[RFC 12/14] drm/i915: Interface for controling engine stats collection

[Tvrtko Ursulin <tursulin@ursulin.net>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Enables other i915 components to enable and disable
the facility as needed.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/intel_engine_cs.c  | 53 +++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_ringbuffer.h |  5 ++++
 2 files changed, 58 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 3e5e08c6b5ef..03e7459bad06 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -29,6 +29,8 @@
 #include "intel_lrc.h"
 
 DEFINE_STATIC_KEY_FALSE(i915_engine_stats_key);
+static DEFINE_MUTEX(i915_engine_stats_mutex);
+static int i915_engine_stats_ref;
 
 /* Haswell does have the CXT_SIZE register however it does not appear to be
  * valid. Now, docs explain in dwords what is in the context object. The full
@@ -1340,6 +1342,57 @@ void intel_engines_mark_idle(struct drm_i915_private *i915)
 	}
 }
 
+int intel_enable_engine_stats(struct drm_i915_private *dev_priv)
+{
+	if (!i915.enable_execlists)
+		return -ENODEV;
+
+	mutex_lock(&i915_engine_stats_mutex);
+	if (i915_engine_stats_ref++ == 0) {
+		struct intel_engine_cs *engine;
+		enum intel_engine_id id;
+
+		for_each_engine(engine, dev_priv, id) {
+			memset(&engine->stats, 0, sizeof(engine->stats));
+			spin_lock_init(&engine->stats.lock);
+		}
+
+		static_branch_enable(&i915_engine_stats_key);
+	}
+	mutex_unlock(&i915_engine_stats_mutex);
+
+	return 0;
+}
+
+void intel_disable_engine_stats(void)
+{
+	mutex_lock(&i915_engine_stats_mutex);
+	if (--i915_engine_stats_ref == 0)
+		static_branch_disable(&i915_engine_stats_key);
+	mutex_unlock(&i915_engine_stats_mutex);
+}
+
+u64 intel_engine_get_current_busy_ns(struct intel_engine_cs *engine)
+{
+	unsigned long flags;
+	u64 total;
+
+	spin_lock_irqsave(&engine->stats.lock, flags);
+
+	total = engine->stats.total;
+
+	/*
+	 * If the engine is executing something at the moment
+	 * add it to the total.
+	 */
+	if (engine->stats.ref)
+		total += ktime_get_real_ns() - engine->stats.start;
+
+	spin_unlock_irqrestore(&engine->stats.lock, flags);
+
+	return total;
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/mock_engine.c"
 #endif
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 2eb1e970ad06..e0f495a6d0d9 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -776,4 +776,9 @@ static inline void intel_engine_context_out(struct intel_engine_cs *engine)
 	}
 }
 
+int intel_enable_engine_stats(struct drm_i915_private *i915);
+void intel_disable_engine_stats(void);
+
+u64 intel_engine_get_current_busy_ns(struct intel_engine_cs *engine);
+
 #endif /* _INTEL_RINGBUFFER_H_ */
-- 
2.9.4

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