Merge pull request #5735 from ameerj/gc-input

input_common: Implement official GameCube adapter support

.gitmodules

@@ -31,6 +31,9 @@
 [submodule "libressl"]
     path = externals/libressl
     url = https://github.com/citra-emu/ext-libressl-portable.git
+[submodule "libusb"]
+    path = externals/libusb/libusb
+    url = https://github.com/libusb/libusb.git
 [submodule "cubeb"]
     path = externals/cubeb
     url = https://github.com/kinetiknz/cubeb.git

CMakeLists.txt

@@ -193,6 +193,17 @@ if (ENABLE_QT)
     endif()
 endif()
 
+# Ensure libusb is properly configured (based on dolphin libusb include)
+if(NOT APPLE)
+    include(FindPkgConfig)
+    find_package(LibUSB)
+endif()
+if (NOT LIBUSB_FOUND)
+    add_subdirectory(externals/libusb)
+    set(LIBUSB_INCLUDE_DIR "")
+    set(LIBUSB_LIBRARIES usb)
+endif()
+
 if (ENABLE_FFMPEG)
     if (CITRA_USE_BUNDLED_FFMPEG)
         if ((MSVC_VERSION GREATER_EQUAL 1910 AND MSVC_VERSION LESS 1930) AND ARCHITECTURE_x86_64)

externals/catch

@@ -1 +1 @@
-Subproject commit de6fe184a9ac1a06895cdd1c9b437f0a0bdf14ad
+Subproject commit 15cf3caaceb21172ea42a24e595a2eb58c3ec960

externals/cmake-modules/FindLibUSB.cmake

@@ -0,0 +1,43 @@
+# - Find libusb-1.0 library
+# This module defines
+#  LIBUSB_INCLUDE_DIR, where to find bluetooth.h
+#  LIBUSB_LIBRARIES, the libraries needed to use libusb-1.0.
+#  LIBUSB_FOUND, If false, do not try to use libusb-1.0.
+#
+# Copyright (c) 2009, Michal Cihar, <michal@cihar.com>
+#
+# vim: expandtab sw=4 ts=4 sts=4:
+
+if(ANDROID)
+       set(LIBUSB_FOUND FALSE CACHE INTERNAL "libusb-1.0 found")
+       message(STATUS "libusb-1.0 not found.")
+elseif (NOT LIBUSB_FOUND)
+    pkg_check_modules (LIBUSB_PKG libusb-1.0)
+
+    find_path(LIBUSB_INCLUDE_DIR NAMES libusb.h
+       PATHS
+       ${LIBUSB_PKG_INCLUDE_DIRS}
+       /usr/include/libusb-1.0
+       /usr/include
+       /usr/local/include/libusb-1.0
+       /usr/local/include
+    )
+
+    find_library(LIBUSB_LIBRARIES NAMES usb-1.0 usb
+       PATHS
+       ${LIBUSB_PKG_LIBRARY_DIRS}
+       /usr/lib
+       /usr/local/lib
+    )
+
+    if(LIBUSB_INCLUDE_DIR AND LIBUSB_LIBRARIES)
+       set(LIBUSB_FOUND TRUE CACHE INTERNAL "libusb-1.0 found")
+       message(STATUS "Found libusb-1.0: ${LIBUSB_INCLUDE_DIR}, ${LIBUSB_LIBRARIES}")
+    else(LIBUSB_INCLUDE_DIR AND LIBUSB_LIBRARIES)
+       set(LIBUSB_FOUND FALSE CACHE INTERNAL "libusb-1.0 found")
+       message(STATUS "libusb-1.0 not found.")
+    endif(LIBUSB_INCLUDE_DIR AND LIBUSB_LIBRARIES)
+
+    mark_as_advanced(LIBUSB_INCLUDE_DIR LIBUSB_LIBRARIES)
+endif ()
+

externals/dynarmic

@@ -1 +1 @@
-Subproject commit 358cf6f0357baae3e3bb5788431acf1068f897b5
+Subproject commit f9d84871fb6dd41c47945d649dc9017aa3762125

externals/libusb/CMakeLists.txt

@@ -0,0 +1,152 @@
+# Ensure libusb compiles with UTF-8 encoding on MSVC
+if(MSVC)
+    add_compile_options(/utf-8)
+endif()
+
+add_library(usb STATIC EXCLUDE_FROM_ALL
+    libusb/libusb/core.c
+    libusb/libusb/core.c
+    libusb/libusb/descriptor.c
+    libusb/libusb/hotplug.c
+    libusb/libusb/io.c
+    libusb/libusb/strerror.c
+    libusb/libusb/sync.c
+)
+set_target_properties(usb PROPERTIES VERSION 1.0.23)
+if(WIN32)
+    target_include_directories(usb
+        BEFORE
+        PUBLIC
+          libusb/libusb
+
+        PRIVATE
+          "${CMAKE_CURRENT_BINARY_DIR}"
+    )
+
+    if (NOT MINGW)
+        target_include_directories(usb BEFORE PRIVATE libusb/msvc)
+    endif()
+else()
+target_include_directories(usb
+    # turns out other projects also have "config.h", so make sure the
+    # LibUSB one comes first
+    BEFORE
+
+    PUBLIC
+      libusb/libusb
+
+    PRIVATE
+      "${CMAKE_CURRENT_BINARY_DIR}"
+)
+endif()
+
+if(WIN32 OR CYGWIN)
+    target_sources(usb PRIVATE
+      libusb/libusb/os/threads_windows.c
+      libusb/libusb/os/windows_winusb.c
+      libusb/libusb/os/windows_usbdk.c
+      libusb/libusb/os/windows_nt_common.c
+    )
+    set(OS_WINDOWS TRUE)
+elseif(APPLE)
+    target_sources(usb PRIVATE
+        libusb/libusb/os/darwin_usb.c
+    )
+    find_library(COREFOUNDATION_LIBRARY CoreFoundation)
+    find_library(IOKIT_LIBRARY IOKit)
+    find_library(OBJC_LIBRARY objc)
+    target_link_libraries(usb PRIVATE
+        ${COREFOUNDATION_LIBRARY}
+        ${IOKIT_LIBRARY}
+        ${OBJC_LIBRARY}
+    )
+    set(OS_DARWIN TRUE)
+elseif(ANDROID)
+    target_sources(usb PRIVATE
+        libusb/libusb/os/linux_usbfs.c
+        libusb/libusb/os/linux_netlink.c
+    )
+    find_library(LOG_LIBRARY log)
+    target_link_libraries(usb PRIVATE ${LOG_LIBRARY})
+    set(OS_LINUX TRUE)
+elseif(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
+    target_sources(usb PRIVATE
+        libusb/libusb/os/linux_usbfs.c
+    )
+    find_package(Libudev)
+    if(LIBUDEV_FOUND)
+        target_sources(usb PRIVATE
+            libusb/libusb/os/linux_udev.c
+        )
+        target_link_libraries(usb PRIVATE "${LIBUDEV_LIBRARIES}")
+        target_include_directories(usb PRIVATE "${LIBUDEV_INCLUDE_DIR}")
+        set(HAVE_LIBUDEV TRUE)
+        set(USE_UDEV TRUE)
+    else()
+        target_sources(usb PRIVATE
+            libusb/libusb/os/linux_netlink.c
+        )
+    endif()
+    set(OS_LINUX TRUE)
+elseif(${CMAKE_SYSTEM_NAME} MATCHES "NetBSD")
+    target_sources(usb PRIVATE
+        libusb/libusb/os/netbsd_usb.c
+    )
+    set(OS_NETBSD TRUE)
+elseif(${CMAKE_SYSTEM_NAME} MATCHES "OpenBSD")
+    target_sources(usb PRIVATE
+        libusb/libusb/os/openbsd_usb.c
+    )
+    set(OS_OPENBSD TRUE)
+endif()
+
+if(UNIX)
+    target_sources(usb PRIVATE
+        libusb/libusb/os/poll_posix.c
+        libusb/libusb/os/threads_posix.c
+    )
+    find_package(Threads REQUIRED)
+    if(THREADS_HAVE_PTHREAD_ARG)
+      target_compile_options(usb PUBLIC "-pthread")
+    endif()
+    if(CMAKE_THREAD_LIBS_INIT)
+      target_link_libraries(usb PRIVATE "${CMAKE_THREAD_LIBS_INIT}")
+    endif()
+    set(THREADS_POSIX TRUE)
+elseif(WIN32)
+    target_sources(usb PRIVATE
+        libusb/libusb/os/poll_windows.c
+        libusb/libusb/os/threads_windows.c
+    )
+endif()
+
+include(CheckFunctionExists)
+include(CheckIncludeFiles)
+include(CheckTypeSize)
+check_include_files(asm/types.h HAVE_ASM_TYPES_H)
+check_function_exists(gettimeofday HAVE_GETTIMEOFDAY)
+check_include_files(linux/filter.h HAVE_LINUX_FILTER_H)
+check_include_files(linux/netlink.h HAVE_LINUX_NETLINK_H)
+check_include_files(poll.h HAVE_POLL_H)
+check_include_files(signal.h HAVE_SIGNAL_H)
+check_include_files(strings.h HAVE_STRINGS_H)
+check_type_size("struct timespec" STRUCT_TIMESPEC)
+check_function_exists(syslog HAVE_SYSLOG_FUNC)
+check_include_files(syslog.h HAVE_SYSLOG_H)
+check_include_files(sys/socket.h HAVE_SYS_SOCKET_H)
+check_include_files(sys/time.h HAVE_SYS_TIME_H)
+check_include_files(sys/types.h HAVE_SYS_TYPES_H)
+
+set(CMAKE_EXTRA_INCLUDE_FILES poll.h)
+check_type_size("nfds_t" nfds_t)
+unset(CMAKE_EXTRA_INCLUDE_FILES)
+if(HAVE_NFDS_T)
+    set(POLL_NFDS_TYPE "nfds_t")
+else()
+    set(POLL_NFDS_TYPE "unsigned int")
+endif()
+
+check_include_files(sys/timerfd.h USBI_TIMERFD_AVAILABLE)
+
+
+configure_file(config.h.in config.h)

