| // 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 5) */ |
| 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 |
| }; |
| |
| 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 */ |
| |
| __builtin_memcpy(data, fixed_rdesc, sizeof(fixed_rdesc)); |
| |
| return sizeof(fixed_rdesc); |
| } |
| |
| /* |
| * 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 != 328; |
| 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"; |
