HID: bpf: Add support for XP-Pen Deco02 (88b5468f) · Commits · git / linux-net

drivers/hid/bpf/progs/XPPen__Deco02.bpf.c

0 → 100644

+359 −0

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		// 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";