HID: bpf: Add support for the XP-Pen Deco 01 V3 (8ba327d5) · Commits · git / linux-net

drivers/hid/bpf/progs/XPPen__Deco01V3.bpf.c

0 → 100644

+305 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0-only
		/* Copyright (c) 2025 Red Hat
		*/

		#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 /* VID is shared with SinoWealth and Glorious and prob others */
		#define PID_DECO_01_V3 0x0947

		HID_BPF_CONFIG(
		HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_UGEE, PID_DECO_01_V3),
		);

		/*
		* Default report descriptor reports:
		* - a report descriptor for the pad buttons, reported as key sequences
		* - a report descriptor for the pen
		* - a vendor-specific report descriptor
		*
		* The Pad report descriptor, see
		* https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/issues/54
		*
		* # 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
		*
		* And key events for buttons top->bottom are:
		* Buttons released: 06 00 00 00 00 00 00 00
		* Button1: 06 00 05 00 00 00 00 00 -> b
		* Button2: 06 00 08 00 00 00 00 00 -> e
		* Button3: 06 04 00 00 00 00 00 00 -> LAlt
		* Button4: 06 00 2c 00 00 00 00 00 -> Space
		* Button5: 06 01 16 00 00 00 00 00 -> LControl + s
		* Button6: 06 01 1d 00 00 00 00 00 -> LControl + z
		* Button7: 06 01 57 00 00 00 00 00 -> LControl + Keypad Plus
		* Button8: 06 01 56 00 00 00 00 00 -> LControl + Keypad Dash
		*
		* When multiple buttons are pressed at the same time, the values used to
		* identify the buttons are identical, but they appear in different bytes of the
		* record. For example, when button 2 (0x08) and button 1 (0x05) are pressed,
		* this is the report:
		*
		* Buttons 2 and 1: 06 00 08 05 00 00 00 00 -> e + b
		*
		* Buttons 1, 2, 4, 5 and 6 can be matched by finding their values in the
		* report.
		*
		* Button 3 is pressed when the 3rd bit is 1. For example, pressing buttons 3
		* and 5 generates this report:
		*
		* Buttons 3 and 5: 06 05 16 00 00 00 00 00 -> LControl + LAlt + s
		* -- --
		* \| \|
		* \| `- Button 5 (0x16)
		* `- 0x05 = 0101. Button 3 is pressed
		* ^
		*
		* pad_buttons contains a list of buttons that can be matched in
		* HID_BPF_DEVICE_EVENT. Button 3 as it has a dedicated bit.
		*
		*
		* The Pen report descriptor announces a wrong tilt range:
		*
		* Report descriptor length: 109 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, 0x01, // Collection (Application) 10
		* 0x09, 0x42, // Usage (Tip Switch) 12
		* 0x09, 0x44, // Usage (Barrel Switch) 14
		* 0x09, 0x45, // Usage (Eraser) 16
		* 0x09, 0x3c, // Usage (Invert) 18
		* 0x15, 0x00, // Logical Minimum (0) 20
		* 0x25, 0x01, // Logical Maximum (1) 22
		* 0x75, 0x01, // Report Size (1) 24
		* 0x95, 0x04, // Report Count (4) 26
		* 0x81, 0x02, // Input (Data,Var,Abs) 28
		* 0x95, 0x01, // Report Count (1) 30
		* 0x81, 0x03, // Input (Cnst,Var,Abs) 32
		* 0x09, 0x32, // Usage (In Range) 34
		* 0x95, 0x01, // Report Count (1) 36
		* 0x81, 0x02, // Input (Data,Var,Abs) 38
		* 0x95, 0x02, // Report Count (2) 40
		* 0x81, 0x03, // Input (Cnst,Var,Abs) 42
		* 0x75, 0x10, // Report Size (16) 44
		* 0x95, 0x01, // Report Count (1) 46
		* 0x35, 0x00, // Physical Minimum (0) 48
		* 0xa4, // Push 50
		* 0x05, 0x01, // Usage Page (Generic Desktop) 51
		* 0x09, 0x30, // Usage (X) 53
		* 0x65, 0x13, // Unit (EnglishLinear: in) 55
		* 0x55, 0x0d, // Unit Exponent (-3) 57
		* 0x46, 0x10, 0x27, // Physical Maximum (10000) 59
		* 0x26, 0xff, 0x7f, // Logical Maximum (32767) 62
		* 0x81, 0x02, // Input (Data,Var,Abs) 65
		* 0x09, 0x31, // Usage (Y) 67
		* 0x46, 0x6a, 0x18, // Physical Maximum (6250) 69
		* 0x26, 0xff, 0x7f, // Logical Maximum (32767) 72
		* 0x81, 0x02, // Input (Data,Var,Abs) 75
		* 0xb4, // Pop 77
		* 0x09, 0x30, // Usage (X) 78
		* 0x45, 0x00, // Physical Maximum (0) 80
		* 0x26, 0xff, 0x3f, // Logical Maximum (16383) 82
		* 0x81, 0x42, // Input (Data,Var,Abs,Null) 85
		* 0x09, 0x3d, // Usage (Start) 87
		* 0x15, 0x81, // Logical Minimum (-127) 89 <- Change from -127 to -60
		* 0x25, 0x7f, // Logical Maximum (127) 91 <- Change from 127 to 60
		* 0x75, 0x08, // Report Size (8) 93
		* 0x95, 0x01, // Report Count (1) 95
		* 0x81, 0x02, // Input (Data,Var,Abs) 97
		* 0x09, 0x3e, // Usage (Select) 99
		* 0x15, 0x81, // Logical Minimum (-127) 101 <- Change from -127 to -60
		* 0x25, 0x7f, // Logical Maximum (127) 103 <- Change from 127 to 60
		* 0x81, 0x02, // Input (Data,Var,Abs) 105
		* 0xc0, // End Collection 107
		* 0xc0, // End Collection 108
		*/

