diff --git a/.gitignore b/.gitignore
index 78d5d3a..5e82c02 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,5 @@ chiaki.rb
 *.jks
 secret.tar
 keystore-env.sh
+compile_commands.json
+.ccls-cache
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4c203ef..841e1d3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -65,6 +65,7 @@ if(CHIAKI_ENABLE_CLI)
 endif()
 
 if(CHIAKI_ENABLE_GUI)
+	add_subdirectory(setsu)
 	add_subdirectory(gui)
 endif()
 
diff --git a/setsu/CMakeLists.txt b/setsu/CMakeLists.txt
new file mode 100644
index 0000000..e230c49
--- /dev/null
+++ b/setsu/CMakeLists.txt
@@ -0,0 +1,24 @@
+
+cmake_minimum_required(VERSION 3.2)
+
+project(libsetsu)
+
+option(SETSU_BUILD_TEST "Build testing executable for libsetsu" OFF)
+
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+
+add_library(setsu
+	include/setsu.h
+	src/setsu.c)
+
+target_include_directories(setsu PUBLIC include)
+
+find_package(UDEV REQUIRED)
+target_link_libraries(setsu UDEV::libudev)
+
+if(SETSU_BUILD_TEST)
+	add_executable(setsutest
+		test/main.c)
+	target_link_libraries(setsutest setsu)
+endif()
+
diff --git a/setsu/cmake/FindUDEV.cmake b/setsu/cmake/FindUDEV.cmake
new file mode 100644
index 0000000..3b6b1e0
--- /dev/null
+++ b/setsu/cmake/FindUDEV.cmake
@@ -0,0 +1,26 @@
+# Provides: UDEV::libudev
+
+set(_prefix UDEV)
+set(_target "${_prefix}::libudev")
+
+find_package(PkgConfig REQUIRED)
+
+pkg_check_modules("${_prefix}" libudev)
+
+function(resolve_location)
+
+endfunction()
+
+if(${_prefix}_FOUND)
+	add_library("${_target}" INTERFACE IMPORTED)
+	target_link_libraries("${_target}" INTERFACE ${${_prefix}_LIBRARIES})
+	target_include_directories("${_target}" INTERFACE ${${_prefix}_INCLUDE_DIRS})
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args("${_prefix}"
+	REQUIRED_VARS "${_prefix}_LIBRARIES"
+	VERSION_VAR "${_prefix}_VERSION")
+
+unset(_prefix)
+unset(_target)
diff --git a/setsu/include/setsu.h b/setsu/include/setsu.h
new file mode 100644
index 0000000..8df7536
--- /dev/null
+++ b/setsu/include/setsu.h
@@ -0,0 +1,26 @@
+/*
+ * This file is part of Chiaki.
+ *
+ * Chiaki is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Chiaki is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Chiaki.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef _SETSU_H
+#define _SETSU_H
+
+typedef struct setsu_ctx_t SetsuCtx;
+
+SetsuCtx *setsu_ctx_new();
+void setsu_ctx_free(SetsuCtx *ctx);
+
+#endif
diff --git a/setsu/src/setsu.c b/setsu/src/setsu.c
new file mode 100644
index 0000000..76ae7d5
--- /dev/null
+++ b/setsu/src/setsu.c
@@ -0,0 +1,177 @@
+
+#include <setsu.h>
+
+#include <libudev.h>
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+
+
+#include <stdio.h>
+
+typedef struct setsu_device_t
+{
+	struct setsu_device_t *next;
+	char *path;
+	int fd;
+} SetsuDevice;
+
+struct setsu_ctx_t
+{
+	struct udev *udev_ctx;
+	SetsuDevice *dev;
+};
+
+
+static void scan(SetsuCtx *ctx);
+static void update_device(SetsuCtx *ctx, struct udev_device *dev, bool added);
+static SetsuDevice *connect(SetsuCtx *ctx, const char *path);
+static void disconnect(SetsuCtx *ctx, SetsuDevice *dev);
+
+SetsuCtx *setsu_ctx_new()
+{
+	SetsuCtx *ctx = malloc(sizeof(SetsuCtx));
+	if(!ctx)
+		return NULL;
+
+	ctx->dev = NULL;
+
+	ctx->udev_ctx = udev_new();
+	if(!ctx->udev_ctx)
+	{
+		free(ctx);