externals/libusb/config.h.in

@@ -0,0 +1,90 @@
+/* Default visibility */
+#if defined(__GNUC__) || defined(__clang__)
+  #define DEFAULT_VISIBILITY __attribute__((visibility("default")))
+#elif defined(_MSC_VER)
+  #define DEFAULT_VISIBILITY __declspec(dllexport)
+#endif
+
+/* Start with debug message logging enabled */
+#undef ENABLE_DEBUG_LOGGING
+
+/* Message logging */
+#undef ENABLE_LOGGING
+
+/* Define to 1 if you have the <asm/types.h> header file. */
+#cmakedefine HAVE_ASM_TYPES_H 1
+
+/* Define to 1 if you have the `gettimeofday' function. */
+#cmakedefine HAVE_GETTIMEOFDAY 1
+
+/* Define to 1 if you have the `udev' library (-ludev). */
+#cmakedefine HAVE_LIBUDEV 1
+
+/* Define to 1 if you have the <linux/filter.h> header file. */
+#cmakedefine HAVE_LINUX_FILTER_H 1
+
+/* Define to 1 if you have the <linux/netlink.h> header file. */
+#cmakedefine HAVE_LINUX_NETLINK_H 1
+
+/* Define to 1 if you have the <poll.h> header file. */
+#cmakedefine HAVE_POLL_H 1
+
+/* Define to 1 if you have the <signal.h> header file. */
+#cmakedefine HAVE_SIGNAL_H 1
+
+/* Define to 1 if you have the <strings.h> header file. */
+#cmakedefine HAVE_STRINGS_H 1
+
+/* Define to 1 if the system has the type `struct timespec'. */
+#cmakedefine HAVE_STRUCT_TIMESPEC 1
+
+/* syslog() function available */
+#cmakedefine HAVE_SYSLOG_FUNC 1
+
+/* Define to 1 if you have the <syslog.h> header file. */
+#cmakedefine HAVE_SYSLOG_H 1
+
+/* Define to 1 if you have the <sys/socket.h> header file. */
+#cmakedefine HAVE_SYS_SOCKET_H 1
+
+/* Define to 1 if you have the <sys/time.h> header file. */
+#cmakedefine HAVE_SYS_TIME_H 1
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#cmakedefine HAVE_SYS_TYPES_H 1
+
+/* Darwin backend */
+#cmakedefine OS_DARWIN 1
+
+/* Linux backend */
+#cmakedefine OS_LINUX 1
+
+/* NetBSD backend */
+#cmakedefine OS_NETBSD 1
+
+/* OpenBSD backend */
+#cmakedefine OS_OPENBSD 1
+
+/* Windows backend */
+#cmakedefine OS_WINDOWS 1
+
+/* type of second poll() argument */
+#define POLL_NFDS_TYPE @POLL_NFDS_TYPE@
+
+/* Use POSIX Threads */
+#cmakedefine THREADS_POSIX
+
+/* timerfd headers available */
+#cmakedefine USBI_TIMERFD_AVAILABLE 1
+
+/* Enable output to system log */
+#define USE_SYSTEM_LOGGING_FACILITY 1
+
+/* Use udev for device enumeration/hotplug */
+#cmakedefine USE_UDEV 1
+
+/* Use GNU extensions */
+#define _GNU_SOURCE
+
+/* Oldest Windows version supported */
+#define WINVER 0x0501

externals/libusb/libusb

@@ -0,0 +1 @@
+Subproject commit e782eeb2514266f6738e242cdcb18e3ae1ed06fa

src/citra_qt/configuration/configure_input.cpp

@@ -56,12 +56,12 @@ static QString ButtonToText(const Common::ParamPackage& param) {
     if (!param.Has("engine")) {
         return QObject::tr("[not set]");
     }
-
+    const auto engine_str = param.Get("engine", "");
-    if (param.Get("engine", "") == "keyboard") {
+    if (engine_str == "keyboard") {
         return GetKeyName(param.Get("code", 0));
     }
 
-    if (param.Get("engine", "") == "sdl") {
+    if (engine_str == "sdl") {
         if (param.Has("hat")) {
             const QString hat_str = QString::fromStdString(param.Get("hat", ""));
             const QString direction_str = QString::fromStdString(param.Get("direction", ""));
@@ -85,6 +85,20 @@ static QString ButtonToText(const Common::ParamPackage& param) {
         return {};
     }
 
+    if (engine_str == "gcpad") {
+        if (param.Has("axis")) {
+            const QString axis_str = QString::fromStdString(param.Get("axis", ""));
+            const QString direction_str = QString::fromStdString(param.Get("direction", ""));
+
+            return QObject::tr("GC Axis %1%2").arg(axis_str, direction_str);
+        }
+        if (param.Has("button")) {
+            const QString button_str = QString::number(int(std::log2(param.Get("button", 0))));
+            return QObject::tr("GC Button %1").arg(button_str);
+        }
+        return GetKeyName(param.Get("code", 0));
+    }
+
     return QObject::tr("[unknown]");
 }
 
