// SPDX-License-Identifier: GPL-2.0+
/*
 * HID driver for Valve Steam Controller
 *
 * Copyright (c) 2018 Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>
 *
 * Supports both the wired and wireless interfaces.
 *
 * This controller has a builtin emulation of mouse and keyboard: the right pad
 * can be used as a mouse, the shoulder buttons are mouse buttons, A and B
 * buttons are ENTER and ESCAPE, and so on. This is implemented as additional
 * HID interfaces.
 *
 * This is known as the "lizard mode", because apparently lizards like to use
 * the computer from the coach, without a proper mouse and keyboard.
 *
 * This driver will disable the lizard mode when the input device is opened
 * and re-enable it when the input device is closed, so as not to break user
 * mode behaviour. The lizard_mode parameter can be used to change that.
 *
 * There are a few user space applications (notably Steam Client) that use
 * the hidraw interface directly to create input devices (XTest, uinput...).
 * In order to avoid breaking them this driver creates a layered hidraw device,
 * so it can detect when the client is running and then:
 *  - it will not send any command to the controller.
 *  - this input device will be disabled, to avoid double input of the same
 *    user action.
 *
 * For additional functions, such as changing the right-pad margin or switching
 * the led, you can use the user-space tool at:
 *
 *   https://github.com/rodrigorc/steamctrl
 */

#include <linux/device.h>
#include <linux/input.h>
#include <linux/hid.h>
#include <linux/module.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include <linux/rcupdate.h>
#include <linux/delay.h>
#include <linux/power_supply.h>
#include "hid-ids.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rodrigo Rivas Costa <rodrigorivascosta@gmail.com>");

static bool lizard_mode = true;

static DEFINE_MUTEX(steam_devices_lock);
static LIST_HEAD(steam_devices);

#define STEAM_QUIRK_WIRELESS            BIT(0)

/* Touch pads are 40 mm in diameter and 65535 units */
#define STEAM_PAD_RESOLUTION 1638
/* Trigger runs are about 5 mm and 256 units */
#define STEAM_TRIGGER_RESOLUTION 51
/* Joystick runs are about 5 mm and 256 units */
#define STEAM_JOYSTICK_RESOLUTION 51

#define STEAM_PAD_FUZZ 256

/*
 * Commands that can be sent in a feature report.
 * Thanks to Valve for some valuable hints.
 */
#define STEAM_CMD_SET_MAPPINGS          0x80
#define STEAM_CMD_CLEAR_MAPPINGS        0x81
#define STEAM_CMD_GET_MAPPINGS          0x82
#define STEAM_CMD_GET_ATTRIB            0x83
#define STEAM_CMD_GET_ATTRIB_LABEL      0x84
#define STEAM_CMD_DEFAULT_MAPPINGS      0x85
#define STEAM_CMD_FACTORY_RESET         0x86
#define STEAM_CMD_WRITE_REGISTER        0x87
#define STEAM_CMD_CLEAR_REGISTER        0x88
#define STEAM_CMD_READ_REGISTER         0x89
#define STEAM_CMD_GET_REGISTER_LABEL    0x8a
#define STEAM_CMD_GET_REGISTER_MAX      0x8b
#define STEAM_CMD_GET_REGISTER_DEFAULT  0x8c
#define STEAM_CMD_SET_MODE              0x8d
#define STEAM_CMD_DEFAULT_MOUSE         0x8e
#define STEAM_CMD_FORCEFEEDBAK          0x8f
#define STEAM_CMD_REQUEST_COMM_STATUS   0xb4
#define STEAM_CMD_GET_SERIAL            0xae

/* Some useful register ids */
#define STEAM_REG_LPAD_MODE             0x07
#define STEAM_REG_RPAD_MODE             0x08
#define STEAM_REG_RPAD_MARGIN           0x18
#define STEAM_REG_LED                   0x2d
#define STEAM_REG_GYRO_MODE             0x30

/* Raw event identifiers */
#define STEAM_EV_INPUT_DATA             0x01
#define STEAM_EV_CONNECT                0x03
#define STEAM_EV_BATTERY                0x04

/* Values for GYRO_MODE (bitmask) */
#define STEAM_GYRO_MODE_OFF             0x0000
#define STEAM_GYRO_MODE_STEERING        0x0001
#define STEAM_GYRO_MODE_TILT            0x0002
#define STEAM_GYRO_MODE_SEND_ORIENTATION        0x0004
#define STEAM_GYRO_MODE_SEND_RAW_ACCEL          0x0008
#define STEAM_GYRO_MODE_SEND_RAW_GYRO           0x0010

