PM / devfreq: Add sysfs node to expose available frequencies

devfreq governors such as ondemand are controlled by a min and
max frequency, while governors like userspace governor allow us
to set a specific frequency.
However, for the same specific device, depending on the SoC, the
available frequencies can vary.

So expose the available frequencies as a snapshot over sysfs to
allow informed decisions.

This was inspired by cpufreq framework's equivalent for similar
usage sysfs node: scaling_available_frequencies.

Cc: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Cc: MyungJoo Ham <myungjoo.ham@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Kevin Hilman <khilman@ti.com>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
index e6cf08e6734d..e672ccb02e7f 100644
--- a/Documentation/ABI/testing/sysfs-class-devfreq
+++ b/Documentation/ABI/testing/sysfs-class-devfreq
@@ -51,3 +51,12 @@ Description:
                 The /sys/class/devfreq/.../userspace/set_freq shows and
                 sets the requested frequency for the devfreq object if
                 userspace governor is in effect.
+
+What:           /sys/class/devfreq/.../available_frequencies
+Date:           October 2012
+Contact:        Nishanth Menon <nm@ti.com>
+Description:
+                The /sys/class/devfreq/.../available_frequencies shows
+                the available frequencies of the corresponding devfreq object.
+                This is a snapshot of available frequencies and not limited
+                by the min/max frequency restrictions.