[PATCH V4 5/6] docs: ABI: sysfs-bus-event_source-devices-htm: Document sysfs event format entries for htm pmu

[Athira Rajeev <atrajeev@linux.ibm.com>]

Add ABI documentation for the sysfs entries exposed by the "htm" PMU
under /sys/bus/event_source/devices/htm/.

Document the format attribute group, which describes the bit layout of
perf_event_attr.config accepted by the htm PMU:

  event            config bits  0-27  (composite: all fields combined)
  htm_type         config bits  0-3   (HTM_CORE=2, HTM_NEST=1)
  nodeindex        config bits  4-11
  nodalchipindex   config bits 12-19
  coreindexonchip  config bits 20-27

Document the events attribute group, which provides named aliases for
the two supported HTM event types.  Users can pass these names directly
to perf:

  # perf record -e htm/htm_core/ ...
  # perf record -e htm/htm_nest/ ...

Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
---
Changes in V3:
- Fixed the format/ attribute table: the doc listed only the composite
  'event' attribute (config:0-27) but omitted the four individual
  format attributes (htm_type, nodeindex, nodalchipindex,
  coreindexonchip) that the commit message described and the driver
  exposes.  Added all four with their correct bit ranges and a
  'For example::' block showing htm_core and htm_nest mappings.
- Fixed the events/ example in the commit message: the previous example
  used format-group key=value syntax
  (htm/nodalchipindex=2,nodeindex=0,htm_type=1/) which conflates the
  format group with the events group.  The events group provides named
  aliases; the correct examples are 'htm/htm_core/' and 'htm/htm_nest/'.
- Fixed grammar: "Supported attribute are" -> "Supported attributes are".

Changes in V2:
- Updated the bit-range descriptions to match the V2 config layout:
  htm_type is bits 0-3 (was listed inconsistently in V1), nodeindex
  is bits 4:11, nodalchipindex is bits 12:19, coreindexonchip is
  bits 20-27.
- Added documentation for the events/ sysfs group which lists named
  events users can pass directly to perf.  This group was not
  documented in V1.
- Patch is now 5/6 instead of 4/5.

 .../sysfs-bus-event_source-devices-htm        | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-event_source-devices-htm

diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-htm b/Documentation/ABI/testing/sysfs-bus-event_source-devices-htm
new file mode 100644
index 000000000000..1c3e17cb124c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-htm
@@ -0,0 +1,34 @@
+What:           /sys/bus/event_source/devices/htm/format
+Date:           June 2026
+Contact:        Linux on PowerPC Developer List <linuxppc-dev at lists.ozlabs.org>
+Description:    Read-only. Attribute group to describe the magic bits
+                that go into perf_event_attr.config for a particular pmu.
+                (See ABI/testing/sysfs-bus-event_source-devices-format).
+
+                Each attribute under this group defines a bit range of the
+                perf_event_attr.config. Supported attributes are listed
+                below::
+
+                  event           = "config:0-27"  - composite event ID
+                  htm_type        = "config:0-3"   - HTM type (HTM_CORE=2, HTM_NEST=1)
+                  nodeindex       = "config:4-11"  - node index
+                  nodalchipindex  = "config:12-19" - nodal chip index
+                  coreindexonchip = "config:20-27" - core index on chip
+
+                For example::
+
+                  htm_core = "htm_type=2"
+                  htm_nest = "htm_type=1"
+
+What:           /sys/bus/event_source/devices/htm/events
+Date:           June 2026
+Contact:        Linux on PowerPC Developer List <linuxppc-dev at lists.ozlabs.org>
+Description:    Read-only. Attribute group to describe performance monitoring
+                events for the Hardware Trace Macro (HTM) trace. Each attribute
+                in this group describes a single performance monitoring event
+                supported by htm pmu.  The name of the file is the name of
+                the event (See ABI/testing/sysfs-bus-event_source-devices-events).
+
+                For example::
+			# perf record -e htm/htm_core/
+			# perf record -e htm/htm_nest/
-- 
2.43.0