/* Other random constants */
#define STEAM_SERIAL_LEN 10

struct steam_device {
        struct list_head list;
        spinlock_t lock;
        struct hid_device *hdev, *client_hdev;
        struct mutex mutex;
        bool client_opened, input_opened;
        struct input_dev __rcu *input;
        unsigned long quirks;
        struct work_struct work_connect;
        bool connected;
        char serial_no[STEAM_SERIAL_LEN + 1];
        struct power_supply_desc battery_desc;
        struct power_supply __rcu *battery;
        u8 battery_charge;
        u16 voltage;
};

static int steam_recv_report(struct steam_device *steam,
                u8 *data, int size)
{
        struct hid_report *r;
        u8 *buf;
        int ret;

        r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];
        if (hid_report_len(r) < 64)
                return -EINVAL;

        buf = hid_alloc_report_buf(r, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /*
         * The report ID is always 0, so strip the first byte from the output.
         * hid_report_len() is not counting the report ID, so +1 to the length
         * or else we get a EOVERFLOW. We are safe from a buffer overflow
         * because hid_alloc_report_buf() allocates +7 bytes.
         */
        ret = hid_hw_raw_request(steam->hdev, 0x00,
                        buf, hid_report_len(r) + 1,
                        HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
        if (ret > 0)
                memcpy(data, buf + 1, min(size, ret - 1));
        kfree(buf);
        return ret;
}

static int steam_send_report(struct steam_device *steam,
                u8 *cmd, int size)
{
        struct hid_report *r;
        u8 *buf;
        unsigned int retries = 50;
        int ret;

        r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];
        if (hid_report_len(r) < 64)
                return -EINVAL;

        buf = hid_alloc_report_buf(r, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /* The report ID is always 0 */
        memcpy(buf + 1, cmd, size);

        /*
         * Sometimes the wireless controller fails with EPIPE
         * when sending a feature report.
         * Doing a HID_REQ_GET_REPORT and waiting for a while
         * seems to fix that.
         */
        do {
                ret = hid_hw_raw_request(steam->hdev, 0,
                                buf, size + 1,
                                HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
                if (ret != -EPIPE)
                        break;
                msleep(20);
        } while (--retries);

        kfree(buf);
        if (ret < 0)
                hid_err(steam->hdev, "%s: error %d (%*ph)\n", __func__,
                                ret, size, cmd);
        return ret;
}

static inline int steam_send_report_byte(struct steam_device *steam, u8 cmd)
{
        return steam_send_report(steam, &cmd, 1);
}

static int steam_write_registers(struct steam_device *steam,
                /* u8 reg, u16 val */...)
{
        /* Send: 0x87 len (reg valLo valHi)* */
        u8 reg;
        u16 val;
        u8 cmd[64] = {STEAM_CMD_WRITE_REGISTER, 0x00};
        va_list args;

        va_start(args, steam);
        for (;;) {
                reg = va_arg(args, int);
                if (reg == 0)
                        break;
                val = va_arg(args, int);
                cmd[cmd[1] + 2] = reg;
                cmd[cmd[1] + 3] = val & 0xff;
                cmd[cmd[1] + 4] = val >> 8;
                cmd[1] += 3;
        }
        va_end(args);

        return steam_send_report(steam, cmd, 2 + cmd[1]);
}

static int steam_get_serial(struct steam_device *steam)
{
        /*
         * Send: 0xae 0x15 0x01
         * Recv: 0xae 0x15 0x01 serialnumber (10 chars)
         */
        int ret;
        u8 cmd[] = {STEAM_CMD_GET_SERIAL, 0x15, 0x01};
        u8 reply[3 + STEAM_SERIAL_LEN + 1];

        ret = steam_send_report(steam, cmd, sizeof(cmd));
        if (ret < 0)
                return ret;
        ret = steam_recv_report(steam, reply, sizeof(reply));
        if (ret < 0)
                return ret;
        if (reply[0] != 0xae || reply[1] != 0x15 || reply[2] != 0x01)
                return -EIO;
        reply[3 + STEAM_SERIAL_LEN] = 0;
        strlcpy(steam->serial_no, reply + 3, sizeof(steam->serial_no));
        return 0;
}

/*
 * This command requests the wireless adaptor to post an event
 * with the connection status. Useful if this driver is loaded when
 * the controller is already connected.
 */
static inline int steam_request_conn_status(struct steam_device *steam)
{
        return steam_send_report_byte(steam, STEAM_CMD_REQUEST_COMM_STATUS);
}

static void steam_set_lizard_mode(struct steam_device *steam, bool enable)
{
        if (enable) {
                /* enable esc, enter, cursors */
                steam_send_report_byte(steam, STEAM_CMD_DEFAULT_MAPPINGS);
                /* enable mouse */
                steam_send_report_byte(steam, STEAM_CMD_DEFAULT_MOUSE);
                steam_write_registers(steam,
                        STEAM_REG_RPAD_MARGIN, 0x01, /* enable margin */
                        0);
        } else {
                /* disable esc, enter, cursor */
                steam_send_report_byte(steam, STEAM_CMD_CLEAR_MAPPINGS);
                steam_write_registers(steam,
                        STEAM_REG_RPAD_MODE, 0x07, /* disable mouse */
                        STEAM_REG_RPAD_MARGIN, 0x00, /* disable margin */
                        0);
        }
}

