| // SPDX-License-Identifier: GPL-2.0-only |
| |
| #include "vmlinux.h" |
| #include "hid_bpf.h" |
| #include "hid_bpf_helpers.h" |
| #include "hid_report_helpers.h" |
| #include <bpf/bpf_tracing.h> |
| |
| #define VID_UGEE 0x28BD |
| #define PID_DECO_02 0x0803 |
| |
| HID_BPF_CONFIG( |
| HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_UGEE, PID_DECO_02), |
| ); |
| |
| /* |
| * Devices are: |
| * - Pad input, including pen (This is the only one we are interested in) |
| * - Pen input as mouse |
| * - Vendor |
| * |
| * Descriptors on main device are: |
| * - 7: Pen |
| * - 6: Vendor settings? Unclear |
| * - 3: Keyboard (This is what we want to modify) |
| * - 5: Feature report |
| * |
| * This creates three event nodes: |
| * - XP-PEN DECO 02 Stylus |
| * - XP-PEN DECO 02 |
| * - XP-PEN DECO 02 Keyboard (Again, what we want to modify) |
| * |
| * # Report descriptor length: 188 bytes |
| * # 0x05, 0x0d, // Usage Page (Digitizers) 0 |
| * # 0x09, 0x02, // Usage (Pen) 2 |
| * # 0xa1, 0x01, // Collection (Application) 4 |
| * # 0x85, 0x07, // Report ID (7) 6 |
| * # 0x09, 0x20, // Usage (Stylus) 8 |
| * # 0xa1, 0x00, // Collection (Physical) 10 |
| * # 0x09, 0x42, // Usage (Tip Switch) 12 |
| * # 0x09, 0x44, // Usage (Barrel Switch) 14 |
| * # 0x09, 0x45, // Usage (Eraser) 16 |
| * # 0x09, 0x3c, // Usage (Invert) 18 |
| * # 0x09, 0x32, // Usage (In Range) 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 |
| * # 0x81, 0x02, // Input (Data,Var,Abs) 30 |
| * # 0x95, 0x03, // Report Count (3) 32 |
| * # 0x81, 0x03, // Input (Cnst,Var,Abs) 34 |
| * # 0x05, 0x01, // Usage Page (Generic Desktop) 36 |
| * # 0x09, 0x30, // Usage (X) 38 |
| * # 0x15, 0x00, // Logical Minimum (0) 40 |
| * # 0x26, 0x50, 0x57, // Logical Maximum (22352) 42 |
| * # 0x55, 0x0d, // Unit Exponent (-3) 45 |
| * # 0x65, 0x13, // Unit (EnglishLinear: in) 47 |
| * # 0x35, 0x00, // Physical Minimum (0) 49 |
| * # 0x46, 0x50, 0x57, // Physical Maximum (22352) 51 |
| * # 0x75, 0x10, // Report Size (16) 54 |
| * # 0x95, 0x01, // Report Count (1) 56 |
| * # 0x81, 0x02, // Input (Data,Var,Abs) 58 |
| * # 0x09, 0x31, // Usage (Y) 60 |
| * # 0x15, 0x00, // Logical Minimum (0) 62 |
| * # 0x26, 0x92, 0x36, // Logical Maximum (13970) 64 |
| * # 0x55, 0x0d, // Unit Exponent (-3) 67 |
| * # 0x65, 0x13, // Unit (EnglishLinear: in) 69 |
| * # 0x35, 0x00, // Physical Minimum (0) 71 |
| * # 0x46, 0x92, 0x36, // Physical Maximum (13970) 73 |
| * # 0x75, 0x10, // Report Size (16) 76 |
| * # 0x95, 0x01, // Report Count (1) 78 |
| * # 0x81, 0x02, // Input (Data,Var,Abs) 80 |
| * # 0x05, 0x0d, // Usage Page (Digitizers) 82 |
| * # 0x09, 0x30, // Usage (Tip Pressure) 84 |
| * # 0x15, 0x00, // Logical Minimum (0) 86 |
| * # 0x26, 0xff, 0x1f, // Logical Maximum (8191) 88 |
| * # 0x75, 0x10, // Report Size (16) 91 |
| * # 0x95, 0x01, // Report Count (1) 93 |
| * # 0x81, 0x02, // Input (Data,Var,Abs) 95 |
| * # 0xc0, // End Collection 97 |
| * # 0xc0, // End Collection 98 |
