1/*
2 Simple DirectMedia Layer
3 Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
4 Copyright (C) 2020 Collabora Ltd.
5
6 This software is provided 'as-is', without any express or implied
7 warranty. In no event will the authors be held liable for any damages
8 arising from the use of this software.
9
10 Permission is granted to anyone to use this software for any purpose,
11 including commercial applications, and to alter it and redistribute it
12 freely, subject to the following restrictions:
13
14 1. The origin of this software must not be misrepresented; you must not
15 claim that you wrote the original software. If you use this software
16 in a product, an acknowledgment in the product documentation would be
17 appreciated but is not required.
18 2. Altered source versions must be plainly marked as such, and must not be
19 misrepresented as being the original software.
20 3. This notice may not be removed or altered from any source distribution.
21*/
22#include "SDL_internal.h"
23
24#include "SDL_evdev_capabilities.h"
25
26#ifdef HAVE_LINUX_INPUT_H
27
28// missing defines in older Linux kernel headers
29#ifndef BTN_TRIGGER_HAPPY
30#define BTN_TRIGGER_HAPPY 0x2c0
31#endif
32#ifndef BTN_DPAD_UP
33#define BTN_DPAD_UP 0x220
34#endif
35#ifndef KEY_ALS_TOGGLE
36#define KEY_ALS_TOGGLE 0x230
37#endif
38
39extern int
40SDL_EVDEV_GuessDeviceClass(const unsigned long bitmask_props[NBITS(INPUT_PROP_MAX)],
41 const unsigned long bitmask_ev[NBITS(EV_MAX)],
42 const unsigned long bitmask_abs[NBITS(ABS_MAX)],
43 const unsigned long bitmask_key[NBITS(KEY_MAX)],
44 const unsigned long bitmask_rel[NBITS(REL_MAX)])
45{
46 struct range
47 {
48 unsigned start;
49 unsigned end;
50 };
51
52 // key code ranges above BTN_MISC (start is inclusive, stop is exclusive)
53 static const struct range high_key_blocks[] = {
54 { KEY_OK, BTN_DPAD_UP },
55 { KEY_ALS_TOGGLE, BTN_TRIGGER_HAPPY }
56 };
57
58 int devclass = 0;
59 unsigned long keyboard_mask;
60
61 // If the kernel specifically says it's an accelerometer, believe it
62 if (test_bit(INPUT_PROP_ACCELEROMETER, bitmask_props)) {
63 return SDL_UDEV_DEVICE_ACCELEROMETER;
64 }
65
66 // We treat pointing sticks as indistinguishable from mice
67 if (test_bit(INPUT_PROP_POINTING_STICK, bitmask_props)) {
68 return SDL_UDEV_DEVICE_MOUSE;
69 }
70
71 // We treat buttonpads as equivalent to touchpads
72 if (test_bit(INPUT_PROP_TOPBUTTONPAD, bitmask_props) ||
73 test_bit(INPUT_PROP_BUTTONPAD, bitmask_props) ||
74 test_bit(INPUT_PROP_SEMI_MT, bitmask_props)) {
75 return SDL_UDEV_DEVICE_TOUCHPAD;
76 }
77
78 // X, Y, Z axes but no buttons probably means an accelerometer
79 if (test_bit(EV_ABS, bitmask_ev) &&
80 test_bit(ABS_X, bitmask_abs) &&
81 test_bit(ABS_Y, bitmask_abs) &&
82 test_bit(ABS_Z, bitmask_abs) &&
83 !test_bit(EV_KEY, bitmask_ev)) {
84 return SDL_UDEV_DEVICE_ACCELEROMETER;
85 }
86