static void steam_update_lizard_mode(struct steam_device *steam)
{
        mutex_lock(&steam->mutex);
        if (!steam->client_opened) {
                if (steam->input_opened)
                        steam_set_lizard_mode(steam, false);
                else
                        steam_set_lizard_mode(steam, lizard_mode);
        }
        mutex_unlock(&steam->mutex);
}

static int steam_input_open(struct input_dev *dev)
{
        struct steam_device *steam = input_get_drvdata(dev);
        int ret;

        ret = hid_hw_open(steam->hdev);
        if (ret)
                return ret;

        mutex_lock(&steam->mutex);
        steam->input_opened = true;
        if (!steam->client_opened && lizard_mode)
                steam_set_lizard_mode(steam, false);
        mutex_unlock(&steam->mutex);
        return 0;
}

static void steam_input_close(struct input_dev *dev)
{
        struct steam_device *steam = input_get_drvdata(dev);

        mutex_lock(&steam->mutex);
        steam->input_opened = false;
        if (!steam->client_opened && lizard_mode)
                steam_set_lizard_mode(steam, true);
        mutex_unlock(&steam->mutex);

        hid_hw_close(steam->hdev);
}

static enum power_supply_property steam_battery_props[] = {
        POWER_SUPPLY_PROP_PRESENT,
        POWER_SUPPLY_PROP_SCOPE,
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
        POWER_SUPPLY_PROP_CAPACITY,
};

static int steam_battery_get_property(struct power_supply *psy,
                                enum power_supply_property psp,
                                union power_supply_propval *val)
{
        struct steam_device *steam = power_supply_get_drvdata(psy);
        unsigned long flags;
        s16 volts;
        u8 batt;
        int ret = 0;

        spin_lock_irqsave(&steam->lock, flags);
        volts = steam->voltage;
        batt = steam->battery_charge;
        spin_unlock_irqrestore(&steam->lock, flags);

        switch (psp) {
        case POWER_SUPPLY_PROP_PRESENT:
                val->intval = 1;
                break;
        case POWER_SUPPLY_PROP_SCOPE:
                val->intval = POWER_SUPPLY_SCOPE_DEVICE;
                break;
        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                val->intval = volts * 1000; /* mV -> uV */
                break;
        case POWER_SUPPLY_PROP_CAPACITY:
                val->intval = batt;
                break;
        default:
                ret = -EINVAL;
                break;
        }
        return ret;
}

static int steam_battery_register(struct steam_device *steam)
{
        struct power_supply *battery;
        struct power_supply_config battery_cfg = { .drv_data = steam, };
        unsigned long flags;
        int ret;

        steam->battery_desc.type = POWER_SUPPLY_TYPE_BATTERY;
        steam->battery_desc.properties = steam_battery_props;
        steam->battery_desc.num_properties = ARRAY_SIZE(steam_battery_props);
        steam->battery_desc.get_property = steam_battery_get_property;
        steam->battery_desc.name = devm_kasprintf(&steam->hdev->dev,
                        GFP_KERNEL, "steam-controller-%s-battery",
                        steam->serial_no);
        if (!steam->battery_desc.name)
                return -ENOMEM;

        /* avoid the warning of 0% battery while waiting for the first info */
        spin_lock_irqsave(&steam->lock, flags);
        steam->voltage = 3000;
        steam->battery_charge = 100;
        spin_unlock_irqrestore(&steam->lock, flags);

        battery = power_supply_register(&steam->hdev->dev,
                        &steam->battery_desc, &battery_cfg);
        if (IS_ERR(battery)) {
                ret = PTR_ERR(battery);
                hid_err(steam->hdev,
                                "%s:power_supply_register failed with error %d\n",
                                __func__, ret);
                return ret;
        }
        rcu_assign_pointer(steam->battery, battery);
        power_supply_powers(battery, &steam->hdev->dev);
        return 0;
}

static int steam_register(struct steam_device *steam)
{
        struct hid_device *hdev = steam->hdev;
        struct input_dev *input;
        int ret;

        rcu_read_lock();
        input = rcu_dereference(steam->input);
        rcu_read_unlock();
        if (input) {
                dbg_hid("%s: already connected\n", __func__);
                return 0;
        }

        /*
         * Unlikely, but getting the serial could fail, and it is not so
         * important, so make up a serial number and go on.
         */
        if (steam_get_serial(steam) < 0)
                strlcpy(steam->serial_no, "XXXXXXXXXX",
                                sizeof(steam->serial_no));

        hid_info(hdev, "Steam Controller '%s' connected",
                        steam->serial_no);

        input = input_allocate_device();
        if (!input)
                return -ENOMEM;

        input_set_drvdata(input, steam);
        input->dev.parent = &hdev->dev;
        input->open = steam_input_open;
        input->close = steam_input_close;

        input->name = (steam->quirks & STEAM_QUIRK_WIRELESS) ?
                "Wireless Steam Controller" :
                "Steam Controller";
        input->phys = hdev->phys;
        input->uniq = steam->serial_no;
        input->id.bustype = hdev->bus;
        input->id.vendor = hdev->vendor;
        input->id.product = hdev->product;
        input->id.version = hdev->version;

