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Chanwoo Choi 4dc3bab868 PM / devfreq: Add support delayed timer for polling mode
Until now, the devfreq driver using polling mode like simple_ondemand
governor have used only deferrable timer for reducing the redundant
power consumption. It reduces the CPU wake-up from idle due to polling mode
which check the status of Non-CPU device.

But, it has a problem for Non-CPU device like DMC device with DMA operation.
Some Non-CPU device need to do monitor continuously regardless of CPU state
in order to decide the proper next status of Non-CPU device.

So, add support the delayed timer for polling mode to support
the repetitive monitoring. The devfreq driver and user can select
the kind of timer on either deferrable and delayed timer.

For example, change the timer type of DMC device
based on Exynos5422-based Odroid-XU3 as following:

- If want to use deferrable timer as following:
echo deferrable > /sys/class/devfreq/10c20000.memory-controller/timer

- If want to use delayed timer as following:
echo delayed > /sys/class/devfreq/10c20000.memory-controller/timer

Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
2020-07-30 17:22:57 +09:00
Kamil Konieczny 14a3439681 PM / devfreq: Add clearing transitions stats
Add clearing transition table and time in states devfreq statistics
by writing 0 (zero) to trans_stat file in devfreq sysfs. An example use
is like following:

echo 0 > /sys/class/devfreq/devfreqX/trans_stat

Signed-off-by: Kamil Konieczny <k.konieczny@samsung.com>
[cw00.choi: Edit return value if entering the wrong value for reset
 and use arrary3_size() to get the size of 3-dimensional array]
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
2019-12-30 09:59:05 +09:00
Chanwoo Choi 2fee1a7cc6 PM / devfreq: Add new name attribute for sysfs
The commit 4585fbcb53 ("PM / devfreq: Modify the device name as devfreq(X) for
sysfs") changed the node name to devfreq(x). After this commit, it is not
possible to get the device name through /sys/class/devfreq/devfreq(X)/*.

Add new name attribute in order to get device name.

Cc: stable@vger.kernel.org
Fixes: 4585fbcb53 ("PM / devfreq: Modify the device name as devfreq(X) for sysfs")
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
2019-12-30 09:59:05 +09:00
Mauro Carvalho Chehab ed66bcd067 ABI: fix some syntax issues at the ABI database
On those three files, the ABI representation described at
README are violated.

- at sysfs-bus-iio-proximity-as3935:
	a ':' character is missing after "What"

- at sysfs-class-devfreq:
	there's a typo at Description

- at sysfs-class-cxl, it is using the ":" character at a
	file preamble, causing it to be misinterpreted as a
	tag.

- On the other files, instead of "What", they use "Where".

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Andrew Donnellan <ajd@linux.ibm.com>  # cxl
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-14 18:17:11 +02:00
MyungJoo Ham de9c739435 PM / devfreq: add comments and Documentation
- Added missing ABI documents
- Added comments to clarify the objectives of functions

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Acked-by: Nishanth Menon <nm@ti.com>
Acked-by: Rajagopal Venkat <rajagopal.venkat@linaro.org>
2013-06-03 20:20:29 +09:00
Nishanth Menon 50a5b33e01 PM / devfreq: Add sysfs node to expose available governors
Now that governor list can be variable, knowing the available governors
is useful to be able to select a governor using relevant sysfs node.

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>
2012-11-20 18:46:24 +09:00
Nishanth Menon 0359d1afe4 PM / devfreq: allow sysfs governor node to switch governor
This allows us to select governor runtime from the
default configuration without having to rebuild kernel
or the devfreq driver using the sysfs node:
/sys/class/devfreq/.../governor
cat of the governor will return valid governor
and an echo 'governor_name'>governor will switch
governor

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>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
2012-11-20 18:46:23 +09:00
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
Nishanth Menon d287de855f 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>
2012-11-20 15:59:32 +09:00
Rajagopal Venkat 7f98a905dc PM / devfreq: Add current freq callback in device profile
Devfreq returns governor predicted frequency as current frequency
via sysfs interface. But device may not support all frequencies
that governor predicts. So add a callback in device profile to get
current freq from driver. Also add a new sysfs node to expose
governor predicted next target frequency.

Signed-off-by: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-15 00:35:04 +01:00
Rajagopal Venkat 7e6fdd4bad PM / devfreq: Core updates to support devices which can idle
Prepare devfreq core framework to support devices which
can idle. When device idleness is detected perhaps through
runtime-pm, need some mechanism to suspend devfreq load
monitoring and resume back when device is online. Present
code continues monitoring unless device is removed from
devfreq core.

This patch introduces following design changes,

 - use per device work instead of global work to monitor device
   load. This enables suspend/resume of device devfreq and
   reduces monitoring code complexity.
 - decouple delayed work based load monitoring logic from core
   by introducing helpers functions to be used by governors. This
   provides flexibility for governors either to use delayed work
   based monitoring functions or to implement their own mechanism.
 - devfreq core interacts with governors via events to perform
   specific actions. These events include start/stop devfreq.
   This sets ground for adding suspend/resume events.

The devfreq apis are not modified and are kept intact.

Signed-off-by: Rajagopal Venkat <rajagopal.venkat@linaro.org>
Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-15 00:35:04 +01:00
MyungJoo Ham ce26c5bb95 PM / devfreq: Add basic governors
Four cpufreq-like governors are provided as examples.

powersave: use the lowest frequency possible. The user (device) should
set the polling_ms as 0 because polling is useless for this governor.

performance: use the highest freqeuncy possible. The user (device)
should set the polling_ms as 0 because polling is useless for this
governor.

userspace: use the user specified frequency stored at
devfreq.user_set_freq. With sysfs support in the following patch, a user
may set the value with the sysfs interface.

simple_ondemand: simplified version of cpufreq's ondemand governor.

When a user updates OPP entries (enable/disable/add), OPP framework
automatically notifies devfreq to update operating frequency
accordingly. Thus, devfreq users (device drivers) do not need to update
devfreq manually with OPP entry updates or set polling_ms for powersave
, performance, userspace, or any other "static" governors.

Note that these are given only as basic examples for governors and any
devices with devfreq may implement their own governors with the drivers
and use them.

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Mike Turquette <mturquette@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-10-02 00:19:34 +02:00
MyungJoo Ham 9005b65099 PM / devfreq: Add common sysfs interfaces
Device specific sysfs interface /sys/devices/.../power/devfreq_*
- governor	R: name of governor
- cur_freq	R: current frequency
- polling_interval	R: polling interval in ms given with devfreq profile
			W: update polling interval.
- central_polling	R: 1 if polling is managed by devfreq framework

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Mike Turquette <mturquette@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
--
 Documentation/ABI/testing/sysfs-class-devfreq |   44 ++++++++++++++++
 drivers/devfreq/devfreq.c                     |   69 ++++++++++++++++++++++++++
 2 files changed, 113 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-devfreq
2011-10-02 00:19:28 +02:00