87 /* RX, RY, RZ axes but no buttons probably means a gyro or
88 * accelerometer (we don't distinguish) */
89 if (test_bit(EV_ABS, bitmask_ev) &&
90 test_bit(ABS_RX, bitmask_abs) &&
91 test_bit(ABS_RY, bitmask_abs) &&
92 test_bit(ABS_RZ, bitmask_abs) &&
93 !test_bit(EV_KEY, bitmask_ev)) {
94 return SDL_UDEV_DEVICE_ACCELEROMETER;
95 }
96
97 if (test_bit(EV_ABS, bitmask_ev) &&
98 test_bit(ABS_X, bitmask_abs) && test_bit(ABS_Y, bitmask_abs)) {
99 if (test_bit(BTN_STYLUS, bitmask_key) || test_bit(BTN_TOOL_PEN, bitmask_key)) {
100 ; // ID_INPUT_TABLET
101 } else if (test_bit(BTN_TOOL_FINGER, bitmask_key) && !test_bit(BTN_TOOL_PEN, bitmask_key)) {
102 devclass |= SDL_UDEV_DEVICE_TOUCHPAD; // ID_INPUT_TOUCHPAD
103 } else if (test_bit(BTN_MOUSE, bitmask_key)) {
104 devclass |= SDL_UDEV_DEVICE_MOUSE; // ID_INPUT_MOUSE
105 } else if (test_bit(BTN_TOUCH, bitmask_key)) {
106 /* TODO: better determining between touchscreen and multitouch touchpad,
107 see https://github.com/systemd/systemd/blob/master/src/udev/udev-builtin-input_id.c */
108 devclass |= SDL_UDEV_DEVICE_TOUCHSCREEN; // ID_INPUT_TOUCHSCREEN
109 }
110
111 if (test_bit(BTN_TRIGGER, bitmask_key) ||
112 test_bit(BTN_A, bitmask_key) ||
113 test_bit(BTN_1, bitmask_key) ||
114 test_bit(ABS_RX, bitmask_abs) ||
115 test_bit(ABS_RY, bitmask_abs) ||
116 test_bit(ABS_RZ, bitmask_abs) ||
117 test_bit(ABS_THROTTLE, bitmask_abs) ||
118 test_bit(ABS_RUDDER, bitmask_abs) ||
119 test_bit(ABS_WHEEL, bitmask_abs) ||
120 test_bit(ABS_GAS, bitmask_abs) ||
121 test_bit(ABS_BRAKE, bitmask_abs)) {
122 devclass |= SDL_UDEV_DEVICE_JOYSTICK; // ID_INPUT_JOYSTICK
123 }
124 }
125
126 if (test_bit(EV_REL, bitmask_ev) &&
127 test_bit(REL_X, bitmask_rel) && test_bit(REL_Y, bitmask_rel) &&
128 test_bit(BTN_MOUSE, bitmask_key)) {
129 devclass |= SDL_UDEV_DEVICE_MOUSE; // ID_INPUT_MOUSE
130 }
131
132 if (test_bit(EV_KEY, bitmask_ev)) {
133 unsigned i;
134 unsigned long found = 0;
135
136 for (i = 0; i < BTN_MISC / BITS_PER_LONG; ++i) {
137 found |= bitmask_key[i];
138 }
139 // If there are no keys in the lower block, check the higher blocks
140 if (!found) {
141 unsigned block;
142 for (block = 0; block < (sizeof(high_key_blocks) / sizeof(struct range)); ++block) {
143 for (i = high_key_blocks[block].start; i < high_key_blocks[block].end; ++i) {
144 if (test_bit(i, bitmask_key)) {
145 found = 1;
146 break;
147 }
148 }
149 }
150 }
151
152 if (found > 0) {
153 devclass |= SDL_UDEV_DEVICE_HAS_KEYS; // ID_INPUT_KEY
154 }
155 }
156
157 /* the first 32 bits are ESC, numbers, and Q to D, so if we have all of
158 * those, consider it to be a fully-featured keyboard;
159 * do not test KEY_RESERVED, though */
160 keyboard_mask = 0xFFFFFFFE;
161 if ((bitmask_key[0] & keyboard_mask) == keyboard_mask) {
162 devclass |= SDL_UDEV_DEVICE_KEYBOARD; // ID_INPUT_KEYBOARD
163 }
164
165 return devclass;
166}
167
168#endif // HAVE_LINUX_INPUT_H
169