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authorBenjamin Tissoires <bentiss@kernel.org>2024-06-27 11:54:17 +0200
committerBenjamin Tissoires <bentiss@kernel.org>2024-07-01 14:48:18 +0200
commit8a89db51873ca574de45b25fce68103f34266459 (patch)
tree950d448761d56272fceb7d76bd76ddcf87d9f6a4 /mm/rmap.c
parentc79de517a226b86419a5baa867e65e3f8118829f (diff)
downloadlwn-8a89db51873ca574de45b25fce68103f34266459.tar.gz
lwn-8a89db51873ca574de45b25fce68103f34266459.zip
HID: bpf: Add a HID report composition helper macros
These macros make it slightly easier and more modular to create a HID report descriptor from scratch. Since they carry the annotation we don't need to comment it and they cannot get stale. For comparison, before we had this: 0x15, 0x00, // Logical Minimum (0) 0x25, 0x01, // Logical Maximum (1) 0x95, 0x04, // Report Count (4) 0x75, 0x01, // Report Size (1) Now we can write this as: LogicalRange_i8(0, 1) ReportCount(4) ReportSize(1) Because these macros are for creating new report descriptors, some bits aren't directly exposed. e.g in the example above: there is a logical range as one macro that sets both min and max. There is seldom a good use case for skipping either anyway. These macros will need to be expanded over time. For Usage Pages and Usage IDs, we use a tool to parse the HUT JSON (attached to the HUT 1.5 PDF [1]) and generate all #defines for all usage pages and usages in the form: #define UsagePage_Foo_Bar #define Usage_FB_SomeOrOther Where the FB is simply the acronym based on the capital letters in the Usage Page name or the first three letters, whichever makes slightly more sense. [1] https://usb.org/document-library/hid-usage-tables-15 Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/92 Link: https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/96 Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net> Link: https://patch.msgid.link/20240627-import-bpf-v1-1-0dbcda4a5b1f@kernel.org Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
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