was send, not every command is supported on every device class, if a command is not
         * supported, the length value in the reply is okay, but the command value is set to 0
         */
        if (p0 != priv->cmd_buffer[0] || p1 != priv->cmd_buffer[1])
                return -EOPNOTSUPP;

        if (data)
                memcpy(data, priv->cmd_buffer + 2, REPLY_SIZE);

        return 0;
}

static int corsairpsu_init(struct corsairpsu_data *priv)
{
        /*
         * PSU_CMD_INIT uses swapped length/command and expects 2 parameter bytes, this command
         * actually generates a reply, but we don't need it
         */
        return corsairpsu_usb_cmd(priv, PSU_CMD_INIT, 3, 0, NULL);
}

static int corsairpsu_fwinfo(struct corsairpsu_data *priv)
{
        int ret;

        ret = corsairpsu_usb_cmd(priv, 3, PSU_CMD_VEND_STR, 0, priv->vendor);
        if (ret < 0)
                return ret;

        ret = corsairpsu_usb_cmd(priv, 3, PSU_CMD_PROD_STR, 0, priv->product);
        if (ret < 0)
                return ret;

        return 0;
}

static int corsairpsu_request(struct corsairpsu_data *priv, u8 cmd, u8 rail, void *data)
{
        int ret;

        mutex_lock(&priv->lock);
        switch (cmd) {
        case PSU_CMD_RAIL_OUT_VOLTS:
        case PSU_CMD_RAIL_AMPS:
        case PSU_CMD_RAIL_WATTS:
                ret = corsairpsu_usb_cmd(priv, 2, PSU_CMD_SELECT_RAIL, rail, NULL);
                if (ret < 0)
                        goto cmd_fail;
                break;
        default:
                break;
        }

        ret = corsairpsu_usb_cmd(priv, 3, cmd, 0, data);

cmd_fail:
        mutex_unlock(&priv->lock);
        return ret;
}

static int corsairpsu_get_value(struct corsairpsu_data *priv, u8 cmd, u8 rail, long *val)
{
        u8 data[REPLY_SIZE];
        long tmp;
        int ret;

        ret = corsairpsu_request(priv, cmd, rail, data);
        if (ret < 0)
                return ret;

        /*
         * the biggest value here comes from the uptime command and to exceed MAXINT total uptime
         * needs to be about 68 years, the rest are u16 values and the biggest value coming out of
         * the LINEAR11 conversion are the watts values which are about 1200 for the strongest psu
         * supported (HX1200i)
         */
        tmp = ((long)data[3] << 24) + (data[2] << 16) + (data[1] << 8) + data[0];
        switch (cmd) {
        case PSU_CMD_IN_VOLTS:
        case PSU_CMD_IN_AMPS:
        case PSU_CMD_RAIL_OUT_VOLTS:
        case PSU_CMD_RAIL_AMPS:
        case PSU_CMD_TEMP0:
        case PSU_CMD_TEMP1:
                *val = corsairpsu_linear11_to_int(tmp & 0xFFFF) * 1000;
                break;
        case PSU_CMD_FAN:
                *val = corsairpsu_linear11_to_int(tmp & 0xFFFF);
                break;
        case PSU_CMD_RAIL_WATTS:
        case PSU_CMD_TOTAL_WATTS:
                *val = corsairpsu_linear11_to_int(tmp & 0xFFFF) * 1000000;
                break;
        case PSU_CMD_TOTAL_UPTIME:
        case PSU_CMD_UPTIME:
                *val = tmp;
                break;
        default:
                ret = -EOPNOTSUPP;
                break;
        }

        return ret;
}

static umode_t corsairpsu_hwmon_ops_is_visible(const void *data, enum hwmon_sensor_types type,
                                               u32 attr, int channel)
{
        if (type == hwmon_temp && (attr == hwmon_temp_input || attr == hwmon_temp_label))
                return 0444;
        else if (type == hwmon_fan && (attr == hwmon_fan_input || attr == hwmon_fan_label))
                return 0444;
        else if (type == hwmon_power && (attr == hwmon_power_input || attr == hwmon_power_label))
                return 0444;
        else if (type == hwmon_in && (attr == hwmon_in_input || attr == hwmon_in_label))
                return 0444;
        else if (type == hwmon_curr && (attr == hwmon_curr_input || attr == hwmon_curr_label))
                return 0444;

