1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2024 Red Hat, Inc
3 */
4
5 #include "vmlinux.h"
6 #include "hid_bpf.h"
7 #include "hid_bpf_helpers.h"
8 #include "hid_report_helpers.h"
9 #include <bpf/bpf_tracing.h>
10
11 #define VID_HUION 0x256C
12 #define PID_DIAL_2 0x0060
13
14
15 HID_BPF_CONFIG(
16 HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_HUION, PID_DIAL_2),
17 );
18
19 /* Filled in by udev-hid-bpf */
20 char UDEV_PROP_HUION_FIRMWARE_ID[64];
21
22 /* The prefix of the firmware ID we expect for this device. The full firmware
23 * string has a date suffix, e.g. HUION_T21j_221221
24 */
25 char EXPECTED_FIRMWARE_ID[] = "HUION_T216_";
26
27 /* How this BPF program works: the tablet has two modes, firmware mode and
28 * tablet mode. In firmware mode (out of the box) the tablet sends button events
29 * and the dial as keyboard combinations. In tablet mode it uses a vendor specific
30 * hid report to report everything instead.
31 * Depending on the mode some hid reports are never sent and the corresponding
32 * devices are mute.
33 *
34 * To switch the tablet use e.g. https://github.com/whot/huion-switcher
35 * or one of the tools from the digimend project
36 *
37 * This BPF works for both modes. The huion-switcher tool sets the
38 * HUION_FIRMWARE_ID udev property - if that is set then we disable the firmware
39 * pad and pen reports (by making them vendor collections that are ignored).
40 * If that property is not set we fix all hidraw nodes so the tablet works in
41 * either mode though the drawback is that the device will show up twice if
42 * you bind it to all event nodes
43 *
44 * Default report descriptor for the first exposed hidraw node:
45 *
46 * # HUION Huion Tablet_Q630M
47 * # 0x06, 0x00, 0xff, // Usage Page (Vendor Defined Page 1) 0
48 * # 0x09, 0x01, // Usage (Vendor Usage 1) 3
49 * # 0xa1, 0x01, // Collection (Application) 5
50 * # 0x85, 0x08, // Report ID (8) 7
51 * # 0x75, 0x58, // Report Size (88) 9
52 * # 0x95, 0x01, // Report Count (1) 11
53 * # 0x09, 0x01, // Usage (Vendor Usage 1) 13
54 * # 0x81, 0x02, // Input (Data,Var,Abs) 15
55 * # 0xc0, // End Collection 17
56 * R: 18 06 00 ff 09 01 a1 01 85 08 75 58 95 01 09 01 81 02 c0
57 *
58 * This rdesc does nothing until the tablet is switched to raw mode, see
59 * https://github.com/whot/huion-switcher
60 *
61 *
62 * Second hidraw node is the Pen. This one sends events until the tablet is
63 * switched to raw mode, then it's mute.
