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Benjamin TissoiresJiri Kosina
Benjamin Tissoires
authored and
Jiri Kosina
committed
HID: bpf: Add support for XP-Pen Deco02
Modifies report to have tablet buttons report as buttons, rather than as keyboard key combinations. The dial is also converted to a relative input, using the dedicated bit previously reserved for modifier key information. Signed-off-by: Hannah Pittman <dev@hannahl.co.uk> Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/203 Signed-off-by: Benjamin Tissoires <bentiss@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.com>
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‎drivers/hid/bpf/progs/XPPen__Deco02.bpf.c‎

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// SPDX-License-Identifier: GPL-2.0-only
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#include "vmlinux.h"
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#include "hid_bpf.h"
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#include "hid_bpf_helpers.h"
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#include "hid_report_helpers.h"
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#include <bpf/bpf_tracing.h>
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#define VID_UGEE 0x28BD
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#define PID_DECO_02 0x0803
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HID_BPF_CONFIG(
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HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_UGEE, PID_DECO_02),
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);
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/*
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* Devices are:
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* - Pad input, including pen (This is the only one we are interested in)
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* - Pen input as mouse
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* - Vendor
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*
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* Descriptors on main device are:
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* - 7: Pen
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* - 6: Vendor settings? Unclear
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* - 3: Keyboard (This is what we want to modify)
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* - 5: Feature report
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*
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* This creates three event nodes:
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* - XP-PEN DECO 02 Stylus
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* - XP-PEN DECO 02
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* - XP-PEN DECO 02 Keyboard (Again, what we want to modify)
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*
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* # Report descriptor length: 188 bytes
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* # 0x05, 0x0d, // Usage Page (Digitizers) 0
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* # 0x09, 0x02, // Usage (Pen) 2
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* # 0xa1, 0x01, // Collection (Application) 4
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* # 0x85, 0x07, // Report ID (7) 6
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* # 0x09, 0x20, // Usage (Stylus) 8
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* # 0xa1, 0x00, // Collection (Physical) 10
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* # 0x09, 0x42, // Usage (Tip Switch) 12
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* # 0x09, 0x44, // Usage (Barrel Switch) 14
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* # 0x09, 0x45, // Usage (Eraser) 16
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* # 0x09, 0x3c, // Usage (Invert) 18
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* # 0x09, 0x32, // Usage (In Range) 20
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* # 0x15, 0x00, // Logical Minimum (0) 22
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* # 0x25, 0x01, // Logical Maximum (1) 24
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* # 0x75, 0x01, // Report Size (1) 26
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* # 0x95, 0x05, // Report Count (5) 28
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* # 0x81, 0x02, // Input (Data,Var,Abs) 30
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* # 0x95, 0x03, // Report Count (3) 32
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* # 0x81, 0x03, // Input (Cnst,Var,Abs) 34
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* # 0x05, 0x01, // Usage Page (Generic Desktop) 36
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* # 0x09, 0x30, // Usage (X) 38
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* # 0x15, 0x00, // Logical Minimum (0) 40
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* # 0x26, 0x50, 0x57, // Logical Maximum (22352) 42
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* # 0x55, 0x0d, // Unit Exponent (-3) 45
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* # 0x65, 0x13, // Unit (EnglishLinear: in) 47
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* # 0x35, 0x00, // Physical Minimum (0) 49
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* # 0x46, 0x50, 0x57, // Physical Maximum (22352) 51
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* # 0x75, 0x10, // Report Size (16) 54
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* # 0x95, 0x01, // Report Count (1) 56
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* # 0x81, 0x02, // Input (Data,Var,Abs) 58
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* # 0x09, 0x31, // Usage (Y) 60
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* # 0x15, 0x00, // Logical Minimum (0) 62
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* # 0x26, 0x92, 0x36, // Logical Maximum (13970) 64
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* # 0x55, 0x0d, // Unit Exponent (-3) 67
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* # 0x65, 0x13, // Unit (EnglishLinear: in) 69
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* # 0x35, 0x00, // Physical Minimum (0) 71
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* # 0x46, 0x92, 0x36, // Physical Maximum (13970) 73
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* # 0x75, 0x10, // Report Size (16) 76
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* # 0x95, 0x01, // Report Count (1) 78
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* # 0x81, 0x02, // Input (Data,Var,Abs) 80