| * # 0x09, 0x0e, // Usage (Device Configuration) 99 |
| * # 0xa1, 0x01, // Collection (Application) 101 |
| * # 0x85, 0x05, // Report ID (5) 103 |
| * # 0x09, 0x23, // Usage (Device Settings) 105 |
| * # 0xa1, 0x02, // Collection (Logical) 107 |
| * # 0x09, 0x52, // Usage (Inputmode) 109 |
| * # 0x09, 0x53, // Usage (Device Index) 111 |
| * # 0x25, 0x0a, // Logical Maximum (10) 113 |
| * # 0x75, 0x08, // Report Size (8) 115 |
| * # 0x95, 0x02, // Report Count (2) 117 |
| * # 0xb1, 0x02, // Feature (Data,Var,Abs) 119 |
| * # 0xc0, // End Collection 121 |
| * # 0xc0, // End Collection 122 |
| * # 0x05, 0x0c, // Usage Page (Consumer Devices) 123 |
| * # 0x09, 0x36, // Usage (Function Buttons) 125 |
| * # 0xa1, 0x00, // Collection (Physical) 127 |
| * # 0x85, 0x06, // Report ID (6) 129 |
| * # 0x05, 0x09, // Usage Page (Button) 131 |
| * # 0x19, 0x01, // Usage Minimum (1) 133 |
| * # 0x29, 0x20, // Usage Maximum (32) 135 |
| * # 0x15, 0x00, // Logical Minimum (0) 137 |
| * # 0x25, 0x01, // Logical Maximum (1) 139 |
| * # 0x95, 0x20, // Report Count (32) 141 |
| * # 0x75, 0x01, // Report Size (1) 143 |
| * # 0x81, 0x02, // Input (Data,Var,Abs) 145 |
| * # 0xc0, // End Collection 147 |
| * # 0x05, 0x01, // Usage Page (Generic Desktop) 148 |
| * # 0x09, 0x06, // Usage (Keyboard) 150 |
| * # 0xa1, 0x01, // Collection (Application) 152 |
| * # 0x85, 0x03, // Report ID (3) 154 |
| * # 0x05, 0x07, // Usage Page (Keyboard) 156 |
| * # 0x19, 0xe0, // Usage Minimum (224) 158 |
| * # 0x29, 0xe7, // Usage Maximum (231) 160 |
| * # 0x15, 0x00, // Logical Minimum (0) 162 |
| * # 0x25, 0x01, // Logical Maximum (1) 164 |
| * # 0x75, 0x01, // Report Size (1) 166 |
| * # 0x95, 0x08, // Report Count (8) 168 |
| * # 0x81, 0x02, // Input (Data,Var,Abs) 170 |
| * # 0x05, 0x07, // Usage Page (Keyboard) 172 |
| * # 0x19, 0x00, // Usage Minimum (0) 174 |
| * # 0x29, 0xff, // Usage Maximum (255) 176 |
| * # 0x26, 0xff, 0x00, // Logical Maximum (255) 178 |
| * # 0x75, 0x08, // Report Size (8) 181 |
| * # 0x95, 0x06, // Report Count (6) 183 |
| * # 0x81, 0x00, // Input (Data,Arr,Abs) 185 |
| * # 0xc0, // End Collection 187 |
| * |
| * Key events; top to bottom: |
| * Buttons released: 03 00 00 00 00 00 00 00 |
| * Button1: 03 00 05 00 00 00 00 00 -> 'b and B' |
| * Button2: 03 00 2c 00 00 00 00 00 -> 'Spacebar' |
| * Button3: 03 00 08 00 00 00 00 00 -> 'e and E' |
| * Button4: 03 00 0c 00 00 00 00 00 -> 'i and I' |
| * Button5: 03 05 1d 00 00 00 00 00 -> LeftControl + LeftAlt + 'z and Z' |
| * Button6: 03 01 16 00 00 00 00 00 -> LeftControl + 's and S' |
| * |
| * Dial Events: |
| * Clockwise: 03 01 2e 00 00 00 00 00 -> LeftControl + '= and +' |
| * Anticlockwise: 03 01 2d 00 00 00 00 00 -> LeftControl + '- and (underscore)' |
| * |
| * NOTE: Input event descriptions begin at byte 2, and progressively build |
| * towards byte 7 as each new key is pressed maintaining the press order. |
| * For example: |
