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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";
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