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 <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250124050411.2189060-5-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

2 files changed, 69 insertions, 4 deletions

diff --git a/drivers/gpu/drm/xe/xe_pmu.c b/drivers/gpu/drm/xe/xe_pmu.c
index 6678340d6195..6e19e08dd617 100644
--- a/drivers/gpu/drm/xe/xe_pmu.c
+++ b/drivers/gpu/drm/xe/xe_pmu.c
@@ -61,7 +61,8 @@ static bool event_supported(struct xe_pmu *pmu, unsigned int gt,
 	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)
@@ -213,16 +214,73 @@ static const struct attribute_group pmu_format_attr_group = {
 	.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
  * @arg: Ptr to pmu
@@ -273,6 +331,7 @@ int xe_pmu_register(struct xe_pmu *pmu)
 
 	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;
@@ -283,6 +342,8 @@ int xe_pmu_register(struct xe_pmu *pmu)
 	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)
 		goto err_name;
diff --git a/drivers/gpu/drm/xe/xe_pmu_types.h b/drivers/gpu/drm/xe/xe_pmu_types.h
index 0e8faae6bc1b..f5ba4d56622c 100644
--- a/drivers/gpu/drm/xe/xe_pmu_types.h
+++ b/drivers/gpu/drm/xe/xe_pmu_types.h
@@ -30,6 +30,10 @@ struct xe_pmu {
 	 * @name: Name as registered with perf core.
 	 */
 	const char *name;
+	/**
+	 * @supported_events: Bitmap of supported events, indexed by event id
+	 */
+	u64 supported_events;
 };
 
 #endif