Revert "thermal: core: Don't update trip points inside the hysteresis range"

It has been reported the commit cf3986f8c01d3 introduced a regression
when the temperature is wavering in the hysteresis region. The
mitigation stops leading to an uncontrolled temperature increase until
reaching the critical trip point.

Here what happens:

* 'throttle' is when the current temperature is greater than the trip
point temperature
* 'target' is the mitigation level
* 'passive' is positive when there is a mitigation, zero otherwise
* these values are computed in the step_wise governor

Configuration:

trip point 1: temp=95°C, hyst=5°C (passive)
trip point 2: temp=115°C, hyst=0°C (critical)
governor: step_wise

1. The temperature crosses the way up the trip point 1 at 95°C

- trend=raising
- throttle=1, target=1
- passive=1
- set_trips: low=90°C, high=115°C

2. The temperature decreases but stays in the hysteresis region at
93°C

- trend=dropping
- throttle=0, target=0
- passive=1

Before cf3986f8c01d3
- set_trips: low=90°C, high=95°C

After cf3986f8c01d3
- set_trips: low=90°C, high=115°C

3. The temperature increases a bit but stays in the hysteresis region
at 94°C (so below the trip point 1 temp 95°C)

- trend=raising
- throttle=0, target=0
- passive=1

Before cf3986f8c01d3
- set_trips: low=90°C, high=95°C

After cf3986f8c01d3
- set_trips: low=90°C, high=115°C

4. The temperature decreases but stays in the hysteresis region at
93°C

- trend=dropping
- throttle=0, target=THERMAL_NO_TARGET
- passive=0

Before cf3986f8c01d3
- set_trips: low=90°C, high=95°C

After cf3986f8c01d3
- set_trips: low=90°C, high=115°C

At this point, the 'passive' value is zero, there is no mitigation,
the temperature is in the hysteresis region, the next trip point is
115°C. As 'passive' is zero, the timer to monitor the thermal zone is
disabled. Consequently if the temperature continues to increase, no
mitigation will happen and it will reach the 115°C trip point and
reboot.

Before the optimization, the high boundary would have been 95°C, thus
triggering the mitigation again and rearming the polling timer.

The optimization make sense but given the current implementation of
the step_wise governor collaborating via this 'passive' flag with the
core framework it can not work.

From a higher perspective it seems like there is a problem between the
governor which sets a variable to be used by the core framework. That
sounds akward and it would make much more sense if the core framework
controls the governor and not the opposite. But as the devil hides in
the details, there are some subtilities to be addressed before.

Elaborating those would be out of the scope this changelog. So let's
stay simple and revert the change first to fixup all broken mobile
platforms.

This reverts commit cf3986f8c01d3 ("thermal: core: Don't update trip
points inside the hysteresis range") and takes a conflict with commit
0c0c4740c9d26 ("0c0c4740c9d2 thermal: trip: Use for_each_trip() in
__thermal_zone_set_trips()") in drivers/thermal/thermal_trip.c into
account.

Fixes: cf3986f8c01d3 ("thermal: core: Don't update trip points inside the hysteresis range")
Reported-by: Manaf Meethalavalappu Pallikunhi <quic_manafm@quicinc.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Cc: 6.7+ <stable@vger.kernel.org> # 6.7+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

thermal: core: Store zone ops in struct thermal_zone_device

The current code requires thermal zone creators to pass pointers to
writable ops structures to thermal_zone_device_register_with_trips()
which needs to modify the target struct thermal_zone_device_ops object
if the "critical" operation in it is NULL.

Moreover, the callers of thermal_zone_device_register_with_trips() are
required to hold on to the struct thermal_zone_device_ops object passed
to it until the given thermal zone is unregistered.

Both of these requirements are quite inconvenient, so modify struct
thermal_zone_device to contain struct thermal_zone_device_ops as field and
make thermal_zone_device_register_with_trips() copy the contents of the
struct thermal_zone_device_ops passed to it via a pointer (which can be
const now) to that field.

Also adjust the code using thermal zone ops accordingly and modify
thermal_of_zone_register() to use a local ops variable during
thermal zone registration so ops do not need to be freed in
thermal_of_zone_unregister() any more.

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

thermal: core: Store zone trips table in struct thermal_zone_device

The current code expects thermal zone creators to pass a pointer to a
writable trips table to thermal_zone_device_register_with_trips() and
that trips table is then used by the thermal core going forward.

Consequently, the callers of thermal_zone_device_register_with_trips()
are required to hold on to the trips table passed to it until the given
thermal zone is unregistered, at which point the trips table can be
freed, but at the same time they are not expected to access that table
directly. This is both error prone and confusing.

To address it, turn the trips table pointer in struct thermal_zone_device
into a flex array (counted by its num_trips field), allocate it during
thermal zone device allocation and copy the contents of the trips table
supplied by the zone creator (which can be const now) into it, which
will allow the callers of thermal_zone_device_register_with_trips() to
drop their trip tables right after the zone registration.