| * BTN1 followed by BTN2 is 03 00 05 2c 00 00 00 00 |
| * BTN2 followed by BTN1 is 03 00 2c 05 00 00 00 00 |
| * |
| * Releasing a button causes its byte to be freed, and the next item in the list |
| * is pushed forwards. Dial events are released immediately after an event is |
| * registered (i.e. after each "click"), so will continually appear pushed |
| * backwards in the report. |
| * |
| * When a button with a modifier key is pressed, the button identifier stacks in |
| * an abnormal way, where the highest modifier byte always supersedes others. |
| * In these cases, the button with the higher modifier is always last. |
| * For example: |
| * BTN6 followed by BTN5 is 03 05 1d 16 00 00 00 00 |
| * BTN5 followed by BTN6 is 03 05 1d 16 00 00 00 00 |
| * BTN5 followed by BTN1 is 03 05 05 1d 00 00 00 00 |
| * |
| * For three button presses in order, demonstrating strictly above rules: |
| * BTN6, BTN1, BTN5 is 03 05 05 1d 16 00 00 00 |
| * BTN5, BTN1, BTN6 is 03 05 05 1d 16 00 00 00 |
| * |
| * In short, when BTN5/6 are pressed, the order of operations is lost, as they |
| * will always float to the end when pressed in combination with others. |
| * |
| * Fortunately, all states are recorded in the same way, with no overlaps. |
| * Byte 1 can be used as a spare for the wheel, since this is for mod keys. |
| */ |
| |
| #define RDESC_SIZE_PAD 188 |
| #define REPORT_SIZE_PAD 8 |
| #define REPORT_ID_BUTTONS 3 |
| #define PAD_BUTTON_COUNT 6 |
| #define RDESC_KEYBOARD_OFFSET 148 |
| |
| static const __u8 fixed_rdesc_pad[] = { |
| /* Copy of pen descriptor to avoid losing functionality */ |
| UsagePage_Digitizers |
| Usage_Dig_Pen |
| CollectionApplication( |
| ReportId(7) |
| Usage_Dig_Stylus |
| CollectionPhysical( |
| Usage_Dig_TipSwitch |
| Usage_Dig_BarrelSwitch |
| Usage_Dig_Eraser |
| Usage_Dig_Invert |
| Usage_Dig_InRange |
| LogicalMinimum_i8(0) |
| LogicalMaximum_i8(1) |
| ReportSize(1) |
| ReportCount(5) |
| Input(Var|Abs) |
| ReportCount(3) |
| Input(Const) /* Input (Const, Var, Abs) */ |
| UsagePage_GenericDesktop |
| Usage_GD_X |
| LogicalMinimum_i16(0) |
| LogicalMaximum_i16(22352) |
| UnitExponent(-3) |
| Unit(in) /* (EnglishLinear: in) */ |
| PhysicalMinimum_i16(0) |
| PhysicalMaximum_i16(22352) |
| ReportSize(16) |
| ReportCount(1) |
| Input(Var|Abs) |
| Usage_GD_Y |
| LogicalMinimum_i16(0) |
| LogicalMaximum_i16(13970) |
| UnitExponent(-3) |
| Unit(in) /* (EnglishLinear: in) */ |
| PhysicalMinimum_i16(0) |
| PhysicalMaximum_i16(13970) |
| ReportSize(16) |
| ReportCount(1) |
| Input(Var|Abs) |
| UsagePage_Digitizers |
| Usage_Dig_TipPressure |
| LogicalMinimum_i16(0) |
| LogicalMaximum_i16(8191) |
| ReportSize(16) |
| ReportCount(1) |
| Input(Var|Abs) |
| ) |
| ) |
| |
| /* FIXES BEGIN */ |
| UsagePage_GenericDesktop |
| Usage_GD_Keypad |
| CollectionApplication( |
| ReportId(REPORT_ID_BUTTONS) /* Retain original ID on byte 0 */ |
| ReportCount(1) |
| ReportSize(REPORT_SIZE_PAD) |
| UsagePage_Digitizers |