@@ -93,30 +107,33 @@ static QString AnalogToText(const Common::ParamPackage& param, const std::string
         return QObject::tr("[not set]");
     }
 
-    if (param.Get("engine", "") == "analog_from_button") {
+    const auto engine_str = param.Get("engine", "");
+    if (engine_str == "analog_from_button") {
         return ButtonToText(Common::ParamPackage{param.Get(dir, "")});
     }
 
-    if (param.Get("engine", "") == "sdl") {
+    const QString axis_x_str{QString::fromStdString(param.Get("axis_x", ""))};
+    const QString axis_y_str{QString::fromStdString(param.Get("axis_y", ""))};
+    static const QString plus_str{QString::fromStdString("+")};
+    static const QString minus_str{QString::fromStdString("-")};
+    if (engine_str == "sdl" || engine_str == "gcpad") {
         if (dir == "modifier") {
             return QObject::tr("[unused]");
         }
-
+        if (dir == "left") {
-        if (dir == "left" || dir == "right") {
+            return QObject::tr("Axis %1%2").arg(axis_x_str, minus_str);
-            const QString axis_x_str = QString::fromStdString(param.Get("axis_x", ""));
-
-            return QObject::tr("Axis %1").arg(axis_x_str);
         }
-
+        if (dir == "right") {
-        if (dir == "up" || dir == "down") {
+            return QObject::tr("Axis %1%2").arg(axis_x_str, plus_str);
-            const QString axis_y_str = QString::fromStdString(param.Get("axis_y", ""));
+        }
-
+        if (dir == "up") {
-            return QObject::tr("Axis %1").arg(axis_y_str);
+            return QObject::tr("Axis %1%2").arg(axis_y_str, plus_str);
+        }
+        if (dir == "down") {
+            return QObject::tr("Axis %1%2").arg(axis_y_str, minus_str);
         }
-
         return {};
     }
-
     return QObject::tr("[unknown]");
 }
 
@@ -257,7 +274,8 @@ ConfigureInput::ConfigureInput(QWidget* parent)
         });
         connect(analog_map_deadzone_and_modifier_slider[analog_id], &QSlider::valueChanged, [=] {
             const int slider_value = analog_map_deadzone_and_modifier_slider[analog_id]->value();
-            if (analogs_param[analog_id].Get("engine", "") == "sdl") {
+            const auto engine = analogs_param[analog_id].Get("engine", "");
+            if (engine == "sdl" || engine == "gcpad") {
                 analog_map_deadzone_and_modifier_slider_label[analog_id]->setText(
                     tr("Deadzone: %1%").arg(slider_value));
                 analogs_param[analog_id].Set("deadzone", slider_value / 100.0f);
@@ -418,25 +436,21 @@ void ConfigureInput::UpdateButtonLabels() {
             analog_map_deadzone_and_modifier_slider_label[analog_id];
 
         if (param.Has("engine")) {
-            if (param.Get("engine", "") == "sdl") {
+            const auto engine{param.Get("engine", "")};
+            if (engine == "sdl" || engine == "gcpad") {
                 if (!param.Has("deadzone")) {
                     param.Set("deadzone", 0.1f);
                 }
-
+                const auto slider_value = static_cast<int>(param.Get("deadzone", 0.1f) * 100);
-                analog_stick_slider->setValue(static_cast<int>(param.Get("deadzone", 0.1f) * 100));
+                analog_stick_slider_label->setText(tr("Deadzone: %1%").arg(slider_value));
-                if (analog_stick_slider->value() == 0) {
+                analog_stick_slider->setValue(slider_value);
-                    analog_stick_slider_label->setText(tr("Deadzone: 0%"));
-                }
             } else {
                 if (!param.Has("modifier_scale")) {
                     param.Set("modifier_scale", 0.5f);
                 }
-
+                const auto slider_value = static_cast<int>(param.Get("modifier_scale", 0.5f) * 100);
-                analog_stick_slider->setValue(
+                analog_stick_slider_label->setText(tr("Modifier Scale: %1%").arg(slider_value));
-                    static_cast<int>(param.Get("modifier_scale", 0.5f) * 100));
+                analog_stick_slider->setValue(slider_value);
-                if (analog_stick_slider->value() == 0) {
-                    analog_stick_slider_label->setText(tr("Modifier Scale: 0%"));
-                }
             }
         }
     }
@@ -448,16 +462,14 @@ void ConfigureInput::MapFromButton(const Common::ParamPackage& params) {
     Common::ParamPackage aux_param;
     bool mapped = false;
     for (int button_id = 0; button_id < Settings::NativeButton::NumButtons; button_id++) {
-        aux_param = InputCommon::GetSDLControllerButtonBindByGUID(params.Get("guid", "0"),
+        aux_param = InputCommon::GetControllerButtonBinds(params, button_id);
-                                                                  params.Get("port", 0), button_id);
         if (aux_param.Has("engine")) {
             buttons_param[button_id] = aux_param;
             mapped = true;
         }
     }
     for (int analog_id = 0; analog_id < Settings::NativeAnalog::NumAnalogs; analog_id++) {
-        aux_param = InputCommon::GetSDLControllerAnalogBindByGUID(params.Get("guid", "0"),
+        aux_param = InputCommon::GetControllerAnalogBinds(params, analog_id);
-                                                                  params.Get("port", 0), analog_id);
         if (aux_param.Has("engine")) {
             analogs_param[analog_id] = aux_param;
             mapped = true;

src/input_common/CMakeLists.txt

@@ -1,6 +1,10 @@
 add_library(input_common STATIC
     analog_from_button.cpp
     analog_from_button.h
+    gcadapter/gc_adapter.cpp
+    gcadapter/gc_adapter.h
+    gcadapter/gc_poller.cpp
+    gcadapter/gc_poller.h
     keyboard.cpp
     keyboard.h
     main.cpp
@@ -30,3 +34,5 @@ endif()
 
 create_target_directory_groups(input_common)
 target_link_libraries(input_common PUBLIC core PRIVATE common ${Boost_LIBRARIES})
+target_include_directories(input_common PRIVATE ${LIBUSB_INCLUDE_DIR})
+target_link_libraries(input_common PUBLIC ${LIBUSB_LIBRARIES})

