This joystick's original HID descriptor is wrong & it shows a ABS_MISC axis in Linux that doesn't exist on the hardware. Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/82 Signed-off-by: K S Iyer <kumar.s.iyer65@xxxxxxxxx> Signed-off-by: Benjamin Tissoires <bentiss@xxxxxxxxxx> --- .../bpf/progs/Thrustmaster__TCA-Yoke-Boeing.bpf.c | 144 +++++++++++++++++++++ 1 file changed, 144 insertions(+) diff --git a/drivers/hid/bpf/progs/Thrustmaster__TCA-Yoke-Boeing.bpf.c b/drivers/hid/bpf/progs/Thrustmaster__TCA-Yoke-Boeing.bpf.c new file mode 100644 index 000000000000..ecf775a99346 --- /dev/null +++ b/drivers/hid/bpf/progs/Thrustmaster__TCA-Yoke-Boeing.bpf.c @@ -0,0 +1,144 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2024 Kumar Swarnam Iyer (kumar.s.iyer65@xxxxxxxxx) + */ + +#include "vmlinux.h" +#include "hid_bpf.h" +#include "hid_bpf_helpers.h" +#include <bpf/bpf_tracing.h> + +#define VID_THRUSTMASTER 0x044F +#define PID_TCA_YOKE_BOEING 0x0409 + +HID_BPF_CONFIG( + HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_THRUSTMASTER, PID_TCA_YOKE_BOEING) +); + +/* The original HID descriptor of the Thrustmaster TCA Yoke Boeing joystick contains + * an Input field that shows up as an axis, ABS_MISC in Linux. But it is not possible + * to assign an actual physical control to this axis as they're all taken up. There + * are 2 vendor-defined inputs where the Input type appears to be defined wrongly. + * This bpf attempts to fix this by changing the Inputs so that it doesn't show up in + * Linux at all. + * This version is the short version fix that only changes 2 fields in the descriptor + * instead of the whole report descriptor. + * For reference, this is the original report descriptor: + * + * 0x05, 0x01, // Usage Page (Generic Desktop) 0 + * 0x09, 0x04, // Usage (Joystick) 2 + * 0xa1, 0x01, // Collection (Application) 4 + * 0x85, 0x01, // Report ID (1) 6 + * 0x09, 0x39, // Usage (Hat switch) 8 + * 0x15, 0x00, // Logical Minimum (0) 10 + * 0x25, 0x07, // Logical Maximum (7) 12 + * 0x35, 0x00, // Physical Minimum (0) 14 + * 0x46, 0x3b, 0x01, // Physical Maximum (315) 16 + * 0x65, 0x14, // Unit (EnglishRotation: deg) 19 + * 0x75, 0x04, // Report Size (4) 21 + * 0x95, 0x01, // Report Count (1) 23 + * 0x81, 0x42, // Input (Data,Var,Abs,Null) 25 + * 0x65, 0x00, // Unit (None) 27 + * 0x05, 0x09, // Usage Page (Button) 29 + * 0x19, 0x01, // Usage Minimum (1) 31 + * 0x29, 0x12, // Usage Maximum (18) 33 + * 0x15, 0x00, // Logical Minimum (0) 35 + * 0x25, 0x01, // Logical Maximum (1) 37 + * 0x75, 0x01, // Report Size (1) 39 + * 0x95, 0x12, // Report Count (18) 41 + * 0x81, 0x02, // Input (Data,Var,Abs) 43 + * 0x95, 0x02, // Report Count (2) 45 + * 0x81, 0x03, // Input (Cnst,Var,Abs) 47 + * 0x05, 0x01, // Usage Page (Generic Desktop) 49 + * 0x09, 0x31, // Usage (Y) 51 + * 0x09, 0x30, // Usage (X) 53 + * 0x09, 0x32, // Usage (Z) 55 + * 0x09, 0x34, // Usage (Ry) 57 + * 0x09, 0x33, // Usage (Rx) 59 + * 0x09, 0x35, // Usage (Rz) 61 + * 0x15, 0x00, // Logical Minimum (0) 63 + * 