drm/xe/pmu: Enable PMU interface

drm/xe/pmu: Enable PMU interface

There are a set of engine group busyness counters provided by HW which are
perfect fit to be exposed via PMU perf events.

BSPEC: 46559, 46560, 46722, 46729, 52071, 71028

events can be listed using:
perf list
  xe_0000_03_00.0/any-engine-group-busy-gt0/         [Kernel PMU event]
  xe_0000_03_00.0/copy-group-busy-gt0/               [Kernel PMU event]
  xe_0000_03_00.0/interrupts/                        [Kernel PMU event]
  xe_0000_03_00.0/media-group-busy-gt0/              [Kernel PMU event]
  xe_0000_03_00.0/render-group-busy-gt0/             [Kernel PMU event]

and can be read using:

perf stat -e "xe_0000_8c_00.0/render-group-busy-gt0/" -I 1000
           time             counts unit events
     1.001139062                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/
     2.003294678                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/
     3.005199582                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/
     4.007076497                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/
     5.008553068                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/
     6.010531563              43520 ns  xe_0000_8c_00.0/render-group-busy-gt0/
     7.012468029              44800 ns  xe_0000_8c_00.0/render-group-busy-gt0/
     8.013463515                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/
     9.015300183                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/
    10.017233010                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/
    10.971934120                  0 ns  xe_0000_8c_00.0/render-group-busy-gt0/

The pmu base implementation is taken from i915.

v2:
Store last known value when device is awake return that while the GT is
suspended and then update the driver copy when read during awake.

v3:
1. drop init_samples, as storing counters before going to suspend should
be sufficient.
2. ported the "drm/i915/pmu: Make PMU sample array two-dimensional" and
dropped helpers to store and read samples.
3. use xe_device_mem_access_get_if_ongoing to check if device is active
before reading the OA registers.
4. dropped format attr as no longer needed
5. introduce xe_pmu_suspend to call engine_group_busyness_store
6. few other nits.

v4: minor nits.

v5: take forcewake when accessing the OAG registers

v6:
1. drop engine_busyness_sample_type
2. update UAPI documentation

v7:
1. update UAPI documentation
2. drop MEDIA_GT specific change for media busyness counter.

Co-developed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Co-developed-by: Bommu Krishnaiah <krishnaiah.bommu@intel.com>
Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty@linux.intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>