src/input_common/gcadapter/gc_adapter.cpp

@@ -0,0 +1,378 @@
+// Copyright 2014 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <chrono>
+#include <thread>
+
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4200) // nonstandard extension used : zero-sized array in struct/union
+#endif
+#include <libusb.h>
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+
+#include "common/logging/log.h"
+#include "common/param_package.h"
+#include "input_common/gcadapter/gc_adapter.h"
+
+namespace GCAdapter {
+
+Adapter::Adapter() {
+    if (usb_adapter_handle != nullptr) {
+        return;
+    }
+    const int init_res = libusb_init(&libusb_ctx);
+    if (init_res == LIBUSB_SUCCESS) {
+        adapter_scan_thread = std::thread(&Adapter::AdapterScanThread, this);
+    } else {
+        LOG_ERROR(Input, "libusb could not be initialized. failed with error = {}", init_res);
+    }
+}
+
+Adapter::~Adapter() {
+    JoinThreads();
+    ClearLibusbHandle();
+    ResetDevices();
+
+    if (libusb_ctx) {
+        libusb_exit(libusb_ctx);
+    }
+}
+
+void Adapter::AdapterInputThread() {
+    LOG_DEBUG(Input, "GC Adapter input thread started");
+    s32 payload_size{};
+    AdapterPayload adapter_payload{};
+
+    if (adapter_scan_thread.joinable()) {
+        adapter_scan_thread.join();
+    }
+
+    while (adapter_input_thread_running) {
+        libusb_interrupt_transfer(usb_adapter_handle, input_endpoint, adapter_payload.data(),
+                                  static_cast<s32>(adapter_payload.size()), &payload_size, 16);
+        if (IsPayloadCorrect(adapter_payload, payload_size)) {
+            UpdateControllers(adapter_payload);
+        }
+        std::this_thread::yield();
+    }
+
+    if (restart_scan_thread) {
+        adapter_scan_thread = std::thread(&Adapter::AdapterScanThread, this);
+        restart_scan_thread = false;
+    }
+}
+
+bool Adapter::IsPayloadCorrect(const AdapterPayload& adapter_payload, s32 payload_size) {
+    if (payload_size != static_cast<s32>(adapter_payload.size()) ||
+        adapter_payload[0] != LIBUSB_DT_HID) {
+        LOG_DEBUG(Input, "Error reading payload (size: {}, type: {:02x})", payload_size,
+                  adapter_payload[0]);
+        if (++input_error_counter > 20) {
+            LOG_ERROR(Input, "GC adapter timeout, Is the adapter connected?");
+            adapter_input_thread_running = false;
+            restart_scan_thread = true;
+        }
+        return false;
+    }
+
+    input_error_counter = 0;
+    return true;
+}
+
+void Adapter::UpdateControllers(const AdapterPayload& adapter_payload) {
+    for (std::size_t port = 0; port < pads.size(); ++port) {
+        const std::size_t offset = 1 + (9 * port);
+        const auto type = static_cast<ControllerTypes>(adapter_payload[offset] >> 4);
+        UpdatePadType(port, type);
+        if (DeviceConnected(port)) {
+            const u8 b1 = adapter_payload[offset + 1];
+            const u8 b2 = adapter_payload[offset + 2];
+            UpdateStateButtons(port, b1, b2);
+            UpdateStateAxes(port, adapter_payload);
+            if (configuring) {
+                UpdateSettings(port);
+            }
+        }
+    }
+}
+
+void Adapter::UpdatePadType(std::size_t port, ControllerTypes pad_type) {
+    if (pads[port].type == pad_type) {
+        return;
+    }
+    // Device changed reset device and set new type
+    ResetDevice(port);
+    pads[port].type = pad_type;
+}
+
+void Adapter::UpdateStateButtons(std::size_t port, u8 b1, u8 b2) {
+    if (port >= pads.size()) {
+        return;
+    }
+
+    static constexpr std::array<PadButton, 8> b1_buttons{
+        PadButton::ButtonA,    PadButton::ButtonB,     PadButton::ButtonX,    PadButton::ButtonY,
+        PadButton::ButtonLeft, PadButton::ButtonRight, PadButton::ButtonDown, PadButton::ButtonUp,
+    };
+
+    static constexpr std::array<PadButton, 4> b2_buttons{
+        PadButton::ButtonStart,
+        PadButton::TriggerZ,
+        PadButton::TriggerR,
+        PadButton::TriggerL,
+    };
+    pads[port].buttons = 0;
+    for (std::size_t i = 0; i < b1_buttons.size(); ++i) {
+        if ((b1 & (1U << i)) != 0) {
+            pads[port].buttons =
+                static_cast<u16>(pads[port].buttons | static_cast<u16>(b1_buttons[i]));
+            pads[port].last_button = b1_buttons[i];
+        }
+    }
+
+    for (std::size_t j = 0; j < b2_buttons.size(); ++j) {
+        if ((b2 & (1U << j)) != 0) {
+            pads[port].buttons =
+                static_cast<u16>(pads[port].buttons | static_cast<u16>(b2_buttons[j]));
+            pads[port].last_button = b2_buttons[j];
+        }
+    }
+}
+
+void Adapter::UpdateStateAxes(std::size_t port, const AdapterPayload& adapter_payload) {
+    if (port >= pads.size()) {
+        return;
+    }
+
+    const std::size_t offset = 1 + (9 * port);
+    static constexpr std::array<PadAxes, 6> axes{
+        PadAxes::StickX,    PadAxes::StickY,      PadAxes::SubstickX,
+        PadAxes::SubstickY, PadAxes::TriggerLeft, PadAxes::TriggerRight,
+    };
+
+    for (const PadAxes axis : axes) {
+        const auto index = static_cast<std::size_t>(axis);
+        const u8 axis_value = adapter_payload[offset + 3 + index];
+        if (pads[port].axis_origin[index] == 255) {
+            pads[port].axis_origin[index] = axis_value;
+        }
+        pads[port].axis_values[index] =
+            static_cast<s16>(axis_value - pads[port].axis_origin[index]);
+    }
+}
+
+void Adapter::UpdateSettings(std::size_t port) {
+    if (port >= pads.size()) {
+        return;
+    }
+
+    constexpr u8 axis_threshold = 50;
+    GCPadStatus pad_status = {port};
+
+    if (pads[port].buttons != 0) {
+        pad_status.button = pads[port].last_button;
+        pad_queue.Push(pad_status);
+    }
+
+    // Accounting for a threshold here to ensure an intentional press
+    for (std::size_t i = 0; i < pads[port].axis_values.size(); ++i) {
+        const s16 value = pads[port].axis_values[i];
+
+        if (value > axis_threshold || value < -axis_threshold) {
+            pad_status.axis = static_cast<PadAxes>(i);
+            pad_status.axis_value = value;
+            pad_status.axis_threshold = axis_threshold;
+            pad_queue.Push(pad_status);