| Usage_Dig_TabletFunctionKeys |
| CollectionPhysical( |
| /* Byte 1: Dial state */ |
| UsagePage_GenericDesktop |
| Usage_GD_Dial |
| LogicalMinimum_i8(-1) |
| LogicalMaximum_i8(1) |
| ReportCount(1) |
| ReportSize(REPORT_SIZE_PAD) |
| Input(Var|Rel) |
| /* Byte 2: Button state */ |
| UsagePage_Button |
| ReportSize(1) |
| ReportCount(PAD_BUTTON_COUNT) |
| UsageMinimum_i8(0x01) |
| UsageMaximum_i8(PAD_BUTTON_COUNT) /* Number of buttons */ |
| LogicalMinimum_i8(0x0) |
| LogicalMaximum_i8(0x1) |
| Input(Var|Abs) |
| /* Byte 3: Exists to be tablet pad */ |
| UsagePage_Digitizers |
| Usage_Dig_BarrelSwitch |
| ReportCount(1) |
| ReportSize(1) |
| Input(Var|Abs) |
| ReportCount(7) /* Padding, to fill full report space */ |
| Input(Const) |
| /* Byte 4/5: Exists to be a tablet pad */ |
| UsagePage_GenericDesktop |
| Usage_GD_X |
| Usage_GD_Y |
| ReportCount(2) |
| ReportSize(8) |
| Input(Var|Abs) |
| /* Bytes 6/7: Padding, to match original length */ |
| ReportCount(2) |
| ReportSize(8) |
| Input(Const) |
| ) |
| FixedSizeVendorReport(RDESC_SIZE_PAD) |
| ) |
| }; |
| |
| SEC(HID_BPF_RDESC_FIXUP) |
| int BPF_PROG(xppen_deco02_rdesc_fixup, struct hid_bpf_ctx *hctx) |
| { |
| __u8 *data = hid_bpf_get_data(hctx, 0, HID_MAX_DESCRIPTOR_SIZE); |
| |
| if (!data) |
| return 0; /* EPERM Check */ |
| |
| if (hctx->size == RDESC_SIZE_PAD) { |
| __builtin_memcpy(data, fixed_rdesc_pad, sizeof(fixed_rdesc_pad)); |
| return sizeof(fixed_rdesc_pad); |
| } |
| |
| return 0; |
| } |
| |
| SEC(HID_BPF_DEVICE_EVENT) |
| int BPF_PROG(xppen_deco02_device_event, struct hid_bpf_ctx *hctx) |
| { |
| __u8 *data = hid_bpf_get_data(hctx, 0, REPORT_SIZE_PAD); |
| |
| if (!data || data[0] != REPORT_ID_BUTTONS) |
| return 0; /* EPERM or wrong report */ |
| |
| __u8 dial_code = 0; |
| __u8 button_mask = 0; |
| size_t d; |
| |
| /* Start from 2; 0 is report ID, 1 is modifier keys, replaced by dial */ |
| for (d = 2; d < 8; d++) { |
| switch (data[d]) { |
| case 0x2e: |
| dial_code = 1; |
| break; |
| case 0x2d: |
| dial_code = -1; |
| break; |
| /* below are buttons, top to bottom */ |
| case 0x05: |
| button_mask |= BIT(0); |
| break; |
| case 0x2c: |
| button_mask |= BIT(1); |
| break; |
| case 0x08: |
| button_mask |= BIT(2); |
| break; |
| case 0x0c: |
| button_mask |= BIT(3); |
| break; |
| case 0x1d: |
| button_mask |= BIT(4); |
| break; |
| case 0x16: |
| button_mask |= BIT(05); |
| break; |
| default: |
| break; |
| } |
| } |
| |
| __u8 report[8] = { REPORT_ID_BUTTONS, dial_code, button_mask, 0x00 }; |
| |
| __builtin_memcpy(data, report, sizeof(report)); |
| return 0; |
| } |
| |
| HID_BPF_OPS(xppen_deco02) = { |
| .hid_rdesc_fixup = (void *)xppen_deco02_rdesc_fixup, |
| .hid_device_event = (void *)xppen_deco02_device_event, |
| }; |
| |
| SEC("syscall") |
| int probe(struct hid_bpf_probe_args *ctx) |
| { |
| ctx->retval = ctx->rdesc_size != RDESC_SIZE_PAD ? -EINVAL : 0; |
| return 0; |
| } |
| |
| char _license[] SEC("license") = "GPL"; |