This requires the imx thermal driver to be adjusted to store the new
temperature in its internal trips table in imx_set_trip_temp(), because
it will be separate from the core's trips table now and it has to be
explicitly kept in sync with the latter.

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

thermal: netlink: Pass pointers to thermal_notify_tz_trip_change()

Instead of requiring the caller of thermal_notify_tz_trip_change() to
provide specific values needed to populate struct param in it, make it
extract those values from objects passed to it by the caller via const
pointers.

No intentional functional impact.

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

thermal: trip: Constify thermal zone argument of thermal_zone_trip_id()

Because thermal_zone_trip_id() does not update the thermal zone object
passed to it, its pointer argument representing the thermal zone can be
const, so adjust its definition accordingly.

No functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>

thermal: trip: Send trip change notifications on all trip updates

The _store callbacks of the trip point temperature and hysteresis sysfs
attributes invoke thermal_notify_tz_trip_change() to send a notification
regarding the trip point change, but when trip points are updated by the
platform firmware, trip point change notifications are not sent.

To make the behavior after a trip point change more consistent,
modify all of the 3 places where trip point temperature is updated
to use a new function called thermal_zone_set_trip_temp() for this
purpose and make that function call thermal_notify_tz_trip_change().

Note that trip point hysteresis can only be updated via sysfs and
trip_point_hyst_store() calls thermal_notify_tz_trip_change() already,
so this code path need not be changed.

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

thermal: trip: Use for_each_trip() in __thermal_zone_set_trips()

Make __thermal_zone_set_trips() use for_each_trip() instead of an open-
coded loop over trip indices.

No intentional functional impact.

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

thermal: sysfs: Rework the handling of trip point updates

Both trip_point_temp_store() and trip_point_hyst_store() use
thermal_zone_set_trip() to update a given trip point, but none of them
actually needs to change more than one field in struct thermal_trip
representing it. However, each of them effectively calls
__thermal_zone_get_trip() twice in a row for the same trip index value,
once directly and once via thermal_zone_set_trip(), which is not
particularly efficient, and the way in which thermal_zone_set_trip()
carries out the update is not particularly straightforward.

Moreover, input processing need not be done under the thermal zone lock
in any of these functions.

Rework trip_point_temp_store() and trip_point_hyst_store() to address
the above, move the part of thermal_zone_set_trip() that is still
useful to a new function called thermal_zone_trip_updated() and drop
the rest of it.

While at it, make trip_point_hyst_store() reject negative hysteresis
values.

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

thermal: trip: Drop a redundant check from thermal_zone_set_trip()

After recent changes in the thermal framework, a trip points array is
required for registering a thermal zone that is not tripless, so the
tz->trips pointer in thermal_zone_set_trip() is never NULL and the
check involving it is redundant. Drop that check.

No functional impact.

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

thermal: core: Don't update trip points inside the hysteresis range

When searching for the trip points that need to be set, the nearest
higher trip point's temperature is used for the high trip, while the
nearest lower trip point's temperature minus the hysteresis is used for
the low trip. The issue with this logic is that when the current
temperature is inside a trip point's hysteresis range, both high and low
trips will come from the same trip point. As a consequence instability
can still occur like this:
* the temperature rises slightly and enters the hysteresis range of a
trip point
* polling happens and updates the trip points to the hysteresis range
* the temperature falls slightly, exiting the hysteresis range, crossing
the trip point and triggering an IRQ, the trip points are updated
* repeat

So even though the current hysteresis implementation prevents
instability from happening due to IRQs triggering on the same
temperature value, both ways, it doesn't prevent it from happening due
to an IRQ on one way and polling on the other.

To properly implement a hysteresis behavior, when inside the hysteresis
range, don't update the trip points. This way, the previously set trip
points will stay in effect, which will in a way remember the previous
state (if the temperature signal came from above or below the range) and
therefore have the right trip point already set.

The exception is if there was no previous trip point set, in which case
a previous state doesn't exist, and so it's sensible to allow the
hysteresis range as trip points.

The following logs show the current behavior when running on a real
machine:

[ 202.524658] thermal thermal_zone0: new temperature boundaries: -2147483647 < x < 40000
203.562817: thermal_temperature: thermal_zone=vpu0-thermal id=0 temp_prev=36986 temp=37979
[ 203.562845] thermal thermal_zone0: new temperature boundaries: 37000 < x < 40000
204.176059: thermal_temperature: thermal_zone=vpu0-thermal id=0 temp_prev=37979 temp=40028
[ 204.176089] thermal thermal_zone0: new temperature boundaries: 37000 < x < 100000
205.226813: thermal_temperature: thermal_zone=vpu0-thermal id=0 temp_prev=40028 temp=38652
[ 205.226842] thermal thermal_zone0: new temperature boundaries: 37000 < x < 40000

And with this patch applied:

[ 184.933415] thermal thermal_zone0: new temperature boundaries: -2147483647 < x < 40000
185.981182: thermal_temperature: thermal_zone=vpu0-thermal id=0 temp_prev=36986 temp=37872
186.744685: thermal_temperature: thermal_zone=vpu0-thermal id=0 temp_prev=37872 temp=40058
[ 186.744716] thermal thermal_zone0: new temperature boundaries: 37000 < x < 100000
187.773284: thermal_temperature: thermal_zone=vpu0-thermal id=0 temp_prev=40058 temp=38698

Fixes: 060c034a9741 ("thermal: Add support for hardware-tracked trip points")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Co-developed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

thermal: trip: Define for_each_trip() macro

Define a new macro for_each_trip() to be used by the thermal core code
and thermal governors for walking trips in a given thermal zone.