+        }
+    }
+}
+
+void Adapter::AdapterScanThread() {
+    adapter_scan_thread_running = true;
+    adapter_input_thread_running = false;
+    if (adapter_input_thread.joinable()) {
+        adapter_input_thread.join();
+    }
+    ClearLibusbHandle();
+    ResetDevices();
+    while (adapter_scan_thread_running && !adapter_input_thread_running) {
+        Setup();
+        std::this_thread::sleep_for(std::chrono::seconds(1));
+    }
+}
+
+void Adapter::Setup() {
+    usb_adapter_handle = libusb_open_device_with_vid_pid(libusb_ctx, 0x057e, 0x0337);
+
+    if (usb_adapter_handle == NULL) {
+        return;
+    }
+    if (!CheckDeviceAccess()) {
+        ClearLibusbHandle();
+        return;
+    }
+
+    libusb_device* device = libusb_get_device(usb_adapter_handle);
+
+    LOG_INFO(Input, "GC adapter is now connected");
+    // GC Adapter found and accessible, registering it
+    if (GetGCEndpoint(device)) {
+        adapter_scan_thread_running = false;
+        adapter_input_thread_running = true;
+        input_error_counter = 0;
+        adapter_input_thread = std::thread(&Adapter::AdapterInputThread, this);
+    }
+}
+
+bool Adapter::CheckDeviceAccess() {
+    // This fixes payload problems from offbrand GCAdapters
+    const s32 control_transfer_error =
+        libusb_control_transfer(usb_adapter_handle, 0x21, 11, 0x0001, 0, nullptr, 0, 1000);
+    if (control_transfer_error < 0) {
+        LOG_ERROR(Input, "libusb_control_transfer failed with error= {}", control_transfer_error);
+    }
+
+    s32 kernel_driver_error = libusb_kernel_driver_active(usb_adapter_handle, 0);
+    if (kernel_driver_error == 1) {
+        kernel_driver_error = libusb_detach_kernel_driver(usb_adapter_handle, 0);
+        if (kernel_driver_error != 0 && kernel_driver_error != LIBUSB_ERROR_NOT_SUPPORTED) {
+            LOG_ERROR(Input, "libusb_detach_kernel_driver failed with error = {}",
+                      kernel_driver_error);
+        }
+    }
+
+    if (kernel_driver_error && kernel_driver_error != LIBUSB_ERROR_NOT_SUPPORTED) {
+        libusb_close(usb_adapter_handle);
+        usb_adapter_handle = nullptr;
+        return false;
+    }
+
+    const int interface_claim_error = libusb_claim_interface(usb_adapter_handle, 0);
+    if (interface_claim_error) {
+        LOG_ERROR(Input, "libusb_claim_interface failed with error = {}", interface_claim_error);
+        libusb_close(usb_adapter_handle);
+        usb_adapter_handle = nullptr;
+        return false;
+    }
+
+    return true;
+}
+
+bool Adapter::GetGCEndpoint(libusb_device* device) {
+    libusb_config_descriptor* config = nullptr;
+    const int config_descriptor_return = libusb_get_config_descriptor(device, 0, &config);
+    if (config_descriptor_return != LIBUSB_SUCCESS) {
+        LOG_ERROR(Input, "libusb_get_config_descriptor failed with error = {}",
+                  config_descriptor_return);
+        return false;
+    }
+
+    for (u8 ic = 0; ic < config->bNumInterfaces; ic++) {
+        const libusb_interface* interfaceContainer = &config->interface[ic];
+        for (int i = 0; i < interfaceContainer->num_altsetting; i++) {
+            const libusb_interface_descriptor* interface = &interfaceContainer->altsetting[i];
+            for (u8 e = 0; e < interface->bNumEndpoints; e++) {
+                const libusb_endpoint_descriptor* endpoint = &interface->endpoint[e];
+                if ((endpoint->bEndpointAddress & LIBUSB_ENDPOINT_IN) != 0) {
+                    input_endpoint = endpoint->bEndpointAddress;
+                } else {
+                    output_endpoint = endpoint->bEndpointAddress;
+                }
+            }
+        }
+    }
+    // This transfer seems to be responsible for clearing the state of the adapter
+    // Used to clear the "busy" state of when the device is unexpectedly unplugged
+    unsigned char clear_payload = 0x13;
+    libusb_interrupt_transfer(usb_adapter_handle, output_endpoint, &clear_payload,
+                              sizeof(clear_payload), nullptr, 16);
+    return true;
+}
+
+void Adapter::JoinThreads() {
+    restart_scan_thread = false;
+    adapter_input_thread_running = false;
+    adapter_scan_thread_running = false;
+
+    if (adapter_scan_thread.joinable()) {
+        adapter_scan_thread.join();
+    }
+
+    if (adapter_input_thread.joinable()) {
+        adapter_input_thread.join();
+    }
+}
+
+void Adapter::ClearLibusbHandle() {
+    if (usb_adapter_handle) {
+        libusb_release_interface(usb_adapter_handle, 1);
+        libusb_close(usb_adapter_handle);
+        usb_adapter_handle = nullptr;
+    }
+}
+
+void Adapter::ResetDevices() {
+    for (std::size_t i = 0; i < pads.size(); ++i) {
+        ResetDevice(i);
+    }
+}
+
+void Adapter::ResetDevice(std::size_t port) {
+    pads[port].type = ControllerTypes::None;
+    pads[port].buttons = 0;
+    pads[port].last_button = PadButton::Undefined;
+    pads[port].axis_values.fill(0);
+    pads[port].axis_origin.fill(255);
+}
+
+std::vector<Common::ParamPackage> Adapter::GetInputDevices() const {
+    std::vector<Common::ParamPackage> devices;
+    for (std::size_t port = 0; port < pads.size(); ++port) {
+        if (!DeviceConnected(port)) {
+            continue;
+        }
+        std::string name = fmt::format("Gamecube Controller {}", port + 1);
+        devices.emplace_back(Common::ParamPackage{
+            {"class", "gcpad"},
+            {"display", std::move(name)},
+            {"port", std::to_string(port)},
+        });
+    }
+    return devices;
+}
+
+bool Adapter::DeviceConnected(std::size_t port) const {
+    return pads[port].type != ControllerTypes::None;
+}
+
+void Adapter::BeginConfiguration() {
+    pad_queue.Clear();
+    configuring = true;
+}
+
+void Adapter::EndConfiguration() {
+    pad_queue.Clear();
+    configuring = false;
+}
+
+Common::SPSCQueue<GCPadStatus>& Adapter::GetPadQueue() {
+    return pad_queue;
+}
+
+const Common::SPSCQueue<GCPadStatus>& Adapter::GetPadQueue() const {
+    return pad_queue;
+}
+
+GCController& Adapter::GetPadState(std::size_t port) {
+    return pads.at(port);
+}
+
+const GCController& Adapter::GetPadState(std::size_t port) const {
+    return pads.at(port);
+}
+
+} // namespace GCAdapter