        input_set_capability(input, EV_KEY, BTN_TR2);
        input_set_capability(input, EV_KEY, BTN_TL2);
        input_set_capability(input, EV_KEY, BTN_TR);
        input_set_capability(input, EV_KEY, BTN_TL);
        input_set_capability(input, EV_KEY, BTN_Y);
        input_set_capability(input, EV_KEY, BTN_B);
        input_set_capability(input, EV_KEY, BTN_X);
        input_set_capability(input, EV_KEY, BTN_A);
        input_set_capability(input, EV_KEY, BTN_DPAD_UP);
        input_set_capability(input, EV_KEY, BTN_DPAD_RIGHT);
        input_set_capability(input, EV_KEY, BTN_DPAD_LEFT);
        input_set_capability(input, EV_KEY, BTN_DPAD_DOWN);
        input_set_capability(input, EV_KEY, BTN_SELECT);
        input_set_capability(input, EV_KEY, BTN_MODE);
        input_set_capability(input, EV_KEY, BTN_START);
        input_set_capability(input, EV_KEY, BTN_GEAR_DOWN);
        input_set_capability(input, EV_KEY, BTN_GEAR_UP);
        input_set_capability(input, EV_KEY, BTN_THUMBR);
        input_set_capability(input, EV_KEY, BTN_THUMBL);
        input_set_capability(input, EV_KEY, BTN_THUMB);
        input_set_capability(input, EV_KEY, BTN_THUMB2);

        input_set_abs_params(input, ABS_HAT2Y, 0, 255, 0, 0);
        input_set_abs_params(input, ABS_HAT2X, 0, 255, 0, 0);
        input_set_abs_params(input, ABS_X, -32767, 32767, 0, 0);
        input_set_abs_params(input, ABS_Y, -32767, 32767, 0, 0);
        input_set_abs_params(input, ABS_RX, -32767, 32767,
                        STEAM_PAD_FUZZ, 0);
        input_set_abs_params(input, ABS_RY, -32767, 32767,
                        STEAM_PAD_FUZZ, 0);
        input_set_abs_params(input, ABS_HAT0X, -32767, 32767,
                        STEAM_PAD_FUZZ, 0);
        input_set_abs_params(input, ABS_HAT0Y, -32767, 32767,
                        STEAM_PAD_FUZZ, 0);
        input_abs_set_res(input, ABS_X, STEAM_JOYSTICK_RESOLUTION);
        input_abs_set_res(input, ABS_Y, STEAM_JOYSTICK_RESOLUTION);
        input_abs_set_res(input, ABS_RX, STEAM_PAD_RESOLUTION);
        input_abs_set_res(input, ABS_RY, STEAM_PAD_RESOLUTION);
        input_abs_set_res(input, ABS_HAT0X, STEAM_PAD_RESOLUTION);
        input_abs_set_res(input, ABS_HAT0Y, STEAM_PAD_RESOLUTION);
        input_abs_set_res(input, ABS_HAT2Y, STEAM_TRIGGER_RESOLUTION);
        input_abs_set_res(input, ABS_HAT2X, STEAM_TRIGGER_RESOLUTION);

        ret = input_register_device(input);
        if (ret)
                goto input_register_fail;

        rcu_assign_pointer(steam->input, input);

        /* ignore battery errors, we can live without it */
        if (steam->quirks & STEAM_QUIRK_WIRELESS)
                steam_battery_register(steam);

        return 0;

input_register_fail:
        input_free_device(input);
        return ret;
}

static void steam_unregister(struct steam_device *steam)
{
        struct input_dev *input;
        struct power_supply *battery;

        rcu_read_lock();
        input = rcu_dereference(steam->input);
        battery = rcu_dereference(steam->battery);
        rcu_read_unlock();

        if (battery) {
                RCU_INIT_POINTER(steam->battery, NULL);
                synchronize_rcu();
                power_supply_unregister(battery);
        }
        if (input) {
                RCU_INIT_POINTER(steam->input, NULL);
                synchronize_rcu();
                hid_info(steam->hdev, "Steam Controller '%s' disconnected",
                                steam->serial_no);
                input_unregister_device(input);
        }
}

static void steam_work_connect_cb(struct work_struct *work)
{
        struct steam_device *steam = container_of(work, struct steam_device,
                                                        work_connect);
        unsigned long flags;
        bool connected;
        int ret;

        spin_lock_irqsave(&steam->lock, flags);
        connected = steam->connected;
        spin_unlock_irqrestore(&steam->lock, flags);

        if (connected) {
                ret = steam_register(steam);
                if (ret) {
                        hid_err(steam->hdev,
                                "%s:steam_register failed with error %d\n",
                                __func__, ret);
                }
        } else {
                steam_unregister(steam);
        }
}

static bool steam_is_valve_interface(struct hid_device *hdev)
{
        struct hid_report_enum *rep_enum;

