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>

2 files changed, 22 insertions, 0 deletions

diff --git a/Documentation/cpu-freq/intel-pstate.txt b/Documentation/cpu-freq/intel-pstate.txt
index 765d7fc0e692..7767ce6756be 100644
--- a/Documentation/cpu-freq/intel-pstate.txt
+++ b/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
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 7d9f822f2031..ed6dd7dac094 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/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
 };