[Bug 207419] Add ACPI support for RTC/CMOS device

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=207419

--- Comment #10 from commit-hook at freebsd.org ---
A commit references this bug:

Author: wulf
Date: Sun Mar 10 20:19:44 UTC 2019
New revision: 344982
URL: https://svnweb.freebsd.org/changeset/base/344982

Log:
  atrtc(4): install ACPI RTC/CMOS operation region handler

  FreeBSD base system does not provide an ACPI handler for the PC/AT RTC/CMOS
  device with PnP ID PNP0B00; on some HP laptops, the absence of this handler
  causes suspend/resume and poweroff(8) to hang or fail [1], [2]. On these
  laptops EC _REG method queries the RTC date/time registers via ACPI
  before suspending/powering off. The handler should be registered before
  acpi_ec driver is loaded.

  This change adds handler to access CMOS RTC operation region described in
  section 9.15 of ACPI-6.2 specification [3]. It is installed only for ACPI
  version of atrtc(4) so it should not affect old ACPI-less i386 systems.

  It is possible to disable the handler with loader tunable:
  debug.acpi.disabled=atrtc

  Informational debugging printf can be enabled by setting hw.acpi.verbose=1
  in loader.conf

  [1] https://wiki.freebsd.org/Laptops/HP_Envy_6Z-1100
  [2] https://wiki.freebsd.org/Laptops/HP_Notebook_15-af104ur
  [3] https://uefi.org/sites/default/files/resources/ACPI_6_2.pdf

  PR:           207419, 213039
  Submitted by: Anthony Jenkins <Scoobi_doo at yahoo.com>
  Reviewed by:  ian
  Discussed on: acpi@, 2013-2015, several threads
  MFC after:    2 weeks
  Differential Revision:        https://reviews.freebsd.org/D19314

Changes:
  head/sys/x86/isa/atrtc.c

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