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af79443be6
Currently the kernel is scheduled to do this call by itself, but it requires a kernel v6.18 at least to have the INPUT_PROP set. For older kernels, we can try to query the property from a HID-BPF probe, and set a udev property based on that. This way we can provide the information to old kernels without modifying them. Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com> Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/220 Signed-off-by: Benjamin Tissoires <bentiss@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.com>
91 lines
1.9 KiB
C
91 lines
1.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (c) 2025 Benjamin Tissoires
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*/
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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 "hid_usages.h"
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#include <bpf/bpf_tracing.h>
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HID_BPF_CONFIG(
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HID_DEVICE(BUS_ANY, HID_GROUP_MULTITOUCH_WIN_8, HID_VID_ANY, HID_PID_ANY),
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);
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EXPORT_UDEV_PROP(HID_DIGITIZER_PAD_TYPE, 32);
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__u8 hw_req_buf[1024];
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/* to be filled by udev-hid-bpf */
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struct hid_rdesc_descriptor HID_REPORT_DESCRIPTOR;
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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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struct hid_rdesc_report *pad_type_feature = NULL;
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struct hid_rdesc_field *pad_type = NULL;
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struct hid_rdesc_report *feature;
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struct hid_bpf_ctx *hid_ctx;
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char *pad_type_str = "";
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int ret;
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hid_bpf_for_each_feature_report(&HID_REPORT_DESCRIPTOR, feature) {
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struct hid_rdesc_field *field;
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hid_bpf_for_each_field(feature, field) {
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if (field->usage_page == HidUsagePage_Digitizers &&
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field->usage_id == HidUsage_Dig_PadType) {
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pad_type = field;
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pad_type_feature = feature;
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break;
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}
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}
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if (pad_type)
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break;
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}
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if (!pad_type || !pad_type_feature) {
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ctx->retval = -EINVAL;
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return 0;
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}
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hid_ctx = hid_bpf_allocate_context(ctx->hid);
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if (!hid_ctx)
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return -1; /* EPERM check */
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hw_req_buf[0] = pad_type_feature->report_id;
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ret = hid_bpf_hw_request(hid_ctx, hw_req_buf, sizeof(hw_req_buf),
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HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
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hid_bpf_release_context(hid_ctx);
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if (ret < 0) {
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ctx->retval = ret;
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return 0;
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}
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ctx->retval = 0;
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switch (EXTRACT_BITS(hw_req_buf, pad_type)) {
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case 0:
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pad_type_str = "Clickpad";
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break;
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case 1:
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pad_type_str = "Pressurepad";
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break;
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case 2:
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pad_type_str = "Discrete";
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break;
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default:
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pad_type_str = "Unknown";
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}
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UDEV_PROP_SPRINTF(HID_DIGITIZER_PAD_TYPE, "%s", pad_type_str);
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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