64 *
65 * # Report descriptor length: 93 bytes
66 * # HUION Huion Tablet_Q630M
67 * # 0x05, 0x0d, // Usage Page (Digitizers) 0
68 * # 0x09, 0x02, // Usage (Pen) 2
69 * # 0xa1, 0x01, // Collection (Application) 4
70 * # 0x85, 0x0a, // Report ID (10) 6
71 * # 0x09, 0x20, // Usage (Stylus) 8
72 * # 0xa1, 0x01, // Collection (Application) 10
73 * # 0x09, 0x42, // Usage (Tip Switch) 12
74 * # 0x09, 0x44, // Usage (Barrel Switch) 14
75 * # 0x09, 0x45, // Usage (Eraser) 16
76 * # 0x09, 0x3c, // Usage (Invert) 18
77 * # 0x15, 0x00, // Logical Minimum (0) 20
78 * # 0x25, 0x01, // Logical Maximum (1) 22
79 * # 0x75, 0x01, // Report Size (1) 24
80 * # 0x95, 0x06, // Report Count (6) 26
81 * # 0x81, 0x02, // Input (Data,Var,Abs) 28
82 * # 0x09, 0x32, // Usage (In Range) 30
83 * # 0x75, 0x01, // Report Size (1) 32
84 * # 0x95, 0x01, // Report Count (1) 34
85 * # 0x81, 0x02, // Input (Data,Var,Abs) 36
86 * # 0x81, 0x03, // Input (Cnst,Var,Abs) 38
87 * # 0x05, 0x01, // Usage Page (Generic Desktop) 40
88 * # 0x09, 0x30, // Usage (X) 42
89 * # 0x09, 0x31, // Usage (Y) 44
90 * # 0x55, 0x0d, // Unit Exponent (-3) 46
91 * # 0x65, 0x33, // Unit (EnglishLinear: in³) 48
92 * # 0x26, 0xff, 0x7f, // Logical Maximum (32767) 50
93 * # 0x35, 0x00, // Physical Minimum (0) 53
94 * # 0x46, 0x00, 0x08, // Physical Maximum (2048) 55
95 * # 0x75, 0x10, // Report Size (16) 58
96 * # 0x95, 0x02, // Report Count (2) 60
97 * # 0x81, 0x02, // Input (Data,Var,Abs) 62
98 * # 0x05, 0x0d, // Usage Page (Digitizers) 64
99 * # 0x09, 0x30, // Usage (Tip Pressure) 66
100 * # 0x26, 0xff, 0x1f, // Logical Maximum (8191) 68
101 * # 0x75, 0x10, // Report Size (16) 71
102 * # 0x95, 0x01, // Report Count (1) 73
103 * # 0x81, 0x02, // Input (Data,Var,Abs) 75
104 * # 0x09, 0x3d, // Usage (X Tilt) 77
105 * # 0x09, 0x3e, // Usage (Y Tilt) 79
106 * # 0x15, 0x81, // Logical Minimum (-127) 81
107 * # 0x25, 0x7f, // Logical Maximum (127) 83
108 * # 0x75, 0x08, // Report Size (8) 85
109 * # 0x95, 0x02, // Report Count (2) 87
110 * # 0x81, 0x02, // Input (Data,Var,Abs) 89
111 * # 0xc0, // End Collection 91
112 * # 0xc0, // End Collection 92
113 * R: 93 05 0d 09 02 a1 01 85 0a 09 20 a1 01 09 42 09 44 09 45 09 3c 15 00 25 01 75 01 95 06 81 02 09 32 75 01 95 01 81 02 81 03 05 01 09 30 09 31 55 0d 65 33 26 ff 7f 35 00 46 00 08 75 10 95 02 81 02 05 0d 09 30 26 ff 1f 75 10 95 01 81 02 09 3d 09 3e 15 81 25 7f 75 08 95 02 81 02 c0 c0
114 *
115 * Third hidraw node is the pad which sends a combination of keyboard shortcuts until
116 * the tablet is switched to raw mode, then it's mute:
117 *
118 * # Report descriptor length: 148 bytes
119 * # HUION Huion Tablet_Q630M
120 * # 0x05, 0x01, // Usage Page (Generic Desktop) 0
121 * # 0x09, 0x0e, // Usage (System Multi-Axis Controller) 2
122 * # 0xa1, 0x01, // Collection (Application) 4
123 * # 0x85, 0x11, // Report ID (17) 6
124 * # 0x05, 0x0d, // Usage Page (Digitizers) 8
