Quelle  Huion__Kamvas-Pro-19.bpf.c

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2024 Benjamin Tissoires
 */

#include "vmlinux.h"
#include "hid_bpf.h"
#include "hid_bpf_helpers.h"
#include <bpf/bpf_tracing.h>

#define VID_HUION 0x256C
#define PID_KAMVAS_PRO_19 0x006B
#define NAME_KAMVAS_PRO_19 "HUION Huion Tablet_GT1902"

#define TEST_PREFIX "uhid test "

HID_BPF_CONFIG(
 HID_DEVICE(BUS_USB, HID_GROUP_MULTITOUCH_WIN_8, VID_HUION, PID_KAMVAS_PRO_19),
);

bool prev_was_out_of_range;
bool in_eraser_mode;

/*
 * We need to amend the report descriptor for the following:
 * - the second button is reported through Secondary Tip Switch instead of Secondary Barrel Switch
 * - the third button is reported through Invert, and we need some room to report it.
 *
 */
static const __u8 fixed_rdesc[] = {
 0x05, 0x0d,                    // Usage Page (Digitizers)             0
 0x09, 0x02,                    // Usage (Pen)                         2
 0xa1, 0x01,                    // Collection (Application)            4
 0x85, 0x0a,                    //  Report ID (10)                     6
 0x09, 0x20,                    //  Usage (Stylus)                     8
 0xa1, 0x01,                    //  Collection (Application)           10
 0x09, 0x42,                    //   Usage (Tip Switch)                12
 0x09, 0x44,                    //   Usage (Barrel Switch)             14
 0x09, 0x5a,                    //   Usage (Secondary Barrel Switch)   16 /* changed from Secondary Tip Switch */
 0x09, 0x3c,                    //   Usage (Invert)                    18
 0x09, 0x45,                    //   Usage (Eraser)                    20
 0x15, 0x00,                    //   Logical Minimum (0)               22
 0x25, 0x01,                    //   Logical Maximum (1)               24
 0x75, 0x01,                    //   Report Size (1)                   26
 0x95, 0x05,                    //   Report Count (5)                  28 /* changed (was 6) */
 0x81, 0x02,                    //   Input (Data,Var,Abs)              30
 0x05, 0x09,                    //   Usage Page (Button)                  /* inserted */
 0x09, 0x4a,                    //   Usage (0x4a)                         /* inserted to be translated as input usage 0x149: BTN_STYLUS3 */
 0x95, 0x01,                    //   Report Count (1)                     /* inserted */
 0x81, 0x02,                    //   Input (Data,Var,Abs)                 /* inserted */
 0x05, 0x0d,                    //   Usage Page (Digitizers)              /* inserted */
 0x09, 0x32,                    //   Usage (In Range)                  32
 0x75, 0x01,                    //   Report Size (1)                   34
 0x95, 0x01,                    //   Report Count (1)                  36
 0x81, 0x02,                    //   Input (Data,Var,Abs)              38
 0x81, 0x03,                    //   Input (Cnst,Var,Abs)              40
 0x05, 0x01,                    //   Usage Page (Generic Desktop)      42
 0x09, 0x30,                    //   Usage (X)                         44
 0x09, 0x31,                    //   Usage (Y)                         46
 0x55, 0x0d,                    //   Unit Exponent (-3)                48
 0x65, 0x33,                    //   Unit (EnglishLinear: in³)         50
 0x26, 0xff, 0x7f,              //   Logical Maximum (32767)           52
 0x35, 0x00,                    //   Physical Minimum (0)              55
 0x46, 0x00, 0x08,              //   Physical Maximum (2048)           57
 0x75, 0x10,                    //   Report Size (16)                  60
 0x95, 0x02,                    //   Report Count (2)                  62
 0x81, 0x02,                    //   Input (Data,Var,Abs)              64
 0x05, 0x0d,                    //   Usage Page (Digitizers)           66
 0x09, 0x30,                    //   Usage (Tip Pressure)              68
 0x26, 0xff, 0x3f,              //   Logical Maximum (16383)           70
 0x75, 0x10,                    //   Report Size (16)                  73
 0x95, 0x01,                    //   Report Count (1)                  75
 0x81, 0x02,                    //   Input (Data,Var,Abs)              77
 0x09, 0x3d,                    //   Usage (X Tilt)                    79
 0x09, 0x3e,                    //   Usage (Y Tilt)                    81