        /*
         * The wired device creates 3 interfaces:
         *  0: emulated mouse.
         *  1: emulated keyboard.
         *  2: the real game pad.
         * The wireless device creates 5 interfaces:
         *  0: emulated keyboard.
         *  1-4: slots where up to 4 real game pads will be connected to.
         * We know which one is the real gamepad interface because they are the
         * only ones with a feature report.
         */
        rep_enum = &hdev->report_enum[HID_FEATURE_REPORT];
        return !list_empty(&rep_enum->report_list);
}

static int steam_client_ll_parse(struct hid_device *hdev)
{
        struct steam_device *steam = hdev->driver_data;

        return hid_parse_report(hdev, steam->hdev->dev_rdesc,
                        steam->hdev->dev_rsize);
}

static int steam_client_ll_start(struct hid_device *hdev)
{
        return 0;
}

static void steam_client_ll_stop(struct hid_device *hdev)
{
}

static int steam_client_ll_open(struct hid_device *hdev)
{
        struct steam_device *steam = hdev->driver_data;
        int ret;

        ret = hid_hw_open(steam->hdev);
        if (ret)
                return ret;

        mutex_lock(&steam->mutex);
        steam->client_opened = true;
        mutex_unlock(&steam->mutex);
        return ret;
}

static void steam_client_ll_close(struct hid_device *hdev)
{
        struct steam_device *steam = hdev->driver_data;

        mutex_lock(&steam->mutex);
        steam->client_opened = false;
        if (steam->input_opened)
                steam_set_lizard_mode(steam, false);
        else
                steam_set_lizard_mode(steam, lizard_mode);
        mutex_unlock(&steam->mutex);

        hid_hw_close(steam->hdev);
}

static int steam_client_ll_raw_request(struct hid_device *hdev,
                                unsigned char reportnum, u8 *buf,
                                size_t count, unsigned char report_type,
                                int reqtype)
{
        struct steam_device *steam = hdev->driver_data;

        return hid_hw_raw_request(steam->hdev, reportnum, buf, count,
                        report_type, reqtype);
}

static struct hid_ll_driver steam_client_ll_driver = {
        .parse = steam_client_ll_parse,
        .start = steam_client_ll_start,
        .stop = steam_client_ll_stop,
        .open = steam_client_ll_open,
        .close = steam_client_ll_close,
        .raw_request = steam_client_ll_raw_request,
};

static struct hid_device *steam_create_client_hid(struct hid_device *hdev)
{
        struct hid_device *client_hdev;

        client_hdev = hid_allocate_device();
        if (IS_ERR(client_hdev))
                return client_hdev;

        client_hdev->ll_driver = &steam_client_ll_driver;
        client_hdev->dev.parent = hdev->dev.parent;
        client_hdev->bus = hdev->bus;
        client_hdev->vendor = hdev->vendor;
        client_hdev->product = hdev->product;
        client_hdev->version = hdev->version;
        client_hdev->type = hdev->type;
        client_hdev->country = hdev->country;
        strlcpy(client_hdev->name, hdev->name,
                        sizeof(client_hdev->name));
        strlcpy(client_hdev->phys, hdev->phys,
                        sizeof(client_hdev->phys));
        /*
         * Since we use the same device info than the real interface to
         * trick userspace, we will be calling steam_probe recursively.
         * We need to recognize the client interface somehow.
         */
        client_hdev->group = HID_GROUP_STEAM;
        return client_hdev;
}

static int steam_probe(struct hid_device *hdev,
                                const struct hid_device_id *id)
{
        struct steam_device *steam;
        int ret;

        ret = hid_parse(hdev);
        if (ret) {
                hid_err(hdev,
                        "%s:parse of hid interface failed\n", __func__);
                return ret;
        }

        /*
         * The virtual client_dev is only used for hidraw.
         * Also avoid the recursive probe.
         */
        if (hdev->group == HID_GROUP_STEAM)
                return hid_hw_start(hdev, HID_CONNECT_HIDRAW);
        /*
         * The non-valve interfaces (mouse and keyboard emulation) are
         * connected without changes.
         */
        if (!steam_is_valve_interface(hdev))
                return hid_hw_start(hdev, HID_CONNECT_DEFAULT);

        steam = devm_kzalloc(&hdev->dev, sizeof(*steam), GFP_KERNEL);
        if (!steam) {
                ret = -ENOMEM;
                goto steam_alloc_fail;
        }
        steam->hdev = hdev;
        hid_set_drvdata(hdev, steam);
        spin_lock_init(&steam->lock);
        mutex_init(&steam->mutex);
        steam->quirks = id->driver_data;
        INIT_WORK(&steam->work_connect, steam_work_connect_cb);

        steam->client_hdev = steam_create_client_hid(hdev);
        if (IS_ERR(steam->client_hdev)) {
                ret = PTR_ERR(steam->client_hdev);
                goto client_hdev_fail;
        }
        steam->client_hdev->driver_data = steam;

