+ 0x95, 0x05, // Report Count (5) 28 /* changed (was 6) */

+ /* 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)

+

+ 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;

+

+ ctx->retval = !((ctx->rdesc_size == PRE_240524_RDESC_SIZE) ||

+ (ctx->rdesc_size == FW_240524_RDESC_SIZE));

+// SPDX-License-Identifier: GPL-2.0-only

+/* Copyright (c) 2024 Red Hat, Inc

+ */

+

+#include "vmlinux.h"

+#include "hid_bpf.h"

+#include "hid_bpf_helpers.h"

+#include "hid_report_helpers.h"

+#include <bpf/bpf_tracing.h>

+

+#define VID_HUION 0x256C

+#define PID_KEYDIAL_K20 0x0069

+

+HID_BPF_CONFIG(

+ HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_HUION, PID_KEYDIAL_K20),

+);

+

+/* Filled in by udev-hid-bpf */

+char UDEV_PROP_HUION_FIRMWARE_ID[64];

+

+/* The prefix of the firmware ID we expect for this device. The full firmware

+ * string has a date suffix, e.g. HUION_T21h_230511

+ */

+char EXPECTED_FIRMWARE_ID[] = "HUION_T21h_";

+

+/* How this BPF program works: the tablet has two modes, firmware mode and

+ * tablet mode. In firmware mode (out of the box) the tablet sends button events

+ * as keyboard shortcuts and the dial as wheel but it's not forwarded by the kernel.

+ * In tablet mode it uses a vendor specific hid report to report everything instead.

+ * Depending on the mode some hid reports are never sent and the corresponding

+ * devices are mute.

+ *

+ * To switch the tablet use e.g. https://github.com/whot/huion-switcher

+ * or one of the tools from the digimend project

+ *

+ * This BPF currently works for both modes only. The huion-switcher tool sets the

+ * HUION_FIRMWARE_ID udev property - if that is set then we disable the firmware

+ * pad and pen reports (by making them vendor collections that are ignored).

+ * If that property is not set we fix all hidraw nodes so the tablet works in

+ * either mode though the drawback is that the device will show up twice if

+ * you bind it to all event nodes

+ *

+ * Default report descriptor for the first exposed hidraw node:

+ *

+ * # HUION Huion Keydial_K20

+ * # Report descriptor length: 18 bytes

+ * # 0x06, 0x00, 0xff, // Usage Page (Vendor Defined Page 0xFF00) 0

+ * # 0x09, 0x01, // Usage (Vendor Usage 0x01) 3

+ * # 0xa1, 0x01, // Collection (Application) 5

+ * # 0x85, 0x08, // Report ID (8) 7

+ * # 0x75, 0x58, // Report Size (88) 9

+ * # 0x95, 0x01, // Report Count (1) 11

+ * # 0x09, 0x01, // Usage (Vendor Usage 0x01) 13

+ * # 0x81, 0x02, // Input (Data,Var,Abs) 15

+ * # 0xc0, // End Collection 17

+ * R: 18 06 00 ff 09 01 a1 01 85 08 75 58 95 01 09 01 81 02 c0

+ *

+ * This report descriptor appears to be identical for all Huion devices.

+ *

+ * Second hidraw node is the Pad. This one sends the button events until the tablet is

+ * switched to raw mode, then it's mute.

