| // SPDX-License-Identifier: GPL-2.0 |
| /* Copyright (c) 2024 Tatsuyuki Ishi |
| */ |
| |
| #include "vmlinux.h" |
| #include "hid_bpf.h" |
| #include "hid_bpf_helpers.h" |
| #include <bpf/bpf_tracing.h> |
| |
| #define VID_HOLTEK 0x04D9 |
| #define PID_MD770 0x0339 |
| #define RDESC_SIZE 203 |
| |
| HID_BPF_CONFIG( |
| HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_HOLTEK, PID_MD770) |
| ); |
| |
| /* |
| * The Mistel MD770 keyboard reports the first 6 simultaneous key presses |
| * through the first interface, and anything beyond that through a second |
| * interface. Unfortunately, the second interface's report descriptor has an |
| * error, causing events to be malformed and ignored. This HID-BPF driver |
| * fixes the descriptor to allow NKRO to work again. |
| * |
| * For reference, this is the original report descriptor: |
| * |
| * 0x05, 0x01, // Usage Page (Generic Desktop) 0 |
| * 0x09, 0x80, // Usage (System Control) 2 |
| * 0xa1, 0x01, // Collection (Application) 4 |
| * 0x85, 0x01, // Report ID (1) 6 |
| * 0x19, 0x81, // Usage Minimum (129) 8 |
| * 0x29, 0x83, // Usage Maximum (131) 10 |
| * 0x15, 0x00, // Logical Minimum (0) 12 |
| * 0x25, 0x01, // Logical Maximum (1) 14 |
| * 0x95, 0x03, // Report Count (3) 16 |
| * 0x75, 0x01, // Report Size (1) 18 |
| * 0x81, 0x02, // Input (Data,Var,Abs) 20 |
| * 0x95, 0x01, // Report Count (1) 22 |
| * 0x75, 0x05, // Report Size (5) 24 |
| * 0x81, 0x01, // Input (Cnst,Arr,Abs) 26 |
| * 0xc0, // End Collection 28 |
| * 0x05, 0x0c, // Usage Page (Consumer Devices) 29 |
| * 0x09, 0x01, // Usage (Consumer Control) 31 |
| * 0xa1, 0x01, // Collection (Application) 33 |
| * 0x85, 0x02, // Report ID (2) 35 |
| * 0x15, 0x00, // Logical Minimum (0) 37 |
| * 0x25, 0x01, // Logical Maximum (1) 39 |
| * 0x95, 0x12, // Report Count (18) 41 |
| * 0x75, 0x01, // Report Size (1) 43 |
| * 0x0a, 0x83, 0x01, // Usage (AL Consumer Control Config) 45 |
| * 0x0a, 0x8a, 0x01, // Usage (AL Email Reader) 48 |
| * 0x0a, 0x92, 0x01, // Usage (AL Calculator) 51 |
| * 0x0a, 0x94, 0x01, // Usage (AL Local Machine Browser) 54 |
| * 0x09, 0xcd, // Usage (Play/Pause) 57 |
| * 0x09, 0xb7, // Usage (Stop) 59 |
| * 0x09, 0xb6, // Usage (Scan Previous Track) 61 |
| * 0x09, 0xb5, // Usage (Scan Next Track) 63 |
| * 0x09, 0xe2, // Usage (Mute) 65 |
| * 0x09, 0xea, // Usage (Volume Down) 67 |
| * 0x09, 0xe9, // Usage (Volume Up) 69 |
| * 0x0a, 0x21, 0x02, // Usage (AC Search) 71 |
| * 0x0a, 0x23, 0x02, // Usage (AC Home) 74 |
| * 0x0a, 0x24, 0x02, // Usage (AC Back) 77 |
| * 0x0a, 0x25, 0x02, // Usage (AC Forward) 80 |
| * 0x0a, 0x26, 0x02, // Usage (AC Stop) 83 |
| * 0x0a, 0x27, 0x02, // Usage (AC Refresh) 86 |
| * 0x0a, 0x2a, 0x02, // Usage (AC Bookmarks) 89 |
| * 0x81, 0x02, // Input (Data,Var,Abs) 92 |
| * 0x95, 0x01, // Report Count (1) 94 |
| * 0x75, 0x0e, // Report Size (14) 96 |
| * 0x81, 0x01, // Input (Cnst,Arr,Abs) 98 |
| * 0xc0, // End Collection 100 |