125 * # 0x09, 0x21, // Usage (Puck) 10
126 * # 0xa1, 0x02, // Collection (Logical) 12
127 * # 0x15, 0x00, // Logical Minimum (0) 14
128 * # 0x25, 0x01, // Logical Maximum (1) 16
129 * # 0x75, 0x01, // Report Size (1) 18
130 * # 0x95, 0x01, // Report Count (1) 20
131 * # 0xa1, 0x00, // Collection (Physical) 22
132 * # 0x05, 0x09, // Usage Page (Button) 24
133 * # 0x09, 0x01, // Usage (Vendor Usage 0x01) 26
134 * # 0x81, 0x02, // Input (Data,Var,Abs) 28
135 * # 0x05, 0x0d, // Usage Page (Digitizers) 30
136 * # 0x09, 0x33, // Usage (Touch) 32
137 * # 0x81, 0x02, // Input (Data,Var,Abs) 34
138 * # 0x95, 0x06, // Report Count (6) 36
139 * # 0x81, 0x03, // Input (Cnst,Var,Abs) 38
140 * # 0xa1, 0x02, // Collection (Logical) 40
141 * # 0x05, 0x01, // Usage Page (Generic Desktop) 42
142 * # 0x09, 0x37, // Usage (Dial) 44
143 * # 0x16, 0x00, 0x80, // Logical Minimum (-32768) 46
144 * # 0x26, 0xff, 0x7f, // Logical Maximum (32767) 49
145 * # 0x75, 0x10, // Report Size (16) 52
146 * # 0x95, 0x01, // Report Count (1) 54
147 * # 0x81, 0x06, // Input (Data,Var,Rel) 56
148 * # 0x35, 0x00, // Physical Minimum (0) 58
149 * # 0x46, 0x10, 0x0e, // Physical Maximum (3600) 60
150 * # 0x15, 0x00, // Logical Minimum (0) 63
151 * # 0x26, 0x10, 0x0e, // Logical Maximum (3600) 65
152 * # 0x09, 0x48, // Usage (Resolution Multiplier) 68
153 * # 0xb1, 0x02, // Feature (Data,Var,Abs) 70
154 * # 0x45, 0x00, // Physical Maximum (0) 72
155 * # 0xc0, // End Collection 74
156 * # 0x75, 0x08, // Report Size (8) 75
157 * # 0x95, 0x01, // Report Count (1) 77
158 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 79
159 * # 0x75, 0x08, // Report Size (8) 81
160 * # 0x95, 0x01, // Report Count (1) 83
161 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 85
162 * # 0x75, 0x08, // Report Size (8) 87
163 * # 0x95, 0x01, // Report Count (1) 89
164 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 91
165 * # 0x75, 0x08, // Report Size (8) 93
166 * # 0x95, 0x01, // Report Count (1) 95
167 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 97
168 * # 0x75, 0x08, // Report Size (8) 99
169 * # 0x95, 0x01, // Report Count (1) 101
170 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 103
171 * # 0xc0, // End Collection 105
172 * # 0xc0, // End Collection 106
173 * # 0xc0, // End Collection 107
174 * # 0x05, 0x01, // Usage Page (Generic Desktop) 108
175 * # 0x09, 0x06, // Usage (Keyboard) 110
176 * # 0xa1, 0x01, // Collection (Application) 112
177 * # 0x85, 0x03, // Report ID (3) 114
178 * # 0x05, 0x07, // Usage Page (Keyboard) 116
179 * # 0x19, 0xe0, // Usage Minimum (224) 118
180 * # 0x29, 0xe7, // Usage Maximum (231) 120
181 * # 0x15, 0x00, // Logical Minimum (0) 122
182 * # 0x25, 0x01, // Logical Maximum (1) 124
183 * # 0x75, 0x01, // Report Size (1) 126
184 * # 0x95, 0x08, // Report Count (8) 128
185 * # 0x81, 0x02, // Input (Data,Var,Abs) 130
186 * # 0x05, 0x07, // Usage Page (Keyboard) 132