+ *

+ * # HUION Huion Keydial_K20

+ * # Report descriptor length: 135 bytes

+ * # 0x05, 0x01, // Usage Page (Generic Desktop) 0

+ * # 0x09, 0x06, // Usage (Keyboard) 2

+ * # 0xa1, 0x01, // Collection (Application) 4

+ * # 0x85, 0x03, // Report ID (3) 6

+ * # 0x05, 0x07, // Usage Page (Keyboard/Keypad) 8

+ * # 0x19, 0xe0, // UsageMinimum (224) 10

+ * # 0x29, 0xe7, // UsageMaximum (231) 12

+ * # 0x15, 0x00, // Logical Minimum (0) 14

+ * # 0x25, 0x01, // Logical Maximum (1) 16

+ * # 0x75, 0x01, // Report Size (1) 18

+ * # 0x95, 0x08, // Report Count (8) 20

+ * # 0x81, 0x02, // Input (Data,Var,Abs) 22

+ * # 0x05, 0x07, // Usage Page (Keyboard/Keypad) 24

+ * # 0x19, 0x00, // UsageMinimum (0) 26

+ * # 0x29, 0xff, // UsageMaximum (255) 28

+ * # 0x26, 0xff, 0x00, // Logical Maximum (255) 30

+ * # 0x75, 0x08, // Report Size (8) 33

+ * # 0x95, 0x06, // Report Count (6) 35

+ * # 0x81, 0x00, // Input (Data,Arr,Abs) 37

+ * # 0xc0, // End Collection 39

+ * # 0x05, 0x0c, // Usage Page (Consumer) 40

+ * # 0x09, 0x01, // Usage (Consumer Control) 42

+ * # 0xa1, 0x01, // Collection (Application) 44

+ * # 0x85, 0x04, // Report ID (4) 46

+ * # 0x05, 0x0c, // Usage Page (Consumer) 48

+ * # 0x19, 0x00, // UsageMinimum (0) 50

+ * # 0x2a, 0x80, 0x03, // UsageMaximum (896) 52

+ * # 0x15, 0x00, // Logical Minimum (0) 55

+ * # 0x26, 0x80, 0x03, // Logical Maximum (896) 57

+ * # 0x75, 0x10, // Report Size (16) 60

+ * # 0x95, 0x01, // Report Count (1) 62

+ * # 0x81, 0x00, // Input (Data,Arr,Abs) 64

+ * # 0xc0, // End Collection 66

+ * # 0x05, 0x01, // Usage Page (Generic Desktop) 67

+ * # 0x09, 0x02, // Usage (Mouse) 69

+ * # 0xa1, 0x01, // Collection (Application) 71

+ * # 0x09, 0x01, // Usage (Pointer) 73

+ * # 0x85, 0x05, // Report ID (5) 75

+ * # 0xa1, 0x00, // Collection (Physical) 77

+ * # 0x05, 0x09, // Usage Page (Button) 79

+ * # 0x19, 0x01, // UsageMinimum (1) 81

+ * # 0x29, 0x05, // UsageMaximum (5) 83

+ * # 0x15, 0x00, // Logical Minimum (0) 85

+ * # 0x25, 0x01, // Logical Maximum (1) 87

+ * # 0x95, 0x05, // Report Count (5) 89

+ * # 0x75, 0x01, // Report Size (1) 91

+ * # 0x81, 0x02, // Input (Data,Var,Abs) 93

+ * # 0x95, 0x01, // Report Count (1) 95

+ * # 0x75, 0x03, // Report Size (3) 97

+ * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 99

+ * # 0x05, 0x01, // Usage Page (Generic Desktop) 101

+ * # 0x09, 0x30, // Usage (X) 103

+ * # 0x09, 0x31, // Usage (Y) 105

+ * # 0x16, 0x00, 0x80, // Logical Minimum (-32768) 107

+ * # 0x26, 0xff, 0x7f, // Logical Maximum (32767) 110

+ * # 0x75, 0x10, // Report Size (16) 113

+ * # 0x95, 0x02, // Report Count (2) 115

+ * # 0x81, 0x06, // Input (Data,Var,Rel) 117

+ * # 0x95, 0x01, // Report Count (1) 119

+ * # 0x75, 0x08, // Report Size (8) 121

+ * # 0x05, 0x01, // Usage Page (Generic Desktop) 123

+ * # 0x09, 0x38, // Usage (Wheel) 125

+ * # 0x15, 0x81, // Logical Minimum (-127) 127

+ * # 0x25, 0x7f, // Logical Maximum (127) 129

+ * # 0x81, 0x06, // Input (Data,Var,Rel) 131

+ * # 0xc0, // End Collection 133

+ * # 0xc0, // End Collection 134

+ * 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

+ *

+ * Third hidraw node is a multi-axis controller which sends the dial events

+ * and the button inside the dial. If the tablet is switched to raw mode it is mute.

+ *

+ * # HUION Huion Keydial_K20

+ * # Report descriptor length: 108 bytes

+ * # 0x05, 0x01, // Usage Page (Generic Desktop) 0

+ * # 0x09, 0x0e, // Usage (System Multi-Axis Controller) 2

+ * # 0xa1, 0x01, // Collection (Application) 4

+ * # 0x85, 0x11, // Report ID (17) 6

+ * # 0x05, 0x0d, // Usage Page (Digitizers) 8

+ * # 0x09, 0x21, // Usage (Puck) 10

+ * # 0xa1, 0x02, // Collection (Logical) 12

+ * # 0x15, 0x00, // Logical Minimum (0) 14

+ * # 0x25, 0x01, // Logical Maximum (1) 16

+ * # 0x75, 0x01, // Report Size (1) 18

+ * # 0x95, 0x01, // Report Count (1) 20

+ * # 0xa1, 0x00, // Collection (Physical) 22

+ * # 0x05, 0x09, // Usage Page (Button) 24

+ * # 0x09, 0x01, // Usage (Button 1) 26

+ * # 0x81, 0x02, // Input (Data,Var,Abs) 28

+ * # 0x05, 0x0d, // Usage Page (Digitizers) 30

+ * # 0x09, 0x33, // Usage (Touch) 32

+ * # 0x81, 0x02, // Input (Data,Var,Abs) 34

+ * # 0x95, 0x06, // Report Count (6) 36

+ * # 0x81, 0x03, // Input (Cnst,Var,Abs) 38

+ * # 0xa1, 0x02, // Collection (Logical) 40

+ * # 0x05, 0x01, // Usage Page (Generic Desktop) 42

+ * # 0x09, 0x37, // Usage (Dial) 44

+ * # 0x16, 0x00, 0x80, // Logical Minimum (-32768) 46

+ * # 0x26, 0xff, 0x7f, // Logical Maximum (32767) 49

+ * # 0x75, 0x10, // Report Size (16) 52

+ * # 0x95, 0x01, // Report Count (1) 54

+ * # 0x81, 0x06, // Input (Data,Var,Rel) 56

+ * # 0x35, 0x00, // Physical Minimum (0) 58

+ * # 0x46, 0x10, 0x0e, // Physical Maximum (3600) 60

+ * # 0x15, 0x00, // Logical Minimum (0) 63

+ * # 0x26, 0x10, 0x0e, // Logical Maximum (3600) 65

+ * # 0x09, 0x48, // Usage (Resolution Multiplier) 68

+ * # 0xb1, 0x02, // Feature (Data,Var,Abs) 70

+ * # 0x45, 0x00, // Physical Maximum (0) 72

+ * # 0xc0, // End Collection 74

+ * # 0x75, 0x08, // Report Size (8) 75

+ * # 0x95, 0x01, // Report Count (1) 77

+ * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 79

+ * # 0x75, 0x08, // Report Size (8) 81

+ * # 0x95, 0x01, // Report Count (1) 83

+ * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 85

+ * # 0x75, 0x08, // Report Size (8) 87

+ * # 0x95, 0x01, // Report Count (1) 89

+ * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 91

+ * # 0x75, 0x08, // Report Size (8) 93

+ * # 0x95, 0x01, // Report Count (1) 95

+ * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 97

+ * # 0x75, 0x08, // Report Size (8) 99

+ * # 0x95, 0x01, // Report Count (1) 101

+ * # 0x81, 0x01, // Input (Cnst,Arr,Abs) 103

+ * # 0xc0, // End Collection 105

+ * # 0xc0, // End Collection 106

+ * # 0xc0, // End Collection 107

+ * 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

+ *

+ */

+

+#define PAD_REPORT_DESCRIPTOR_LENGTH 135

+#define PUCK_REPORT_DESCRIPTOR_LENGTH 108

+#define VENDOR_REPORT_DESCRIPTOR_LENGTH 18

+#define PAD_KBD_REPORT_ID 3

+#define PAD_CC_REPORT_ID 3 // never sends events

+#define PAD_MOUSE_REPORT_ID 4 // never sends events

+#define PUCK_REPORT_ID 17

+#define VENDOR_REPORT_ID 8

+#define PAD_KBD_REPORT_LENGTH 8

+#define PAD_CC_REPORT_LENGTH 3

+#define PAD_MOUSE_REPORT_LENGTH 7

+#define PUCK_REPORT_LENGTH 9

+#define VENDOR_REPORT_LENGTH 12

+

+__u32 last_button_state;

+

+static const __u8 disabled_rdesc_puck[] = {

+ FixedSizeVendorReport(PUCK_REPORT_LENGTH)

+};

+

+static const __u8 disabled_rdesc_pad[] = {

+ FixedSizeVendorReport(PAD_KBD_REPORT_LENGTH)

+ FixedSizeVendorReport(PAD_CC_REPORT_LENGTH)

+ FixedSizeVendorReport(PAD_MOUSE_REPORT_LENGTH)

+};

+

+static const __u8 fixed_rdesc_vendor[] = {

+ UsagePage_GenericDesktop

+ Usage_GD_Keypad

+ CollectionApplication(

+ // Byte 0

+ // We send our pad events on the vendor report id because why not

+ ReportId(VENDOR_REPORT_ID)

