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Huion__KeydialK20.bpf.c
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linux-6.19.14/drivers/hid/bpf/progs/Huion__KeydialK20.bpf.c
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_KEYDIAL_K20 0x0069 13 14HID_BPF_CONFIG( 15 HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_HUION, PID_KEYDIAL_K20), 16); 17 18/* Filled in by udev-hid-bpf */ 19char UDEV_PROP_HUION_FIRMWARE_ID[64]; 20 21/* The prefix of the firmware ID we expect for this device. The full firmware 22 * string has a date suffix, e.g. HUION_T21h_230511 23 */ 24char EXPECTED_FIRMWARE_ID[] = "HUION_T21h_"; 25 26/* How this BPF program works: the tablet has two modes, firmware mode and 27 * tablet mode. In firmware mode (out of the box) the tablet sends button events 28 * as keyboard shortcuts and the dial as wheel but it's not forwarded by the kernel. 29 * In tablet mode it uses a vendor specific hid report to report everything instead. 30 * Depending on the mode some hid reports are never sent and the corresponding 31 * devices are mute. 32 * 33 * To switch the tablet use e.g. https://github.com/whot/huion-switcher 34 * or one of the tools from the digimend project 35 * 36 * This BPF currently works for both modes only. The huion-switcher tool sets the 37 * HUION_FIRMWARE_ID udev property - if that is set then we disable the firmware 38 * pad and pen reports (by making them vendor collections that are ignored). 39 * If that property is not set we fix all hidraw nodes so the tablet works in 40 * either mode though the drawback is that the device will show up twice if 41 * you bind it to all event nodes 42 * 43 * Default report descriptor for the first exposed hidraw node: 44 * 45 * # HUION Huion Keydial_K20 46 * # Report descriptor length: 18 bytes 47 * # 0x06, 0x00, 0xff, // Usage Page (Vendor Defined Page 0xFF00) 0 48 * # 0x09, 0x01, // Usage (Vendor Usage 0x01) 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 0x01) 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 report descriptor appears to be identical for all Huion devices. 59 * 60 * Second hidraw node is the Pad. This one sends the button events until the tablet is 61 * switched to raw mode, then it's mute. 62 * 63 * # HUION Huion Keydial_K20 64 * # Report descriptor length: 135 bytes 65 * # 0x05, 0x01, // Usage Page (Generic Desktop) 0 66 * # 0x09, 0x06, // Usage (Keyboard) 2 67 * # 0xa1, 0x01, // Collection (Application) 4 68 * # 0x85, 0x03, // Report ID (3) 6 69 * # 0x05, 0x07, // Usage Page (Keyboard/Keypad) 8 70 * # 0x19, 0xe0, // UsageMinimum (224) 10 71 * # 0x29, 0xe7, // UsageMaximum (231) 12 72 * # 0x15, 0x00, // Logical Minimum (0) 14 73 * # 0x25, 0x01, // Logical Maximum (1) 16 74 * # 0x75, 0x01, // Report Size (1) 18 75 * # 0x95, 0x08, // Report Count (8) 20 76 * # 0x81, 0x02, // Input (Data,Var,Abs) 22 77 * # 0x05, 0x07, // Usage Page (Keyboard/Keypad) 24 78 * # 0x19, 0x00, // UsageMinimum (0) 26 79 * # 0x29, 0xff, // UsageMaximum (255) 28 80 * # 0x26, 