        /*
         * With the real steam controller interface, do not connect hidraw.
         * Instead, create the client_hid and connect that.
         */
        ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_HIDRAW);
        if (ret)
                goto hid_hw_start_fail;

        ret = hid_add_device(steam->client_hdev);
        if (ret)
                goto client_hdev_add_fail;

        if (steam->quirks & STEAM_QUIRK_WIRELESS) {
                ret = hid_hw_open(hdev);
                if (ret) {
                        hid_err(hdev,
                                "%s:hid_hw_open for wireless\n",
                                __func__);
                        goto hid_hw_open_fail;
                }
                hid_info(hdev, "Steam wireless receiver connected");
                steam_request_conn_status(steam);
        } else {
                ret = steam_register(steam);
                if (ret) {
                        hid_err(hdev,
                                "%s:steam_register failed with error %d\n",
                                __func__, ret);
                        goto input_register_fail;
                }
        }

        mutex_lock(&steam_devices_lock);
        steam_update_lizard_mode(steam);
        list_add(&steam->list, &steam_devices);
        mutex_unlock(&steam_devices_lock);

        return 0;

hid_hw_open_fail:
input_register_fail:
client_hdev_add_fail:
        hid_hw_stop(hdev);
hid_hw_start_fail:
        hid_destroy_device(steam->client_hdev);
client_hdev_fail:
        cancel_work_sync(&steam->work_connect);
steam_alloc_fail:
        hid_err(hdev, "%s: failed with error %d\n",
                        __func__, ret);
        return ret;
}

static void steam_remove(struct hid_device *hdev)
{
        struct steam_device *steam = hid_get_drvdata(hdev);

        if (!steam || hdev->group == HID_GROUP_STEAM) {
                hid_hw_stop(hdev);
                return;
        }

        mutex_lock(&steam_devices_lock);
        list_del(&steam->list);
        mutex_unlock(&steam_devices_lock);

        hid_destroy_device(steam->client_hdev);
        steam->client_opened = false;
        cancel_work_sync(&steam->work_connect);
        if (steam->quirks & STEAM_QUIRK_WIRELESS) {
                hid_info(hdev, "Steam wireless receiver disconnected");
                hid_hw_close(hdev);
        }
        hid_hw_stop(hdev);
        steam_unregister(steam);
}

static void steam_do_connect_event(struct steam_device *steam, bool connected)
{
        unsigned long flags;

        spin_lock_irqsave(&steam->lock, flags);
        steam->connected = connected;
        spin_unlock_irqrestore(&steam->lock, flags);

        if (schedule_work(&steam->work_connect) == 0)
                dbg_hid("%s: connected=%d event already queued\n",
                                __func__, connected);
}

/*
 * Some input data in the protocol has the opposite sign.
 * Clamp the values to 32767..-32767 so that the range is
 * symmetrical and can be negated safely.
 */
static inline s16 steam_le16(u8 *data)
{
        s16 x = (s16) le16_to_cpup((__le16 *)data);

        return x == -32768 ? -32767 : x;
}

/*
 * The size for this message payload is 60.
 * The known values are:
 *  (* values are not sent through wireless)
 *  (* accelerator/gyro is disabled by default)
 *  Offset| Type  | Mapped to |Meaning
 * -------+-------+-----------+--------------------------
 *  4-7   | u32   | --        | sequence number
 *  8-10  | 24bit | see below | buttons
 *  11    | u8    | ABS_HAT2Y | left trigger
 *  12    | u8    | ABS_HAT2X | right trigger
 *  13-15 | --    | --        | always 0
 *  16-17 | s16   | ABS_X/ABS_HAT0X     | X value
 *  18-19 | s16   | ABS_Y/ABS_HAT0Y     | Y value
 *  20-21 | s16   | ABS_RX    | right-pad X value
 *  22-23 | s16   | ABS_RY    | right-pad Y value
 *  24-25 | s16   | --        | * left trigger
 *  26-27 | s16   | --        | * right trigger
 *  28-29 | s16   | --        | * accelerometer X value
 *  30-31 | s16   | --        | * accelerometer Y value
 *  32-33 | s16   | --        | * accelerometer Z value
 *  34-35 | s16   | --        | gyro X value
 *  36-36 | s16   | --        | gyro Y value
 *  38-39 | s16   | --        | gyro Z value
 *  40-41 | s16   | --        | quaternion W value
 *  42-43 | s16   | --        | quaternion X value
 *  44-45 | s16   | --        | quaternion Y value
 *  46-47 | s16   | --        | quaternion Z value
 *  48-49 | --    | --        | always 0
 *  50-51 | s16   | --        | * left trigger (uncalibrated)
 *  52-53 | s16   | --        | * right trigger (uncalibrated)
 *  54-55 | s16   | --        | * joystick X value (uncalibrated)
 *  56-57 | s16   | --        | * joystick Y value (uncalibrated)
 *  58-59 | s16   | --        | * left-pad X value
 *  60-61 | s16   | --        | * left-pad Y value
 *  62-63 | u16   | --        | * battery voltage
 *
 * The buttons are:
 *  Bit  | Mapped to  | Description
 * ------+------------+--------------------------------
 *  8.0  | BTN_TR2    | right trigger fully pressed
 *  8.1  | BTN_TL2    | left trigger fully pressed
 *  8.2  | BTN_TR     | right shoulder
 *  8.3  | BTN_TL     | left shoulder
 *  8.4  | BTN_Y      | button Y
 *  8.5  | BTN_B      | button B
 *  8.6  | BTN_X      | button X
 *  8.7  | BTN_A      | button A
 *  9.0  | BTN_DPAD_UP    | lef-pad up
 *  9.1  | BTN_DPAD_RIGHT | lef-pad right
 *  9.2  | BTN_DPAD_LEFT  | lef-pad left
 *  9.3  | BTN_DPAD_DOWN  | lef-pad down
 *  9.4  | BTN_SELECT | menu left
 *  9.5  | BTN_MODE   | steam logo
 *  9.6  | BTN_START  | menu right
 *  9.7  | BTN_GEAR_DOWN | left back lever
 * 10.0  | BTN_GEAR_UP   | right back lever
 * 10.1  | --         | left-pad clicked
 * 10.2  | BTN_THUMBR | right-pad clicked
 * 10.3  | BTN_THUMB  | left-pad touched (but see explanation below)
 * 10.4  | BTN_THUMB2 | right-pad touched
 * 10.5  | --         | unknown
 * 10.6  | BTN_THUMBL | joystick clicked
 * 10.7  | --         | lpad_and_joy
 */