 0x15, 0xa6,                    //   Logical Minimum (-90)             83
 0x25, 0x5a,                    //   Logical Maximum (90)              85
 0x75, 0x08,                    //   Report Size (8)                   87
 0x95, 0x02,                    //   Report Count (2)                  89
 0x81, 0x02,                    //   Input (Data,Var,Abs)              91
 0xc0,                          //  End Collection                     93
 0xc0,                          // End Collection                      94
 0x05, 0x0d,                    // Usage Page (Digitizers)             95
 0x09, 0x04,                    // Usage (Touch Screen)                97
 0xa1, 0x01,                    // Collection (Application)            99
 0x85, 0x04,                    //  Report ID (4)                      101
 0x09, 0x22,                    //  Usage (Finger)                     103
 0xa1, 0x02,                    //  Collection (Logical)               105
 0x05, 0x0d,                    //   Usage Page (Digitizers)           107
 0x95, 0x01,                    //   Report Count (1)                  109
 0x75, 0x06,                    //   Report Size (6)                   111
 0x09, 0x51,                    //   Usage (Contact Id)                113
 0x15, 0x00,                    //   Logical Minimum (0)               115
 0x25, 0x3f,                    //   Logical Maximum (63)              117
 0x81, 0x02,                    //   Input (Data,Var,Abs)              119
 0x09, 0x42,                    //   Usage (Tip Switch)                121
 0x25, 0x01,                    //   Logical Maximum (1)               123
 0x75, 0x01,                    //   Report Size (1)                   125
 0x95, 0x01,                    //   Report Count (1)                  127
 0x81, 0x02,                    //   Input (Data,Var,Abs)              129
 0x75, 0x01,                    //   Report Size (1)                   131
 0x95, 0x01,                    //   Report Count (1)                  133
 0x81, 0x03,                    //   Input (Cnst,Var,Abs)              135
 0x05, 0x01,                    //   Usage Page (Generic Desktop)      137
 0x75, 0x10,                    //   Report Size (16)                  139
 0x55, 0x0e,                    //   Unit Exponent (-2)                141
 0x65, 0x11,                    //   Unit (SILinear: cm)               143
 0x09, 0x30,                    //   Usage (X)                         145
 0x26, 0xff, 0x7f,              //   Logical Maximum (32767)           147
 0x35, 0x00,                    //   Physical Minimum (0)              150
 0x46, 0x15, 0x0c,              //   Physical Maximum (3093)           152
 0x81, 0x42,                    //   Input (Data,Var,Abs,Null)         155
 0x09, 0x31,                    //   Usage (Y)                         157
 0x26, 0xff, 0x7f,              //   Logical Maximum (32767)           159
 0x46, 0xcb, 0x06,              //   Physical Maximum (1739)           162
 0x81, 0x42,                    //   Input (Data,Var,Abs,Null)         165
 0x05, 0x0d,                    //   Usage Page (Digitizers)           167
 0x09, 0x30,                    //   Usage (Tip Pressure)              169
 0x26, 0xff, 0x1f,              //   Logical Maximum (8191)            171
 0x75, 0x10,                    //   Report Size (16)                  174
 0x95, 0x01,                    //   Report Count (1)                  176
 0x81, 0x02,                    //   Input (Data,Var,Abs)              178
 0xc0,                          //  End Collection                     180
 0x05, 0x0d,                    //  Usage Page (Digitizers)            181
 0x09, 0x22,                    //  Usage (Finger)                     183
 0xa1, 0x02,                    //  Collection (Logical)               185
 0x05, 0x0d,                    //   Usage Page (Digitizers)           187
 0x95, 0x01,                    //   Report Count (1)                  189
 0x75, 0x06,                    //   Report Size (6)                   191
 0x09, 0x51,                    //   Usage (Contact Id)                193
 0x15, 0x00,                    //   Logical Minimum (0)               195
 0x25, 0x3f,                    //   Logical Maximum (63)              197
 0x81, 0x02,                    //   Input (Data,Var,Abs)              199
 0x09, 0x42,                    //   Usage (Tip Switch)                201