+ UsagePage_Digitizers

+ Usage_Dig_TabletFunctionKeys

+ CollectionPhysical(

+ // Byte 1 is a button so we look like a tablet

+ Usage_Dig_BarrelSwitch // BTN_STYLUS, needed so we get to be a tablet pad

+ ReportCount(1)

+ ReportSize(1)

+ Input(Var|Abs)

+ ReportCount(7) // Padding

+ Input(Const)

+ // Bytes 2/3 - x/y just exist so we get to be a tablet pad

+ UsagePage_GenericDesktop

+ Usage_GD_X

+ Usage_GD_Y

+ LogicalMinimum_i8(0x0)

+ LogicalMaximum_i8(0x1)

+ ReportCount(2)

+ ReportSize(8)

+ Input(Var|Abs)

+ // Bytes 4-7 are the button state for 19 buttons + pad out to u32

+ // We send the first 10 buttons as buttons 1-10 which is BTN_0 -> BTN_9

+ UsagePage_Button

+ UsageMinimum_i8(1)

+ UsageMaximum_i8(10)

+ LogicalMinimum_i8(0x0)

+ LogicalMaximum_i8(0x1)

+ ReportCount(10)

+ ReportSize(1)

+ Input(Var|Abs)

+ // We send the other 9 buttons as buttons 0x31 and above -> BTN_A - BTN_TL2

+ UsageMinimum_i8(0x31)

+ UsageMaximum_i8(0x3a)

+ ReportCount(9)

+ ReportSize(1)

+ Input(Var|Abs)

+ ReportCount(13)

+ ReportSize(1)

+ Input(Const) // padding

+ // Byte 6 is the wheel

+ UsagePage_GenericDesktop

+ Usage_GD_Wheel

+ LogicalMinimum_i8(-1)

+ LogicalMaximum_i8(1)

+ ReportCount(1)

+ ReportSize(8)

+ Input(Var|Rel)

+ )

+ // Make sure we match our original report length

+ FixedSizeVendorReport(VENDOR_REPORT_LENGTH)

+ )

+};

+

+/* Identical to fixed_rdesc_pad but with different FixedSizeVendorReport */

+static const __u8 fixed_rdesc_pad[] = {

+ UsagePage_GenericDesktop

+ Usage_GD_Keypad

+ CollectionApplication(

+ // Byte 0

+ // We send our pad events on the vendor report id because why not

+ ReportId(VENDOR_REPORT_ID)

+ UsagePage_Digitizers

+ Usage_Dig_TabletFunctionKeys

+ CollectionPhysical(

+ // Byte 1 is a button so we look like a tablet

+ Usage_Dig_BarrelSwitch // BTN_STYLUS, needed so we get to be a tablet pad

+ ReportCount(1)

+ ReportSize(1)

+ Input(Var|Abs)

+ ReportCount(7) // Padding

+ Input(Const)

+ // Bytes 2/3 - x/y just exist so we get to be a tablet pad

+ UsagePage_GenericDesktop

+ Usage_GD_X

+ Usage_GD_Y

+ LogicalMinimum_i8(0x0)

+ LogicalMaximum_i8(0x1)

+ ReportCount(2)

+ ReportSize(8)

+ Input(Var|Abs)

+ // Bytes 4-7 are the button state for 19 buttons + pad out to u32

+ // We send the first 10 buttons as buttons 1-10 which is BTN_0 -> BTN_9

+ UsagePage_Button

+ UsageMinimum_i8(1)

+ UsageMaximum_i8(10)

+ LogicalMinimum_i8(0x0)

+ LogicalMaximum_i8(0x1)

+ ReportCount(10)

+ ReportSize(1)

+ Input(Var|Abs)

+ // We send the other 9 buttons as buttons 0x31 and above -> BTN_A - BTN_TL2

+ UsageMinimum_i8(0x31)

+ UsageMaximum_i8(0x3a)

+ ReportCount(9)

+ ReportSize(1)

+ Input(Var|Abs)

+ ReportCount(13)

+ ReportSize(1)

+ Input(Const) // padding

+ // Byte 6 is the wheel

+ UsagePage_GenericDesktop

+ Usage_GD_Wheel

+ LogicalMinimum_i8(-1)

+ LogicalMaximum_i8(1)

+ ReportCount(1)

+ ReportSize(8)

+ Input(Var|Rel)

+ )

+ // Make sure we match our original report lengths

+ FixedSizeVendorReport(PAD_KBD_REPORT_LENGTH)

+ FixedSizeVendorReport(PAD_CC_REPORT_LENGTH)

+ FixedSizeVendorReport(PAD_MOUSE_REPORT_LENGTH)

+ )

+};

+

+SEC(HID_BPF_RDESC_FIXUP)

+int BPF_PROG(k20_fix_rdesc, struct hid_bpf_ctx *hctx)

+{

+ __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, HID_MAX_DESCRIPTOR_SIZE /* size */);

+ __s32 rdesc_size = hctx->size;

+ __u8 have_fw_id;

+

+ if (!data)

+ return 0; /* EPERM check */

+

+ /* If we have a firmware ID and it matches our expected prefix, we

+ * disable the default pad/puck nodes. They won't send events

+ * but cause duplicate devices.

+ */

+ have_fw_id = __builtin_memcmp(UDEV_PROP_HUION_FIRMWARE_ID,

+ EXPECTED_FIRMWARE_ID,

+ sizeof(EXPECTED_FIRMWARE_ID) - 1) == 0;

+ if (rdesc_size == PAD_REPORT_DESCRIPTOR_LENGTH) {

+ if (have_fw_id) {

+ __builtin_memcpy(data, disabled_rdesc_pad, sizeof(disabled_rdesc_pad));

+ return sizeof(disabled_rdesc_pad);

+ } else {

+ __builtin_memcpy(data, fixed_rdesc_pad, sizeof(fixed_rdesc_pad));

+ return sizeof(fixed_rdesc_pad);

+

+ }

+ }

+ if (rdesc_size == PUCK_REPORT_DESCRIPTOR_LENGTH) {

+ if (have_fw_id) {

+ __builtin_memcpy(data, disabled_rdesc_puck, sizeof(disabled_rdesc_puck));

+ return sizeof(disabled_rdesc_puck);

+ }

+ }

+ /* Always fix the vendor mode so the tablet will work even if nothing sets

+ * the udev property (e.g. huion-switcher run manually)

+ */

+ if (rdesc_size == VENDOR_REPORT_DESCRIPTOR_LENGTH) {

+ __builtin_memcpy(data, fixed_rdesc_vendor, sizeof(fixed_rdesc_vendor));