src/input_common/gcadapter/gc_adapter.h

@@ -0,0 +1,153 @@
+// Copyright 2014 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <algorithm>
+#include <array>
+#include <functional>
+#include <mutex>
+#include <thread>
+#include <unordered_map>
+#include "common/common_types.h"
+#include "common/threadsafe_queue.h"
+
+struct libusb_context;
+struct libusb_device;
+struct libusb_device_handle;
+
+namespace Common {
+class ParamPackage;
+}
+
+namespace GCAdapter {
+
+enum class PadButton {
+    Undefined = 0x0000,
+    ButtonLeft = 0x0001,
+    ButtonRight = 0x0002,
+    ButtonDown = 0x0004,
+    ButtonUp = 0x0008,
+    TriggerZ = 0x0010,
+    TriggerR = 0x0020,
+    TriggerL = 0x0040,
+    ButtonA = 0x0100,
+    ButtonB = 0x0200,
+    ButtonX = 0x0400,
+    ButtonY = 0x0800,
+    ButtonStart = 0x1000,
+    // Below is for compatibility with "AxisButton" type
+    Stick = 0x2000,
+};
+
+enum class PadAxes : u8 {
+    StickX,
+    StickY,
+    SubstickX,
+    SubstickY,
+    TriggerLeft,
+    TriggerRight,
+    Undefined,
+};
+
+enum class ControllerTypes {
+    None,
+    Wired,
+    Wireless,
+};
+
+struct GCPadStatus {
+    std::size_t port{};
+
+    PadButton button{PadButton::Undefined}; // Or-ed PAD_BUTTON_* and PAD_TRIGGER_* bits
+
+    PadAxes axis{PadAxes::Undefined};
+    s16 axis_value{};
+    u8 axis_threshold{50};
+};
+
+struct GCController {
+    ControllerTypes type{};
+    u16 buttons{};
+    PadButton last_button{};
+    std::array<s16, 6> axis_values{};
+    std::array<u8, 6> axis_origin{};
+};
+
+class Adapter {
+public:
+    Adapter();
+    ~Adapter();
+
+    /// Used for polling
+    void BeginConfiguration();
+    void EndConfiguration();
+
+    Common::SPSCQueue<GCPadStatus>& GetPadQueue();
+    const Common::SPSCQueue<GCPadStatus>& GetPadQueue() const;
+
+    GCController& GetPadState(std::size_t port);
+    const GCController& GetPadState(std::size_t port) const;
+
+    /// Returns true if there is a device connected to port
+    bool DeviceConnected(std::size_t port) const;
+
+    std::vector<Common::ParamPackage> GetInputDevices() const;
+
+private:
+    using AdapterPayload = std::array<u8, 37>;
+
+    void UpdatePadType(std::size_t port, ControllerTypes pad_type);
+    void UpdateControllers(const AdapterPayload& adapter_payload);
+    void UpdateSettings(std::size_t port);
+    void UpdateStateButtons(std::size_t port, u8 b1, u8 b2);
+    void UpdateStateAxes(std::size_t port, const AdapterPayload& adapter_payload);
+
+    void AdapterInputThread();
+
+    void AdapterScanThread();
+
+    bool IsPayloadCorrect(const AdapterPayload& adapter_payload, s32 payload_size);
+
+    /// For use in initialization, querying devices to find the adapter
+    void Setup();
+
+    /// Resets status of all GC controller devices to a disconnected state
+    void ResetDevices();
+
+    /// Resets status of device connected to a disconnected state
+    void ResetDevice(std::size_t port);
+
+    /// Returns true if we successfully gain access to GC Adapter
+    bool CheckDeviceAccess();
+
+    /// Captures GC Adapter endpoint address
+    /// Returns true if the endpoint was set correctly
+    bool GetGCEndpoint(libusb_device* device);
+
+    // Join all threads
+    void JoinThreads();
+
+    // Release usb handles
+    void ClearLibusbHandle();
+
+    libusb_device_handle* usb_adapter_handle = nullptr;
+    std::array<GCController, 4> pads;
+    Common::SPSCQueue<GCPadStatus> pad_queue;
+
+    std::thread adapter_input_thread;
+    std::thread adapter_scan_thread;
+    bool adapter_input_thread_running;
+    bool adapter_scan_thread_running;
+    bool restart_scan_thread;
+
+    libusb_context* libusb_ctx;
+
+    u8 input_endpoint{0};
+    u8 output_endpoint{0};
+    u8 input_error_counter{0};
+
+    bool configuring{false};
+};
+} // namespace GCAdapter

