[PATCH v4 0/5] Add support for T-HEAD C9xx PMU extensions

[Heiko Stuebner]

The T-HEAD C9XX cores implement functionality very similar to SSCOFPMF.
Instead of implementing a separate interface into SBI as done in v1,
we can add the C9XX tidbits with quite minimal overhead and leaverage
the existing SBI pmu interface including giving access to the firmware
counters.

The current only hickup is the detection override in sbi_hart, where
I still need to find out why the MHPMCOUNTERs are not writeable
at _that_ point of the boot, but with this series on top of openSBI 1.1
and the matching kernel perf patch I get reasonable results for example
for:

perf stat -e cycles -e instructions -e L1-icache-load-misses -e L1-icache-loads ls

 Performance counter stats for 'ls':

          17119496      cycles
           2867765      instructions              #    0.17  insn per cycle
             55929      L1-icache-load-misses     #    1.61% of all L1-icache accesses
           3467346      L1-icache-loads

       0.030156216 seconds time elapsed

       0.000000000 seconds user
       0.023496000 seconds sys

changes in v4:
- use the new sbi_pmu_device structure for holding the
  overrides and extend it where needed

changes in v3:
- follow Atish's advice and implement an abstraction
  to not pollute the core pmu with cpu-specific variants

changes in v2:
- don't implement a separate interface but instead modify
  the sbi-pmu to allow the c9xx to use standard pmu interface


Heiko Stuebner (5):
  lib: sbi: do platform-specific extension population earlier
  lib: sbi_pmu: move pmu irq information into pmu itself
  lib: sbi_pmu: add override for counter data
  platform: generic: add extensions_init handler and platform-override
  platform: generic: allwinner: add support for c9xx pmu

 include/sbi/sbi_pmu.h                        |  16 +++
 lib/sbi/sbi_hart.c                           |  21 ++-
 lib/sbi/sbi_pmu.c                            |  19 +++
 platform/generic/allwinner/sun20i-d1.c       |  72 +++++++++++
 platform/generic/include/platform_override.h |   1 +
 platform/generic/include/thead_c9xx.h        | 127 +++++++++++++++++++
 platform/generic/platform.c                  |   9 ++
 7 files changed, 258 insertions(+), 7 deletions(-)
 create mode 100644 platform/generic/include/thead_c9xx.h

-- 
2.35.1