+ return sizeof(fixed_rdesc_vendor);

+

+ }

+ return 0;

+}

+

+SEC(HID_BPF_DEVICE_EVENT)

+int BPF_PROG(k20_fix_events, struct hid_bpf_ctx *hctx)

+{

+ __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 10 /* size */);

+

+ if (!data)

+ return 0; /* EPERM check */

+

+ /* Only sent if tablet is in raw mode */

+ if (data[0] == VENDOR_REPORT_ID) {

+ /* See fixed_rdesc_pad */

+ struct pad_report {

+ __u8 report_id;

+ __u8 btn_stylus:1;

+ __u8 pad:7;

+ __u8 x;

+ __u8 y;

+ __u32 buttons;

+ __u8 wheel;

+ } __attribute__((packed)) *pad_report;

+

+ __u8 wheel = 0;

+

+ /* Wheel report */

+ if (data[1] == 0xf1) {

+ if (data[5] == 2)

+ wheel = 0xff;

+ else

+ wheel = data[5];

+ } else {

+ /* data[4..6] are the buttons, mapped correctly */

+ last_button_state = data[4] | (data[5] << 8) | (data[6] << 16);

+ wheel = 0; // wheel

+ }

+

+ pad_report = (struct pad_report *)data;

+ pad_report->report_id = VENDOR_REPORT_ID;

+ pad_report->btn_stylus = 0;

+ pad_report->x = 0;

+ pad_report->y = 0;

+ pad_report->buttons = last_button_state;

+ pad_report->wheel = wheel;

+

+ return sizeof(struct pad_report);

+ }

+

+ if (data[0] == PAD_KBD_REPORT_ID) {

+ const __u8 button_mapping[] = {

+ 0x0e, /* Button 1: K */

+ 0x0a, /* Button 2: G */

+ 0x0f, /* Button 3: L */

+ 0x4c, /* Button 4: Delete */

+ 0x0c, /* Button 5: I */

+ 0x07, /* Button 6: D */

+ 0x05, /* Button 7: B */

+ 0x08, /* Button 8: E */

+ 0x16, /* Button 9: S */

+ 0x1d, /* Button 10: Z */

+ 0x06, /* Button 11: C */

+ 0x19, /* Button 12: V */

+ 0xff, /* Button 13: LeftControl */

+ 0xff, /* Button 14: LeftAlt */

+ 0xff, /* Button 15: LeftShift */

+ 0x28, /* Button 16: Return Enter */

+ 0x2c, /* Button 17: Spacebar */

+ 0x11, /* Button 18: N */

+ };

+ /* See fixed_rdesc_pad */

+ struct pad_report {

+ __u8 report_id;

+ __u8 btn_stylus:1;

+ __u8 pad:7;

+ __u8 x;

+ __u8 y;

+ __u32 buttons;

+ __u8 wheel;

+ } __attribute__((packed)) *pad_report;

+ int i, b;

+ __u8 modifiers = data[1];

+ __u32 buttons = 0;

+

+ if (modifiers & 0x01) { /* Control */

+ buttons |= BIT(12);

+ }

+ if (modifiers & 0x02) { /* Shift */

+ buttons |= BIT(14);

+ }

+ if (modifiers & 0x04) { /* Alt */

+ buttons |= BIT(13);

+ }

+

+ for (i = 2; i < PAD_KBD_REPORT_LENGTH; i++) {

+ if (!data[i])

+ break;

+

+ for (b = 0; b < ARRAY_SIZE(button_mapping); b++) {

+ if (data[i] == button_mapping[b]) {

+ buttons |= BIT(b);

+ break;

+ }

+ }

+ data[i] = 0;

+ }

+

+ pad_report = (struct pad_report *)data;

+ pad_report->report_id = VENDOR_REPORT_ID;

+ pad_report->btn_stylus = 0;

+ pad_report->x = 0;

+ pad_report->y = 0;

+ pad_report->buttons = buttons;

+ // The wheel happens on a different hidraw node but its

+ // values are unreliable (as is the button inside the wheel).

+ // So the wheel is simply always zero, if you want the wheel

+ // to work reliably, use the tablet mode.

+ pad_report->wheel = 0;

+

+ return sizeof(struct pad_report);

+ }

+

+ return 0;

+}

+

+HID_BPF_OPS(keydial_k20) = {

+ .hid_device_event = (void *)k20_fix_events,

+ .hid_rdesc_fixup = (void *)k20_fix_rdesc,

+};

+

+SEC("syscall")

+int probe(struct hid_bpf_probe_args *ctx)

+{

+ switch (ctx->rdesc_size) {

+ case PAD_REPORT_DESCRIPTOR_LENGTH:

+ case PUCK_REPORT_DESCRIPTOR_LENGTH:

+ case VENDOR_REPORT_DESCRIPTOR_LENGTH:

+ ctx->retval = 0;

+ break;

+ default:

+ ctx->retval = -EINVAL;

+ }

+

+ return 0;

+}

+

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

+// SPDX-License-Identifier: GPL-2.0-or-later

+/* Copyright (c) 2025 TUXEDO Computers GmbH

+ */

+

+#include "vmlinux.h"

+#include "hid_bpf.h"

+#include "hid_bpf_helpers.h"

+#include <bpf/bpf_tracing.h>

+

+HID_BPF_CONFIG(

+ HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, 0x048D, 0x8910)

+);

+

+SEC(HID_BPF_DEVICE_EVENT)

+int BPF_PROG(ignore_key_fix_event, struct hid_bpf_ctx *hid_ctx)

+{

+ const int expected_length = 37;

+ const int expected_report_id = 1;

+ __u8 *data;

+ int i;

+

+ if (hid_ctx->size < expected_length)

+ return 0;

+

+ data = hid_bpf_get_data(hid_ctx, 0, expected_length);

+ if (!data || data[0] != expected_report_id)

+ return 0;

+

+ // Zero out F13 (HID usage ID: 0x68) key press.

+ // The first 6 parallel key presses (excluding modifier keys) are

+ // encoded in an array containing usage IDs.

+ for (i = 3; i < 9; ++i)

+ if (data[i] == 0x68)

+ data[i] = 0x00;

+ // Additional parallel key presses starting with the 7th (excluding

+ // modifier keys) are encoded as a bit flag with the offset being

+ // the usage ID.

