This series enables future IP trace features Embedded Trace Extension (ETE) and Trace Buffer Extension (TRBE). This series depends on the ETM system register instruction support series [0] which is available here [1]. This series which applies on [1] is avaialble here [2] for quick access.
ETE is the PE (CPU) trace unit for CPUs, implementing future architecture extensions. ETE overlaps with the ETMv4 architecture, with additions to support the newer architecture features and some restrictions on the supported features w.r.t ETMv4. The ETE support is added by extending the ETMv4 driver to recognise the ETE and handle the features as exposed by the TRCIDRx registers. ETE only supports system instructions access from the host CPU. The ETE could be integrated with a TRBE (see below), or with the legacy CoreSight trace bus (e.g, ETRs). Thus the ETE follows same firmware description as the ETMs and requires a node per instance.
Trace Buffer Extensions (TRBE) implements a per CPU trace buffer, which is accessible via the system registers and can be combined with the ETE to provide a 1x1 configuration of source & sink. TRBE is being represented here as a CoreSight sink. Primary reason is that the ETE source could work with other traditional CoreSight sink devices. As TRBE captures the trace data which is produced by ETE, it cannot work alone.
TRBE representation here have some distinct deviations from a traditional CoreSight sink device. Coresight path between ETE and TRBE are not built during boot looking at respective DT or ACPI entries.
Unlike traditional sinks, TRBE can generate interrupts to signal including many other things, buffer got filled. The interrupt is a PPI and should be communicated from the platform. DT or ACPI entry representing TRBE should have the PPI number for a given platform. During perf session, the TRBE IRQ handler should capture trace for perf auxiliary buffer before restarting it back. System registers being used here to configure ETE and TRBE could be referred in the link below.
https://developer.arm.com/docs/ddi0601/g/aarch64-system-registers.
Question:
- Should we implement sysfs based trace sessions for TRBE ?
[0] https://lore.kernel.org/linux-arm-kernel/20210110224850.1880240-1-suzuki.pou... [1] https://gitlab.arm.com/linux-arm/linux-skp/-/tree/coresight/etm/sysreg-v7 [2] https://gitlab.arm.com/linux-arm/linux-anshuman/-/tree/coresight/ete_trbe_v2
Changes in V2:
- Converted both ETE and TRBE DT bindings into Yaml - TRBE changes have been captured in the respective patches
Changes in V1:
https://lore.kernel.org/linux-arm-kernel/1608717823-18387-1-git-send-email-a...
- There are not much ETE changes from Suzuki apart from splitting of the ETE DTS patch - TRBE changes have been captured in the respective patches
Changes in RFC:
https://lore.kernel.org/linux-arm-kernel/1605012309-24812-1-git-send-email-a...
Cc: Mathieu Poirier mathieu.poirier@linaro.org Cc: Suzuki K Poulose suzuki.poulose@arm.com Cc: Mike Leach mike.leach@linaro.org Cc: Linu Cherian lcherian@marvell.com Cc: coresight@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org
Anshuman Khandual (4): arm64: Add TRBE definitions coresight: core: Add support for dedicated percpu sinks coresight: etm-perf: Truncate the perf record if handle has no space coresight: sink: Add TRBE driver
Suzuki K Poulose (7): coresight: etm-perf: Allow an event to use different sinks coresight: Do not scan for graph if none is present coresight: etm4x: Add support for PE OS lock coresight: ete: Add support for ETE sysreg access coresight: ete: Add support for ETE tracing dts: bindings: Document device tree bindings for ETE dts: bindings: Document device tree bindings for Arm TRBE
Documentation/devicetree/bindings/arm/ete.yaml | 71 ++ Documentation/devicetree/bindings/arm/trbe.yaml | 46 + Documentation/trace/coresight/coresight-trbe.rst | 39 + arch/arm64/include/asm/sysreg.h | 51 ++ drivers/hwtracing/coresight/Kconfig | 21 +- drivers/hwtracing/coresight/Makefile | 1 + drivers/hwtracing/coresight/coresight-core.c | 14 + drivers/hwtracing/coresight/coresight-etm-perf.c | 51 +- drivers/hwtracing/coresight/coresight-etm4x-core.c | 138 ++- .../hwtracing/coresight/coresight-etm4x-sysfs.c | 19 +- drivers/hwtracing/coresight/coresight-etm4x.h | 81 +- drivers/hwtracing/coresight/coresight-platform.c | 6 + drivers/hwtracing/coresight/coresight-trbe.c | 966 +++++++++++++++++++++ drivers/hwtracing/coresight/coresight-trbe.h | 216 +++++ include/linux/coresight.h | 12 + 15 files changed, 1683 insertions(+), 49 deletions(-) create mode 100644 Documentation/devicetree/bindings/arm/ete.yaml create mode 100644 Documentation/devicetree/bindings/arm/trbe.yaml create mode 100644 Documentation/trace/coresight/coresight-trbe.rst create mode 100644 drivers/hwtracing/coresight/coresight-trbe.c create mode 100644 drivers/hwtracing/coresight/coresight-trbe.h