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 support for devcoredump

In the event of a job timeout, debug dump information will be written into
/sys/class/devcoredump.

Inspired by etnaviv's similar feature.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.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/20220729144610.2105223-3-adrian.larumbe@collabora.com

drm/panfrost: Add madvise and shrinker support

Add support for madvise and a shrinker similar to other drivers. This
allows userspace to mark BOs which can be freed when there is memory
pressure.

Unlike other implementations, we don't depend on struct_mutex. The
driver maintains a list of BOs which can be freed when the shrinker
is called. Access to the list is serialized with the shrinker_lock.

Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190805143358.21245-2-robh@kernel.org

drm/panfrost: Expose performance counters through unstable ioctls

Expose performance counters through 2 driver specific ioctls: one to
enable/disable the perfcnt block, and one to dump the counter values.

There are discussions to expose global performance monitors (those
counters that can't be retrieved on a per-job basis) in a consistent
way, but this is likely to take time to settle on something that works
for various HW/users.
The ioctls are marked unstable so we can get rid of them when the time
comes. We initally went for a debugfs-based interface, but this was
making the transition to per-FD address space more complicated (we need
to specify the namespace the GPU has to use when dumping the perf
counters), hence the decision to switch back to driver specific ioctls
which are passed the FD they operate on and thus will have a dedicated
address space attached to them.

Other than that, the implementation is pretty simple: it basically dumps
all counters and copy the values to a userspace buffer. The parsing is
left to userspace which has to know the specific layout that's used
by the GPU (layout differs on a per-revision basis).

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190618081648.17297-5-boris.brezillon@collabora.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