+ data[22] &= 0xfe;

+

+ return 0;

+}

+

+HID_BPF_OPS(ignore_button) = {

+ .hid_device_event = (void *)ignore_key_fix_event,

+};

+

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

+// SPDX-License-Identifier: GPL-2.0-only

+/* Copyright (c) 2024 Red Hat, Inc

+ */

+

+#include "vmlinux.h"

+#include "hid_bpf.h"

+#include "hid_bpf_helpers.h"

+#include "hid_report_helpers.h"

+#include <bpf/bpf_tracing.h>

+

+#define HID_BPF_ASYNC_MAX_CTX 1

+#include "hid_bpf_async.h"

+

+#define VID_UGEE 0x28BD

+/* same PID whether connected directly or through the provided dongle: */

+#define PID_ACK05_REMOTE 0x0202

+

+

+HID_BPF_CONFIG(

+ HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_UGEE, PID_ACK05_REMOTE),

+);

+

+/*

+ * By default, the pad reports the buttons through a set of key sequences.

+ *

+ * The pad reports a classic keyboard report descriptor:

+ * # HANVON UGEE Shortcut Remote

+ * Report descriptor length: 102 bytes

+ * 0x05, 0x01, // Usage Page (Generic Desktop) 0

+ * 0x09, 0x02, // Usage (Mouse) 2

+ * 0xa1, 0x01, // Collection (Application) 4

+ * 0x85, 0x09, // Report ID (9) 6

+ * 0x09, 0x01, // Usage (Pointer) 8

+ * 0xa1, 0x00, // Collection (Physical) 10

+ * 0x05, 0x09, // Usage Page (Button) 12

+ * 0x19, 0x01, // UsageMinimum (1) 14

+ * 0x29, 0x03, // UsageMaximum (3) 16

+ * 0x15, 0x00, // Logical Minimum (0) 18

+ * 0x25, 0x01, // Logical Maximum (1) 20

+ * 0x95, 0x03, // Report Count (3) 22

+ * 0x75, 0x01, // Report Size (1) 24

+ * 0x81, 0x02, // Input (Data,Var,Abs) 26

+ * 0x95, 0x05, // Report Count (5) 28

+ * 0x81, 0x01, // Input (Cnst,Arr,Abs) 30

+ * 0x05, 0x01, // Usage Page (Generic Desktop) 32

+ * 0x09, 0x30, // Usage (X) 34

+ * 0x09, 0x31, // Usage (Y) 36

+ * 0x26, 0xff, 0x7f, // Logical Maximum (32767) 38

+ * 0x95, 0x02, // Report Count (2) 41

+ * 0x75, 0x10, // Report Size (16) 43

+ * 0x81, 0x02, // Input (Data,Var,Abs) 45

+ * 0x05, 0x0d, // Usage Page (Digitizers) 47

+ * 0x09, 0x30, // Usage (Tip Pressure) 49

+ * 0x26, 0xff, 0x07, // Logical Maximum (2047) 51

+ * 0x95, 0x01, // Report Count (1) 54

+ * 0x75, 0x10, // Report Size (16) 56

+ * 0x81, 0x02, // Input (Data,Var,Abs) 58

+ * 0xc0, // End Collection 60

+ * 0xc0, // End Collection 61

+ * 0x05, 0x01, // Usage Page (Generic Desktop) 62

+ * 0x09, 0x06, // Usage (Keyboard) 64

+ * 0xa1, 0x01, // Collection (Application) 66

+ * 0x85, 0x06, // Report ID (6) 68

+ * 0x05, 0x07, // Usage Page (Keyboard/Keypad) 70

+ * 0x19, 0xe0, // UsageMinimum (224) 72

+ * 0x29, 0xe7, // UsageMaximum (231) 74

+ * 0x15, 0x00, // Logical Minimum (0) 76

+ * 0x25, 0x01, // Logical Maximum (1) 78

+ * 0x75, 0x01, // Report Size (1) 80

+ * 0x95, 0x08, // Report Count (8) 82

+ * 0x81, 0x02, // Input (Data,Var,Abs) 84

+ * 0x05, 0x07, // Usage Page (Keyboard/Keypad) 86

+ * 0x19, 0x00, // UsageMinimum (0) 88

+ * 0x29, 0xff, // UsageMaximum (255) 90

+ * 0x26, 0xff, 0x00, // Logical Maximum (255) 92

+ * 0x75, 0x08, // Report Size (8) 95

+ * 0x95, 0x06, // Report Count (6) 97

+ * 0x81, 0x00, // Input (Data,Arr,Abs) 99

+ * 0xc0, // End Collection 101

+ *

+ * Each button gets assigned the following events:

+ *

+ * Buttons released: 06 00 00 00 00 00 00 00

+ * Button 1: 06 01 12 00 00 00 00 00 -> LControl + o

+ * Button 2: 06 01 11 00 00 00 00 00 -> LControl + n

+ * Button 3: 06 00 3e 00 00 00 00 00 -> F5

+ * Button 4: 06 02 00 00 00 00 00 00 -> LShift

+ * Button 5: 06 01 00 00 00 00 00 00 -> LControl

+ * Button 6: 06 04 00 00 00 00 00 00 -> LAlt

+ * Button 7: 06 01 16 00 00 00 00 00 -> LControl + s

+ * Button 8: 06 01 1d 00 00 00 00 00 -> LControl + z

+ * Button 9: 06 00 2c 00 00 00 00 00 -> Space

+ * Button 10: 06 03 1d 00 00 00 00 00 -> LControl + LShift + z

+ * Wheel: 06 01 57 00 00 00 00 00 -> clockwise rotation (LControl + Keypad Plus)

+ * Wheel: 06 01 56 00 00 00 00 00 -> counter-clockwise rotation

+ * (LControl + Keypad Minus)

+ *

+ * However, multiple buttons can be pressed at the same time, and when this happens,

+ * each button gets assigned a new slot in the Input (Data,Arr,Abs):

+ *

+ * Button 1 + 3: 06 01 12 3e 00 00 00 00 -> LControl + o + F5

+ *

+ * When a modifier is pressed (Button 4, 5, or 6), the assigned key is set to 00:

+ *

+ * Button 5 + 7: 06 01 00 16 00 00 00 00 -> LControl + s

+ *

+ * This is mostly fine, but with Button 8 and Button 10 sharing the same

+ * key value ("z"), there are cases where we can not know which is which.