src/input_common/gcadapter/gc_poller.cpp

@@ -0,0 +1,323 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <atomic>
+#include <list>
+#include <mutex>
+#include <utility>
+#include "common/assert.h"
+#include "common/threadsafe_queue.h"
+#include "input_common/gcadapter/gc_adapter.h"
+#include "input_common/gcadapter/gc_poller.h"
+
+namespace InputCommon {
+namespace {
+constexpr std::array<GCAdapter::PadButton, Settings::NativeButton::NumButtons> gc_to_3ds_mapping{{
+    GCAdapter::PadButton::ButtonA,
+    GCAdapter::PadButton::ButtonB,
+    GCAdapter::PadButton::ButtonX,
+    GCAdapter::PadButton::ButtonY,
+    GCAdapter::PadButton::ButtonUp,
+    GCAdapter::PadButton::ButtonDown,
+    GCAdapter::PadButton::ButtonLeft,
+    GCAdapter::PadButton::ButtonRight,
+    GCAdapter::PadButton::TriggerL,
+    GCAdapter::PadButton::TriggerR,
+    GCAdapter::PadButton::ButtonStart,
+    GCAdapter::PadButton::TriggerZ,
+    GCAdapter::PadButton::Undefined,
+    GCAdapter::PadButton::Undefined,
+    GCAdapter::PadButton::Undefined,
+    GCAdapter::PadButton::Undefined,
+    GCAdapter::PadButton::Undefined,
+}};
+}
+class GCButton final : public Input::ButtonDevice {
+public:
+    explicit GCButton(int port_, int button_, GCAdapter::Adapter* adapter)
+        : port(port_), button(button_), gcadapter(adapter) {}
+
+    ~GCButton() override;
+
+    bool GetStatus() const override {
+        if (gcadapter->DeviceConnected(port)) {
+            return (gcadapter->GetPadState(port).buttons & button) != 0;
+        }
+        return false;
+    }
+
+private:
+    const int port;
+    const int button;
+    GCAdapter::Adapter* gcadapter;
+};
+
+class GCAxisButton final : public Input::ButtonDevice {
+public:
+    explicit GCAxisButton(int port_, int axis_, float threshold_, bool trigger_if_greater_,
+                          GCAdapter::Adapter* adapter)
+        : port(port_), axis(axis_), threshold(threshold_), trigger_if_greater(trigger_if_greater_),
+          gcadapter(adapter) {}
+
+    bool GetStatus() const override {
+        if (gcadapter->DeviceConnected(port)) {
+            const float current_axis_value = gcadapter->GetPadState(port).axis_values.at(axis);
+            const float axis_value = current_axis_value / 128.0f;
+            if (trigger_if_greater) {
+                return axis_value > threshold;
+            }
+            return axis_value < -threshold;
+        }
+        return false;
+    }
+
+private:
+    const u32 port;
+    const u32 axis;
+    float threshold;
+    bool trigger_if_greater;
+    const GCAdapter::Adapter* gcadapter;
+};
+
+GCButtonFactory::GCButtonFactory(std::shared_ptr<GCAdapter::Adapter> adapter_)
+    : adapter(std::move(adapter_)) {}
+
+GCButton::~GCButton() = default;
+
+std::unique_ptr<Input::ButtonDevice> GCButtonFactory::Create(const Common::ParamPackage& params) {
+    const int button_id = params.Get("button", 0);
+    const int port = params.Get("port", 0);
+
+    constexpr s32 PAD_STICK_ID = static_cast<s32>(GCAdapter::PadButton::Stick);
+
+    // button is not an axis/stick button
+    if (button_id != PAD_STICK_ID) {
+        return std::make_unique<GCButton>(port, button_id, adapter.get());
+    }
+
+    // For Axis buttons, used by the binary sticks.
+    if (button_id == PAD_STICK_ID) {
+        const int axis = params.Get("axis", 0);
+        const float threshold = params.Get("threshold", 0.25f);
+        const std::string direction_name = params.Get("direction", "");
+        bool trigger_if_greater;
+        if (direction_name == "+") {
+            trigger_if_greater = true;
+        } else if (direction_name == "-") {
+            trigger_if_greater = false;
+        } else {
+            trigger_if_greater = true;
+            LOG_ERROR(Input, "Unknown direction {}", direction_name);
+        }
+        return std::make_unique<GCAxisButton>(port, axis, threshold, trigger_if_greater,
+                                              adapter.get());
+    }
+
+    UNREACHABLE();
+    return nullptr;
+}
+
+Common::ParamPackage GCButtonFactory::GetNextInput() {
+    Common::ParamPackage params;
+    GCAdapter::GCPadStatus pad;
+    auto& queue = adapter->GetPadQueue();
+    while (queue.Pop(pad)) {
+        // This while loop will break on the earliest detected button
+        params.Set("engine", "gcpad");
+        params.Set("port", static_cast<s32>(pad.port));
+        if (pad.button != GCAdapter::PadButton::Undefined) {
+            params.Set("button", static_cast<u16>(pad.button));
+        }
+
+        // For Axis button implementation
+        if (pad.axis != GCAdapter::PadAxes::Undefined) {
+            params.Set("axis", static_cast<u8>(pad.axis));
+            params.Set("button", static_cast<u16>(GCAdapter::PadButton::Stick));
+            params.Set("threshold", "0.25");
+            if (pad.axis_value > 0) {
+                params.Set("direction", "+");
+            } else {
+                params.Set("direction", "-");
+            }
+            break;
+        }
+    }
+    return params;
+}
+
+Common::ParamPackage GCButtonFactory::GetGcTo3DSMappedButton(
+    int port, Settings::NativeButton::Values button) {
+    Common::ParamPackage params({{"engine", "gcpad"}});
+    params.Set("port", port);
+    auto mapped_button = gc_to_3ds_mapping[static_cast<int>(button)];
+    if (mapped_button != GCAdapter::PadButton::Undefined) {
+        params.Set("button", static_cast<u16>(mapped_button));
+    }
+    return params;
+}
+
+void GCButtonFactory::Start() {
+    polling = true;
+    adapter->BeginConfiguration();
+}
+
+void GCButtonFactory::Stop() {
+    polling = false;
+    adapter->EndConfiguration();
+}
+
+class GCAnalog final : public Input::AnalogDevice {
+public:
+    explicit GCAnalog(u32 port_, u32 axis_x_, u32 axis_y_, float deadzone_,
+                      const GCAdapter::Adapter* adapter)
+        : port(port_), axis_x(axis_x_), axis_y(axis_y_), deadzone(deadzone_), gcadapter(adapter) {}
+
+    float GetAxis(u32 axis) const {
+        if (gcadapter->DeviceConnected(port)) {
+            std::lock_guard lock{mutex};
+            const auto axis_value =
+                static_cast<float>(gcadapter->GetPadState(port).axis_values.at(axis));
+            return (axis_value) / 50.0f;
+        }
+        return 0.0f;
+    }
+
+    std::pair<float, float> GetAnalog(u32 analog_axis_x, u32 analog_axis_y) const {
+        float x = GetAxis(analog_axis_x);
+        float y = GetAxis(analog_axis_y);
+        // Make sure the coordinates are in the unit circle,
+        // otherwise normalize it.
+        float r = x * x + y * y;
+        if (r > 1.0f) {
+            r = std::sqrt(r);
+            x /= r;
+            y /= r;
+        }
+
+        return {x, y};
+    }
+
+    std::tuple<float, float> GetStatus() const override {
+        const auto [x, y] = GetAnalog(axis_x, axis_y);
+        const float r = std::sqrt((x * x) + (y * y));
+        if (r > deadzone) {
+            return {x / r * (r - deadzone) / (1 - deadzone),
+                    y / r * (r - deadzone) / (1 - deadzone)};
+        }
+        return {0.0f, 0.0f};
+    }
+
+private:
+    const u32 port;
+    const u32 axis_x;
+    const u32 axis_y;
+    const float deadzone;
+    const GCAdapter::Adapter* gcadapter;
+    mutable std::mutex mutex;
+};
+
+/// An analog device factory that creates analog devices from GC Adapter
+GCAnalogFactory::GCAnalogFactory(std::shared_ptr<GCAdapter::Adapter> adapter_)
+    : adapter(std::move(adapter_)) {}
+
+/**
+ * Creates analog device from joystick axes
+ * @param params contains parameters for creating the device:
+ *     - "port": the nth gcpad on the adapter
+ *     - "axis_x": the index of the axis to be bind as x-axis
+ *     - "axis_y": the index of the axis to be bind as y-axis
+ */
+std::unique_ptr<Input::AnalogDevice> GCAnalogFactory::Create(const Common::ParamPackage& params) {
+    const auto port = static_cast<u32>(params.Get("port", 0));
+    const auto axis_x = static_cast<u32>(params.Get("axis_x", 0));
+    const auto axis_y = static_cast<u32>(params.Get("axis_y", 1));
+    const auto deadzone = std::clamp(params.Get("deadzone", 0.0f), 0.0f, 1.0f);
+
+    return std::make_unique<GCAnalog>(port, axis_x, axis_y, deadzone, adapter.get());
+}
+
+void GCAnalogFactory::Start() {
+    polling = true;
+    adapter->BeginConfiguration();
+}
+
+void GCAnalogFactory::Stop() {
+    polling = false;
+    adapter->EndConfiguration();
+}
+
+Common::ParamPackage GCAnalogFactory::GetNextInput() {
+    GCAdapter::GCPadStatus pad;
+    Common::ParamPackage params;
+    auto& queue = adapter->GetPadQueue();
+    while (queue.Pop(pad)) {
+        if (pad.button != GCAdapter::PadButton::Undefined) {
+            params.Set("engine", "gcpad");
+            params.Set("port", static_cast<s32>(pad.port));
+            params.Set("button", static_cast<u16>(pad.button));
+            return params;
+        }
+        if (pad.axis == GCAdapter::PadAxes::Undefined ||
+            std::abs(static_cast<float>(pad.axis_value) / 128.0f) < 0.1f) {
+            continue;
+        }
+        // An analog device needs two axes, so we need to store the axis for later and wait for
+        // a second input event. The axes also must be from the same joystick.
+        const u8 axis = static_cast<u8>(pad.axis);
+        if (axis == 0 || axis == 1) {
+            analog_x_axis = 0;
+            analog_y_axis = 1;
+            controller_number = static_cast<s32>(pad.port);
+            break;
+        }
+        if (axis == 2 || axis == 3) {
+            analog_x_axis = 2;
+            analog_y_axis = 3;
+            controller_number = static_cast<s32>(pad.port);
+            break;
+        }
+
+        if (analog_x_axis == -1) {
+            analog_x_axis = axis;
+            controller_number = static_cast<s32>(pad.port);
+        } else if (analog_y_axis == -1 && analog_x_axis != axis &&
+                   controller_number == static_cast<s32>(pad.port)) {
+            analog_y_axis = axis;
+            break;
+        }
+    }
+    if (analog_x_axis != -1 && analog_y_axis != -1) {
+        params.Set("engine", "gcpad");
+        params.Set("port", controller_number);
+        params.Set("axis_x", analog_x_axis);
+        params.Set("axis_y", analog_y_axis);
+        analog_x_axis = -1;
+        analog_y_axis = -1;
+        controller_number = -1;
+        return params;
+    }
+    return params;
+}
+
+Common::ParamPackage GCAnalogFactory::GetGcTo3DSMappedAnalog(
+    int port, Settings::NativeAnalog::Values analog) {
+    int x_axis, y_axis;
+    Common::ParamPackage params({{"engine", "gcpad"}});
+    params.Set("port", port);
+    if (analog == Settings::NativeAnalog::Values::CirclePad) {
+        x_axis = static_cast<s32>(GCAdapter::PadAxes::StickX);
+        y_axis = static_cast<s32>(GCAdapter::PadAxes::StickY);
+    } else if (analog == Settings::NativeAnalog::Values::CStick) {
+        x_axis = static_cast<s32>(GCAdapter::PadAxes::SubstickX);
+        y_axis = static_cast<s32>(GCAdapter::PadAxes::SubstickY);
+    } else {
+        LOG_WARNING(Input, "analog value out of range {}", analog);
+        return {{}};
+    }
+    params.Set("axis_x", x_axis);
+    params.Set("axis_y", y_axis);
+    return params;
+}
+
+} // namespace InputCommon

