cpufreq: intel_pstate: Add base_frequency attribute

mainline inclusion
from mainline-v4.20-rc1
commit 86d333a8
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=44


CVE: NA

-----------------------------------------------

Upstream commit 86d333a8 upstream

Expose base_frequency to user space via cpufreq sysfs when HWP is in
use.

This HWP base frequency is read from the ACPI _CPC object if present,
or from the HWP Capabilities MSR otherwise.

On the majority of the HWP platforms the _CPC object will point to
the HWP Capabilities MSR using the "Functional Fixed Hardware"
address space type.  The address space type also can simply be
ACPI_TYPE_INTEGER, however, in which case the platform firmware
can set its value at the initialization time based on the system
constraints.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Backported-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>