root/drivers/hwmon/powerz.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Copyright (C) 2023 Thomas Weißschuh <linux@weissschuh.net>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/completion.h>
#include <linux/device.h>
#include <linux/hwmon.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/types.h>
#include <linux/usb.h>

#define DRIVER_NAME     "powerz"
#define POWERZ_EP_CMD_OUT       0x01
#define POWERZ_EP_DATA_IN       0x81

struct powerz_sensor_data {
        u8 _unknown_1[8];
        __le32 V_bus;
        __le32 I_bus;
        __le32 V_bus_avg;
        __le32 I_bus_avg;
        u8 _unknown_2[8];
        u8 temp[2];
        __le16 V_cc1;
        __le16 V_cc2;
        __le16 V_dp;
        __le16 V_dm;
        __le16 V_dd;
        u8 _unknown_3[4];
} __packed;

struct powerz_priv {
        char transfer_buffer[64];       /* first member to satisfy DMA alignment */
        struct mutex mutex;
        struct completion completion;
        struct urb *urb;
        int status;
};

static const struct hwmon_channel_info *const powerz_info[] = {
        HWMON_CHANNEL_INFO(in,
                           HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_AVERAGE,
                           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_I_INPUT | HWMON_I_LABEL),
        HWMON_CHANNEL_INFO(curr,
                           HWMON_C_INPUT | HWMON_C_LABEL | HWMON_C_AVERAGE),
            HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_LABEL),
        NULL
};

static int powerz_read_string(struct device *dev, enum hwmon_sensor_types type,
                              u32 attr, int channel, const char **str)
{
        if (type == hwmon_curr && attr == hwmon_curr_label) {
                *str = "IBUS";
        } else if (type == hwmon_in && attr == hwmon_in_label) {
                if (channel == 0)
                        *str = "VBUS";
                else if (channel == 1)
                        *str = "VCC1";
                else if (channel == 2)
                        *str = "VCC2";
                else if (channel == 3)
                        *str = "VDP";
                else if (channel == 4)
                        *str = "VDM";
                else if (channel == 5)
                        *str = "VDD";
                else
                        return -EOPNOTSUPP;
        } else if (type == hwmon_temp && attr == hwmon_temp_label) {
                *str = "TEMP";
        } else {
                return -EOPNOTSUPP;
        }

        return 0;
}

static void powerz_usb_data_complete(struct urb *urb)
{
        struct powerz_priv *priv = urb->context;

        complete(&priv->completion);
}

static void powerz_usb_cmd_complete(struct urb *urb)
{
        struct powerz_priv *priv = urb->context;

        usb_fill_bulk_urb(urb, urb->dev,
                          usb_rcvbulkpipe(urb->dev, POWERZ_EP_DATA_IN),
                          priv->transfer_buffer, sizeof(priv->transfer_buffer),
                          powerz_usb_data_complete, priv);

        priv->status = usb_submit_urb(urb, GFP_ATOMIC);
        if (priv->status)
                complete(&priv->completion);
}

static int powerz_read_data(struct usb_device *udev, struct powerz_priv *priv)
{
        int ret;

        priv->status = -ETIMEDOUT;
        reinit_completion(&priv->completion);

        priv->transfer_buffer[0] = 0x0c;
        priv->transfer_buffer[1] = 0x00;
        priv->transfer_buffer[2] = 0x02;
        priv->transfer_buffer[3] = 0x00;

        usb_fill_bulk_urb(priv->urb, udev,
                          usb_sndbulkpipe(udev, POWERZ_EP_CMD_OUT),
                          priv->transfer_buffer, 4, powerz_usb_cmd_complete,
                          priv);
        ret = usb_submit_urb(priv->urb, GFP_KERNEL);
        if (ret)
                return ret;

        if (!wait_for_completion_interruptible_timeout
            (&priv->completion, msecs_to_jiffies(5))) {
                usb_kill_urb(priv->urb);
                return -EIO;
        }

        if (priv->urb->actual_length < sizeof(struct powerz_sensor_data))
                return -EIO;

        return priv->status;
}

static int powerz_read(struct device *dev, enum hwmon_sensor_types type,
                       u32 attr, int channel, long *val)
{
        struct usb_interface *intf = to_usb_interface(dev->parent);
        struct usb_device *udev = interface_to_usbdev(intf);
        struct powerz_priv *priv = usb_get_intfdata(intf);
        struct powerz_sensor_data *data;
        int ret;

