// 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 #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("fmod_ret/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("fmod_ret/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; } 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";