187 * # 0x19, 0x00, // Usage Minimum (0) 134
188 * # 0x29, 0xff, // Usage Maximum (255) 136
189 * # 0x26, 0xff, 0x00, // Logical Maximum (255) 138
190 * # 0x75, 0x08, // Report Size (8) 141
191 * # 0x95, 0x06, // Report Count (6) 143
192 * # 0x81, 0x00, // Input (Data,Arr,Abs) 145
193 * # 0xc0, // End Collection 147
194 * R: 148 05 01 09 0e a1 01 85 11 05 0d 09 21 a1 02 15 00 25 01 75 01 95 01 a1 00 05 09 09 01 81 02 05 0d 09 33 81 02 95 06 81 03 a1 02 05 01 09 37 16 00 80 26 ff 7f 75 10 95 01 81 06 35 00 46 10 0e 15 00 26 10 0e 09 48 b1 02 45 00 c0 75 08 95 01 81 01 75 08 95 01 81 01 75 08 95 01 81 01 75 08 95 01 81 01 75 08 95 01 81 01 c0 c0 c0 05 01 09 06 a1 01 85 03 05 07 19 e0 29 e7 15 00 25 01 75 01 95 08 81 02 05 07 19 00 29 ff 26 ff 00 75 08 95 06 81 00 c0
195 */
196
197 #define PAD_REPORT_DESCRIPTOR_LENGTH 148
198 #define PEN_REPORT_DESCRIPTOR_LENGTH 93
199 #define VENDOR_REPORT_DESCRIPTOR_LENGTH 18
200 #define PAD_REPORT_ID 3
201 #define DIAL_REPORT_ID 17
202 #define PEN_REPORT_ID 10
203 #define VENDOR_REPORT_ID 8
204 #define PAD_REPORT_LENGTH 9
205 #define PEN_REPORT_LENGTH 10
206 #define VENDOR_REPORT_LENGTH 12
207
208
209 __u8 last_button_state;
210
211 static const __u8 fixed_rdesc_pad[] = {
212 UsagePage_GenericDesktop
213 Usage_GD_Keypad
214 CollectionApplication(
215 // -- Byte 0 in report
216 ReportId(PAD_REPORT_ID)
217 LogicalRange_i8(0, 1)
218 UsagePage_Digitizers
219 Usage_Dig_TabletFunctionKeys
220 CollectionPhysical(
221 // Byte 1 in report - just exists so we get to be a tablet pad
222 Usage_Dig_BarrelSwitch // BTN_STYLUS
223 ReportCount(1)
224 ReportSize(1)
225 Input(Var|Abs)
226 ReportCount(7) // padding
227 Input(Const)
228 // Bytes 2/3 in report - just exists so we get to be a tablet pad
229 UsagePage_GenericDesktop
230 Usage_GD_X
231 Usage_GD_Y
232 ReportCount(2)
233 ReportSize(8)
234 Input(Var|Abs)
235 // Byte 4 in report is the dial
236 Usage_GD_Wheel
237 LogicalRange_i8(-1, 1)
238 ReportCount(1)
239 ReportSize(8)
240 Input(Var|Rel)
241 // Byte 5 is the button state
242 UsagePage_Button
243 UsageRange_i8(0x01, 0x8)
244 LogicalRange_i8(0x0, 0x1)
245 ReportCount(7)
246 ReportSize(1)
247 Input(Var|Abs)
248 ReportCount(1) // padding
249 Input(Const)
250 )
251 // Make sure we match our original report length
252 FixedSizeVendorReport(PAD_REPORT_LENGTH)
253 )
254 };
255
256 static const __u8 fixed_rdesc_pen[] = {
257 UsagePage_Digitizers
258 Usage_Dig_Pen
259 CollectionApplication(
260 // -- Byte 0 in report
261 ReportId(PEN_REPORT_ID)
262 Usage_Dig_Pen
263 CollectionPhysical(
264 // -- Byte 1 in report
265 Usage_Dig_TipSwitch
266 Usage_Dig_BarrelSwitch
267 Usage_Dig_SecondaryBarrelSwitch // maps eraser to BTN_STYLUS2
268 LogicalRange_i8(0, 1)
269 ReportSize(1)
270 ReportCount(3)
271 Input(Var|Abs)
272 ReportCount(4) // Padding
273 Input(Const)
274 Usage_Dig_InRange
275 ReportCount(1)
276 Input(Var|Abs)
