Add support for T-HEAD C9xx PMU extensions

A patchset in state Accepted for opensbi

From: Heiko Stuebner <heiko@...> Date: Mon, 26 Sep 2022 12:10:28 +0200

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

Patches in this set


  • 5 individual patches
  • 258 lines added
  • 7 lines removed

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