xref: /linux/Documentation/ABI/testing/sysfs-class-devfreq (revision a04c75704678cce818c8250385c11d5efa0128c4)
1What:		/sys/class/devfreq/.../
2Date:		September 2011
3Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
4Description:
5		Provide a place in sysfs for the devfreq objects.
6		This allows accessing various devfreq specific variables.
7		The name of devfreq object denoted as ... is same as the
8		name of device using devfreq.
9
10What:		/sys/class/devfreq/.../name
11Date:		November 2019
12Contact:	Chanwoo Choi <cw00.choi@samsung.com>
13Description:
14		The /sys/class/devfreq/.../name shows the name of device
15		of the corresponding devfreq object.
16
17What:		/sys/class/devfreq/.../governor
18Date:		September 2011
19Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
20Description:
21		The /sys/class/devfreq/.../governor show or set the name of the
22		governor used by the corresponding devfreq object.
23
24What:		/sys/class/devfreq/.../cur_freq
25Date:		September 2011
26Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
27Description:
28		The /sys/class/devfreq/.../cur_freq shows the current
29		frequency of the corresponding devfreq object. Same as
30		target_freq when get_cur_freq() is not implemented by
31		devfreq driver.
32
33What:		/sys/class/devfreq/.../target_freq
34Date:		September 2012
35Contact:	Rajagopal Venkat <rajagopal.venkat@linaro.org>
36Description:
37		The /sys/class/devfreq/.../target_freq shows the next governor
38		predicted target frequency of the corresponding devfreq object.
39
40What:		/sys/class/devfreq/.../trans_stat
41Date:		October 2012
42Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
43Description:
44		This ABI shows or clears the statistics of devfreq behavior
45		on a specific device. It shows the time spent in each state
46		and the number of transitions between states.
47		In order to activate this ABI, the devfreq target device
48		driver should provide the list of available frequencies
49		with its profile. If need to reset the statistics of devfreq
50		behavior on a specific device, enter 0(zero) to 'trans_stat'
51		as following:
52			echo 0 > /sys/class/devfreq/.../trans_stat
53
54What:		/sys/class/devfreq/.../available_frequencies
55Date:		October 2012
56Contact:	Nishanth Menon <nm@ti.com>
57Description:
58		The /sys/class/devfreq/.../available_frequencies shows
59		the available frequencies of the corresponding devfreq object.
60		This is a snapshot of available frequencies and not limited
61		by the min/max frequency restrictions.
62
63What:		/sys/class/devfreq/.../available_governors
64Date:		October 2012
65Contact:	Nishanth Menon <nm@ti.com>
66Description:
67		The /sys/class/devfreq/.../available_governors shows
68		currently available governors in the system.
69
70What:		/sys/class/devfreq/.../min_freq
71Date:		January 2013
72Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
73Description:
74		The /sys/class/devfreq/.../min_freq shows and stores
75		the minimum frequency requested by users. It is 0 if
76		the user does not care. min_freq overrides the
77		frequency requested by governors.
78
79What:		/sys/class/devfreq/.../max_freq
80Date:		January 2013
81Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
82Description:
83		The /sys/class/devfreq/.../max_freq shows and stores
84		the maximum frequency requested by users. It is 0 if
85		the user does not care. max_freq overrides the
86		frequency requested by governors and min_freq.
87		The max_freq overrides min_freq because max_freq may be
88		used to throttle devices to avoid overheating.
89
90What:		/sys/class/devfreq/.../polling_interval
91Date:		September 2011
92Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
93Description:
94		The /sys/class/devfreq/.../polling_interval shows and sets
95		the requested polling interval of the corresponding devfreq
96		object. The values are represented in ms. If the value is
97		less than 1 jiffy, it is considered to be 0, which means
98		no polling. This value is meaningless if the governor is
99		not polling; thus. If the governor is not using
100		devfreq-provided central polling
101		(/sys/class/devfreq/.../central_polling is 0), this value
102		may be useless.
103
104		A list of governors that support the node:
105		- simple_ondmenad
106		- tegra_actmon
107
108What:		/sys/class/devfreq/.../userspace/set_freq
109Date:		September 2011
110Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
111Description:
112		The /sys/class/devfreq/.../userspace/set_freq shows and
113		sets the requested frequency for the devfreq object if
114		userspace governor is in effect.
115
116		A list of governors that support the node:
117		- userspace
118
119What:		/sys/class/devfreq/.../timer
120Date:		July 2020
121Contact:	Chanwoo Choi <cw00.choi@samsung.com>
122Description:
123		This ABI shows and stores the kind of work timer by users.
124		This work timer is used by devfreq workqueue in order to
125		monitor the device status such as utilization. The user
126		can change the work timer on runtime according to their demand
127		as following:
128			echo deferrable > /sys/class/devfreq/.../timer
129			echo delayed > /sys/class/devfreq/.../timer
130
131		A list of governors that support the node:
132		- simple_ondemand
133