277 ReportSize(16)
278 ReportCount(1)
279 PushPop(
280 UsagePage_GenericDesktop
281 Unit(cm)
282 UnitExponent(-1)
283 PhysicalRange_i16(0, 266)
284 LogicalRange_i16(0, 32767)
285 Usage_GD_X
286 Input(Var|Abs) // Bytes 2+3
287 PhysicalRange_i16(0, 166)
288 LogicalRange_i16(0, 32767)
289 Usage_GD_Y
290 Input(Var|Abs) // Bytes 4+5
291 )
292 UsagePage_Digitizers
293 Usage_Dig_TipPressure
294 LogicalRange_i16(0, 8191)
295 Input(Var|Abs) // Byte 6+7
296 ReportSize(8)
297 ReportCount(2)
298 LogicalRange_i8(-60, 60)
299 Usage_Dig_XTilt
300 Usage_Dig_YTilt
301 Input(Var|Abs) // Byte 8+9
302 )
303 )
304 };
305
306 static const __u8 fixed_rdesc_vendor[] = {
307 UsagePage_Digitizers
308 Usage_Dig_Pen
309 CollectionApplication(
310 // Byte 0
311 // We leave the pen on the vendor report ID
312 ReportId(VENDOR_REPORT_ID)
313 Usage_Dig_Pen
314 CollectionPhysical(
315 // Byte 1 are the buttons
316 LogicalRange_i8(0, 1)
317 ReportSize(1)
318 Usage_Dig_TipSwitch
319 Usage_Dig_BarrelSwitch
320 Usage_Dig_SecondaryBarrelSwitch
321 ReportCount(3)
322 Input(Var|Abs)
323 ReportCount(4) // Padding
324 Input(Const)
325 Usage_Dig_InRange
326 ReportCount(1)
327 Input(Var|Abs)
328 ReportSize(16)
329 ReportCount(1)
330 PushPop(
331 UsagePage_GenericDesktop
332 Unit(cm)
333 UnitExponent(-1)
334 // Note: reported logical range differs
335 // from the pen report ID for x and y
336 LogicalRange_i16(0, 53340)
337 PhysicalRange_i16(0, 266)
338 // Bytes 2/3 in report
339 Usage_GD_X
340 Input(Var|Abs)
341 LogicalRange_i16(0, 33340)
342 PhysicalRange_i16(0, 166)
343 // Bytes 4/5 in report
344 Usage_GD_Y
345 Input(Var|Abs)
346 )
347 // Bytes 6/7 in report
348 LogicalRange_i16(0, 8191)
349 Usage_Dig_TipPressure
350 Input(Var|Abs)
351 // Bytes 8/9 in report
352 ReportCount(1) // Padding
353 Input(Const)
354 LogicalRange_i8(-60, 60)
355 // Byte 10 in report
356 Usage_Dig_XTilt
357 // Byte 11 in report
358 Usage_Dig_YTilt
359 ReportSize(8)
360 ReportCount(2)
361 Input(Var|Abs)
362 )
363 )
364 UsagePage_GenericDesktop
365 Usage_GD_Keypad
366 CollectionApplication(
367 // Byte 0
368 ReportId(PAD_REPORT_ID)
369 LogicalRange_i8(0, 1)
370 UsagePage_Digitizers
371 Usage_Dig_TabletFunctionKeys
372 CollectionPhysical(
373 // Byte 1 are the buttons
374 Usage_Dig_BarrelSwitch // BTN_STYLUS, needed so we get to be a tablet pad
375 ReportCount(1)
376 ReportSize(1)
377 Input(Var|Abs)
378 ReportCount(7) // Padding
379 Input(Const)
380 // Bytes 2/3 - x/y just exist so we get to be a tablet pad
381 UsagePage_GenericDesktop
382 Usage_GD_X
383 Usage_GD_Y
384 ReportCount(2)
385 ReportSize(8)
386 Input(Var|Abs)
387 // Byte 4 is the button state
388 UsagePage_Button
389 UsageRange_i8(0x01, 0x8)
390 LogicalRange_i8(0x0, 0x1)
391 ReportCount(8)
392 ReportSize(1)
393 Input(Var|Abs)
394 // Byte 5 is the top dial
395 UsagePage_GenericDesktop
396 Usage_GD_Wheel
397 LogicalRange_i8(-1, 1)
398 ReportCount(1)
399 ReportSize(8)