src/input_common/gcadapter/gc_poller.h

@@ -0,0 +1,70 @@
+// Copyright 2020 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include "core/frontend/input.h"
+#include "core/settings.h"
+#include "input_common/gcadapter/gc_adapter.h"
+#include "input_common/main.h"
+
+namespace InputCommon {
+
+/**
+ * A button device factory representing a gcpad. It receives gcpad events and forward them
+ * to all button devices it created.
+ */
+class GCButtonFactory final : public Input::Factory<Input::ButtonDevice>,
+                              public Polling::DevicePoller {
+public:
+public:
+    explicit GCButtonFactory(std::shared_ptr<GCAdapter::Adapter> adapter_);
+
+    std::unique_ptr<Input::ButtonDevice> Create(const Common::ParamPackage& params) override;
+
+    Common::ParamPackage GetNextInput() override;
+    Common::ParamPackage GetGcTo3DSMappedButton(int port, Settings::NativeButton::Values button);
+
+    /// For device input configuration/polling
+    void Start() override;
+    void Stop() override;
+
+    bool IsPolling() const {
+        return polling;
+    }
+
+private:
+    std::shared_ptr<GCAdapter::Adapter> adapter;
+    bool polling{false};
+};
+
+/// An analog device factory that creates analog devices from GC Adapter
+class GCAnalogFactory final : public Input::Factory<Input::AnalogDevice>,
+                              public Polling::DevicePoller {
+public:
+    explicit GCAnalogFactory(std::shared_ptr<GCAdapter::Adapter> adapter_);
+
+    std::unique_ptr<Input::AnalogDevice> Create(const Common::ParamPackage& params) override;
+
+    Common::ParamPackage GetNextInput() override;
+    Common::ParamPackage GetGcTo3DSMappedAnalog(int port, Settings::NativeAnalog::Values analog);
+
+    /// For device input configuration/polling
+    void Start() override;
+    void Stop() override;
+
+    bool IsPolling() const {
+        return polling;
+    }
+
+private:
+    std::shared_ptr<GCAdapter::Adapter> adapter;
+    int analog_x_axis{-1};
+    int analog_y_axis{-1};
+    int controller_number{-1};
+    bool polling{false};
+};
+
+} // namespace InputCommon

src/input_common/main.cpp

@@ -6,6 +6,8 @@
 #include <thread>
 #include "common/param_package.h"
 #include "input_common/analog_from_button.h"
+#include "input_common/gcadapter/gc_adapter.h"
+#include "input_common/gcadapter/gc_poller.h"
 #include "input_common/keyboard.h"
 #include "input_common/main.h"
 #include "input_common/motion_emu.h"
@@ -16,12 +18,20 @@
 
 namespace InputCommon {
 
+std::shared_ptr<GCButtonFactory> gcbuttons;
+std::shared_ptr<GCAnalogFactory> gcanalog;
+std::shared_ptr<GCAdapter::Adapter> gcadapter;
 static std::shared_ptr<Keyboard> keyboard;
 static std::shared_ptr<MotionEmu> motion_emu;
 static std::unique_ptr<CemuhookUDP::State> udp;
 static std::unique_ptr<SDL::State> sdl;
 
 void Init() {
+    gcadapter = std::make_shared<GCAdapter::Adapter>();
+    gcbuttons = std::make_shared<GCButtonFactory>(gcadapter);
+    Input::RegisterFactory<Input::ButtonDevice>("gcpad", gcbuttons);
+    gcanalog = std::make_shared<GCAnalogFactory>(gcadapter);
+    Input::RegisterFactory<Input::AnalogDevice>("gcpad", gcanalog);
     keyboard = std::make_shared<Keyboard>();
     Input::RegisterFactory<Input::ButtonDevice>("keyboard", keyboard);
     Input::RegisterFactory<Input::AnalogDevice>("analog_from_button",
@@ -37,6 +47,10 @@ void Init() {
 }
 
 void Shutdown() {
+    Input::UnregisterFactory<Input::ButtonDevice>("gcpad");
+    Input::UnregisterFactory<Input::AnalogDevice>("gcpad");
+    gcbuttons.reset();
+    gcanalog.reset();
     Input::UnregisterFactory<Input::ButtonDevice>("keyboard");
     keyboard.reset();
     Input::UnregisterFactory<Input::AnalogDevice>("analog_from_button");
@@ -77,16 +91,30 @@ std::string GenerateAnalogParamFromKeys(int key_up, int key_down, int key_left,
     return circle_pad_param.Serialize();
 }
 
-Common::ParamPackage GetSDLControllerButtonBindByGUID(const std::string& guid, int port,
+Common::ParamPackage GetControllerButtonBinds(const Common::ParamPackage& params, int button) {
-                                                      int button) {
+    const auto native_button{static_cast<Settings::NativeButton::Values>(button)};
+    const auto engine{params.Get("engine", "")};
+    if (engine == "sdl") {
         return dynamic_cast<SDL::SDLState*>(sdl.get())->GetSDLControllerButtonBindByGUID(
-        guid, port, static_cast<Settings::NativeButton::Values>(button));
+            params.Get("guid", "0"), params.Get("port", 0), native_button);
+    }
+    if (engine == "gcpad") {
+        return gcbuttons->GetGcTo3DSMappedButton(params.Get("port", 0), native_button);
+    }
+    return {};
 }
 
-Common::ParamPackage GetSDLControllerAnalogBindByGUID(const std::string& guid, int port,
+Common::ParamPackage GetControllerAnalogBinds(const Common::ParamPackage& params, int analog) {
-                                                      int analog) {
+    const auto native_analog{static_cast<Settings::NativeAnalog::Values>(analog)};
+    const auto engine{params.Get("engine", "")};
+    if (engine == "sdl") {
         return dynamic_cast<SDL::SDLState*>(sdl.get())->GetSDLControllerAnalogBindByGUID(
-        guid, port, static_cast<Settings::NativeAnalog::Values>(analog));
+            params.Get("guid", "0"), params.Get("port", 0), native_analog);
+    }
+    if (engine == "gcpad") {
+        return gcanalog->GetGcTo3DSMappedAnalog(params.Get("port", 0), native_analog);
+    }
+    return {};
 }
 
 void ReloadInputDevices() {
@@ -102,6 +130,16 @@ std::vector<std::unique_ptr<DevicePoller>> GetPollers(DeviceType type) {
 #ifdef HAVE_SDL2
     pollers = sdl->GetPollers(type);
 #endif
+    switch (type) {
+    case DeviceType::Analog:
+        pollers.push_back(std::make_unique<GCAnalogFactory>(*gcanalog));
+        break;
+    case DeviceType::Button:
+        pollers.push_back(std::make_unique<GCButtonFactory>(*gcbuttons));
+        break;
+    default:
+        break;
+    }
 
     return pollers;
 }

src/input_common/main.h

@@ -37,10 +37,8 @@ std::string GenerateKeyboardParam(int key_code);
 std::string GenerateAnalogParamFromKeys(int key_up, int key_down, int key_left, int key_right,
                                         int key_modifier, float modifier_scale);
 
-Common::ParamPackage GetSDLControllerButtonBindByGUID(const std::string& guid, int port,
+Common::ParamPackage GetControllerButtonBinds(const Common::ParamPackage& params, int button);
-                                                      int button);
+Common::ParamPackage GetControllerAnalogBinds(const Common::ParamPackage& params, int analog);
-Common::ParamPackage GetSDLControllerAnalogBindByGUID(const std::string& guid, int port,
-                                                      int analog);
 
 /// Reloads the input devices
 void ReloadInputDevices();