Modify for_each_thermal_trip() to use this macro instead of an open-
coded loop over trips.

No intentional functional impact.

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

thermal: trip: Simplify computing trip indices

A trip index can be computed right away as a difference between the
value of a trip pointer pointing to the given trip object and the
start of the trips[] table in the given thermal zone, so change
thermal_zone_trip_id() accordingly.

No intentional functional impact (except for some speedup).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>

thermal: trip: Drop lockdep assertion from thermal_zone_trip_id()

The lockdep assertion in thermal_zone_trip_id() triggers when the
trip point sysfs attribute of a thermal instance is read, because
there is no thermal zone locking in that code path.

This is not verly useful, though, because there is no mechanism by which
the location of the trips[] table in a thermal zone or its size can
change after binding cooling devices to the trips in that thermal
zone and before those cooling devices are unbound from them. Thus
it is not in fact necessary to hold the thermal zone lock when
thermal_zone_trip_id() is called from trip_point_show() and so the
lockdep asserion in the former is invalid.

Accordingly, drop that lockdep assertion.

Fixes: 2c7b4bfadef0 ("thermal: core: Store trip pointer in struct thermal_instance")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

thermal: trip: Remove lockdep assertion from for_each_thermal_trip()

The lockdep assertion in for_each_thermal_trip() was added to possibly
catch incorrect usage of that function without the thermal zone lock.
However, it turns out that the ACPI thermal driver has a legitimate
reason to call for_each_thermal_trip() without locking.

Namely, it is called by acpi_thermal_bind_unbind_cdev() in the thermal
zone registration and unregistration paths. That function cannot acquire
the thermal zone lock by itself, because it calls functions that acquire
it, thermal_bind_cdev_to_trip() or thermal_unbind_cdev_from_trip().
However, it is invoked when the ACPI notify handler for the thermal
zone in question has not been registered yet (in the registration path)
or after that handler has been unregistered (in the unregistration
path). Therefore, when for_each_thermal_trip() is called by
acpi_thermal_bind_unbind_cdev(), thermal trip changes induced by the
platform firmware cannot take place and so the thermal zone's trips[]
table is effectively immutable. Hence, it is valid to call
for_each_thermal_trip() from acpi_thermal_bind_unbind_cdev() without
locking and the lockdep assertion in the former is in fact incorrect, so
remove it.

Fixes: d5ea889246b1 ("ACPI: thermal: Do not use trip indices for cooling device binding")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

thermal: core: Add function to walk trips under zone lock

Add a wrapper around for_each_thermal_trip(), called
thermal_zone_for_each_trip(), that will invoke the former under the
thermal zone lock and pass its return value to the caller.

Two drivers will be modified subsequently to use this new function.

No functional impact.

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: trip: Drop redundant trips check from for_each_thermal_trip()

It is invalid to call for_each_thermal_trip() on an unregistered thermal
zone anyway, and as per thermal_zone_device_register_with_trips(), the
trips[] table must be present if num_trips is greater than zero for the
given thermal zone.

Hence, the trips check in for_each_thermal_trip() is redundant and so it
can be dropped.

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

thermal: core: Drop unused .get_trip_*() callbacks

After recent changes in the ACPI thermal driver and in the Intel DTS
IOSF thermal driver, all thermal zone drivers are expected to use trip
tables for initialization and none of them should implement
.get_trip_type(), .get_trip_temp() or .get_trip_hyst() callbacks, so
drop these callbacks entirely from the core.

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

thermal: core: Rework and rename __for_each_thermal_trip()

Rework the currently unused __for_each_thermal_trip() to pass original
pointers to struct thermal_trip objects to the callback, so it can be
used for updating trip data (e.g. temperatures), rename it to
for_each_thermal_trip() and make it available to modular drivers.

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

thermal/core: Move the thermal trip code to a dedicated file

The thermal_core.c files contains a lot of functions handling
different thermal components like the governors, the trip points, the
cooling device, the OF cooling device, etc ...

This organization does not help to migrate to a more sane code where
there is a better self-encapsulation as all the components' internals
can be directly accessed from a single file.

For the sake of clarity, let's move the thermal trip points code in a
dedicated thermal_trip.c file and add a function to browse all the
trip points like we do with the thermal zones, the govenors and the
cooling devices.

The same can be done for the cooling devices and the governor code but
that will come later as the current work in the thermal framework is
to fix the trip point handling and use a generic trip point structure.

No functional changes intended.

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