[PATCH v15 4/6] drm/xe/pmu: Add attribute skeleton

[Lucas De Marchi]

Add the generic support for defining new attributes. This uses
gt-c6-residency as first attribute to bootstrap it, but its
implementation will be added by a follow up commit: until proper support
is added, it will always be invisible in sysfs since the corresponding
bit is not set in the supported_events bitmap.

Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
---
 drivers/gpu/drm/xe/xe_pmu.c       | 60 ++++++++++++++++++++++++++++---
 drivers/gpu/drm/xe/xe_pmu_types.h |  4 +++
 2 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_pmu.c b/drivers/gpu/drm/xe/xe_pmu.c
index 33598272db6aa..5e5a9fcf30ace 100644
--- a/drivers/gpu/drm/xe/xe_pmu.c
+++ b/drivers/gpu/drm/xe/xe_pmu.c
@@ -46,6 +46,8 @@ static unsigned int config_to_gt_id(u64 config)
 	return FIELD_GET(XE_PMU_EVENT_GT_MASK, config);
 }
 
+#define XE_PMU_EVENT_GT_C6_RESIDENCY	0x01
+
 static struct xe_gt *event_to_gt(struct perf_event *event)
 {
 	struct xe_device *xe = container_of(event->pmu, typeof(*xe), pmu.base);
@@ -60,7 +62,8 @@ 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)
@@ -210,16 +213,62 @@ static const struct attribute_group pmu_format_attr_group = {
 	.attrs = pmu_format_attrs,
 };
 
-static struct attribute *pmu_event_attrs[] = {
-	/* No events yet */
+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_, unit_)				\
+	PMU_EVENT_ATTR(name_, pmu_event_ ## v_, id_, event_attr_show)	\
+	PMU_EVENT_ATTR_STRING(name_.unit, pmu_event_unit_ ## v_, unit_)	\
+	static struct attribute *pmu_attr_ ##v_[] = {			\
+		&pmu_event_ ##v_.attr.attr,				\
+		&pmu_event_unit_ ##v_.attr.attr,			\
+		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_,			\
+	}
+
+XE_EVENT_ATTR(gt-c6-residency, gt_c6_residency, XE_PMU_EVENT_GT_C6_RESIDENCY, "ms");
+
+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[] = {
+	&pmu_group_gt_c6_residency,
+	NULL,
+};
+
+static void set_supported_events(struct xe_pmu *pmu)
+{
+}
+
 /**
  * xe_pmu_unregister() - Remove/cleanup PMU registration
  * @arg: Ptr to pmu
@@ -270,6 +319,7 @@ 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;
@@ -280,6 +330,8 @@ 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 0e8faae6bc1b3..f5ba4d56622cb 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
-- 
2.48.0