+ *

+ */

+

+#define PAD_WIRED_DESCRIPTOR_LENGTH 102

+#define PAD_DONGLE_DESCRIPTOR_LENGTH 177

+#define STYLUS_DESCRIPTOR_LENGTH 109

+#define VENDOR_DESCRIPTOR_LENGTH 36

+#define PAD_REPORT_ID 6

+#define RAW_PAD_REPORT_ID 0xf0

+#define RAW_BATTERY_REPORT_ID 0xf2

+#define VENDOR_REPORT_ID 2

+#define PAD_REPORT_LENGTH 8

+#define VENDOR_REPORT_LENGTH 12

+

+__u16 last_button_state;

+

+static const __u8 disabled_rdesc[] = {

+ // Make sure we match our original report length

+ FixedSizeVendorReport(VENDOR_REPORT_LENGTH)

+};

+

+static const __u8 fixed_rdesc_vendor[] = {

+ UsagePage_GenericDesktop

+ Usage_GD_Keypad

+ CollectionApplication(

+ // -- Byte 0 in report

+ ReportId(RAW_PAD_REPORT_ID)

+ // Byte 1 in report - same than report ID

+ ReportCount(1)

+ ReportSize(8)

+ Input(Const) // padding (internal report ID)

+ LogicalMaximum_i8(0)

+ LogicalMaximum_i8(1)

+ UsagePage_Digitizers

+ Usage_Dig_TabletFunctionKeys

+ CollectionPhysical(

+ // Byte 2-3 is the button state

+ UsagePage_Button

+ UsageMinimum_i8(0x01)

+ UsageMaximum_i8(0x0a)

+ LogicalMinimum_i8(0x0)

+ LogicalMaximum_i8(0x1)

+ ReportCount(10)

+ ReportSize(1)

+ Input(Var|Abs)

+ Usage_i8(0x31) // will be mapped as BTN_A / BTN_SOUTH

+ ReportCount(1)

+ Input(Var|Abs)

+ ReportCount(5) // padding

+ Input(Const)

+ // Byte 4 in report - just exists so we get to be a tablet pad

+ Usage_Dig_BarrelSwitch // BTN_STYLUS

+ ReportCount(1)

+ ReportSize(1)

+ Input(Var|Abs)

+ ReportCount(7) // padding

+ Input(Const)

+ // Bytes 5/6 in report - just exists so we get to be a tablet pad

+ UsagePage_GenericDesktop

+ Usage_GD_X

+ Usage_GD_Y

+ ReportCount(2)

+ ReportSize(8)

+ Input(Var|Abs)

+ // Byte 7 in report is the dial

+ Usage_GD_Wheel

+ LogicalMinimum_i8(-1)

+ LogicalMaximum_i8(1)

+ ReportCount(1)

+ ReportSize(8)

+ Input(Var|Rel)

+ )

+ // -- Byte 0 in report

+ ReportId(RAW_BATTERY_REPORT_ID)

+ // Byte 1 in report - same than report ID

+ ReportCount(1)

+ ReportSize(8)

+ Input(Const) // padding (internal report ID)

+ // Byte 2 in report - always 0x01

+ Input(Const) // padding (internal report ID)

+ UsagePage_Digitizers

+ /*

+ * We represent the device as a stylus to force the kernel to not

+ * directly query its battery state. Instead the kernel will rely

+ * only on the provided events.

+ */

+ Usage_Dig_Stylus

+ CollectionPhysical(

+ // Byte 3 in report - battery value

+ UsagePage_BatterySystem

+ Usage_BS_AbsoluteStateOfCharge

+ LogicalMinimum_i8(0)

+ LogicalMaximum_i8(100)

+ ReportCount(1)

+ ReportSize(8)

+ Input(Var|Abs)

+ // Byte 4 in report - charging state

+ Usage_BS_Charging

+ LogicalMinimum_i8(0)

+ LogicalMaximum_i8(1)

+ ReportCount(1)

+ ReportSize(8)

+ Input(Var|Abs)

+ )

+ )

+};

+

+SEC(HID_BPF_RDESC_FIXUP)

+int BPF_PROG(ack05_fix_rdesc, struct hid_bpf_ctx *hctx)

+{

+ __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, HID_MAX_DESCRIPTOR_SIZE /* size */);

+ __s32 rdesc_size = hctx->size;

+

+ if (!data)

+ return 0; /* EPERM check */

+

+ if (rdesc_size == VENDOR_DESCRIPTOR_LENGTH) {

+ /*

+ * The vendor fixed rdesc is appended after the current one,

+ * to keep the output reports working.

+ */

+ __builtin_memcpy(data + rdesc_size, fixed_rdesc_vendor, sizeof(fixed_rdesc_vendor));

+ return sizeof(fixed_rdesc_vendor) + rdesc_size;

+ }

+

+ hid_set_name(hctx->hid, "Disabled by HID-BPF Hanvon Ugee Shortcut Remote");

+

+ __builtin_memcpy(data, disabled_rdesc, sizeof(disabled_rdesc));

+ return sizeof(disabled_rdesc);

+}

+

+static int HID_BPF_ASYNC_FUN(switch_to_raw_mode)(struct hid_bpf_ctx *hid)

+{

+ static __u8 magic_0[32] = {0x02, 0xb0, 0x04, 0x00, 0x00};

+ int err;

+

+ /*

+ * The proprietary driver sends the 3 following packets after the

+ * above one.

+ * These don't seem to have any effect, so we don't send them to save

+ * some processing time.

+ *

+ * static __u8 magic_1[32] = {0x02, 0xb4, 0x01, 0x00, 0x01};

+ * static __u8 magic_2[32] = {0x02, 0xb4, 0x01, 0x00, 0xff};

+ * static __u8 magic_3[32] = {0x02, 0xb8, 0x04, 0x00, 0x00};

+ */

+

+ err = hid_bpf_hw_output_report(hid, magic_0, sizeof(magic_0));

+ if (err < 0)

+ return err;

+

+ return 0;

+}

+

+SEC(HID_BPF_DEVICE_EVENT)

+int BPF_PROG(ack05_fix_events, struct hid_bpf_ctx *hctx)

+{

+ __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, PAD_REPORT_LENGTH);

+ int ret = 0;

+

+ if (!data)

+ return 0; /* EPERM check */

+

+ if (data[0] != VENDOR_REPORT_ID)

+ return 0;

+

+ /* reconnect event */

+ if (data[1] == 0xf8 && data[2] == 02 && data[3] == 0x01)

+ HID_BPF_ASYNC_DELAYED_CALL(switch_to_raw_mode, hctx, 10);

+

+ /* button event */

+ if (data[1] == RAW_PAD_REPORT_ID) {

+ data[0] = data[1];

+ if (data[7] == 0x02)

+ data[7] = 0xff;

+ ret = 8;

+ } else if (data[1] == RAW_BATTERY_REPORT_ID) {

+ data[0] = data[1];

+ ret = 5;

+ }

+

+ return ret;

+}

+

+HID_BPF_OPS(xppen_ack05_remote) = {

+ .hid_device_event = (void *)ack05_fix_events,

+ .hid_rdesc_fixup = (void *)ack05_fix_rdesc,

+};

+

+SEC("syscall")