        return 0;
}

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

        if (type == hwmon_temp && attr == hwmon_temp_input && channel < 2) {
                ret = corsairpsu_get_value(priv, channel ? PSU_CMD_TEMP1 : PSU_CMD_TEMP0, channel,
                                           val);
        } else if (type == hwmon_fan && attr == hwmon_fan_input) {
                ret = corsairpsu_get_value(priv, PSU_CMD_FAN, 0, val);
        } else if (type == hwmon_power && attr == hwmon_power_input) {
                switch (channel) {
                case 0:
                        ret = corsairpsu_get_value(priv, PSU_CMD_TOTAL_WATTS, 0, val);
                        break;
                case 1 ... 3:
                        ret = corsairpsu_get_value(priv, PSU_CMD_RAIL_WATTS, channel - 1, val);
                        break;
                default:
                        return -EOPNOTSUPP;
                }
        } else if (type == hwmon_in && attr == hwmon_in_input) {
                switch (channel) {
                case 0:
                        ret = corsairpsu_get_value(priv, PSU_CMD_IN_VOLTS, 0, val);
                        break;
                case 1 ... 3:
                        ret = corsairpsu_get_value(priv, PSU_CMD_RAIL_OUT_VOLTS, channel - 1, val);
                        break;
                default:
                        return -EOPNOTSUPP;
                }
        } else if (type == hwmon_curr && attr == hwmon_curr_input) {
                switch (channel) {
                case 0:
                        ret = corsairpsu_get_value(priv, PSU_CMD_IN_AMPS, 0, val);
                        break;
                case 1 ... 3:
                        ret = corsairpsu_get_value(priv, PSU_CMD_RAIL_AMPS, channel - 1, val);
                        break;
                default:
                        return -EOPNOTSUPP;
                }
        } else {
                return -EOPNOTSUPP;
        }

        if (ret < 0)
                return ret;

        return 0;
}

static int corsairpsu_hwmon_ops_read_string(struct device *dev, enum hwmon_sensor_types type,
                                            u32 attr, int channel, const char **str)
{
        if (type == hwmon_temp && attr == hwmon_temp_label) {
                *str = channel ? L_TEMP1 : L_TEMP0;
                return 0;
        } else if (type == hwmon_fan && attr == hwmon_fan_label) {
                *str = L_FAN;
                return 0;
        } else if (type == hwmon_power && attr == hwmon_power_label && channel < 4) {
                *str = label_watts[channel];
                return 0;
        } else if (type == hwmon_in && attr == hwmon_in_label && channel < 4) {
                *str = label_volts[channel];
                return 0;
        } else if (type == hwmon_curr && attr == hwmon_curr_label && channel < 4) {
                *str = label_amps[channel];
                return 0;
        }

        return -EOPNOTSUPP;
}

static const struct hwmon_ops corsairpsu_hwmon_ops = {
        .is_visible     = corsairpsu_hwmon_ops_is_visible,
        .read           = corsairpsu_hwmon_ops_read,
        .read_string    = corsairpsu_hwmon_ops_read_string,
};

static const struct hwmon_channel_info *corsairpsu_info[] = {
        HWMON_CHANNEL_INFO(chip,
                           HWMON_C_REGISTER_TZ),
        HWMON_CHANNEL_INFO(temp,
                           HWMON_T_INPUT | HWMON_T_LABEL,
                           HWMON_T_INPUT | HWMON_T_LABEL),
        HWMON_CHANNEL_INFO(fan,
                           HWMON_F_INPUT | HWMON_F_LABEL),
        HWMON_CHANNEL_INFO(power,
                           HWMON_P_INPUT | HWMON_P_LABEL,
                           HWMON_P_INPUT | HWMON_P_LABEL,
                           HWMON_P_INPUT | HWMON_P_LABEL,
                           HWMON_P_INPUT | HWMON_P_LABEL),
        HWMON_CHANNEL_INFO(in,
                           HWMON_I_INPUT | HWMON_I_LABEL,
                           HWMON_I_INPUT | HWMON_I_LABEL,
                           HWMON_I_INPUT | HWMON_I_LABEL,
                           HWMON_I_INPUT | HWMON_I_LABEL),
        HWMON_CHANNEL_INFO(curr,
                           HWMON_C_INPUT | HWMON_C_LABEL,
                           HWMON_C_INPUT | HWMON_C_LABEL,
                           HWMON_C_INPUT | HWMON_C_LABEL,
                           HWMON_C_INPUT | HWMON_C_LABEL),
        NULL
};

static const struct hwmon_chip_info corsairpsu_chip_info = {
        .ops    = &corsairpsu_hwmon_ops,
        .info   = corsairpsu_info,
};

#ifdef CONFIG_DEBUG_FS

static void print_uptime(struct seq_file *seqf, u8 cmd)
{
        struct corsairpsu_data *priv = seqf->private;
        long val;
        int ret;

        ret = corsairpsu_get_value(priv, cmd, 0, &val);
        if (ret < 0) {
                seq_puts(seqf, "N/A\n");
                return;
        }

        if (val > SECONDS_PER_DAY) {
                seq_printf(seqf, "%ld day(s), %02ld:%02ld:%02ld\n", val / SECONDS_PER_DAY,
                           val % SECONDS_PER_DAY / SECONDS_PER_HOUR, val % SECONDS_PER_HOUR / 60,
                           val % 60);
                return;
        }

        seq_printf(seqf, "%02ld:%02ld:%02ld\n", val % SECONDS_PER_DAY / SECONDS_PER_HOUR,
                   val % SECONDS_PER_HOUR / 60, val % 60);
}

static int uptime_show(struct seq_file *seqf, void *unused)
{
        print_uptime(seqf, PSU_CMD_UPTIME);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(uptime);

static int uptime_total_show(struct seq_file *seqf, void *unused)
{
        print_uptime(seqf, PSU_CMD_TOTAL_UPTIME);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(uptime_total);