0xff, 0x00, // Logical Maximum (255) 30 81 * # 0x75, 0x08, // Report Size (8) 33 82 * # 0x95, 0x06, // Report Count (6) 35 83 * # 0x81, 0x00, // Input (Data,Arr,Abs) 37 84 * # 0xc0, // End Collection 39 85 * # 0x05, 0x0c, // Usage Page (Consumer) 40 86 * # 0x09, 0x01, // Usage (Consumer Control) 42 87 * # 0xa1, 0x01, // Collection (Application) 44 88 * # 0x85, 0x04, // Report ID (4) 46 89 * # 0x05, 0x0c, // Usage Page (Consumer) 48 90 * # 0x19, 0x00, // UsageMinimum (0) 50 91 * # 0x2a, 0x80, 0x03, // UsageMaximum (896) 52 92 * # 0x15, 0x00, // Logical Minimum (0) 55 93 * # 0x26, 0x80, 0x03, // Logical Maximum (896) 57 94 * # 0x75, 0x10, // Report Size (16) 60 95 * # 0x95, 0x01, // Report Count (1) 62 96 * # 0x81, 0x00, // Input (Data,Arr,Abs) 64 97 * # 0xc0, // End Collection 66 98 * # 0x05, 0x01, // Usage Page (Generic Desktop) 67 99 * # 0x09, 0x02, // Usage (Mouse) 69 100 * # 0xa1, 0x01, // Collection (Application) 71 101 * # 0x09, 0x01, // Usage (Pointer) 73 102 * # 0x85, 0x05, // Report ID (5) 75 103 * # 0xa1, 0x00, // Collection (Physical) 77 104 * # 0x05, 0x09, // Usage Page (Button) 79 105 * # 0x19, 0x01, // UsageMinimum (1) 81 106 * # 0x29, 0x05, // UsageMaximum (5) 83 107 * # 0x15, 0x00, // Logical Minimum (0) 85 108 * # 0x25, 0x01, // Logical Maximum (1) 87 109 * # 0x95, 0x05, // Report Count (5) 89 110 * # 0x75, 0x01, // Report Size (1) 91 111 * # 0x81, 0x02, // Input (Data,Var,Abs) 93 112 * # 0x95, 0x01, // Report Count (1) 95 113 * # 0x75, 0x03, // Report Size (3) 97 114 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 99 115 * # 0x05, 0x01, // Usage Page (Generic Desktop) 101 116 * # 0x09, 0x30, // Usage (X) 103 117 * # 0x09, 0x31, // Usage (Y) 105 118 * # 0x16, 0x00, 0x80, // Logical Minimum (-32768) 107 119 * # 0x26, 0xff, 0x7f, // Logical Maximum (32767) 110 120 * # 0x75, 0x10, // Report Size (16) 113 121 * # 0x95, 0x02, // Report Count (2) 115 122 * # 0x81, 0x06, // Input (Data,Var,Rel) 117 123 * # 0x95, 0x01, // Report Count (1) 119 124 * # 0x75, 0x08, // Report Size (8) 121 125 * # 0x05, 0x01, // Usage Page (Generic Desktop) 123 126 * # 0x09, 0x38, // Usage (Wheel) 125 127 * # 0x15, 0x81, // Logical Minimum (-127) 127 128 * # 0x25, 0x7f, // Logical Maximum (127) 129 129 * # 0x81, 0x06, // Input (Data,Var,Rel) 131 130 * # 0xc0, // End Collection 133 131 * # 0xc0, // End Collection 134 132 * R: 135 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 05 0c 09 01 a1 01 85 04 05 0c 19 00 2a 80 03 15 00 26 80 03 75 10 95 01 81 00 c0 05 01 09 02 a1 01 09 01 85 05 a1 00 05 09 19 01 29 05 15 00 25 01 95 05 75 01 81 02 95 01 75 03 81 01 05 01 09 30 09 31 16 00 80 26 ff 7f 7510 95 02 81 06 95 01 75 08 05 01 09 38 15 81 25 7f 81 06 c0 c0 133 * 134 * Third hidraw node is a multi-axis controller which sends the dial events 135 * and the button inside the dial. If the tablet is switched to raw mode it is mute. 136 * 137 * # HUION Huion Keydial_K20 138 * # Report descriptor length: 108 bytes 139 * # 0x05, 0x01, // Usage Page (Generic Desktop) 0 140 * # 0x09, 0x0e, // Usage (System Multi-Axis Controller) 2 141 * # 0xa1, 0x01, // Collection (Application) 4 142 * # 0x85, 0x11, // Report ID (17) 6 143 * # 0x05, 0x0d, // Usage Page (Digitizers) 8 144 * # 0x09, 0x21, // Usage (Puck) 10 145 * # 0xa1, 0x02, // Collection (Logical) 12 146 * # 0x15, 0x00, // Logical Minimum (0) 14 147 * # 0x25, 0x01, // Logical Maximum (1) 16 148 * # 0x75, 0x01, // Report Size (1) 18 149 * # 0x95, 0x01, // Report Count (1) 20 150 * # 0xa1, 0x00, // Collection (Physical) 22 151 * # 0x05, 0x09, // Usage Page (Button) 24 152 * # 0x09, 0x01, // Usage (Button 1) 26 153 * # 0x81, 0x02, // Input (Data,Var,Abs) 28 154 * # 0x05, 0x0d, // Usage Page (Digitizers) 30 155 * # 0x09, 0x33, // Usage (Touch) 32 156 * # 0x81, 0x02, // Input (Data,Var,Abs) 34 157 * # 0x95, 0x06, // Report Count (6) 36 158 * # 0x81, 0x03, // Input (Cnst,Var,Abs) 38 159 * # 0xa1, 0x02, // Collection (Logical) 40 160 * # 0x05, 0x01, // Usage Page (Generic Desktop) 42 161 * # 0x09, 0x37, // Usage (Dial) 44 162 * # 0x16, 0x00, 0x80, // Logical Minimum (-32768) 46 163 * # 0x26, 0xff, 0x7f, // Logical Maximum (32767) 49 164 * # 0x75, 0x10, // Report Size (16) 52 165 * # 0x95, 0x01, // Report Count (1) 54 166 * # 0x81, 0x06, // Input (Data,Var,Rel) 56 167 * # 0x35, 0x00, // Physical Minimum (0) 58 168 * # 0x46, 0x10, 0x0e, // Physical Maximum (3600) 60 169 * # 0x15, 0x00, // Logical Minimum (0) 63 170 * # 0x26, 0x10, 0x0e, // Logical Maximum (3600) 65 171 * # 0x09, 0x48, // Usage (Resolution Multiplier) 68 172 * # 0xb1, 0x02, // Feature (Data,Var,Abs) 70 173 * # 0x45, 0x00, // Physical Maximum (0) 72 174 * # 0xc0, // End Collection 74 175 * # 0x75, 0x08, // Report Size (8) 75 176 * # 0x95, 0x01, // Report Count (1) 77 177 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 79 178 * # 0x75, 0x08, // Report Size (8) 81 179 * # 0x95, 0x01, // Report Count (1) 83 180 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 85 181 * # 0x75, 0x08, // Report Size (8) 87 182 * # 0x95, 0x01, // Report Count (1) 89 183 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 91 184 * # 0x75, 0x08, // Report Size (8) 93 185 * # 0x95, 0x01, // Report Count (1) 95 186 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 97 187 * # 0x75, 0x08, // Report Size (8) 99 188 * # 0x95, 0x01, // Report Count (1) 101 189 * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 103 190 * # 0xc0, // End Collection 105 191 * # 0xc0, // End Collection 106 192 * # 0xc0, // End Collection 107 193 * R: 108 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 194 * 195 */ 196 197#define PAD_REPORT_DESCRIPTOR_LENGTH 135 198#define PUCK_REPORT_DESCRIPTOR_LENGTH 108 199#define VENDOR_REPORT_DESCRIPTOR_LENGTH 18 200#define PAD_KBD_REPORT_ID 3 201#define PAD_CC_REPORT_ID 3 // never sends events 202#define PAD_MOUSE_REPORT_ID 4 // never sends events 203#define PUCK_REPORT_ID 17 204#define VENDOR_REPORT_ID 8 205#define PAD_KBD_REPORT_LENGTH 8 206#define PAD_CC_REPORT_LENGTH 3 207#define PAD_MOUSE_REPORT_LENGTH 7 