[PATCH v2 0/4] coresight: Pulse an ETM external output for a PMU event

[Amir Ayupov]

Add an ETMv4 configuration, pmu_pulse, that drives trace unit external
output 1 on every traced cycle, so a PMU event counting it (TRCEXTOUT1)
can end a fixed-length ETM window, for example with aux-action=pause.
The feature only loads on ETMs whose PMU counts that output.

Changes in v2:
- Split the -EINVAL fix for a configuration that is active but not loaded
  on the device into its own patch, with a Fixes tag and an early return
  (Leo).
- Match capability flags separately from the device class: a feature
  loads on a device that shares one of its classes and has all of its
  capabilities, checked once in cscfg_load_feat_csdev() (Leo).
- Report each external output the PMU counts, TRCEXTOUT0-3, instead of
  only output 1 (Leo).
- Detect the outputs from TRCIDR0.NUMEVENT and PMCEID0_EL0, and drop the
  MIDR list (Leo, James).
- extout_pulse requires CS_CFG_MATCH_CLASS_SRC_ETM4 and
  CS_CFG_MATCH_CAP_PMU_EXTOUT(1). It still uses event and output 1:
  event 0 is the trace unit trigger, which the TRBE driver treats as
  fatal (James).
- Link to v1: https://lore.kernel.org/r/20261001063744.2143819-1-aaupov@fb.com

Tested on Grace/Neoverse V2, pmu_pulse config loaded successfully.


Amir Ayupov (4):
  coresight: syscfg: Fail to enable a configuration not loaded on the
    device
  coresight: syscfg: Match feature capabilities separately from device
    class
  coresight: etm4x: Report the external outputs the PMU counts
  coresight: Add pmu_pulse/extout_pulse

 .../trace/coresight/coresight-config.rst      |  5 ++
 .../trace/coresight/coresight-perf.rst        | 19 ++++
 drivers/hwtracing/coresight/Makefile          |  1 +
 .../coresight/coresight-cfg-pmu-pulse.c       | 55 ++++++++++++
 .../coresight/coresight-cfg-preload.c         |  2 +
 .../coresight/coresight-cfg-preload.h         |  2 +
 .../hwtracing/coresight/coresight-config.h    | 10 +++
 .../hwtracing/coresight/coresight-etm4x-cfg.c |  5 +-
 .../coresight/coresight-etm4x-core.c          | 32 +++++++
 drivers/hwtracing/coresight/coresight-etm4x.h |  3 +
 .../coresight/coresight-syscfg-configfs.c     |  7 ++
 .../hwtracing/coresight/coresight-syscfg.c    | 88 +++++++++++--------
 12 files changed, 193 insertions(+), 36 deletions(-)
 create mode 100644 drivers/hwtracing/coresight/coresight-cfg-pmu-pulse.c


base-commit: bc01105ed65d15787b2eb93ac26e8624a2139e35
-- 
2.52.0