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* # 0x05, 0x0d, // Usage Page (Digitizers) 82
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* # 0x09, 0x30, // Usage (Tip Pressure) 84
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* # 0x15, 0x00, // Logical Minimum (0) 86
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* # 0x26, 0xff, 0x1f, // Logical Maximum (8191) 88
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* # 0x75, 0x10, // Report Size (16) 91
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* # 0x95, 0x01, // Report Count (1) 93
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* # 0x81, 0x02, // Input (Data,Var,Abs) 95
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* # 0xc0, // End Collection 97
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* # 0xc0, // End Collection 98
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* # 0x09, 0x0e, // Usage (Device Configuration) 99
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* # 0xa1, 0x01, // Collection (Application) 101
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* # 0x85, 0x05, // Report ID (5) 103
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* # 0x09, 0x23, // Usage (Device Settings) 105
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* # 0xa1, 0x02, // Collection (Logical) 107
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* # 0x09, 0x52, // Usage (Inputmode) 109
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* # 0x09, 0x53, // Usage (Device Index) 111
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* # 0x25, 0x0a, // Logical Maximum (10) 113
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* # 0x75, 0x08, // Report Size (8) 115
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* # 0x95, 0x02, // Report Count (2) 117
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* # 0xb1, 0x02, // Feature (Data,Var,Abs) 119
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* # 0xc0, // End Collection 121
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* # 0xc0, // End Collection 122
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* # 0x05, 0x0c, // Usage Page (Consumer Devices) 123
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* # 0x09, 0x36, // Usage (Function Buttons) 125
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* # 0xa1, 0x00, // Collection (Physical) 127
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* # 0x85, 0x06, // Report ID (6) 129
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* # 0x05, 0x09, // Usage Page (Button) 131
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* # 0x19, 0x01, // Usage Minimum (1) 133
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* # 0x29, 0x20, // Usage Maximum (32) 135
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* # 0x15, 0x00, // Logical Minimum (0) 137
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* # 0x25, 0x01, // Logical Maximum (1) 139
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* # 0x95, 0x20, // Report Count (32) 141
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* # 0x75, 0x01, // Report Size (1) 143
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* # 0x81, 0x02, // Input (Data,Var,Abs) 145
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* # 0xc0, // End Collection 147
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* # 0x05, 0x01, // Usage Page (Generic Desktop) 148
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* # 0x09, 0x06, // Usage (Keyboard) 150
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* # 0xa1, 0x01, // Collection (Application) 152
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* # 0x85, 0x03, // Report ID (3) 154
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* # 0x05, 0x07, // Usage Page (Keyboard) 156
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* # 0x19, 0xe0, // Usage Minimum (224) 158
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* # 0x29, 0xe7, // Usage Maximum (231) 160
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* # 0x15, 0x00, // Logical Minimum (0) 162
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* # 0x25, 0x01, // Logical Maximum (1) 164
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* # 0x75, 0x01, // Report Size (1) 166
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* # 0x95, 0x08, // Report Count (8) 168
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* # 0x81, 0x02, // Input (Data,Var,Abs) 170
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* # 0x05, 0x07, // Usage Page (Keyboard) 172
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* # 0x19, 0x00, // Usage Minimum (0) 174
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* # 0x29, 0xff, // Usage Maximum (255) 176
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* # 0x26, 0xff, 0x00, // Logical Maximum (255) 178
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* # 0x75, 0x08, // Report Size (8) 181
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* # 0x95, 0x06, // Report Count (6) 183
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* # 0x81, 0x00, // Input (Data,Arr,Abs) 185
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* # 0xc0, // End Collection 187
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*
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* Key events; top to bottom:
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* Buttons released: 03 00 00 00 00 00 00 00
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* Button1: 03 00 05 00 00 00 00 00 -> 'b and B'
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* Button2: 03 00 2c 00 00 00 00 00 -> 'Spacebar'
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* Button3: 03 00 08 00 00 00 00 00 -> 'e and E'
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* Button4: 03 00 0c 00 00 00 00 00 -> 'i and I'
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* Button5: 03 05 1d 00 00 00 00 00 -> LeftControl + LeftAlt + 'z and Z'
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* Button6: 03 01 16 00 00 00 00 00 -> LeftControl + 's and S'
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*
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* Dial Events:
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* Clockwise: 03 01 2e 00 00 00 00 00 -> LeftControl + '= and +'
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* Anticlockwise: 03 01 2d 00 00 00 00 00 -> LeftControl + '- and (underscore)'
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*
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* NOTE: Input event descriptions begin at byte 2, and progressively build
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* towards byte 7 as each new key is pressed maintaining the press order.
