thermal: gov_bang_bang: Fix possible cooling device state ping-pong

The current behavior of thermal_zone_trip_update() in the bang-bang
thermal governor may be problematic for trip points with 0 hysteresis,
because when the zone temperature reaches the trip temperature and
stays there, it will then cause the cooling device go "on" and "off"
alternately, which is not desirable.

Address this by requiring the zone temperature to actually fall below
trip->temperature - trip->hysteresis for the cooling device to go off.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

thermal: core: Pass trip pointer to governor throttle callback

Modify the governor .throttle() callback definition so that it takes a
trip pointer instead of a trip index as its second argument, adjust the
governors accordingly and update the core code invoking .throttle().

This causes the governors to become independent of the representation
of the list of trips in the thermal zone structure.

This change is not expected to alter the general functionality.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

thermal: core: Store trip pointer in struct thermal_instance

Replace the integer trip number stored in struct thermal_instance with
a pointer to the relevant trip and adjust the code using the structure
in question accordingly.

The main reason for making this change is to allow the trip point to
cooling device binding code more straightforward, as illustrated by
subsequent modifications of the ACPI thermal driver, but it also helps
to clarify the overall design and allows the governor code overhead to
be reduced (through subsequent modifications).

The only case in which it adds complexity is trip_point_show() that
needs to walk the trips[] table to find the index of the given trip
point, but this is not a critical path and the interface that
trip_point_show() belongs to is problematic anyway (for instance, it
doesn't cover the case when the same cooling devices is associated
with multiple trip points).

This is a preliminary change and the affected code will be refined by
a series of subsequent modifications of thermal governors, the core and
the ACPI thermal driver.

The general functionality is not expected to be affected by this change.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

thermal/core/governors: Use thermal_zone_get_trip() instead of ops functions

The governors are using the ops->get_trip_* functions, Replace these
calls with thermal_zone_get_trip().

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com> # IPA
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/20221003092602.1323944-5-daniel.lezcano@linaro.org

thermal/core: Move the thermal zone lock out of the governors

All the governors throttling ops are taking/releasing the lock at the
beginning and the end of the function.

We can move the mutex to the throttling call site instead.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220805153834.2510142-4-daniel.lezcano@linaro.org

thermal/governors: Group the thermal zone lock inside the throttle function

The thermal zone lock is taken in the different places in the
throttling path.

At the first glance it does not hurt to move them at the beginning and
the end of the 'throttle' function. That will allow a consolidation of
the lock in the next following changes.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220805153834.2510142-3-daniel.lezcano@linaro.org

thermal: step_wise: Appease the kernel-doc deity

Replace - with : to appease the kernel-doc gods and fix warnings such as
the following when compiled with make W=1:

linux-amit.git/drivers/thermal/step_wise.c:187: warning: Function
parameter or member 'tz' not described in 'step_wise_throttle'
linux-amit.git/drivers/thermal/step_wise.c:187: warning: Function
parameter or member 'trip' not described in 'step_wise_throttle'

linux.git/drivers/thermal/fair_share.c:79: warning: Function parameter
or member 'tz' not described in 'fair_share_throttle'
linux.git/drivers/thermal/fair_share.c:79: warning: Function parameter
or member 'trip' not described in 'fair_share_throttle'

Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/5d48ac6f85667a53902092ad5bbfef8cc89a7162.1574242756.git.amit.kucheria@linaro.org

treewide: Rename Peter Feuerer to Peter Kaestle

Rename Peter Feuerer to Peter Kaestle.

Cc: Darren Hart <dvhart@infradead.org>
Cc: Andy Shevchenko <andy@infradead.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Peter Kaestle <peter@piie.net>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

thermal/drivers/core: Use governor table to initialize

Now that the governor table is in place and the macro allows to browse the
table, declare the governor so the entry is added in the governor table
in the init section.

The [un]register_thermal_governors function does no longer need to use the
exported [un]register thermal governor's specific function which in turn
call the [un]register_thermal_governor. The governors are fully
self-encapsulated.

The cyclic dependency is no longer needed, remove it.

Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 286

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 this program is distributed
in the hope that it will be useful but without any warranty without
even the implied warranty of merchantability or fitness for a
particular purpose see the gnu general public license for more
details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 97 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.025053186@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

thermal: bang-bang governor: act on lower trip boundary

With interrupt driven thermal zones we pass the lower and upper
temperature on which shall be acted, so in the governor we have to act on
the exact lower temperature to be consistent. Otherwise an interrupt maybe
generated on the exact lower temperature, but the bang bang governor does
not react since The polling driven zones have to be one step cooler before
the governor reacts.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: linux-pm@vger.kernel.org
Acked-by: Peter Feuerer <peter@piie.net>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

thermal: fix race condition when updating cooling device

When multiple thermal zones are bound to the same cooling device, multiple
kernel threads may want to update the cooling device state by calling
thermal_cdev_update(). Having cdev not protected by a mutex can lead to a race
condition. Consider the following situation with two kernel threads k1 and k2:

Thread k1 Thread k2
||
|| call thermal_cdev_update()
|| ...
|| set_cur_state(cdev, target);
call power_actor_set_power() ||
... ||
instance->target = state; ||
cdev->updated = false; ||
|| cdev->updated = true;
|| // completes execution
call thermal_cdev_update() ||
// cdev->updated == true ||
return; ||
\/
time

k2 has already looped through the thermal instances looking for the deepest
cooling device state and is preempted right before setting cdev->updated to
true. Now, k1 runs, modifies the thermal instance state and sets cdev->updated
to false. Then, k1 is preempted and k2 continues the execution by setting
cdev->updated to true, therefore preventing k1 from performing the update.
Notice that this is not an issue if k2 looks at the instance->target modified by
k1 "after" it is assigned by k1. In fact, in this case the update will happen
anyway and k1 can safely return immediately from thermal_cdev_update().

This may lead to a situation where a thermal governor never updates the cooling
device. For example, this is the case for the step_wise governor: when calling
the function thermal_zone_trip_update(), the governor may always get a new state
equal to the old one (which, however, wasn't notified to the cooling device) and
will therefore skip the update.

CC: Zhang Rui <rui.zhang@intel.com>
CC: Eduardo Valentin <edubezval@gmail.com>
CC: Peter Feuerer <peter@piie.net>
Reported-by: Toby Huang <toby.huang@arm.com>
Signed-off-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Reviewed-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

thermal: check validity get_trip_hyst function pointer in bang-bang governor

Bang-bang thermal governor uses trip point hysteresis to make decisions.
Hysteresis is a required property in the device tree for trip points, but it is
an optional thermal zone device operation. Hence, we need to check whether the
function pointer is valid or not.

If it is not available, we assume the hysteresis to be zero. Consequently, a
highly varying temperature will make the governor continuosly switch a cooling
device ON and OFF.

CC: Zhang Rui <rui.zhang@intel.com>
CC: Eduardo Valentin <edubezval@gmail.com>
CC: Peter Feuerer <peter@piie.net>
Signed-off-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

thermal: consistently use int for temperatures

The thermal code uses int, long and unsigned long for temperatures
in different places.

Using an unsigned type limits the thermal framework to positive
temperatures without need. Also several drivers currently will report
temperatures near UINT_MAX for temperatures below 0°C. This will probably
immediately shut the machine down due to overtemperature if started below
0°C.

'long' is 64bit on several architectures. This is not needed since INT_MAX °mC
is above the melting point of all known materials.

Consistently use a plain 'int' for temperatures throughout the thermal code and
the drivers. This only changes the places in the drivers where the temperature
is passed around as pointer, when drivers internally use another type this is
not changed.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>
Reviewed-by: Darren Hart <dvhart@linux.intel.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Peter Feuerer <peter@piie.net>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Jean Delvare <jdelvare@suse.de>
Cc: Peter Feuerer <peter@piie.net>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: Lukasz Majewski <l.majewski@samsung.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: linux-acpi@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-omap@vger.kernel.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: lm-sensors@lm-sensors.org
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

thermal: Added Bang-bang thermal governor

The bang-bang thermal governor uses a hysteresis to switch abruptly on
or off a cooling device. It is intended to control fans, which can
not be throttled but just switched on or off.
Bang-bang cannot be set as default governor as it is intended for
special devices only. For those special devices the driver needs to
explicitely request it.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Andreas Mohr <andi@lisas.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Javi Merino <javi.merino@arm.com>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Peter Feuerer <peter@piie.net>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>