0x27, 0xff, 0xff, 0x00, 0x00, // Logical Maximum (65535) 65 + * 0x75, 0x10, // Report Size (16) 70 + * 0x95, 0x06, // Report Count (6) 72 + * 0x81, 0x02, // Input (Data,Var,Abs) 74 + * 0x06, 0xf0, 0xff, // Usage Page (Vendor Usage Page 0xfff0) 76 + * 0x09, 0x59, // Usage (Vendor Usage 0x59) 79 + * 0x15, 0x00, // Logical Minimum (0) 81 + * 0x26, 0xff, 0x00, // Logical Maximum (255) 83 + * 0x75, 0x08, // Report Size (8) 86 + * 0x95, 0x01, // Report Count (1) 88 + * 0x81, 0x02, // Input (Data,Var,Abs) 90 --> Needs to be changed + * 0x09, 0x51, // Usage (Vendor Usage 0x51) 92 + * 0x15, 0x00, // Logical Minimum (0) 94 + * 0x26, 0xff, 0x00, // Logical Maximum (255) 96 + * 0x75, 0x08, // Report Size (8) 99 + * 0x95, 0x20, // Report Count (32) 101 --> Needs to be changed + * 0x81, 0x02, // Input (Data,Var,Abs) 103 + * 0x09, 0x50, // Usage (Vendor Usage 0x50) 105 + * 0x15, 0x00, // Logical Minimum (0) 107 + * 0x26, 0xff, 0x00, // Logical Maximum (255) 109 + * 0x75, 0x08, // Report Size (8) 112 + * 0x95, 0x0f, // Report Count (15) 114 + * 0x81, 0x03, // Input (Cnst,Var,Abs) 116 + * 0x09, 0x47, // Usage (Vendor Usage 0x47) 118 + * 0x85, 0xf2, // Report ID (242) 120 + * 0x15, 0x00, // Logical Minimum (0) 122 + * 0x26, 0xff, 0x00, // Logical Maximum (255) 124 + * 0x75, 0x08, // Report Size (8) 127 + * 0x95, 0x3f, // Report Count (63) 129 + * 0xb1, 0x02, // Feature (Data,Var,Abs) 131 + * 0x09, 0x48, // Usage (Vendor Usage 0x48) 133 + * 0x85, 0xf3, // Report ID (243) 135 + * 0x15, 0x00, // Logical Minimum (0) 137 + * 0x26, 0xff, 0x00, // Logical Maximum (255) 139 + * 0x75, 0x08, // Report Size (8) 142 + * 0x95, 0x3f, // Report Count (63) 144 + * 0xb1, 0x02, // Feature (Data,Var,Abs) 146 + * 0xc0, // End Collection 148 + */ + +SEC(HID_BPF_RDESC_FIXUP) +int BPF_PROG(hid_fix_rdesc_tca_yoke, struct hid_bpf_ctx *hctx) +{ + const int expected_length = 148; + + if (hctx->size != expected_length) + return 0; + + __u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, HID_MAX_DESCRIPTOR_SIZE /* size */); + + if (!data) + return 0; /* EPERM */ + + /* Safety check, our probe() should take care of this though */ + if (data[1] != 0x01 /* Generic Desktop */ || data[3] != 0x04 /* Joystick */) + return 0; + + /* The report descriptor sets incorrect Input items in 2 places, resulting in a + * non-existing axis showing up. + * This change sets the correct Input which prevents the axis from showing up in Linux. + */ + + if (data[90] == 0x81 && /* Input */ + data[103] == 0x81) { /* Input */ + data[91] = 0x03; /* Input set to 0x03 Constant, Variable Absolute */ + data[104] = 0x03; /* Input set to 0X03 Constant, Variable Absolute */ + } + + return 0; +} + +HID_BPF_OPS(tca_yoke) = { + .hid_rdesc_fixup = (void *)hid_fix_rdesc_tca_yoke, +}; + +SEC("syscall") +int probe(struct hid_bpf_probe_args *ctx) +{ + /* ensure the kernel isn't fixed already */ + if (ctx->rdesc[91] != 0x02) /* Input for 0x59 Usage type has changed */ + ctx->retval = -EINVAL; + + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.44.0