 0x25, 0x01,                    //   Logical Maximum (1)               203
 0x75, 0x01,                    //   Report Size (1)                   205
 0x95, 0x01,                    //   Report Count (1)                  207
 0x81, 0x02,                    //   Input (Data,Var,Abs)              209
 0x75, 0x01,                    //   Report Size (1)                   211
 0x95, 0x01,                    //   Report Count (1)                  213
 0x81, 0x03,                    //   Input (Cnst,Var,Abs)              215
 0x05, 0x01,                    //   Usage Page (Generic Desktop)      217
 0x75, 0x10,                    //   Report Size (16)                  219
 0x55, 0x0e,                    //   Unit Exponent (-2)                221
 0x65, 0x11,                    //   Unit (SILinear: cm)               223
 0x09, 0x30,                    //   Usage (X)                         225
 0x26, 0xff, 0x7f,              //   Logical Maximum (32767)           227
 0x35, 0x00,                    //   Physical Minimum (0)              230
 0x46, 0x15, 0x0c,              //   Physical Maximum (3093)           232
 0x81, 0x42,                    //   Input (Data,Var,Abs,Null)         235
 0x09, 0x31,                    //   Usage (Y)                         237
 0x26, 0xff, 0x7f,              //   Logical Maximum (32767)           239
 0x46, 0xcb, 0x06,              //   Physical Maximum (1739)           242
 0x81, 0x42,                    //   Input (Data,Var,Abs,Null)         245
 0x05, 0x0d,                    //   Usage Page (Digitizers)           247
 0x09, 0x30,                    //   Usage (Tip Pressure)              249
 0x26, 0xff, 0x1f,              //   Logical Maximum (8191)            251
 0x75, 0x10,                    //   Report Size (16)                  254
 0x95, 0x01,                    //   Report Count (1)                  256
 0x81, 0x02,                    //   Input (Data,Var,Abs)              258
 0xc0,                          //  End Collection                     260
 0x05, 0x0d,                    //  Usage Page (Digitizers)            261
 0x09, 0x56,                    //  Usage (Scan Time)                  263
 0x55, 0x00,                    //  Unit Exponent (0)                  265
 0x65, 0x00,                    //  Unit (None)                        267
 0x27, 0xff, 0xff, 0xff, 0x7f,  //  Logical Maximum (2147483647)       269
 0x95, 0x01,                    //  Report Count (1)                   274
 0x75, 0x20,                    //  Report Size (32)                   276
 0x81, 0x02,                    //  Input (Data,Var,Abs)               278
 0x09, 0x54,                    //  Usage (Contact Count)              280
 0x25, 0x7f,                    //  Logical Maximum (127)              282
 0x95, 0x01,                    //  Report Count (1)                   284
 0x75, 0x08,                    //  Report Size (8)                    286
 0x81, 0x02,                    //  Input (Data,Var,Abs)               288
 0x75, 0x08,                    //  Report Size (8)                    290
 0x95, 0x08,                    //  Report Count (8)                   292
 0x81, 0x03,                    //  Input (Cnst,Var,Abs)               294
 0x85, 0x05,                    //  Report ID (5)                      296
 0x09, 0x55,                    //  Usage (Contact Max)                298
 0x25, 0x0a,                    //  Logical Maximum (10)               300
 0x75, 0x08,                    //  Report Size (8)                    302
 0x95, 0x01,                    //  Report Count (1)                   304
 0xb1, 0x02,                    //  Feature (Data,Var,Abs)             306
 0x06, 0x00, 0xff,              //  Usage Page (Vendor Defined Page 1) 308
 0x09, 0xc5,                    //  Usage (Vendor Usage 0xc5)          311
 0x85, 0x06,                    //  Report ID (6)                      313
 0x15, 0x00,                    //  Logical Minimum (0)                315
 0x26, 0xff, 0x00,              //  Logical Maximum (255)              317
 0x75, 0x08,                    //  Report Size (8)                    320
 0x96, 0x00, 0x01,              //  Report Count (256)                 322
 0xb1, 0x02,                    //  Feature (Data,Var,Abs)             325
 0xc0,                          // End Collection                      327
