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cpufreq: intel_pstate: Add base_frequency attribute

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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>
This commit is contained in:
Srinivas Pandruvada 2018-10-15 10:37:20 -07:00 committed by Rafael J. Wysocki
parent 29523f0953
commit 86d333a8cc
1 changed files with 38 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

38
drivers/cpufreq/intel_pstate.c
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@ -373,10 +373,28 @@ static void intel_pstate_set_itmt_prio(int cpu)
}
}
}
static int intel_pstate_get_cppc_guranteed(int cpu)
{
struct cppc_perf_caps cppc_perf;
int ret;
ret = cppc_get_perf_caps(cpu, &cppc_perf);
if (ret)
return ret;
return cppc_perf.guaranteed_perf;
}
#else
static void intel_pstate_set_itmt_prio(int cpu)
{
}
static int intel_pstate_get_cppc_guranteed(int cpu)
{
return -ENOTSUPP;
}
#endif
static void intel_pstate_init_acpi_perf_limits(struct cpufreq_policy *policy)
@ -699,9 +717,29 @@ static ssize_t show_energy_performance_preference(
cpufreq_freq_attr_rw(energy_performance_preference);
static ssize_t show_base_frequency(struct cpufreq_policy *policy, char *buf)
{
struct cpudata *cpu;
u64 cap;
int ratio;
ratio = intel_pstate_get_cppc_guranteed(policy->cpu);
if (ratio <= 0) {
rdmsrl_on_cpu(policy->cpu, MSR_HWP_CAPABILITIES, &cap);
ratio = HWP_GUARANTEED_PERF(cap);
}
cpu = all_cpu_data[policy->cpu];
return sprintf(buf, "%d\n", ratio * cpu->pstate.scaling);
}
cpufreq_freq_attr_ro(base_frequency);
static struct freq_attr *hwp_cpufreq_attrs[] = {
&energy_performance_preference,
&energy_performance_available_preferences,
&base_frequency,
NULL,
};