drivers/hid/bpf/progs/Generic__touchpad.bpf.c

Source file repositories/reference/linux-study-clean/drivers/hid/bpf/progs/Generic__touchpad.bpf.c

File Facts

System
Linux kernel
Corpus path
drivers/hid/bpf/progs/Generic__touchpad.bpf.c
Extension
.c
Size
1901 bytes
Lines
91
Domain
Driver Families
Bucket
drivers/hid
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

hid_bpf_for_each_field(feature, field) {
			if (field->usage_page == HidUsagePage_Digitizers &&
			    field->usage_id == HidUsage_Dig_PadType) {
				pad_type = field;
				pad_type_feature = feature;
				break;
			}
		}
		if (pad_type)
			break;
	}

	if (!pad_type || !pad_type_feature) {
		ctx->retval = -EINVAL;
		return 0;
	}

	hid_ctx = hid_bpf_allocate_context(ctx->hid);

	if (!hid_ctx)
		return -1; /* EPERM check */

	hw_req_buf[0] = pad_type_feature->report_id;

	ret = hid_bpf_hw_request(hid_ctx, hw_req_buf, sizeof(hw_req_buf),
					HID_FEATURE_REPORT, HID_REQ_GET_REPORT);
	hid_bpf_release_context(hid_ctx);

	if (ret < 0) {
		ctx->retval = ret;
		return 0;
	}

	ctx->retval = 0;

	switch (EXTRACT_BITS(hw_req_buf, pad_type)) {
	case 0:
		pad_type_str = "Clickpad";
		break;
	case 1:
		pad_type_str = "Pressurepad";
		break;
	case 2:
		pad_type_str = "Discrete";
		break;
	default:
		pad_type_str = "Unknown";
	}

	UDEV_PROP_SPRINTF(HID_DIGITIZER_PAD_TYPE, "%s", pad_type_str);

	return 0;
}

char _license[] SEC("license") = "GPL";

Annotation

Implementation Notes