 /* New in Firmware Version: HUION_M220_240524 */
 0x05, 0x01,                    // Usage Page (Generic Desktop)            328
 0x09, 0x01,                    // Usage (Pointer)                         330
 0xa1, 0x01,                    // Collection (Application)                332
 0x09, 0x01,                    //   Usage (Pointer)                       334
 0xa1, 0x00,                    //   Collection (Physical)                 336
 0x05, 0x09,                    //     Usage Page (Button)                 338
 0x19, 0x01,                    //     UsageMinimum (1)                    340
 0x29, 0x03,                    //     UsageMaximum (3)                    342
 0x15, 0x00,                    //     Logical Minimum (0)                 344
 0x25, 0x01,                    //     Logical Maximum (1)                 346
 0x85, 0x02,                    //     Report ID (2)                       348
 0x95, 0x03,                    //     Report Count (3)                    350
 0x75, 0x01,                    //     Report Size (1)                     352
 0x81, 0x02,                    //     Input (Data,Var,Abs)                354
 0x95, 0x01,                    //     Report Count (1)                    356
 0x75, 0x05,                    //     Report Size (5)                     358
 0x81, 0x01,                    //     Input (Cnst,Arr,Abs)                360
 0x05, 0x01,                    //     Usage Page (Generic Desktop)        362
 0x09, 0x30,                    //     Usage (X)                           364
 0x09, 0x31,                    //     Usage (Y)                           366
 0x15, 0x81,                    //     Logical Minimum (-127)              368
 0x25, 0x7f,                    //     Logical Maximum (127)               370
 0x75, 0x08,                    //     Report Size (8)                     372
 0x95, 0x02,                    //     Report Count (2)                    374
 0x81, 0x06,                    //     Input (Data,Var,Rel)                376
 0x95, 0x04,                    //     Report Count (4)                    378
 0x75, 0x08,                    //     Report Size (8)                     380
 0x81, 0x01,                    //     Input (Cnst,Arr,Abs)                382
 0xc0,                          //   End Collection                        384
 0xc0,                          // End Collection                          385
 0x05, 0x0d,                    // Usage Page (Digitizers)                 386
 0x09, 0x05,                    // Usage (Touch Pad)                       388
 0xa1, 0x01,                    // Collection (Application)                390
 0x06, 0x00, 0xff,              //   Usage Page (Vendor Defined Page FF00) 392
 0x09, 0x0c,                    //   Usage (Vendor Usage 0x0c)             395
 0x15, 0x00,                    //   Logical Minimum (0)                   397
 0x26, 0xff, 0x00,              //   Logical Maximum (255)                 399
 0x75, 0x08,                    //   Report Size (8)                       402
 0x95, 0x10,                    //   Report Count (16)                     404
 0x85, 0x3f,                    //   Report ID (63)                        406
 0x81, 0x22,                    //   Input (Data,Var,Abs,NoPref)           408
 0xc0,                          // End Collection                          410
 0x06, 0x00, 0xff,              // Usage Page (Vendor Defined Page FF00)   411
 0x09, 0x0c,                    // Usage (Vendor Usage 0x0c)               414
 0xa1, 0x01,                    // Collection (Application)                416
 0x06, 0x00, 0xff,              //   Usage Page (Vendor Defined Page FF00) 418
 0x09, 0x0c,                    //   Usage (Vendor Usage 0x0c)             421
 0x15, 0x00,                    //   Logical Minimum (0)                   423
 0x26, 0xff, 0x00,              //   Logical Maximum (255)                 425
 0x85, 0x44,                    //   Report ID (68)                        428
 0x75, 0x08,                    //   Report Size (8)                       430
 0x96, 0x6b, 0x05,              //   Report Count (1387)                   432
 0x81, 0x00,                    //   Input (Data,Arr,Abs)                  435
 0xc0,                          // End Collection                          437
};