208#define PUCK_REPORT_LENGTH 9 209#define VENDOR_REPORT_LENGTH 12 210 211__u32 last_button_state; 212 213static const __u8 disabled_rdesc_puck[] = { 214 FixedSizeVendorReport(PUCK_REPORT_LENGTH) 215}; 216 217static const __u8 disabled_rdesc_pad[] = { 218 FixedSizeVendorReport(PAD_KBD_REPORT_LENGTH) 219 FixedSizeVendorReport(PAD_CC_REPORT_LENGTH) 220 FixedSizeVendorReport(PAD_MOUSE_REPORT_LENGTH) 221}; 222 223static const __u8 fixed_rdesc_vendor[] = { 224 UsagePage_GenericDesktop 225 Usage_GD_Keypad 226 CollectionApplication( 227 // Byte 0 228 // We send our pad events on the vendor report id because why not 229 ReportId(VENDOR_REPORT_ID) 230 UsagePage_Digitizers 231 Usage_Dig_TabletFunctionKeys 232 CollectionPhysical( 233 // Byte 1 is a button so we look like a tablet 234 Usage_Dig_BarrelSwitch // BTN_STYLUS, needed so we get to be a tablet pad 235 ReportCount(1) 236 ReportSize(1) 237 Input(Var|Abs) 238 ReportCount(7) // Padding 239 Input(Const) 240 // Bytes 2/3 - x/y just exist so we get to be a tablet pad 241 UsagePage_GenericDesktop 242 Usage_GD_X 243 Usage_GD_Y 244 LogicalMinimum_i8(0x0) 245 LogicalMaximum_i8(0x1) 246 ReportCount(2) 247 ReportSize(8) 248 Input(Var|Abs) 249 // Bytes 4-7 are the button state for 19 buttons + pad out to u32 250 // We send the first 10 buttons as buttons 1-10 which is BTN_0 -> BTN_9 251 UsagePage_Button 252 UsageMinimum_i8(1) 253 UsageMaximum_i8(10) 254 LogicalMinimum_i8(0x0) 255 LogicalMaximum_i8(0x1) 256 ReportCount(10) 257 ReportSize(1) 258 Input(Var|Abs) 259 // We send the other 9 buttons as buttons 0x31 and above -> BTN_A - BTN_TL2 260 UsageMinimum_i8(0x31) 261 UsageMaximum_i8(0x3a) 262 ReportCount(9) 263 ReportSize(1) 264 Input(Var|Abs) 265 ReportCount(13) 266 ReportSize(1) 267 Input(Const) // padding 268 // Byte 6 is the wheel 269 UsagePage_GenericDesktop 270 Usage_GD_Wheel 271 LogicalMinimum_i8(-1) 272 LogicalMaximum_i8(1) 273 ReportCount(1) 274 ReportSize(8) 275 Input(Var|Rel) 276 ) 277 // Make sure we match our original report length 278 FixedSizeVendorReport(VENDOR_REPORT_LENGTH) 279 ) 280}; 281 282/* Identical to fixed_rdesc_pad but with different FixedSizeVendorReport */ 283static const __u8 fixed_rdesc_pad[] = { 284 UsagePage_GenericDesktop 285 Usage_GD_Keypad 286 CollectionApplication( 287 // Byte 0 288 // We send our pad events on the vendor report id because why not 289 ReportId(VENDOR_REPORT_ID) 290 UsagePage_Digitizers 291 Usage_Dig_TabletFunctionKeys 292 CollectionPhysical( 293 // Byte 1 is a button so we look like a tablet 294 Usage_Dig_BarrelSwitch // BTN_STYLUS, needed so we get to be a tablet pad 295 ReportCount(1) 296 ReportSize(1) 297 Input(Var|Abs) 298 ReportCount(7) // Padding 299 Input(Const) 300 // Bytes 2/3 - x/y just exist so we get to be a tablet pad 301 UsagePage_GenericDesktop 302 Usage_GD_X 303 Usage_GD_Y 304 LogicalMinimum_i8(0x0) 305 LogicalMaximum_i8(0x1) 306 ReportCount(2) 307 ReportSize(8) 308 Input(Var|Abs) 309 // Bytes 4-7 are the button state for 19 buttons + pad out to u32 310 // We