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Subject[PATCH v4 2/3] cpufreq: intel_pstate: Add base_frequency attribute
Date
Present base_frequency to user space via cpufreq sysfs when HWP is in
use.

This HWP base frequency is read from HWP Capabilities MSR, if platform
doesn't have ACPI _CPC object. On most of the HWP platforms the _CPC
object will point to the HWP Capabilities MSR using address space id as
"Functional Fixed Hardware". But the address space id can be simply
ACPI_TYPE_INTEGER, where the platform firmware can modify this value
based on the system constraints.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
drivers/cpufreq/intel_pstate.c | 38 ++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index b6a1aadaff9f..2a99e2fd9412 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -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,
};

--
2.17.1
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