#define PRE_240524_RDESC_SIZE 328
#define PRE_240524_RDESC_FIXED_SIZE 338 /* The original bits of the descriptor */
#define FW_240524_RDESC_SIZE 438
#define FW_240524_RDESC_FIXED_SIZE sizeof(fixed_rdesc)

SEC(HID_BPF_RDESC_FIXUP)
int BPF_PROG(hid_fix_rdesc_huion_kamvas_pro_19, struct hid_bpf_ctx *hctx)
{
 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, HID_MAX_DESCRIPTOR_SIZE /* size */);

 if (!data)
  return 0; /* EPERM check */

 if (hctx->size == FW_240524_RDESC_SIZE) {
  __builtin_memcpy(data, fixed_rdesc, FW_240524_RDESC_FIXED_SIZE);
  return sizeof(fixed_rdesc);
 }

 __builtin_memcpy(data, fixed_rdesc, PRE_240524_RDESC_FIXED_SIZE);

 return PRE_240524_RDESC_FIXED_SIZE;
}

/*
 * This tablet reports the 3rd button through invert, but this conflict
 * with the normal eraser mode.
 * Fortunately, before entering eraser mode, (so Invert = 1),
 * the tablet always sends an out-of-proximity event.
 * So we can detect that single event and:
 * - if there was none but the invert bit was toggled: this is the
 *   third button
 * - if there was this out-of-proximity event, we are entering
 *   eraser mode, and we will until the next out-of-proximity.
 */
SEC(HID_BPF_DEVICE_EVENT)
int BPF_PROG(kamvas_pro_19_fix_3rd_button, struct hid_bpf_ctx *hctx)
{
 __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 10 /* size */);

 if (!data)
  return 0; /* EPERM check */

 if (data[0] != 0x0a) /* not the pen report ID */
  return 0;

 /* stylus is out of range */
 if (!(data[1] & 0x40)) {
  prev_was_out_of_range = true;
  in_eraser_mode = false;
  return 0;
 }

 /* going into eraser mode (Invert = 1) only happens after an
 * out of range event
 */
 if (prev_was_out_of_range && (data[1] & 0x18))
  in_eraser_mode = true;

 /* eraser mode works fine */
 if (in_eraser_mode)
  return 0;

 /* copy the Invert bit reported for the 3rd button in bit 7 */
 if (data[1] & 0x08)
  data[1] |= 0x20;

 /* clear Invert bit now that it was copied */
 data[1] &= 0xf7;

 prev_was_out_of_range = false;

 return 0;
}

HID_BPF_OPS(huion_Kamvas_pro_19) = {
 .hid_rdesc_fixup = (void *)hid_fix_rdesc_huion_kamvas_pro_19,
 .hid_device_event = (void *)kamvas_pro_19_fix_3rd_button,
};

SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{

 ctx->retval = !((ctx->rdesc_size == PRE_240524_RDESC_SIZE) ||
   (ctx->rdesc_size == FW_240524_RDESC_SIZE));
 if (ctx->retval)
  ctx->retval = -EINVAL;

 /* ensure the kernel isn't fixed already */
 if (ctx->rdesc[17] != 0x43) /* Secondary Tip Switch */
  ctx->retval = -EINVAL;

 struct hid_bpf_ctx *hctx = hid_bpf_allocate_context(ctx->hid);

 if (!hctx) {
  return ctx->retval = -EINVAL;
  return 0;
 }

 const char *name = hctx->hid->name;

 /* strip out TEST_PREFIX */
 if (!__builtin_memcmp(name, TEST_PREFIX, sizeof(TEST_PREFIX) - 1))
  name += sizeof(TEST_PREFIX) - 1;

 if (__builtin_memcmp(name, NAME_KAMVAS_PRO_19, sizeof(NAME_KAMVAS_PRO_19)))
  ctx->retval = -EINVAL;

 hid_bpf_release_context(hctx);

 return 0;
}

char _license[] SEC("license") = "GPL";