This is a core part of all proposed HID changes.
It introduces layered model and it`'s interfaces.
In the new HID world drivers are stcked in following order:
Front drivers (mouse, kbd, e.t.c.) hidbus Transport backend (usbhid, iichid, ...?) Transport bus (usbus, iicbus, ...?)
hidbus(4) itself provides support for multiple front HID driver attachments
to single HID transport backend. This ability existed in Net/OpenBSD
(uhidev and ihidev drivers) but has never been ported to FreeBSD.
Unlike Net/OpenBSD we do not use report number alone to
distinct report source but we follow MS way and use a top level
collection (TLC) usage index that report belongs to as a location key.
The driver performs child device autodiscovery based on HID report
descriptor data, proxying of HID requests from child devices to parent
transport backends and broadcasting of interrupts in backward direction.
Also this changes create an abstract HID interface that provides hardware independent
access to HID capabilities and functions through the device tree.
hid_if.m resembles existing USBHID KPI and consist of next methods:
HID method USBHID variant ------------------------------------------------------ hid_intr_setup usbd_transfer_setup (INTERRUPT IN xfer) hid_intr_unsetup usbd_transfer_unsetup (INTERRUPT IN xfer) hid_intr_start usbd_transfer_start (INTERRUPT IN xfer) hid_intr_stop usbd_transfer_stop (INTERRUPT IN xfer) hid_intr_poll usbd_transfer_poll (INTERRUPT IN xfer) hid_get_rdesc usbd_req_get_report_descriptor hid_read No direct analog. Not intended for common use. hid_write uhid(4) write() hid_get_report usbd_req_get_report hid_set_report usbd_req_set_report hid_set_idle usbd_req_set_idle hid_set_protocol usbd_req_set_protocol
The revision is subset of https://reviews.freebsd.org/D27777