400 Input(Var|Rel)
401 // Byte 6 is the bottom dial
402 UsagePage_Consumer
403 Usage_Con_ACPan
404 Input(Var|Rel)
405 )
406 // Make sure we match our original report length
407 FixedSizeVendorReport(VENDOR_REPORT_LENGTH)
408 )
409 };
410
411 static const __u8 disabled_rdesc_pen[] = {
412 FixedSizeVendorReport(PEN_REPORT_LENGTH)
413 };
414
415 static const __u8 disabled_rdesc_pad[] = {
416 FixedSizeVendorReport(PAD_REPORT_LENGTH)
417 };
418
SEC(HID_BPF_RDESC_FIXUP)419 SEC(HID_BPF_RDESC_FIXUP)
420 int BPF_PROG(dial_2_fix_rdesc, struct hid_bpf_ctx *hctx)
421 {
422 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, HID_MAX_DESCRIPTOR_SIZE /* size */);
423 __s32 rdesc_size = hctx->size;
424 __u8 have_fw_id;
425
426 if (!data)
427 return 0; /* EPERM check */
428
429 /* If we have a firmware ID and it matches our expected prefix, we
430 * disable the default pad/pen nodes. They won't send events
431 * but cause duplicate devices.
432 */
433 have_fw_id = __builtin_memcmp(UDEV_PROP_HUION_FIRMWARE_ID,
434 EXPECTED_FIRMWARE_ID,
435 sizeof(EXPECTED_FIRMWARE_ID) - 1) == 0;
436 if (rdesc_size == PAD_REPORT_DESCRIPTOR_LENGTH) {
437 if (have_fw_id) {
438 __builtin_memcpy(data, disabled_rdesc_pad, sizeof(disabled_rdesc_pad));
439 return sizeof(disabled_rdesc_pad);
440 }
441
442 __builtin_memcpy(data, fixed_rdesc_pad, sizeof(fixed_rdesc_pad));
443 return sizeof(fixed_rdesc_pad);
444 }
445 if (rdesc_size == PEN_REPORT_DESCRIPTOR_LENGTH) {
446 if (have_fw_id) {
447 __builtin_memcpy(data, disabled_rdesc_pen, sizeof(disabled_rdesc_pen));
448 return sizeof(disabled_rdesc_pen);
449 }
450
451 __builtin_memcpy(data, fixed_rdesc_pen, sizeof(fixed_rdesc_pen));
452 return sizeof(fixed_rdesc_pen);
453 }
454 /* Always fix the vendor mode so the tablet will work even if nothing sets
455 * the udev property (e.g. huion-switcher run manually)
456 */
457 if (rdesc_size == VENDOR_REPORT_DESCRIPTOR_LENGTH) {
458 __builtin_memcpy(data, fixed_rdesc_vendor, sizeof(fixed_rdesc_vendor));
459 return sizeof(fixed_rdesc_vendor);
460
461 }
462 return 0;
463 }
464
SEC(HID_BPF_DEVICE_EVENT)465 SEC(HID_BPF_DEVICE_EVENT)
466 int BPF_PROG(dial_2_fix_events, struct hid_bpf_ctx *hctx)
467 {
468 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 16 /* size */);
469 static __u8 button;
470
471 if (!data)
472 return 0; /* EPERM check */
473
474 /* Only sent if tablet is in default mode */
475 if (data[0] == PAD_REPORT_ID) {
476 /* Nicely enough, this device only supports one button down at a time so
477 * the reports are easy to match. Buttons numbered from the top
478 * Button released: 03 00 00 00 00 00 00 00
479 * Button 1: 03 00 05 00 00 00 00 00 -> b
480 * Button 2: 03 00 08 00 00 00 00 00 -> e
481 * Button 3: 03 00 0c 00 00 00 00 00 -> i
482 * Button 4: 03 00 e0 16 00 00 00 00 -> Ctrl S
483 * Button 5: 03 00 2c 00 00 00 00 00 -> space
484 * Button 6: 03 00 e0 e2 1d 00 00 00 -> Ctrl Alt Z
