perf pmu: Add data structure documentation

Add documentation to 'struct perf_pmu' and the associated structs of
'perf_pmu_alias' and 'perf_pmu_format'.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Caleb Biggers <caleb.biggers@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Perry Taylor <perry.taylor@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Xin Gao <gaoxin@cdjrlc.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: http://lore.kernel.org/lkml/20221114210723.2749751-3-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/pmu.c

@@ -31,10 +31,26 @@
 
 struct perf_pmu perf_pmu__fake;
 
+/**
+ * struct perf_pmu_format - Values from a format file read from
+ * <sysfs>/devices/cpu/format/ held in struct perf_pmu.
+ *
+ * For example, the contents of <sysfs>/devices/cpu/format/event may be
+ * "config:0-7" and will be represented here as name="event",
+ * value=PERF_PMU_FORMAT_VALUE_CONFIG and bits 0 to 7 will be set.
+ */
 struct perf_pmu_format {
+	/** @name: The modifier/file name. */
 	char *name;
+	/**
+	 * @value : Which config value the format relates to. Supported values
+	 * are from PERF_PMU_FORMAT_VALUE_CONFIG to
+	 * PERF_PMU_FORMAT_VALUE_CONFIG_END.
+	 */
 	int value;
+	/** @bits: Which config bits are set by this format value. */
 	DECLARE_BITMAP(bits, PERF_PMU_FORMAT_BITS);
+	/** @list: Element on list within struct perf_pmu. */
 	struct list_head list;
 };
 

tools/perf/util/pmu.h

@@ -33,30 +33,101 @@ struct perf_pmu_caps {
 	struct list_head list;
 };
 
+/**
+ * struct perf_pmu - hi
+ */
 struct perf_pmu {
+	/** @name: The name of the PMU such as "cpu". */
 	char *name;
+	/**
+	 * @alias_name: Optional alternate name for the PMU determined in
+	 * architecture specific code.
+	 */
 	char *alias_name;
+	/**
+	 * @id: Optional PMU identifier read from
+	 * <sysfs>/bus/event_source/devices/<name>/identifier.
+	 */
 	char *id;
+	/**
+	 * @type: Perf event attributed type value, read from
+	 * <sysfs>/bus/event_source/devices/<name>/type.
+	 */
 	__u32 type;
+	/**
+	 * @selectable: Can the PMU name be selected as if it were an event?
+	 */
 	bool selectable;
+	/**
+	 * @is_uncore: Is the PMU not within the CPU core? Determined by the
+	 * presence of <sysfs>/bus/event_source/devices/<name>/cpumask.
+	 */
 	bool is_uncore;
+	/**
+	 * @auxtrace: Are events auxiliary events? Determined in architecture
+	 * specific code.
+	 */
 	bool auxtrace;
+	/**
+	 * @max_precise: Number of levels of :ppp precision supported by the
+	 * PMU, read from
+	 * <sysfs>/bus/event_source/devices/<name>/caps/max_precise.
+	 */
 	int max_precise;
+	/**
+	 * @default_config: Optional default perf_event_attr determined in
+	 * architecture specific code.
+	 */
 	struct perf_event_attr *default_config;
+	/**
+	 * @cpus: Empty or the contents of either of:
+	 * <sysfs>/bus/event_source/devices/<name>/cpumask.
+	 * <sysfs>/bus/event_source/devices/<cpu>/cpus.
+	 */
 	struct perf_cpu_map *cpus;
-	struct list_head format;  /* HEAD struct perf_pmu_format -> list */
-	struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
+	/**
+	 * @format: Holds the contents of files read from
+	 * <sysfs>/bus/event_source/devices/<name>/format/. The contents specify
+	 * which event parameter changes what config, config1 or config2 bits.
+	 */
+	struct list_head format;
+	/**
+	 * @aliases: List of struct perf_pmu_alias. Each alias corresponds to an
+	 * event read from <sysfs>/bus/event_source/devices/<name>/events/ or
+	 * from json events in pmu-events.c.
+	 */
+	struct list_head aliases;
+	/** @caps_initialized: Has the list caps been initialized? */
 	bool caps_initialized;
+	/** @nr_caps: The length of the list caps. */
 	u32 nr_caps;
-	struct list_head caps;    /* HEAD struct perf_pmu_caps -> list */
-	struct list_head list;    /* ELEM */
+	/**
+	 * @caps: Holds the contents of files read from
+	 * <sysfs>/bus/event_source/devices/<name>/caps/.
+	 *
+	 * The contents are pairs of the filename with the value of its
+	 * contents, for example, max_precise (see above) may have a value of 3.
+	 */
+	struct list_head caps;
+	/** @list: Element on pmus list in pmu.c. */
+	struct list_head list;
+	/** @hybrid_list: Element on perf_pmu__hybrid_pmus. */
 	struct list_head hybrid_list;
 
+	/**
+	 * @missing_features: Features to inhibit when events on this PMU are
+	 * opened.
+	 */
 	struct {
+		/**
+		 * @exclude_guest: Disables perf_event_attr exclude_guest and
+		 * exclude_host.
+		 */
 		bool exclude_guest;
 	} missing_features;
 };
 
+/** @perf_pmu__fake: A special global PMU used for testing. */
 extern struct perf_pmu perf_pmu__fake;
 
 struct perf_pmu_info {
@@ -70,21 +141,60 @@ struct perf_pmu_info {
 
 #define UNIT_MAX_LEN	31 /* max length for event unit name */
 
+/**
+ * struct perf_pmu_alias - An event either read from sysfs or builtin in
+ * pmu-events.c, created by parsing the pmu-events json files.
+ */
 struct perf_pmu_alias {
+	/** @name: Name of the event like "mem-loads". */
 	char *name;
+	/** @desc: Optional short description of the event. */
 	char *desc;
+	/** @long_desc: Optional long description. */
 	char *long_desc;
+	/**
+	 * @topic: Optional topic such as cache or pipeline, particularly for
+	 * json events.
+	 */
 	char *topic;
+	/**
+	 * @str: Comma separated parameter list like
+	 * "event=0xcd,umask=0x1,ldlat=0x3".
+	 */
 	char *str;
-	struct list_head terms; /* HEAD struct parse_events_term -> list */
-	struct list_head list;  /* ELEM */
+	/** @terms: Owned list of the original parsed parameters. */
+	struct list_head terms;
+	/** @list: List element of struct perf_pmu aliases. */
+	struct list_head list;
+	/** @unit: Units for the event, such as bytes or cache lines. */
 	char unit[UNIT_MAX_LEN+1];
+	/** @scale: Value to scale read counter values by. */
 	double scale;
+	/**
+	 * @per_pkg: Does the file
+	 * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.per-pkg or
+	 * equivalent json value exist and have the value 1.
+	 */
 	bool per_pkg;
+	/**
+	 * @snapshot: Does the file
+	 * <sysfs>/bus/event_source/devices/<pmu_name>/events/<name>.snapshot
+	 * exist and have the value 1.
+	 */
 	bool snapshot;
+	/**
+	 * @deprecated: Is the event hidden and so not shown in perf list by
+	 * default.
+	 */
 	bool deprecated;
+	/**
+	 * @metric_expr: A metric expression associated with an event. Doing
+	 * this makes little sense due to scale and unit applying to both.
+	 */
 	char *metric_expr;
+	/** @metric_name: A name for the metric. unit applying to both. */
 	char *metric_name;
+	/** @pmu_name: The name copied from struct perf_pmu. */
 	char *pmu_name;
 };