static void steam_do_input_event(struct steam_device *steam,
                struct input_dev *input, u8 *data)
{
        /* 24 bits of buttons */
        u8 b8, b9, b10;
        s16 x, y;
        bool lpad_touched, lpad_and_joy;

        b8 = data[8];
        b9 = data[9];
        b10 = data[10];

        input_report_abs(input, ABS_HAT2Y, data[11]);
        input_report_abs(input, ABS_HAT2X, data[12]);

        /*
         * These two bits tells how to interpret the values X and Y.
         * lpad_and_joy tells that the joystick and the lpad are used at the
         * same time.
         * lpad_touched tells whether X/Y are to be read as lpad coord or
         * joystick values.
         * (lpad_touched || lpad_and_joy) tells if the lpad is really touched.
         */
        lpad_touched = b10 & BIT(3);
        lpad_and_joy = b10 & BIT(7);
        x = steam_le16(data + 16);
        y = -steam_le16(data + 18);

        input_report_abs(input, lpad_touched ? ABS_HAT0X : ABS_X, x);
        input_report_abs(input, lpad_touched ? ABS_HAT0Y : ABS_Y, y);
        /* Check if joystick is centered */
        if (lpad_touched && !lpad_and_joy) {
                input_report_abs(input, ABS_X, 0);
                input_report_abs(input, ABS_Y, 0);
        }
        /* Check if lpad is untouched */
        if (!(lpad_touched || lpad_and_joy)) {
                input_report_abs(input, ABS_HAT0X, 0);
                input_report_abs(input, ABS_HAT0Y, 0);
        }

        input_report_abs(input, ABS_RX, steam_le16(data + 20));
        input_report_abs(input, ABS_RY, -steam_le16(data + 22));

        input_event(input, EV_KEY, BTN_TR2, !!(b8 & BIT(0)));
        input_event(input, EV_KEY, BTN_TL2, !!(b8 & BIT(1)));
        input_event(input, EV_KEY, BTN_TR, !!(b8 & BIT(2)));
        input_event(input, EV_KEY, BTN_TL, !!(b8 & BIT(3)));
        input_event(input, EV_KEY, BTN_Y, !!(b8 & BIT(4)));
        input_event(input, EV_KEY, BTN_B, !!(b8 & BIT(5)));
        input_event(input, EV_KEY, BTN_X, !!(b8 & BIT(6)));
        input_event(input, EV_KEY, BTN_A, !!(b8 & BIT(7)));
        input_event(input, EV_KEY, BTN_SELECT, !!(b9 & BIT(4)));
        input_event(input, EV_KEY, BTN_MODE, !!(b9 & BIT(5)));
        input_event(input, EV_KEY, BTN_START, !!(b9 & BIT(6)));
        input_event(input, EV_KEY, BTN_GEAR_DOWN, !!(b9 & BIT(7)));
        input_event(input, EV_KEY, BTN_GEAR_UP, !!(b10 & BIT(0)));
        input_event(input, EV_KEY, BTN_THUMBR, !!(b10 & BIT(2)));
        input_event(input, EV_KEY, BTN_THUMBL, !!(b10 & BIT(6)));
        input_event(input, EV_KEY, BTN_THUMB, lpad_touched || lpad_and_joy);
        input_event(input, EV_KEY, BTN_THUMB2, !!(b10 & BIT(4)));
        input_event(input, EV_KEY, BTN_DPAD_UP, !!(b9 & BIT(0)));
        input_event(input, EV_KEY, BTN_DPAD_RIGHT, !!(b9 & BIT(1)));
        input_event(input, EV_KEY, BTN_DPAD_LEFT, !!(b9 & BIT(2)));
        input_event(input, EV_KEY, BTN_DPAD_DOWN, !!(b9 & BIT(3)));

        input_sync(input);
}

/*
 * The size for this message payload is 11.
 * The known values are:
 *  Offset| Type  | Meaning
 * -------+-------+---------------------------
 *  4-7   | u32   | sequence number
 *  8-11  | --    | always 0
 *  12-13 | u16   | voltage (mV)
 *  14    | u8    | battery percent
 */
static void steam_do_battery_event(struct steam_device *steam,
                struct power_supply *battery, u8 *data)
{
        unsigned long flags;

        s16 volts = steam_le16(data + 12);
        u8 batt = data[14];

