[CPUFREQ] Introduce /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_transition_latency

It's not only useful for the ondemand and conservative governors, but
also for userspace daemons to know about the HW transition latency of
the CPU.
It is especially useful for userspace to know about this value when
the ondemand or conservative governors are run. The sampling rate
control value depends on it and for userspace being able to set sane
tuning values there it has to know about the transition latency.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 1867dac35aff..6fe466efb0b5 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -452,6 +452,7 @@ static ssize_t show_##file_name				\
 
 show_one(cpuinfo_min_freq, cpuinfo.min_freq);
 show_one(cpuinfo_max_freq, cpuinfo.max_freq);
+show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
 show_one(scaling_min_freq, min);
 show_one(scaling_max_freq, max);
 show_one(scaling_cur_freq, cur);
@@ -659,6 +660,7 @@ __ATTR(_name, 0644, show_##_name, store_##_name)
 define_one_ro0400(cpuinfo_cur_freq);
 define_one_ro(cpuinfo_min_freq);
 define_one_ro(cpuinfo_max_freq);
+define_one_ro(cpuinfo_transition_latency);
 define_one_ro(scaling_available_governors);
 define_one_ro(scaling_driver);
 define_one_ro(scaling_cur_freq);
@@ -672,6 +674,7 @@ define_one_rw(scaling_setspeed);
 static struct attribute *default_attrs[] = {
         &cpuinfo_min_freq.attr,
         &cpuinfo_max_freq.attr,
+        &cpuinfo_transition_latency.attr,
         &scaling_min_freq.attr,
         &scaling_max_freq.attr,
         &affected_cpus.attr,