1 files changed, 106 insertions, 1 deletions

diff --git a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
index 8b0c7db85a4..f8a8e46acb7 100644
--- a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
+++ b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -58,10 +58,12 @@ enum {
 };
 
 #define INTEL_MSR_RANGE		(0xffff)
+#define CPUID_6_ECX_APERFMPERF_CAPABILITY	(0x1)
 
 struct acpi_cpufreq_data {
 	struct acpi_processor_performance *acpi_data;
 	struct cpufreq_frequency_table *freq_table;
+	unsigned int max_freq;
 	unsigned int resume;
 	unsigned int cpu_feature;
 };
@@ -258,6 +260,100 @@ static u32 get_cur_val(cpumask_t mask)
 	return cmd.val;
 }
 
+/*
+ * Return the measured active (C0) frequency on this CPU since last call
+ * to this function.
+ * Input: cpu number
+ * Return: Average CPU frequency in terms of max frequency (zero on error)
+ *
+ * We use IA32_MPERF and IA32_APERF MSRs to get the measured performance
+ * over a period of time, while CPU is in C0 state.
+ * IA32_MPERF counts at the rate of max advertised frequency
+ * IA32_APERF counts at the rate of actual CPU frequency
+ * Only IA32_APERF/IA32_MPERF ratio is architecturally defined and
+ * no meaning should be associated with absolute values of these MSRs.
+ */
+static unsigned int get_measured_perf(unsigned int cpu)
+{
+	union {
+		struct {
+			u32 lo;
+			u32 hi;
+		} split;
+		u64 whole;
+	} aperf_cur, mperf_cur;
+
+	cpumask_t saved_mask;
+	unsigned int perf_percent;
+	unsigned int retval;
+
+	saved_mask = current->cpus_allowed;
+	set_cpus_allowed(current, cpumask_of_cpu(cpu));
+	if (get_cpu() != cpu) {
+		/* We were not able to run on requested processor */
+		put_cpu();
+		return 0;
+	}
+
+	rdmsr(MSR_IA32_APERF, aperf_cur.split.lo, aperf_cur.split.hi);
+	rdmsr(MSR_IA32_MPERF, mperf_cur.split.lo, mperf_cur.split.hi);
+
+	wrmsr(MSR_IA32_APERF, 0,0);
+	wrmsr(MSR_IA32_MPERF, 0,0);
+
+#ifdef __i386__
+	/*
+	 * We dont want to do 64 bit divide with 32 bit kernel
+	 * Get an approximate value. Return failure in case we cannot get
+	 * an approximate value.
+	 */
+	if (unlikely(aperf_cur.split.hi || mperf_cur.split.hi)) {
+		int shift_count;
+		u32 h;
+
+		h = max_t(u32, aperf_cur.split.hi, mperf_cur.split.hi);
+		shift_count = fls(h);
+
+		aperf_cur.whole >>= shift_count;
+		mperf_cur.whole >>= shift_count;
+	}
+
+	if (((unsigned long)(-1) / 100) < aperf_cur.split.lo) {
+		int shift_count = 7;
+		aperf_cur.split.lo >>= shift_count;
+		mperf_cur.split.lo >>= shift_count;
+	}
+
+	if (aperf_cur.split.lo && mperf_cur.split.lo) {
+		perf_percent = (aperf_cur.split.lo * 100) / mperf_cur.split.lo;
+	} else {
+		perf_percent = 0;
+	}
+
+#else
+	if (unlikely(((unsigned long)(-1) / 100) < aperf_cur.whole)) {
+		int shift_count = 7;
+		aperf_cur.whole >>= shift_count;
+		mperf_cur.whole >>= shift_count;
+	}
+
+	if (aperf_cur.whole && mperf_cur.whole) {
+		perf_percent = (aperf_cur.whole * 100) / mperf_cur.whole;
+	} else {
+		perf_percent = 0;
+	}
+
+#endif
+
+	retval = drv_data[cpu]->max_freq * perf_percent / 100;
+
+	put_cpu();
+	set_cpus_allowed(current, saved_mask);
+
+	dprintk("cpu %d: performance percent %d\n", cpu, perf_percent);
+	return retval;
+}
+
 static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
 {
 	struct acpi_cpufreq_data *data = drv_data[cpu];
@@ -497,7 +593,6 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	unsigned int valid_states = 0;
 	unsigned int cpu = policy->cpu;
 	struct acpi_cpufreq_data *data;
-	unsigned int l, h;
 	unsigned int result = 0;
 	struct cpuinfo_x86 *c = &cpu_data[policy->cpu];
 	struct acpi_processor_performance *perf;
@@ -591,6 +686,7 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	}
 	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 
+	data->max_freq = perf->states[0].core_frequency * 1000;
 	/* table init */
 	for (i = 0; i < perf->state_count; i++) {
 		if (i > 0 && perf->states[i].core_frequency ==
@@ -625,6 +721,15 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	/* notify BIOS that we exist */
 	acpi_processor_notify_smm(THIS_MODULE);
 
+	/* Check for APERF/MPERF support in hardware */
+	if (c->x86_vendor == X86_VENDOR_INTEL && c->cpuid_level >= 6) {
+		unsigned int ecx;
+		ecx = cpuid_ecx(6);
+		if (ecx & CPUID_6_ECX_APERFMPERF_CAPABILITY) {
+			acpi_cpufreq_driver.getavg = get_measured_perf;
+		}
+	}
+
 	dprintk("CPU%u - ACPI performance management activated.\n", cpu);
 	for (i = 0; i < perf->state_count; i++)
 		dprintk("     %cP%d: %d MHz, %d mW, %d uS\n",