CTIs are defined in the device tree and associated with other CoreSight devices. The core CoreSight code has been modified to enable the registration of the CTI devices on the same bus as the other CoreSight components, but as these are not actually trace generation / capture devices, they are not part of the Coresight path when generating trace.
However, the definition of the standard CoreSight device has been extended to include a reference to an associated CTI device, and the enable / disable trace path operations will auto enable/disable any associated CTI devices at the same time.
Programming is at present via sysfs - a full API is provided to utilise the hardware capabilities. As CTI devices are unprogrammed by default, the auto enable describe above will have no effect until explicit programming takes place.
A set of device tree bindings specific to the CTI topology has been defined. The driver accesses these in a platform agnostic manner, so ACPI bindings can be added later, once they have been agreed and defined for the CTI device.
Documentation has been updated to describe both the CTI hardware, its use and programming in sysfs, and the new dts bindings required.
Tested on DB410 board.
Applies on coresight/next tree after following dependent set applied for documentation directory changes [1]. Kernel version 5.4-rc7.
[1] https://www.spinics.net/lists/linux-doc/msg71062.html
Changes since v4: Multiple changes following feedback from Mathieu, Leo and Suzuki. 1) Dropped RFC tag - wider distribution 2) CTI bindings definition now presented as a .yaml file - tested with with 'dt-doc-validate' from devicetree.org/dt-schema project and in kernel build tree with 'make dtbs_check' per kernel docs. 3) Sysfs links to other CoreSight devices moved out of this set into a following set that deals with all CoreSight devices & sysfs links. 4) Documentation in .rst format and new directory following patchset in [1]. Extended example provided in docs. 5) Rationalised devicetree of_ specifics to use generic fwnode functions where possible to enable easier addition of ACPI support later. 6) Other minor changes as requested in feedback from last patchset.
Changes since v3: 1) After discussion on CS mailing list, each CTI connection has a triggers<N> sysfs directory with name and trigger signals listed for the connection. 2) Initial code for creating sysfs links between CoreSight components is introduced and implementation for CTI provided. This allows exploration of the CoreSight topology within the sysfs infrastructure. Patches for links between other CoreSight components to follow. 3) Power management - CPU hotplug and idle omitted from this set as ongoing developments may define required direction. Additional patch set to follow. 4) Multiple fixes applied as requested by reviewers esp. Matthieu, Suzuki and Leo.
Changes since v2: Updates to allow for new features on coresight/next and feedback from Mathieu and Leo.
1) Rebase and restructuring to apply on top of ACPI support patch set, currently on coresight/next. of_coresight_cti has been renamed to coresight-cti-platform and device tree bindings added to this but accessed in a platform agnostic manner using fwnode for later ACPI support to be added. 2) Split the sysfs patch info a series of functional patches. 3) Revised the refcount and enabling support. 4) Adopted the generic naming protocol - CTIs are either cti_cpuN or cti_sysM 5) Various minor presentation /checkpatch issues highlighted in feedback. 6) revised CPU hotplug to cover missing cases needed by ETM.
Changes since v1: 1) Significant restructuring of the source code. Adds cti-sysfs file and cti device tree file. Patches add per feature rather than per source file. 2) CPU type power event handling for hotplug moved to CoreSight core, with generic registration interface provided for all CPU bound CS devices to use. 3) CTI signal interconnection details in sysfs now generated dynamically from connection lists in driver. This to fix issue with multi-line sysfs output in previous version. 4) Full device tree bindings for DB410 and Juno provided (to the extent that CTI information is available). 5) AMBA driver update for UCI IDs are now upstream so no longer included in this set.
Mike Leach (14): coresight: cti: Initial CoreSight CTI Driver coresight: cti: Add sysfs coresight mgmt reg access. coresight: cti: Add sysfs access to program function regs coresight: cti: Add sysfs trigger / channel programming API dt-bindings: arm: Adds CoreSight CTI hardware definitions. coresight: cti: Add device tree support for v8 arch CTI coresight: cti: Add device tree support for custom CTI. coresight: cti: Enable CTI associated with devices. coresight: cti: Add connection information to sysfs dt-bindings: qcom: Add CTI options for qcom msm8916 dt-bindings: arm: Juno platform - add CTI entries to device tree. dt-bindings: hisilicon: Add CTI bindings for hi-6220 docs: coresight: Update documentation for CoreSight to cover CTI. docs: sysfs: coresight: Add sysfs ABI documentation for CTI
.../testing/sysfs-bus-coresight-devices-cti | 221 +++ .../bindings/arm/coresight-cti.yaml | 303 ++++ .../devicetree/bindings/arm/coresight.txt | 7 + .../trace/coresight/coresight-ect.rst | 200 +++ Documentation/trace/coresight/coresight.rst | 13 + MAINTAINERS | 2 + arch/arm64/boot/dts/arm/juno-base.dtsi | 150 +- arch/arm64/boot/dts/arm/juno-cs-r1r2.dtsi | 31 +- arch/arm64/boot/dts/arm/juno-r1.dts | 25 + arch/arm64/boot/dts/arm/juno-r2.dts | 25 + arch/arm64/boot/dts/arm/juno.dts | 25 + .../boot/dts/hisilicon/hi6220-coresight.dtsi | 130 +- arch/arm64/boot/dts/qcom/msm8916.dtsi | 85 +- drivers/hwtracing/coresight/Kconfig | 12 + drivers/hwtracing/coresight/Makefile | 3 + .../coresight/coresight-cti-platform.c | 500 +++++++ .../hwtracing/coresight/coresight-cti-sysfs.c | 1219 +++++++++++++++++ drivers/hwtracing/coresight/coresight-cti.c | 712 ++++++++++ drivers/hwtracing/coresight/coresight-cti.h | 232 ++++ .../hwtracing/coresight/coresight-platform.c | 23 + drivers/hwtracing/coresight/coresight-priv.h | 7 + drivers/hwtracing/coresight/coresight.c | 61 +- include/dt-bindings/arm/coresight-cti-dt.h | 37 + include/linux/coresight.h | 28 + 24 files changed, 4028 insertions(+), 23 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-bus-coresight-devices-cti create mode 100644 Documentation/devicetree/bindings/arm/coresight-cti.yaml create mode 100644 Documentation/trace/coresight/coresight-ect.rst create mode 100644 drivers/hwtracing/coresight/coresight-cti-platform.c create mode 100644 drivers/hwtracing/coresight/coresight-cti-sysfs.c create mode 100644 drivers/hwtracing/coresight/coresight-cti.c create mode 100644 drivers/hwtracing/coresight/coresight-cti.h create mode 100644 include/dt-bindings/arm/coresight-cti-dt.h