| * 0x05, 0x01, // Usage Page (Generic Desktop) 101 |
| * 0x09, 0x02, // Usage (Mouse) 103 |
| * 0xa1, 0x01, // Collection (Application) 105 |
| * 0x09, 0x01, // Usage (Pointer) 107 |
| * 0xa1, 0x00, // Collection (Physical) 109 |
| * 0x85, 0x03, // Report ID (3) 111 |
| * 0x05, 0x09, // Usage Page (Button) 113 |
| * 0x19, 0x01, // Usage Minimum (1) 115 |
| * 0x29, 0x08, // Usage Maximum (8) 117 |
| * 0x15, 0x00, // Logical Minimum (0) 119 |
| * 0x25, 0x01, // Logical Maximum (1) 121 |
| * 0x75, 0x01, // Report Size (1) 123 |
| * 0x95, 0x08, // Report Count (8) 125 |
| * 0x81, 0x02, // Input (Data,Var,Abs) 127 |
| * 0x05, 0x01, // Usage Page (Generic Desktop) 129 |
| * 0x09, 0x30, // Usage (X) 131 |
| * 0x09, 0x31, // Usage (Y) 133 |
| * 0x16, 0x01, 0x80, // Logical Minimum (-32767) 135 |
| * 0x26, 0xff, 0x7f, // Logical Maximum (32767) 138 |
| * 0x75, 0x10, // Report Size (16) 141 |
| * 0x95, 0x02, // Report Count (2) 143 |
| * 0x81, 0x06, // Input (Data,Var,Rel) 145 |
| * 0x09, 0x38, // Usage (Wheel) 147 |
| * 0x15, 0x81, // Logical Minimum (-127) 149 |
| * 0x25, 0x7f, // Logical Maximum (127) 151 |
| * 0x75, 0x08, // Report Size (8) 153 |
| * 0x95, 0x01, // Report Count (1) 155 |
| * 0x81, 0x06, // Input (Data,Var,Rel) 157 |
| * 0x05, 0x0c, // Usage Page (Consumer Devices) 159 |
| * 0x0a, 0x38, 0x02, // Usage (AC Pan) 161 |
| * 0x95, 0x01, // Report Count (1) 164 |
| * 0x81, 0x06, // Input (Data,Var,Rel) 166 |
| * 0xc0, // End Collection 168 |
| * 0xc0, // End Collection 169 |
| * 0x05, 0x01, // Usage Page (Generic Desktop) 170 |
| * 0x09, 0x06, // Usage (Keyboard) 172 |
| * 0xa1, 0x01, // Collection (Application) 174 |
| * 0x85, 0x04, // Report ID (4) 176 |
| * 0x05, 0x07, // Usage Page (Keyboard) 178 |
| * 0x95, 0x01, // Report Count (1) 180 |
| * 0x75, 0x08, // Report Size (8) 182 |
| * 0x81, 0x03, // Input (Cnst,Var,Abs) 184 |
| * 0x95, 0xe8, // Report Count (232) 186 |
| * 0x75, 0x01, // Report Size (1) 188 |
| * 0x15, 0x00, // Logical Minimum (0) 190 |
| * 0x25, 0x01, // Logical Maximum (1) 192 |
| * 0x05, 0x07, // Usage Page (Keyboard) 194 |
| * 0x19, 0x00, // Usage Minimum (0) 196 |
| * 0x29, 0xe7, // Usage Maximum (231) 198 |
| * 0x81, 0x00, // Input (Data,Arr,Abs) 200 <- change to 0x81, 0x02 (Data,Var,Abs) |
| * 0xc0, // End Collection 202 |
| */ |
| |
| SEC(HID_BPF_RDESC_FIXUP) |
| int BPF_PROG(hid_rdesc_fixup_mistel_md770, struct hid_bpf_ctx *hctx) |
| { |
| __u8 *data = hid_bpf_get_data(hctx, 0, HID_MAX_DESCRIPTOR_SIZE); |
| |
| if (!data) |
| return 0; /* EPERM check */ |
| |
| if (data[201] == 0x00) |
| data[201] = 0x02; |
| |
| return 0; |
| } |
| |
| HID_BPF_OPS(mistel_md770) = { |
| .hid_rdesc_fixup = (void *)hid_rdesc_fixup_mistel_md770, |
| }; |
| |
| SEC("syscall") |
| int probe(struct hid_bpf_probe_args *ctx) |
| { |
| ctx->retval = ctx->rdesc_size != RDESC_SIZE; |
| if (ctx->retval) |
| ctx->retval = -EINVAL; |
| |
| return 0; |
| } |
| |
| char _license[] SEC("license") = "GPL"; |