485 */
486 button &= 0xc0;
487
488 switch ((data[2] << 16) | (data[3] << 8) | data[4]) {
489 case 0x000000:
490 break;
491 case 0x050000:
492 button |= BIT(0);
493 break;
494 case 0x080000:
495 button |= BIT(1);
496 break;
497 case 0x0c0000:
498 button |= BIT(2);
499 break;
500 case 0xe01600:
501 button |= BIT(3);
502 break;
503 case 0x2c0000:
504 button |= BIT(4);
505 break;
506 case 0xe0e21d:
507 button |= BIT(5);
508 break;
509 }
510
511 __u8 report[8] = {PAD_REPORT_ID, 0x0, 0x0, 0x0, 0x00, button};
512
513 __builtin_memcpy(data, report, sizeof(report));
514 return sizeof(report);
515 }
516
517 /* Only sent if tablet is in default mode */
518 if (data[0] == DIAL_REPORT_ID) {
519 /*
520 * In default mode, both dials are merged together:
521 *
522 * Dial down: 11 00 ff ff 00 00 00 00 00 -> Dial -1
523 * Dial up: 11 00 01 00 00 00 00 00 00 -> Dial 1
524 */
525 __u16 dial = data[3] << 8 | data[2];
526
527 button &= 0x3f;
528 button |= !!data[1] << 6;
529
530 __u8 report[] = {PAD_REPORT_ID, 0x0, 0x0, 0x0, dial, button};
531
532 __builtin_memcpy(data, report, sizeof(report));
533 return sizeof(report);
534 }
535
536 /* Nothing to do for the PEN_REPORT_ID, it's already mapped */
537
538 /* Only sent if tablet is in raw mode */
539 if (data[0] == VENDOR_REPORT_ID) {
540 /* Pad reports */
541 if (data[1] & 0x20) {
542 /* See fixed_rdesc_pad */
543 struct pad_report {
544 __u8 report_id;
545 __u8 btn_stylus;
546 __u8 x;
547 __u8 y;
548 __u8 buttons;
549 __u8 dial_1;
550 __u8 dial_2;
551 } __attribute__((packed)) *pad_report;
552 __u8 dial_1 = 0, dial_2 = 0;
553
554 /* Dial report */
555 if (data[1] == 0xf1) {
556 __u8 d = 0;
557
558 if (data[5] == 2)
559 d = 0xff;
560 else
561 d = data[5];
562
563 if (data[3] == 1)
564 dial_1 = d;
565 else
566 dial_2 = d;
567 } else {
568 /* data[4] are the buttons, mapped correctly */
569 last_button_state = data[4];
570 dial_1 = 0; // dial
571 dial_2 = 0;
572 }
573
574 pad_report = (struct pad_report *)data;
575
576 pad_report->report_id = PAD_REPORT_ID;
577 pad_report->btn_stylus = 0;
578 pad_report->x = 0;
579 pad_report->y = 0;
580 pad_report->buttons = last_button_state;
581 pad_report->dial_1 = dial_1;
582 pad_report->dial_2 = dial_2;
583
584 return sizeof(struct pad_report);
585 }
586
587 /* Pen reports need nothing done */
588 }
589
590 return 0;
591 }
592
593 HID_BPF_OPS(inspiroy_dial2) = {
594 .hid_device_event = (void *)dial_2_fix_events,
595 .hid_rdesc_fixup = (void *)dial_2_fix_rdesc,
596 };
597
598 SEC("syscall")
probe(struct hid_bpf_probe_args * ctx)599 int probe(struct hid_bpf_probe_args *ctx)
600 {
601 switch (ctx->rdesc_size) {
602 case PAD_REPORT_DESCRIPTOR_LENGTH:
603 case PEN_REPORT_DESCRIPTOR_LENGTH:
604 case VENDOR_REPORT_DESCRIPTOR_LENGTH:
605 ctx->retval = 0;
606 break;
607 default:
608 ctx->retval = -EINVAL;
609 }
610
611 return 0;
612 }
613
614 char _license[] SEC("license") = "GPL";
615