+int probe(struct hid_bpf_probe_args *ctx)

+{

+ switch (ctx->rdesc_size) {

+ case PAD_WIRED_DESCRIPTOR_LENGTH:

+ case PAD_DONGLE_DESCRIPTOR_LENGTH:

+ case STYLUS_DESCRIPTOR_LENGTH:

+ case VENDOR_DESCRIPTOR_LENGTH:

+ ctx->retval = 0;

+ break;

+ default:

+ ctx->retval = -EINVAL;

+ break;

+ }

+

+ if (ctx->rdesc_size == VENDOR_DESCRIPTOR_LENGTH) {

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

+

+ if (!hctx) {

+ ctx->retval = -EINVAL;

+ return 0;

+ }

+

+ ctx->retval = HID_BPF_ASYNC_INIT(switch_to_raw_mode) ||

+ switch_to_raw_mode(hctx);

+

+ hid_bpf_release_context(hctx);

+ }

+

+ return 0;

+}

+

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

+#define PID_ARTIST_PRO19_GEN2 0x096A

+ HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_UGEE, PID_ARTIST_PRO16_GEN2),

+ HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_UGEE, PID_ARTIST_PRO19_GEN2)

+ * This descriptor uses the physical dimensions of the 16" device.

+ } else if (hctx->hid->product == PID_ARTIST_PRO19_GEN2) {

+ /* 19" screen reports 16.101" x 9.057" */

+ data[63] = 0x3e;

+ data[62] = 0xe5;

+ data[73] = 0x23;

+ data[72] = 0x61;

+/* 19" inch screen 16.101" x 9.057" */

+static const __u16 angle_offsets_horizontal_19[128] = {

+ 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 25, 27, 29, 31, 33, 35, 37, 39, 41,

+ 42, 44, 46, 48, 50, 51, 53, 55, 57, 58, 60, 62, 63, 65, 67, 68, 70, 71, 73, 74, 76,

+ 77, 79, 80, 82, 83, 84, 86, 87, 88, 89, 90, 92, 93, 94, 95, 96, 97, 98, 99, 100,

+ 101, 102, 103, 104, 104, 105, 106, 106, 107, 108, 108, 109, 109, 110, 110, 111,

+ 111, 112, 112, 112, 112, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113, 113,

+ 113, 113, 112, 112, 112, 112, 111, 111, 110, 110, 109, 109, 108, 108, 107, 106,

+ 106, 105, 104, 104, 103, 102, 101, 100, 99, 98, 97, 96, 95, 94, 93, 92, 90

+};

+static const __u16 angle_offsets_vertical_19[128] = {

+ 0, 4, 7, 11, 14, 18, 21, 25, 28, 32, 35, 38, 42, 45, 49, 52, 56, 59, 62, 66, 69, 72,

+ 75, 79, 82, 85, 88, 91, 95, 98, 101, 104, 107, 110, 113, 116, 118, 121, 124, 127,

+ 129, 132, 135, 137, 140, 142, 145, 147, 150, 152, 154, 157, 159, 161, 163, 165, 167,

+ 169, 171, 173, 174, 176, 178, 179, 181, 183, 184, 185, 187, 188, 189, 190, 192, 193,

+ 194, 195, 195, 196, 197, 198, 198, 199, 199, 200, 200, 201, 201, 201, 201, 201, 201,

+ 201, 201, 201, 201, 201, 200, 200, 199, 199, 198, 198, 197, 196, 195, 195, 194, 193,

+ 192, 190, 189, 188, 187, 185, 184, 183, 181, 179, 178, 176, 174, 173, 171, 169, 167,

+ 165, 163, 161

+};

+

+ switch (hctx->hid->product) {

+ case PID_ARTIST_PRO14_GEN2:

+ break;

+ case PID_ARTIST_PRO16_GEN2:

+ break;

+ case PID_ARTIST_PRO19_GEN2:

+ compensate_coordinates_by_tilt(data, 2, tilt_x, &angle_offsets_horizontal_19);

+ compensate_coordinates_by_tilt(data, 4, tilt_y, &angle_offsets_vertical_19);

+ break;

+/* SPDX-License-Identifier: GPL-2.0-only

+ * Copyright (c) 2024 Benjamin Tissoires

+ */

+

+#ifndef __HID_BPF_ASYNC_H__

+#define __HID_BPF_ASYNC_H__

+

+#ifndef HID_BPF_ASYNC_MAX_CTX

+#error "HID_BPF_ASYNC_MAX_CTX should be set to the maximum number of concurrent async functions"

+#endif /* HID_BPF_ASYNC_MAX_CTX */

+

+#define CLOCK_MONOTONIC 1

+

+typedef int (*hid_bpf_async_callback_t)(void *map, int *key, void *value);

+

+enum hid_bpf_async_state {

+ HID_BPF_ASYNC_STATE_UNSET = 0,

+ HID_BPF_ASYNC_STATE_INITIALIZING,

+ HID_BPF_ASYNC_STATE_INITIALIZED,

+ HID_BPF_ASYNC_STATE_STARTING,

+ HID_BPF_ASYNC_STATE_RUNNING,

+};

+

+struct hid_bpf_async_map_elem {

+ struct bpf_spin_lock lock;

+ enum hid_bpf_async_state state;

+ struct bpf_timer t;

+ struct bpf_wq wq;

+ u32 hid;

+};

+

+struct {

+ __uint(type, BPF_MAP_TYPE_ARRAY);

+ __uint(max_entries, HID_BPF_ASYNC_MAX_CTX);

+ __type(key, u32);

+ __type(value, struct hid_bpf_async_map_elem);

+} hid_bpf_async_ctx_map SEC(".maps");

+

+/**

+ * HID_BPF_ASYNC_CB: macro to define an async callback used in a bpf_wq

+ *

+ * The caller is responsible for allocating a key in the async map

+ * with hid_bpf_async_get_ctx().