send the first 10 buttons as buttons 1-10 which is BTN_0 -> BTN_9 311 UsagePage_Button 312 UsageMinimum_i8(1) 313 UsageMaximum_i8(10) 314 LogicalMinimum_i8(0x0) 315 LogicalMaximum_i8(0x1) 316 ReportCount(10) 317 ReportSize(1) 318 Input(Var|Abs) 319 // We send the other 9 buttons as buttons 0x31 and above -> BTN_A - BTN_TL2 320 UsageMinimum_i8(0x31) 321 UsageMaximum_i8(0x3a) 322 ReportCount(9) 323 ReportSize(1) 324 Input(Var|Abs) 325 ReportCount(13) 326 ReportSize(1) 327 Input(Const) // padding 328 // Byte 6 is the wheel 329 UsagePage_GenericDesktop 330 Usage_GD_Wheel 331 LogicalMinimum_i8(-1) 332 LogicalMaximum_i8(1) 333 ReportCount(1) 334 ReportSize(8) 335 Input(Var|Rel) 336 ) 337 // Make sure we match our original report lengths 338 FixedSizeVendorReport(PAD_KBD_REPORT_LENGTH) 339 FixedSizeVendorReport(PAD_CC_REPORT_LENGTH) 340 FixedSizeVendorReport(PAD_MOUSE_REPORT_LENGTH) 341 ) 342}; 343 344SEC(HID_BPF_RDESC_FIXUP) 345int BPF_PROG(k20_fix_rdesc, struct hid_bpf_ctx *hctx) 346{ 347 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, HID_MAX_DESCRIPTOR_SIZE /* size */); 348 __s32 rdesc_size = hctx->size; 349 __u8 have_fw_id; 350 351 if (!data) 352 return 0; /* EPERM check */ 353 354 /* If we have a firmware ID and it matches our expected prefix, we 355 * disable the default pad/puck nodes. They won't send events 356 * but cause duplicate devices. 357 */ 358 have_fw_id = __builtin_memcmp(UDEV_PROP_HUION_FIRMWARE_ID, 359 EXPECTED_FIRMWARE_ID, 360 sizeof(EXPECTED_FIRMWARE_ID) - 1) == 0; 361 if (rdesc_size == PAD_REPORT_DESCRIPTOR_LENGTH) { 362 if (have_fw_id) { 363 __builtin_memcpy(data, disabled_rdesc_pad, sizeof(disabled_rdesc_pad)); 364 return sizeof(disabled_rdesc_pad); 365 } else { 366 __builtin_memcpy(data, fixed_rdesc_pad, sizeof(fixed_rdesc_pad)); 367 return sizeof(fixed_rdesc_pad); 368 369 } 370 } 371 if (rdesc_size == PUCK_REPORT_DESCRIPTOR_LENGTH) { 372 if (have_fw_id) { 373 __builtin_memcpy(data, disabled_rdesc_puck, sizeof(disabled_rdesc_puck)); 374 return sizeof(disabled_rdesc_puck); 375 } 376 } 377 /* Always fix the vendor mode so the tablet will work even if nothing sets 378 * the udev property (e.g. huion-switcher run manually) 379 */ 380 if (rdesc_size == VENDOR_REPORT_DESCRIPTOR_LENGTH) { 381 __builtin_memcpy(data, fixed_rdesc_vendor, sizeof(fixed_rdesc_vendor)); 382 return sizeof(fixed_rdesc_vendor); 383 384 } 385 return 0; 386} 387 388SEC(HID_BPF_DEVICE_EVENT) 389int BPF_PROG(k20_fix_events, struct hid_bpf_ctx *hctx) 390{ 391 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 10 /* size */); 392 393 if (!data) 394 return 0; /* EPERM check */ 395 396 /* Only sent if tablet is in raw mode */ 397 if (data[0] == VENDOR_REPORT_ID) { 398 /* See fixed_rdesc_pad */ 399 struct pad_report { 400 __u8 report_id; 401 __u8 btn_stylus:1; 402 __u8 pad:7; 403 __u8 x; 404 __u8 y; 405 __u32 buttons; 406 __u8 wheel; 407 } __attribute__((packed)) *pad_report; 408 409 __u8 wheel = 0; 410 411 /* Wheel report */ 412 if (data[1] == 0xf1) { 413 if (data[5] == 