        /* Creating the battery may have failed */
        rcu_read_lock();
        battery = rcu_dereference(steam->battery);
        if (likely(battery)) {
                spin_lock_irqsave(&steam->lock, flags);
                steam->voltage = volts;
                steam->battery_charge = batt;
                spin_unlock_irqrestore(&steam->lock, flags);
                power_supply_changed(battery);
        }
        rcu_read_unlock();
}

static int steam_raw_event(struct hid_device *hdev,
                        struct hid_report *report, u8 *data,
                        int size)
{
        struct steam_device *steam = hid_get_drvdata(hdev);
        struct input_dev *input;
        struct power_supply *battery;

        if (!steam)
                return 0;

        if (steam->client_opened)
                hid_input_report(steam->client_hdev, HID_FEATURE_REPORT,
                                data, size, 0);
        /*
         * All messages are size=64, all values little-endian.
         * The format is:
         *  Offset| Meaning

         * -------+--------------------------------------------
         *  0-1   | always 0x01, 0x00, maybe protocol version?
         *  2     | type of message
         *  3     | length of the real payload (not checked)
         *  4-n   | payload data, depends on the type
         *
         * There are these known types of message:
         *  0x01: input data (60 bytes)
         *  0x03: wireless connect/disconnect (1 byte)
         *  0x04: battery status (11 bytes)
         */

        if (size != 64 || data[0] != 1 || data[1] != 0)
                return 0;

        switch (data[2]) {
        case STEAM_EV_INPUT_DATA:
                if (steam->client_opened)
                        return 0;
                rcu_read_lock();
                input = rcu_dereference(steam->input);
                if (likely(input)) {
                        steam_do_input_event(steam, input, data);
                } else {
                        dbg_hid("%s: input data without connect event\n",
                                        __func__);
                        steam_do_connect_event(steam, true);
                }
                rcu_read_unlock();
                break;
        case STEAM_EV_CONNECT:
                /*
                 * The payload of this event is a single byte:
                 *  0x01: disconnected.
                 *  0x02: connected.
                 */
                switch (data[4]) {
                case 0x01:
                        steam_do_connect_event(steam, false);
                        break;
                case 0x02:
                        steam_do_connect_event(steam, true);
                        break;
                }
                break;
        case STEAM_EV_BATTERY:
                if (steam->quirks & STEAM_QUIRK_WIRELESS) {
                        rcu_read_lock();
                        battery = rcu_dereference(steam->battery);
                        if (likely(battery)) {
                                steam_do_battery_event(steam, battery, data);
                        } else {
                                dbg_hid(
                                        "%s: battery data without connect event\n",
                                        __func__);
                                steam_do_connect_event(steam, true);
                        }
                        rcu_read_unlock();
                }
                break;
        }
        return 0;
}

static int steam_param_set_lizard_mode(const char *val,
                                        const struct kernel_param *kp)
{
        struct steam_device *steam;
        int ret;

        ret = param_set_bool(val, kp);
        if (ret)
                return ret;

        mutex_lock(&steam_devices_lock);
        list_for_each_entry(steam, &steam_devices, list) {
                steam_update_lizard_mode(steam);
        }
        mutex_unlock(&steam_devices_lock);
        return 0;
}

static const struct kernel_param_ops steam_lizard_mode_ops = {
        .set    = steam_param_set_lizard_mode,
        .get    = param_get_bool,
};

module_param_cb(lizard_mode, &steam_lizard_mode_ops, &lizard_mode, 0644);
MODULE_PARM_DESC(lizard_mode,
        "Enable mouse and keyboard emulation (lizard mode) when the gamepad is not in use");

static const struct hid_device_id steam_controllers[] = {
        { /* Wired Steam Controller */
          HID_USB_DEVICE(USB_VENDOR_ID_VALVE,
                USB_DEVICE_ID_STEAM_CONTROLLER)
        },
        { /* Wireless Steam Controller */
          HID_USB_DEVICE(USB_VENDOR_ID_VALVE,
                USB_DEVICE_ID_STEAM_CONTROLLER_WIRELESS),
          .driver_data = STEAM_QUIRK_WIRELESS
        },
        {}
};

MODULE_DEVICE_TABLE(hid, steam_controllers);

static struct hid_driver steam_controller_driver = {
        .name = "hid-steam",
        .id_table = steam_controllers,
        .probe = steam_probe,
        .remove = steam_remove,
        .raw_event = steam_raw_event,
};

module_hid_driver(steam_controller_driver);