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

        seq_printf(seqf, "%s\n", priv->vendor);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(vendor);

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

        seq_printf(seqf, "%s\n", priv->product);

        return 0;
}
DEFINE_SHOW_ATTRIBUTE(product);

static void corsairpsu_debugfs_init(struct corsairpsu_data *priv)
{
        char name[32];

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

        priv->debugfs = debugfs_create_dir(name, NULL);
        debugfs_create_file("uptime", 0444, priv->debugfs, priv, &uptime_fops);
        debugfs_create_file("uptime_total", 0444, priv->debugfs, priv, &uptime_total_fops);
        debugfs_create_file("vendor", 0444, priv->debugfs, priv, &vendor_fops);
        debugfs_create_file("product", 0444, priv->debugfs, priv, &product_fops);
}

#else

static void corsairpsu_debugfs_init(struct corsairpsu_data *priv)
{
}

#endif

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

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

        priv->cmd_buffer = devm_kmalloc(&hdev->dev, CMD_BUFFER_SIZE, GFP_KERNEL);
        if (!priv->cmd_buffer)
                return -ENOMEM;

        ret = hid_parse(hdev);
        if (ret)
                return ret;

        ret = hid_hw_start(hdev, HID_CONNECT_HIDRAW);
        if (ret)
                return ret;

        ret = hid_hw_open(hdev);
        if (ret)
                goto fail_and_stop;

        priv->hdev = hdev;
        hid_set_drvdata(hdev, priv);
        mutex_init(&priv->lock);
        init_completion(&priv->wait_completion);

        hid_device_io_start(hdev);

        ret = corsairpsu_init(priv);
        if (ret < 0) {
                dev_err(&hdev->dev, "unable to initialize device (%d)\n", ret);
                goto fail_and_stop;
        }

        ret = corsairpsu_fwinfo(priv);
        if (ret < 0) {
                dev_err(&hdev->dev, "unable to query firmware (%d)\n", ret);
                goto fail_and_stop;
        }

        priv->hwmon_dev = hwmon_device_register_with_info(&hdev->dev, "corsairpsu", priv,
                                                          &corsairpsu_chip_info, 0);

        if (IS_ERR(priv->hwmon_dev)) {
                ret = PTR_ERR(priv->hwmon_dev);
                goto fail_and_close;
        }

        corsairpsu_debugfs_init(priv);

        return 0;

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

static void corsairpsu_remove(struct hid_device *hdev)
{
        struct corsairpsu_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 int corsairpsu_raw_event(struct hid_device *hdev, struct hid_report *report, u8 *data,
                                int size)
{
        struct corsairpsu_data *priv = hid_get_drvdata(hdev);

        if (completion_done(&priv->wait_completion))
                return 0;

        memcpy(priv->cmd_buffer, data, min(CMD_BUFFER_SIZE, size));
        complete(&priv->wait_completion);

        return 0;
}

static const struct hid_device_id corsairpsu_idtable[] = {
        { HID_USB_DEVICE(0x1b1c, 0x1c03) }, /* Corsair HX550i */
        { HID_USB_DEVICE(0x1b1c, 0x1c04) }, /* Corsair HX650i */
        { HID_USB_DEVICE(0x1b1c, 0x1c05) }, /* Corsair HX750i */
        { HID_USB_DEVICE(0x1b1c, 0x1c06) }, /* Corsair HX850i */
        { HID_USB_DEVICE(0x1b1c, 0x1c07) }, /* Corsair HX1000i */
        { HID_USB_DEVICE(0x1b1c, 0x1c08) }, /* Corsair HX1200i */
        { HID_USB_DEVICE(0x1b1c, 0x1c09) }, /* Corsair RM550i */
        { HID_USB_DEVICE(0x1b1c, 0x1c0a) }, /* Corsair RM650i */
        { HID_USB_DEVICE(0x1b1c, 0x1c0b) }, /* Corsair RM750i */
        { HID_USB_DEVICE(0x1b1c, 0x1c0c) }, /* Corsair RM850i */
        { HID_USB_DEVICE(0x1b1c, 0x1c0d) }, /* Corsair RM1000i */
        { },
};
MODULE_DEVICE_TABLE(hid, corsairpsu_idtable);

static struct hid_driver corsairpsu_driver = {
        .name           = DRIVER_NAME,
        .id_table       = corsairpsu_idtable,
        .probe          = corsairpsu_probe,
        .remove         = corsairpsu_remove,
        .raw_event      = corsairpsu_raw_event,
};
module_hid_driver(corsairpsu_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Wilken Gottwalt <wilken.gottwalt@posteo.net>");
MODULE_DESCRIPTION("Linux driver for Corsair power supplies with HID sensors interface");