linux/Documentation/ABI/testing/sysfs-class-devfreq
Jonghwa Lee e552bbaf5b PM / devfreq: Add sysfs node for representing frequency transition information.
This patch adds sysfs node which can be used to get information of frequency
transition. It represents transition table which contains total number of transition of
each freqeuncy state and time spent. It is inspired CPUFREQ's status driver.

Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com>
[Added Documentation/ABI entry, updated kernel-doc, and resolved merge conflict]
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
2012-11-20 16:05:44 +09:00

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What: /sys/class/devfreq/.../
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
Provide a place in sysfs for the devfreq objects.
This allows accessing various devfreq specific variables.
The name of devfreq object denoted as ... is same as the
name of device using devfreq.
What: /sys/class/devfreq/.../governor
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/devfreq/.../governor shows the name of the
governor used by the corresponding devfreq object.
What: /sys/class/devfreq/.../cur_freq
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/devfreq/.../cur_freq shows the current
frequency of the corresponding devfreq object. Same as
target_freq when get_cur_freq() is not implemented by
devfreq driver.
What: /sys/class/devfreq/.../target_freq
Date: September 2012
Contact: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Description:
The /sys/class/devfreq/.../target_freq shows the next governor
predicted target frequency of the corresponding devfreq object.
What: /sys/class/devfreq/.../polling_interval
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
The /sys/class/devfreq/.../polling_interval shows and sets
the requested polling interval of the corresponding devfreq
object. The values are represented in ms. If the value is
less than 1 jiffy, it is considered to be 0, which means
no polling. This value is meaningless if the governor is
not polling; thus. If the governor is not using
devfreq-provided central polling
(/sys/class/devfreq/.../central_polling is 0), this value
may be useless.
What: /sys/class/devfreq/.../trans_stat
Date: October 2012
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
Descrtiption:
This ABI shows the statistics of devfreq behavior on a
specific device. It shows the time spent in each state and
the number of transitions between states.
In order to activate this ABI, the devfreq target device
driver should provide the list of available frequencies
with its profile.
What: /sys/class/devfreq/.../userspace/set_freq
Date: September 2011
Contact: MyungJoo Ham <myungjoo.ham@samsung.com>
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.