        if (!priv)
                return -EIO;    /* disconnected */

        mutex_lock(&priv->mutex);
        ret = powerz_read_data(udev, priv);
        if (ret)
                goto out;

        data = (struct powerz_sensor_data *)priv->transfer_buffer;

        if (type == hwmon_curr) {
                if (attr == hwmon_curr_input)
                        *val = ((s32)le32_to_cpu(data->I_bus)) / 1000;
                else if (attr == hwmon_curr_average)
                        *val = ((s32)le32_to_cpu(data->I_bus_avg)) / 1000;
                else
                        ret = -EOPNOTSUPP;
        } else if (type == hwmon_in) {
                if (attr == hwmon_in_input) {
                        if (channel == 0)
                                *val = le32_to_cpu(data->V_bus) / 1000;
                        else if (channel == 1)
                                *val = le16_to_cpu(data->V_cc1) / 10;
                        else if (channel == 2)
                                *val = le16_to_cpu(data->V_cc2) / 10;
                        else if (channel == 3)
                                *val = le16_to_cpu(data->V_dp) / 10;
                        else if (channel == 4)
                                *val = le16_to_cpu(data->V_dm) / 10;
                        else if (channel == 5)
                                *val = le16_to_cpu(data->V_dd) / 10;
                        else
                                ret = -EOPNOTSUPP;
                } else if (attr == hwmon_in_average && channel == 0) {
                        *val = le32_to_cpu(data->V_bus_avg) / 1000;
                } else {
                        ret = -EOPNOTSUPP;
                }
        } else if (type == hwmon_temp && attr == hwmon_temp_input) {
                *val = data->temp[1] * 2000 + data->temp[0] * 1000 / 128;
        } else {
                ret = -EOPNOTSUPP;
        }

out:
        mutex_unlock(&priv->mutex);
        return ret;
}

static const struct hwmon_ops powerz_hwmon_ops = {
        .visible = 0444,
        .read = powerz_read,
        .read_string = powerz_read_string,
};

static const struct hwmon_chip_info powerz_chip_info = {
        .ops = &powerz_hwmon_ops,
        .info = powerz_info,
};

static int powerz_probe(struct usb_interface *intf,
                        const struct usb_device_id *id)
{
        struct powerz_priv *priv;
        struct device *hwmon_dev;
        struct device *parent;

        parent = &intf->dev;

        priv = devm_kzalloc(parent, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->urb = usb_alloc_urb(0, GFP_KERNEL);
        if (!priv->urb)
                return -ENOMEM;
        mutex_init(&priv->mutex);
        init_completion(&priv->completion);

        hwmon_dev =
            devm_hwmon_device_register_with_info(parent, DRIVER_NAME, priv,
                                                 &powerz_chip_info, NULL);
        if (IS_ERR(hwmon_dev)) {
                usb_free_urb(priv->urb);
                return PTR_ERR(hwmon_dev);
        }

        usb_set_intfdata(intf, priv);

        return 0;
}

static void powerz_disconnect(struct usb_interface *intf)
{
        struct powerz_priv *priv = usb_get_intfdata(intf);

        mutex_lock(&priv->mutex);
        usb_kill_urb(priv->urb);
        usb_free_urb(priv->urb);
        mutex_unlock(&priv->mutex);
}

static const struct usb_device_id powerz_id_table[] = {
        { USB_DEVICE_INTERFACE_NUMBER(0x5FC9, 0x0061, 0x00) },  /* ChargerLAB POWER-Z KM002C */
        { USB_DEVICE_INTERFACE_NUMBER(0x5FC9, 0x0063, 0x00) },  /* ChargerLAB POWER-Z KM003C */
        { }
};

MODULE_DEVICE_TABLE(usb, powerz_id_table);

static struct usb_driver powerz_driver = {
        .name = DRIVER_NAME,
        .id_table = powerz_id_table,
        .probe = powerz_probe,
        .disconnect = powerz_disconnect,
};

module_usb_driver(powerz_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Thomas Weißschuh <linux@weissschuh.net>");
MODULE_DESCRIPTION("ChargerLAB POWER-Z USB-C tester");