Add _BIX (Battery Information Extended) object support.
ACPI Control Method Batteries have a _BIF and/or _BIX object which
provides static properties of the battery. FreeBSD acpi_cmbat module
supports _BIF object only, which was deprecated as of ACPI 4.0. _BIX
is an extended version of _BIF defined in ACPI 4.0 or later.
As of writing, _BIX has two revisions. One is in ACPI 4.0 (rev.0) and
another is in ACPI 6.0 (rev.1). It seems that hardware vendors still
stick to _BIF only or _BIX rev.0 + _BIF for the maximum compatibility.
Microsoft mandates _BIX rev.0 for Windows machines, so there are some
laptop machines with _BIX rev.0 only. In this case, FreeBSD does not
recognize the battery information.
After this change, acpi_cmbat module gets battery information from
_BIX or _BIF object and internally uses _BIX rev.1 data structure as
the primary information store in the kernel. ACPIIO_BATT_GET_BI[FX]
will return an acpi_bi[fx] structure built by using information
obtained from a _BIF or a _BIX object found on the system. The
revision number field can be used to check which field is available.
The acpiconf(8) utility will show additional information if _BIX is
available.
Although ABIs of ACPIIO_BATT_* were changed, the existing APIs for
userland utilities are not changed and the backward-compatible ABIs
are provided. This means that older versions of acpiconf(8) can also
work with the new kernel. The (union acpi_battery_ioctl_arg) was
padded to 256 byte long to avoid another ABI change in the future. A
_BIX object with its revision number >1 will be treated as compatible
with the rev.1 _BIX format.