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* For example:
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* BTN1 followed by BTN2 is 03 00 05 2c 00 00 00 00
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* BTN2 followed by BTN1 is 03 00 2c 05 00 00 00 00
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*
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* Releasing a button causes its byte to be freed, and the next item in the list
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* is pushed forwards. Dial events are released immediately after an event is
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* registered (i.e. after each "click"), so will continually appear pushed
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* backwards in the report.
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*
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* When a button with a modifier key is pressed, the button identifier stacks in
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* an abnormal way, where the highest modifier byte always supersedes others.
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* In these cases, the button with the higher modifier is always last.
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* For example:
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* BTN6 followed by BTN5 is 03 05 1d 16 00 00 00 00
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* BTN5 followed by BTN6 is 03 05 1d 16 00 00 00 00
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* BTN5 followed by BTN1 is 03 05 05 1d 00 00 00 00
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*
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* For three button presses in order, demonstrating strictly above rules:
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* BTN6, BTN1, BTN5 is 03 05 05 1d 16 00 00 00
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* BTN5, BTN1, BTN6 is 03 05 05 1d 16 00 00 00
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*
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* In short, when BTN5/6 are pressed, the order of operations is lost, as they
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* will always float to the end when pressed in combination with others.
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*
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* Fortunately, all states are recorded in the same way, with no overlaps.
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* Byte 1 can be used as a spare for the wheel, since this is for mod keys.
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*/
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#define RDESC_SIZE_PAD 188
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#define REPORT_SIZE_PAD 8
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#define REPORT_ID_BUTTONS 3
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#define PAD_BUTTON_COUNT 6
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#define RDESC_KEYBOARD_OFFSET 148
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static const __u8 fixed_rdesc_pad[] = {
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/* Copy of pen descriptor to avoid losing functionality */
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UsagePage_Digitizers
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Usage_Dig_Pen
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CollectionApplication(
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ReportId(7)
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Usage_Dig_Stylus
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CollectionPhysical(
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Usage_Dig_TipSwitch
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Usage_Dig_BarrelSwitch
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Usage_Dig_Eraser
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Usage_Dig_Invert
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Usage_Dig_InRange
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LogicalMinimum_i8(0)
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LogicalMaximum_i8(1)
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ReportSize(1)
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ReportCount(5)
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Input(Var|Abs)
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ReportCount(3)
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Input(Const) /* Input (Const, Var, Abs) */
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UsagePage_GenericDesktop
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Usage_GD_X
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LogicalMinimum_i16(0)
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LogicalMaximum_i16(22352)
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UnitExponent(-3)
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Unit(in) /* (EnglishLinear: in) */
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PhysicalMinimum_i16(0)
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PhysicalMaximum_i16(22352)
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ReportSize(16)
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ReportCount(1)
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Input(Var|Abs)
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Usage_GD_Y
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LogicalMinimum_i16(0)
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LogicalMaximum_i16(13970)
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UnitExponent(-3)
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Unit(in) /* (EnglishLinear: in) */
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PhysicalMinimum_i16(0)
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PhysicalMaximum_i16(13970)
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ReportSize(16)
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ReportCount(1)
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Input(Var|Abs)
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UsagePage_Digitizers
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Usage_Dig_TipPressure
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LogicalMinimum_i16(0)
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LogicalMaximum_i16(8191)
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ReportSize(16)
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ReportCount(1)
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Input(Var|Abs)
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)
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)
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/* FIXES BEGIN */
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UsagePage_GenericDesktop
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Usage_GD_Keypad
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CollectionApplication(
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ReportId(REPORT_ID_BUTTONS) /* Retain original ID on byte 0 */
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ReportCount(1)
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ReportSize(REPORT_SIZE_PAD)
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UsagePage_Digitizers
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Usage_Dig_TabletFunctionKeys
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CollectionPhysical(
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/* Byte 1: Dial state */
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UsagePage_GenericDesktop
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Usage_GD_Dial
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LogicalMinimum_i8(-1)
