intel_pstate: expose turbo range to sysfs

This patch adds "turbo_pct" to the intel_pstate sysfs interface.
turbo_pct will display the percentage of the total supported
pstates that are in the turbo range.  This value is independent
of whether turbo has been disabled or not.

Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/cpu-freq/intel-pstate.txt

@@ -37,6 +37,10 @@ controlling P state selection. These files have been added to
       no_turbo: limits the driver to selecting P states below the turbo
       frequency range.
 
+      turbo_pct: displays the percentage of the total performance that
+      is supported by hardware that is in the turbo range.  This number
+      is independent of whether turbo has been disabled or not.
+
 For contemporary Intel processors, the frequency is controlled by the
 processor itself and the P-states exposed to software are related to
 performance levels.  The idea that frequency can be set to a single

drivers/cpufreq/intel_pstate.c

@@ -338,6 +338,22 @@ static void __init intel_pstate_debug_expose_params(void)
 		return sprintf(buf, "%u\n", limits.object);		\
 	}
 
+static ssize_t show_turbo_pct(struct kobject *kobj,
+				struct attribute *attr, char *buf)
+{
+	struct cpudata *cpu;
+	int total, no_turbo, turbo_pct;
+	uint32_t turbo_fp;
+
+	cpu = all_cpu_data[0];
+
+	total = cpu->pstate.turbo_pstate - cpu->pstate.min_pstate + 1;
+	no_turbo = cpu->pstate.max_pstate - cpu->pstate.min_pstate + 1;
+	turbo_fp = div_fp(int_tofp(no_turbo), int_tofp(total));
+	turbo_pct = 100 - fp_toint(mul_fp(turbo_fp, int_tofp(100)));
+	return sprintf(buf, "%u\n", turbo_pct);
+}
+
 static ssize_t show_no_turbo(struct kobject *kobj,
 			     struct attribute *attr, char *buf)
 {
@@ -418,11 +434,13 @@ show_one(min_perf_pct, min_perf_pct);
 define_one_global_rw(no_turbo);
 define_one_global_rw(max_perf_pct);
 define_one_global_rw(min_perf_pct);
+define_one_global_ro(turbo_pct);
 
 static struct attribute *intel_pstate_attributes[] = {
 	&no_turbo.attr,
 	&max_perf_pct.attr,
 	&min_perf_pct.attr,
+	&turbo_pct.attr,
 	NULL
 };