drm/xe/pmu: Add attribute skeleton

Add the generic support for defining new attributes. This only adds
the macros and common infra for the event counters, but no counters
yet. This is going to be added as follow up changes.

Reviewed-by: Rodrigo Vivi <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Lucas De Marchi <[e-mail]>

drivers/gpu/drm/xe/xe_pmu.c

···
 	if (gt >= XE_MAX_GT_PER_TILE)
 		return false;
 
-	return false;
+	return id < sizeof(pmu->supported_events) * BITS_PER_BYTE &&
+		pmu->supported_events & BIT_ULL(id);
 }
 
 static void xe_pmu_event_destroy(struct perf_event *event)
···
 	.attrs = pmu_format_attrs,
 };
 
-static struct attribute *pmu_event_attrs[] = {
-	/* No events yet */
+__maybe_unused static ssize_t event_attr_show(struct device *dev,
+					      struct device_attribute *attr, char *buf)
+{
+	struct perf_pmu_events_attr *pmu_attr =
+		container_of(attr, struct perf_pmu_events_attr, attr);
+
+	return sprintf(buf, "event=%#04llx\n", pmu_attr->id);
+}
+
+#define XE_EVENT_ATTR(name_, v_, id_)					\
+	PMU_EVENT_ATTR(name_, pmu_event_ ## v_, id_, event_attr_show)
+
+#define XE_EVENT_ATTR_UNIT(name_, v_, unit_)				\
+	PMU_EVENT_ATTR_STRING(name_.unit, pmu_event_unit_ ## v_, unit_)
+
+#define XE_EVENT_ATTR_GROUP(v_, id_, ...)				\
+	static struct attribute *pmu_attr_ ##v_[] = {			\
+		__VA_ARGS__,						\
+		NULL							\
+	};								\
+	static umode_t is_visible_##v_(struct kobject *kobj,		\
+				       struct attribute *attr, int idx) \
+	{								\
+		struct perf_pmu_events_attr *pmu_attr;			\
+		struct xe_pmu *pmu;					\
+									\
+		pmu_attr = container_of(attr, typeof(*pmu_attr), attr.attr); \
+		pmu = container_of(dev_get_drvdata(kobj_to_dev(kobj)),	\
+				   typeof(*pmu), base);			\
+									\
+		return event_supported(pmu, 0, id_) ? attr->mode : 0;	\
+	}								\
+	static const struct attribute_group pmu_group_ ##v_ = {		\
+		.name = "events",					\
+		.attrs = pmu_attr_ ## v_,				\
+		.is_visible = is_visible_ ## v_,			\
+	}
+
+#define XE_EVENT_ATTR_SIMPLE(name_, v_, id_, unit_)			\
+	XE_EVENT_ATTR(name_, v_, id_)					\
+	XE_EVENT_ATTR_UNIT(name_, v_, unit_)				\
+	XE_EVENT_ATTR_GROUP(v_, id_, &pmu_event_ ##v_.attr.attr,	\
+			    &pmu_event_unit_ ##v_.attr.attr)
+
+#define XE_EVENT_ATTR_NOUNIT(name_, v_, id_)				\
+	XE_EVENT_ATTR(name_, v_, id_)					\
+	XE_EVENT_ATTR_GROUP(v_, id_, &pmu_event_ ##v_.attr.attr)
+
+static struct attribute *pmu_empty_event_attrs[] = {
+	/* Empty - all events are added as groups with .attr_update() */
 	NULL,
 };
 
 static const struct attribute_group pmu_events_attr_group = {
 	.name = "events",
-	.attrs = pmu_event_attrs,
+	.attrs = pmu_empty_event_attrs,
 };
+
+static const struct attribute_group *pmu_events_attr_update[] = {
+	/* No events yet */
+	NULL,
+};
+
+static void set_supported_events(struct xe_pmu *pmu)
+{
+}
 
 /**
  * xe_pmu_unregister() - Remove/cleanup PMU registration
···
 
 	pmu->name		= name;
 	pmu->base.attr_groups	= attr_groups;
+	pmu->base.attr_update	= pmu_events_attr_update;
 	pmu->base.scope		= PERF_PMU_SCOPE_SYS_WIDE;
 	pmu->base.module	= THIS_MODULE;
 	pmu->base.task_ctx_nr	= perf_invalid_context;
···
 	pmu->base.start		= xe_pmu_event_start;
 	pmu->base.stop		= xe_pmu_event_stop;
 	pmu->base.read		= xe_pmu_event_read;
+
+	set_supported_events(pmu);
 
 	ret = perf_pmu_register(&pmu->base, pmu->name, -1);
 	if (ret)

drivers/gpu/drm/xe/xe_pmu_types.h

···
 	 * @name: Name as registered with perf core.
 	 */
 	const char *name;
+	/**
+	 * @supported_events: Bitmap of supported events, indexed by event id
+	 */
+	u64 supported_events;
 };
 
 #endif