2) 414 wheel = 0xff; 415 else 416 wheel = data[5]; 417 } else { 418 /* data[4..6] are the buttons, mapped correctly */ 419 last_button_state = data[4] | (data[5] << 8) | (data[6] << 16); 420 wheel = 0; // wheel 421 } 422 423 pad_report = (struct pad_report *)data; 424 pad_report->report_id = VENDOR_REPORT_ID; 425 pad_report->btn_stylus = 0; 426 pad_report->x = 0; 427 pad_report->y = 0; 428 pad_report->buttons = last_button_state; 429 pad_report->wheel = wheel; 430 431 return sizeof(struct pad_report); 432 } 433 434 if (data[0] == PAD_KBD_REPORT_ID) { 435 const __u8 button_mapping[] = { 436 0x0e, /* Button 1: K */ 437 0x0a, /* Button 2: G */ 438 0x0f, /* Button 3: L */ 439 0x4c, /* Button 4: Delete */ 440 0x0c, /* Button 5: I */ 441 0x07, /* Button 6: D */ 442 0x05, /* Button 7: B */ 443 0x08, /* Button 8: E */ 444 0x16, /* Button 9: S */ 445 0x1d, /* Button 10: Z */ 446 0x06, /* Button 11: C */ 447 0x19, /* Button 12: V */ 448 0xff, /* Button 13: LeftControl */ 449 0xff, /* Button 14: LeftAlt */ 450 0xff, /* Button 15: LeftShift */ 451 0x28, /* Button 16: Return Enter */ 452 0x2c, /* Button 17: Spacebar */ 453 0x11, /* Button 18: N */ 454 }; 455 /* See fixed_rdesc_pad */ 456 struct pad_report { 457 __u8 report_id; 458 __u8 btn_stylus:1; 459 __u8 pad:7; 460 __u8 x; 461 __u8 y; 462 __u32 buttons; 463 __u8 wheel; 464 } __attribute__((packed)) *pad_report; 465 int i, b; 466 __u8 modifiers = data[1]; 467 __u32 buttons = 0; 468 469 if (modifiers & 0x01) { /* Control */ 470 buttons |= BIT(12); 471 } 472 if (modifiers & 0x02) { /* Shift */ 473 buttons |= BIT(14); 474 } 475 if (modifiers & 0x04) { /* Alt */ 476 buttons |= BIT(13); 477 } 478 479 for (i = 2; i < PAD_KBD_REPORT_LENGTH; i++) { 480 if (!data[i]) 481 break; 482 483 for (b = 0; b < ARRAY_SIZE(button_mapping); b++) { 484 if (data[i] == button_mapping[b]) { 485 buttons |= BIT(b); 486 break; 487 } 488 } 489 data[i] = 0; 490 } 491 492 pad_report = (struct pad_report *)data; 493 pad_report->report_id = VENDOR_REPORT_ID; 494 pad_report->btn_stylus = 0; 495 pad_report->x = 0; 496 pad_report->y = 0; 497 pad_report->buttons = buttons; 498 // The wheel happens on a different hidraw node but its 499 // values are unreliable (as is the button inside the wheel). 500 // So the wheel is simply always zero, if you want the wheel 501 // to work reliably, use the tablet mode. 502 pad_report->wheel = 0; 503 504 return sizeof(struct pad_report); 505 } 506 507 return 0; 508} 509 510HID_BPF_OPS(keydial_k20) = { 511 .hid_device_event = (void *)k20_fix_events, 512 .hid_rdesc_fixup = (void *)k20_fix_rdesc, 513}; 514 515SEC("syscall") 516int probe(struct hid_bpf_probe_args *ctx) 517{ 518 switch (ctx->rdesc_size) { 519 case PAD_REPORT_DESCRIPTOR_LENGTH: 520 case PUCK_REPORT_DESCRIPTOR_LENGTH: 521 case VENDOR_REPORT_DESCRIPTOR_LENGTH: 522 ctx->retval = 0; 523 break; 524 default: 525 ctx->retval = -EINVAL; 526 } 527 528 return 0; 529} 530 531char _license[] SEC("license") = "GPL";
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