+ */

+#define HID_BPF_ASYNC_CB(cb) \

+cb(void *map, int *key, void *value); \

+static __always_inline int \

+____##cb(struct hid_bpf_ctx *ctx); \

+typeof(cb(0, 0, 0)) cb(void *map, int *key, void *value) \

+{ \

+ struct hid_bpf_async_map_elem *e; \

+ struct hid_bpf_ctx *ctx; \

+ \

+ e = (struct hid_bpf_async_map_elem *)value; \

+ ctx = hid_bpf_allocate_context(e->hid); \

+ if (!ctx) \

+ return 0; /* EPERM check */ \

+ \

+ e->state = HID_BPF_ASYNC_STATE_RUNNING; \

+ \

+ ____##cb(ctx); \

+ \

+ e->state = HID_BPF_ASYNC_STATE_INITIALIZED; \

+ hid_bpf_release_context(ctx); \

+ return 0; \

+} \

+static __always_inline int \

+____##cb

+

+/**

+ * ASYNC: macro to automatically handle async callbacks contexts

+ *

+ * Needs to be used in conjunction with HID_BPF_ASYNC_INIT and HID_BPF_ASYNC_DELAYED_CALL

+ */

+#define HID_BPF_ASYNC_FUN(fun) \

+fun(struct hid_bpf_ctx *ctx); \

+int ____key__##fun; \

+static int ____async_init_##fun(void) \

+{ \

+ ____key__##fun = hid_bpf_async_get_ctx(); \

+ if (____key__##fun < 0) \

+ return ____key__##fun; \

+ return 0; \

+} \

+static int HID_BPF_ASYNC_CB(____##fun##_cb)(struct hid_bpf_ctx *hctx) \

+{ \

+ return fun(hctx); \

+} \

+typeof(fun(0)) fun

+

+#define HID_BPF_ASYNC_INIT(fun) ____async_init_##fun()

+#define HID_BPF_ASYNC_DELAYED_CALL(fun, ctx, delay) \

+ hid_bpf_async_delayed_call(ctx, delay, ____key__##fun, ____##fun##_cb)

+

+/*

+ * internal cb for starting the delayed work callback in a workqueue.

+ */

+static int __start_wq_timer_cb(void *map, int *key, void *value)

+{

+ struct hid_bpf_async_map_elem *e = (struct hid_bpf_async_map_elem *)value;

+

+ bpf_wq_start(&e->wq, 0);

+

+ return 0;

+}

+

+static int hid_bpf_async_find_empty_key(void)

+{

+ int i;

+

+ bpf_for(i, 0, HID_BPF_ASYNC_MAX_CTX) {

+ struct hid_bpf_async_map_elem *elem;

+ int key = i;

+

+ elem = bpf_map_lookup_elem(&hid_bpf_async_ctx_map, &key);

+ if (!elem)

+ return -ENOMEM; /* should never happen */

+

+ bpf_spin_lock(&elem->lock);

+

+ if (elem->state == HID_BPF_ASYNC_STATE_UNSET) {

+ elem->state = HID_BPF_ASYNC_STATE_INITIALIZING;

+ bpf_spin_unlock(&elem->lock);

+ return i;

+ }

+

+ bpf_spin_unlock(&elem->lock);

+ }

+

+ return -EINVAL;

+}

+

+static int hid_bpf_async_get_ctx(void)

+{

+ int key = hid_bpf_async_find_empty_key();

+ struct hid_bpf_async_map_elem *elem;

+ int err;

+

+ if (key < 0)

+ return key;

+

+ elem = bpf_map_lookup_elem(&hid_bpf_async_ctx_map, &key);

+ if (!elem)

+ return -EINVAL;

+

+ err = bpf_timer_init(&elem->t, &hid_bpf_async_ctx_map, CLOCK_MONOTONIC);

+ if (err)

+ return err;

+

+ err = bpf_timer_set_callback(&elem->t, __start_wq_timer_cb);

+ if (err)

+ return err;

+

+ err = bpf_wq_init(&elem->wq, &hid_bpf_async_ctx_map, 0);

+ if (err)

+ return err;

+

+ elem->state = HID_BPF_ASYNC_STATE_INITIALIZED;

+

+ return key;

+}

+

+static inline u64 ms_to_ns(u64 milliseconds)

+{

+ return (u64)milliseconds * 1000UL * 1000UL;

+}

+

+static int hid_bpf_async_delayed_call(struct hid_bpf_ctx *hctx, u64 milliseconds, int key,

+ hid_bpf_async_callback_t wq_cb)

+{

+ struct hid_bpf_async_map_elem *elem;

+ int err;

+

+ elem = bpf_map_lookup_elem(&hid_bpf_async_ctx_map, &key);

+ if (!elem)

+ return -EINVAL;

+

+ bpf_spin_lock(&elem->lock);

+ /* The wq must be:

+ * - HID_BPF_ASYNC_STATE_INITIALIZED -> it's been initialized and ready to be called

+ * - HID_BPF_ASYNC_STATE_RUNNING -> possible re-entry from the wq itself

+ */

+ if (elem->state != HID_BPF_ASYNC_STATE_INITIALIZED &&

+ elem->state != HID_BPF_ASYNC_STATE_RUNNING) {

+ bpf_spin_unlock(&elem->lock);

+ return -EINVAL;

+ }

+ elem->state = HID_BPF_ASYNC_STATE_STARTING;

+ bpf_spin_unlock(&elem->lock);

+

+ elem->hid = hctx->hid->id;

+

+ err = bpf_wq_set_callback(&elem->wq, wq_cb, 0);

+ if (err)

+ return err;

+

+ if (milliseconds) {

+ /* needed for every call because a cancel might unset this */

+ err = bpf_timer_set_callback(&elem->t, __start_wq_timer_cb);

+ if (err)

+ return err;

+

+ err = bpf_timer_start(&elem->t, ms_to_ns(milliseconds), 0);

+ if (err)

+ return err;

+

+ return 0;

+ }

+

+ return bpf_wq_start(&elem->wq, 0);

+}

+

+static inline int hid_bpf_async_call(struct hid_bpf_ctx *ctx, int key,

+ hid_bpf_async_callback_t wq_cb)

+{

+ return hid_bpf_async_delayed_call(ctx, 0, key, wq_cb);

+}

+

+#endif /* __HID_BPF_ASYNC_H__ */

+extern int hid_bpf_hw_output_report(struct hid_bpf_ctx *ctx,

+ __u8 *buf, size_t buf__sz) __weak __ksym;

+extern int hid_bpf_input_report(struct hid_bpf_ctx *ctx,

+ enum hid_report_type type,

+ __u8 *data,

+ size_t buf__sz) __weak __ksym;

+extern int hid_bpf_try_input_report(struct hid_bpf_ctx *ctx,

+ enum hid_report_type type,

+ __u8 *data,

+ size_t buf__sz) __weak __ksym;

+

+/* bpf_wq implementation */

+extern int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int flags) __weak __ksym;

+extern int bpf_wq_start(struct bpf_wq *wq, unsigned int flags) __weak __ksym;

+extern int bpf_wq_set_callback_impl(struct bpf_wq *wq,

+ int (callback_fn)(void *map, int *key, void *value),

+ unsigned int flags__k, void *aux__ign) __ksym;

+#define bpf_wq_set_callback(wq, cb, flags) \

+ bpf_wq_set_callback_impl(wq, cb, flags, NULL)