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LogicalMaximum_i8(1)
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ReportCount(1)
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ReportSize(REPORT_SIZE_PAD)
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Input(Var|Rel)
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/* Byte 2: Button state */
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UsagePage_Button
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ReportSize(1)
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ReportCount(PAD_BUTTON_COUNT)
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UsageMinimum_i8(0x01)
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UsageMaximum_i8(PAD_BUTTON_COUNT) /* Number of buttons */
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LogicalMinimum_i8(0x0)
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LogicalMaximum_i8(0x1)
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Input(Var|Abs)
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/* Byte 3: Exists to be tablet pad */
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UsagePage_Digitizers
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Usage_Dig_BarrelSwitch
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ReportCount(1)
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ReportSize(1)
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Input(Var|Abs)
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ReportCount(7) /* Padding, to fill full report space */
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Input(Const)
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/* Byte 4/5: Exists to be a tablet pad */
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UsagePage_GenericDesktop
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Usage_GD_X
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Usage_GD_Y
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ReportCount(2)
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ReportSize(8)
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Input(Var|Abs)
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/* Bytes 6/7: Padding, to match original length */
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ReportCount(2)
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ReportSize(8)
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Input(Const)
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)
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FixedSizeVendorReport(RDESC_SIZE_PAD)
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)
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};
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SEC(HID_BPF_RDESC_FIXUP)
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int BPF_PROG(xppen_deco02_rdesc_fixup, struct hid_bpf_ctx *hctx)
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{
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__u8 *data = hid_bpf_get_data(hctx, 0, HID_MAX_DESCRIPTOR_SIZE);
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if (!data)
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return 0; /* EPERM Check */
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if (hctx->size == RDESC_SIZE_PAD) {
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__builtin_memcpy(data, fixed_rdesc_pad, sizeof(fixed_rdesc_pad));
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return sizeof(fixed_rdesc_pad);
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}
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return 0;
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}
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SEC(HID_BPF_DEVICE_EVENT)
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int BPF_PROG(xppen_deco02_device_event, struct hid_bpf_ctx *hctx)
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{
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__u8 *data = hid_bpf_get_data(hctx, 0, REPORT_SIZE_PAD);
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if (!data || data[0] != REPORT_ID_BUTTONS)
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return 0; /* EPERM or wrong report */
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__u8 dial_code = 0;
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__u8 button_mask = 0;
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size_t d;
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/* Start from 2; 0 is report ID, 1 is modifier keys, replaced by dial */
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for (d = 2; d < 8; d++) {
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switch (data[d]) {
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case 0x2e:
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dial_code = 1;
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break;
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case 0x2d:
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dial_code = -1;
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break;
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/* below are buttons, top to bottom */
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case 0x05:
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button_mask |= BIT(0);
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break;
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case 0x2c:
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button_mask |= BIT(1);
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break;
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case 0x08:
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button_mask |= BIT(2);
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break;
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case 0x0c:
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button_mask |= BIT(3);
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break;
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case 0x1d:
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button_mask |= BIT(4);
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break;
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case 0x16:
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button_mask |= BIT(05);
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break;
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default:
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break;
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}
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}
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__u8 report[8] = { REPORT_ID_BUTTONS, dial_code, button_mask, 0x00 };
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__builtin_memcpy(data, report, sizeof(report));
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return 0;
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}
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HID_BPF_OPS(xppen_deco02) = {
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.hid_rdesc_fixup = (void *)xppen_deco02_rdesc_fixup,
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.hid_device_event = (void *)xppen_deco02_device_event,
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};
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SEC("syscall")
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int probe(struct hid_bpf_probe_args *ctx)
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{
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ctx->retval = ctx->rdesc_size != RDESC_SIZE_PAD ? -EINVAL : 0;
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return 0;
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}
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char _license[] SEC("license") = "GPL";

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