drm/panfrost: Add fdinfo support GPU load metrics

The drm-stats fdinfo tags made available to user space are drm-engine,
drm-cycles, drm-max-freq and drm-curfreq, one per job slot.

This deviates from standard practice in other DRM drivers, where a single
set of key:value pairs is provided for the whole render engine. However,
Panfrost has separate queues for fragment and vertex/tiler jobs, so a
decision was made to calculate bus cycles and workload times separately.

Maximum operating frequency is calculated at devfreq initialisation time.
Current frequency is made available to user space because nvtop uses it
when performing engine usage calculations.

It is important to bear in mind that both GPU cycle and kernel time numbers
provided are at best rough estimations, and always reported in excess from
the actual figure because of two reasons:
- Excess time because of the delay between the end of a job processing,
the subsequent job IRQ and the actual time of the sample.
- Time spent in the engine queue waiting for the GPU to pick up the next
job.

To avoid race conditions during enablement/disabling, a reference counting
mechanism was introduced, and a job flag that tells us whether a given job
increased the refcount. This is necessary, because user space can toggle
cycle counting through a debugfs file, and a given job might have been in
flight by the time cycle counting was disabled.

The main goal of the debugfs cycle counter knob is letting tools like nvtop
or IGT's gputop switch it at any time, to avoid power waste in case no
engine usage measuring is necessary.

Also add a documentation file explaining the possible values for fdinfo's
engine keystrings and Panfrost-specific drm-curfreq-<keystr> pairs.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230929181616.2769345-3-adrian.larumbe@collabora.com

drm/panfrost: Add governor data with pre-defined thresholds

The simple_ondemand devfreq governor uses two thresholds to decide about
the frequency change: upthreshold, downdifferential. These two tunable
change the behavior of the governor decision, e.g. how fast to increase
the frequency or how rapidly limit the frequency. This patch adds needed
governor data with thresholds values gathered experimentally in different
workloads.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210121170445.19761-1-lukasz.luba@arm.com

drm/panfrost: Convert to use resource-managed OPP API

Use resource-managed OPP API to simplify code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drm/panfrost: add regulators to devfreq

Some OPP tables specify voltage for each frequency. Devfreq can
handle these regulators but they should be get only 1 time to avoid
issue and know who is in charge.

If OPP table is probe don't init regulator.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200710095409.407087-11-peron.clem@gmail.com

drm/panfrost: properly handle error in probe

Introduce a boolean to know if opp table has been added.

With this, we can call panfrost_devfreq_fini() in case of error
and release what has been initialised.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200710095409.407087-7-peron.clem@gmail.com

drm/panfrost: use spinlock instead of atomic

Convert busy_count to a simple int protected by spinlock.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200710095409.407087-6-peron.clem@gmail.com

drm/panfrost: introduce panfrost_devfreq struct

Introduce a proper panfrost_devfreq to deal with devfreq variables.

Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200710095409.407087-5-peron.clem@gmail.com

drm/panfrost: Simplify devfreq utilisation tracking

Instead of tracking per-slot utilisation track a single value for the
entire GPU. Ultimately it doesn't matter if the GPU is busy with only
vertex or a combination of vertex and fragment processing - if it's busy
then it's busy and devfreq should be scaling appropriately.

This also makes way for being able to submit multiple jobs per slot
which requires more values than the original boolean per slot.

Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20191025134143.14324-3-steven.price@arm.com

drm/panfrost: Remove opp table when unloading

The devfreq opp table needs to be removed when unloading the driver to
free the memory associated with it.

Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190816093107.30518-3-steven.price@arm.com

drm/panfrost: Add initial panfrost driver

This adds the initial driver for panfrost which supports Arm Mali
Midgard and Bifrost family of GPUs. Currently, only the T860 and
T760 Midgard GPUs have been tested.

v2:
- Add GPU reset on job hangs (Tomeu)
- Add RuntimePM and devfreq support (Tomeu)
- Fix T760 support (Tomeu)
- Add a TODO file (Rob, Tomeu)
- Support multiple in fences (Tomeu)
- Drop support for shared fences (Tomeu)
- Fill in MMU de-init (Rob)
- Move register definitions back to single header (Rob)
- Clean-up hardcoded job submit todos (Rob)
- Implement feature setup based on features/issues (Rob)
- Add remaining Midgard DT compatible strings (Rob)

v3:
- Add support for reset lines (Neil)
- Add a MAINTAINERS entry (Rob)
- Call dma_set_mask_and_coherent (Rob)
- Do MMU invalidate on map and unmap. Restructure to do a single
operation per map/unmap call. (Rob)
- Add a missing explicit padding to struct drm_panfrost_create_bo (Rob)
- Fix 0-day error: "panfrost_devfreq.c:151:9-16: ERROR: PTR_ERR applied after initialization to constant on line 150"
- Drop HW_FEATURE_AARCH64_MMU conditional (Rob)
- s/DRM_PANFROST_PARAM_GPU_ID/DRM_PANFROST_PARAM_GPU_PROD_ID/ (Rob)
- Check drm_gem_shmem_prime_import_sg_table() error code (Rob)
- Re-order power on sequence (Rob)
- Move panfrost_acquire_object_fences() before scheduling job (Rob)
- Add NULL checks on array pointers in job clean-up (Rob)
- Rework devfreq (Tomeu)
- Fix devfreq init with no regulator (Rob)
- Various WS and comments clean-up (Rob)

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marty E. Plummer <hanetzer@startmail.com>
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190409205427.6943-4-robh@kernel.org