		#define PEN_REPORT_DESCRIPTOR_LENGTH 109
		#define PAD_REPORT_DESCRIPTOR_LENGTH 102
		#define PAD_REPORT_LENGTH 8
		#define PAD_REPORT_ID 6
		#define PAD_NUM_BUTTONS 8

		static const __u8 fixed_rdesc_pad[] = {
		UsagePage_GenericDesktop
		Usage_GD_Keypad
		CollectionApplication(
		// Byte 0 in report is the report ID
		ReportId(PAD_REPORT_ID)
		ReportCount(1)
		ReportSize(8)
		UsagePage_Digitizers
		Usage_Dig_TabletFunctionKeys
		CollectionPhysical(
		// Byte 1 is the button state
		UsagePage_Button
		UsageMinimum_i8(0x01)
		UsageMaximum_i8(PAD_NUM_BUTTONS)
		LogicalMinimum_i8(0x0)
		LogicalMaximum_i8(0x1)
		ReportCount(PAD_NUM_BUTTONS)
		ReportSize(1)
		Input(Var\|Abs)
		// Byte 2 in report - just exists so we get to be a tablet pad
		UsagePage_Digitizers
		Usage_Dig_BarrelSwitch // BTN_STYLUS
		ReportCount(1)
		ReportSize(1)
		Input(Var\|Abs)
		ReportCount(7) // padding
		Input(Const)
		// Bytes 3/4 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 5-7 are padding so we match the original report lengtth
		ReportCount(3)
		ReportSize(8)
		Input(Const)
		)
		)
		};

		SEC(HID_BPF_RDESC_FIXUP)
		int BPF_PROG(xppen_deco01v3_rdesc_fixup, struct hid_bpf_ctx *hctx)
		{
		__u8 data = hid_bpf_get_data(hctx, 0 / offset /, HID_MAX_DESCRIPTOR_SIZE / size */);

		const __u8 wrong_logical_range[] = {0x15, 0x81, 0x25, 0x7f};
		const __u8 correct_logical_range[] = {0x15, 0xc4, 0x25, 0x3c};

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

		switch (hctx->size) {
		case PAD_REPORT_DESCRIPTOR_LENGTH:
		__builtin_memcpy(data, fixed_rdesc_pad, sizeof(fixed_rdesc_pad));
		return sizeof(fixed_rdesc_pad);
		case PEN_REPORT_DESCRIPTOR_LENGTH:
		if (__builtin_memcmp(&data[89], wrong_logical_range,
		sizeof(wrong_logical_range)) == 0)
		__builtin_memcpy(&data[89], correct_logical_range,
		sizeof(correct_logical_range));
		if (__builtin_memcmp(&data[101], wrong_logical_range,
		sizeof(wrong_logical_range)) == 0)
		__builtin_memcpy(&data[101], correct_logical_range,
		sizeof(correct_logical_range));
		break;
		}

		return 0;
		}

		SEC(HID_BPF_DEVICE_EVENT)
		int BPF_PROG(xppen_deco01v3_device_event, struct hid_bpf_ctx *hctx)
		{
		static const __u8 pad_buttons[] = { 0x05, 0x08, 0x00, 0x2c, 0x16, 0x1d, 0x57, 0x56 };
		__u8 data = hid_bpf_get_data(hctx, 0 / offset /, PAD_REPORT_LENGTH / size */);

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

		if (data[0] == PAD_REPORT_ID) {
		__u8 button_mask = 0;
		size_t d, b;

		/* data[1] stores the status of BTN_2 in the 3rd bit*/
		if (data[1] & BIT(2))
		button_mask \|= BIT(2);

		/* The rest of the descriptor stores the buttons as in pad_buttons */
		for (d = 2; d < 8; d++) {
		for (b = 0; b < sizeof(pad_buttons); b++) {
		if (data[d] != 0 && data[d] == pad_buttons[b])
		button_mask \|= BIT(b);
		}
		}

		__u8 report[8] = {PAD_REPORT_ID, button_mask, 0x00};

		__builtin_memcpy(data, report, sizeof(report));
		}
		return 0;
		}

		HID_BPF_OPS(xppen_deco01v3) = {
		.hid_rdesc_fixup = (void *)xppen_deco01v3_rdesc_fixup,
		.hid_device_event = (void *)xppen_deco01v3_device_event,
		};

		SEC("syscall")
		int probe(struct hid_bpf_probe_args *ctx)
		{
		switch (ctx->rdesc_size) {
		case PAD_REPORT_DESCRIPTOR_LENGTH:
		case PEN_REPORT_DESCRIPTOR_LENGTH:
		ctx->retval = 0;
		break;
		default:
		ctx->retval = -EINVAL;
		}

		return 0;
		}

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