+		return NULL;
+	}
+
+	// TODO: monitor
+
+	scan(ctx);
+
+	return ctx;
+}
+
+void setsu_ctx_free(SetsuCtx *ctx)
+{
+	while(ctx->dev)
+		disconnect(ctx, ctx->dev);
+	udev_unref(ctx->udev_ctx);
+	free(ctx);
+}
+
+static void scan(SetsuCtx *ctx)
+{
+	struct udev_enumerate *udev_enum = udev_enumerate_new(ctx->udev_ctx);
+	if(!udev_enum)
+		return;
+
+	if(udev_enumerate_add_match_subsystem(udev_enum, "input") < 0)
+		goto beach;
+
+	if(udev_enumerate_add_match_property(udev_enum, "ID_INPUT_TOUCHPAD", "1") < 0)
+		goto beach;
+	
+	if(udev_enumerate_scan_devices(udev_enum) < 0)
+		goto beach;
+
+	for(struct udev_list_entry *entry = udev_enumerate_get_list_entry(udev_enum); entry; entry = udev_list_entry_get_next(entry))
+	{
+		const char *path = udev_list_entry_get_name(entry);
+		if(!path)
+			continue;
+		struct udev_device *dev = udev_device_new_from_syspath(ctx->udev_ctx, path);
+		if(!dev)
+			continue;
+		update_device(ctx, dev, true);
+		udev_device_unref(dev);
+	}
+
+beach:
+	udev_enumerate_unref(udev_enum);
+}
+
+static bool is_device_interesting(struct udev_device *dev)
+{
+	static const char *device_ids[] = {
+		// vendor id, model id
+		"054c",       "05c4", // DualShock 4 USB
+		NULL
+	};
+
+	// Filter mouse-device (/dev/input/mouse*) away and only keep the evdev (/dev/input/event*) one: 
+	if(!udev_device_get_property_value(dev, "ID_INPUT_TOUCHPAD_INTEGRATION"))
+		return false;
+
+	const char *vendor = udev_device_get_property_value(dev, "ID_VENDOR_ID");
+	const char *model = udev_device_get_property_value(dev, "ID_MODEL_ID");
+	if(!vendor || !model)
+		return false;
+
+	for(const char **dev_id = device_ids; *dev_id; dev_id += 2)
+	{
+		if(!strcmp(vendor, dev_id[0]) && !strcmp(model, dev_id[1]))
+			return true;
+	}
+	return false;
+}
+
+static void update_device(SetsuCtx *ctx, struct udev_device *dev, bool added)
+{
+	if(!is_device_interesting(dev))
+		return;
+	const char *path = udev_device_get_devnode(dev);
+	if(!path)
+		return;
+	
+	for(SetsuDevice *dev = ctx->dev; dev; dev=dev->next)
+	{
+		if(!strcmp(dev->path, path))
+		{
+			if(added)
+				return; // already added, do nothing
+			disconnect(ctx, dev);
+		}
+	}
+	connect(ctx, path);
+}
+
+static SetsuDevice *connect(SetsuCtx *ctx, const char *path)
+{
+	SetsuDevice *dev = malloc(sizeof(SetsuDevice));
+	if(!dev)
+		return NULL;
+	dev->path = strdup(path);
+	if(!dev->path)
+	{
+		free(dev);
+		return NULL;
+	}
+
+	printf("connect %s\n", dev->path);
+	//dev->fd = open(dev->path, O_RDONLY | O_NONBLOCK);
+
+	dev->next = ctx->dev;
+	ctx->dev = dev;
+	return dev;
+}
+
+static void disconnect(SetsuCtx *ctx, SetsuDevice *dev)
+{
+	if(ctx->dev == dev)
+		ctx->dev = dev->next;
+	else
+	{
+		for(SetsuDevice *pdev = ctx->dev; pdev; pdev=pdev->next)
+		{
+			if(pdev->next == dev)
+			{
+				pdev->next = dev->next;
+				break;
+			}
+		}
+	}
+
+	free(dev->path);
+	free(dev);
+}
+
diff --git a/setsu/test/main.c b/setsu/test/main.c
new file mode 100644
index 0000000..823c283
--- /dev/null
+++ b/setsu/test/main.c
@@ -0,0 +1,25 @@
+
+#include <setsu.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+
+SetsuCtx *ctx;
+
+void quit()
+{
+	setsu_ctx_free(ctx);
+}
+
+int main()
+{
+	ctx = setsu_ctx_new();
+	if(!ctx)
+	{
+		printf("Failed to init setsu\n");
+		return 1;
+	}
+	atexit(quit);
+	return 0;
+}
+