drm/i915: advertise available metrics via sysfs

Each metric set is given a sysfs entry like:

/sys/class/drm/card0/metrics/<guid>/id

This allows userspace to enumerate the specific sets that are available
for the current system. The 'id' file contains an unsigned integer that
can be used to open the associated metric set via
DRM_IOCTL_I915_PERF_OPEN. The <guid> is a globally unique ID for a
specific OA unit register configuration that can be reliably used by
userspace as a key to lookup corresponding counter meta data and
normalization equations.

The guid registry is currently maintained as part of gputop along with
the XML metric set descriptions and code generation scripts, ref:

 https://github.com/rib/gputop
 > gputop-data/guids.xml
 > scripts/update-guids.py
 > gputop-data/oa-*.xml
 > scripts/i915-perf-kernelgen.py

 $ make -C gputop-data -f Makefile.xml SYSFS=1 WHITELIST=RenderBasic

Signed-off-by: Robert Bragg <robert@sixbynine.org>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Sourab Gupta <sourab.gupta@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161107194957.3385-8-robert@sixbynine.org

1 files changed, 52 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 54653bcf0d79..c427cd8cbe1b 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -812,6 +812,15 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
 	int format_size;
 	int ret;
 
+	/* If the sysfs metrics/ directory wasn't registered for some
+	 * reason then don't let userspace try their luck with config
+	 * IDs
+	 */
+	if (!dev_priv->perf.metrics_kobj) {
+		DRM_ERROR("OA metrics weren't advertised via sysfs\n");
+		return -EINVAL;
+	}
+
 	if (!(props->sample_flags & SAMPLE_OA_REPORT)) {
 		DRM_ERROR("Only OA report sampling supported\n");
 		return -EINVAL;
@@ -1408,6 +1417,49 @@ int i915_perf_open_ioctl(struct drm_device *dev, void *data,
 	return ret;
 }
 
+void i915_perf_register(struct drm_i915_private *dev_priv)
+{
+	if (!IS_HASWELL(dev_priv))
+		return;
+
+	if (!dev_priv->perf.initialized)
+		return;
+
+	/* To be sure we're synchronized with an attempted
+	 * i915_perf_open_ioctl(); considering that we register after
+	 * being exposed to userspace.
+	 */
+	mutex_lock(&dev_priv->perf.lock);
+
+	dev_priv->perf.metrics_kobj =
+		kobject_create_and_add("metrics",
+				       &dev_priv->drm.primary->kdev->kobj);
+	if (!dev_priv->perf.metrics_kobj)
+		goto exit;
+
+	if (i915_perf_register_sysfs_hsw(dev_priv)) {
+		kobject_put(dev_priv->perf.metrics_kobj);
+		dev_priv->perf.metrics_kobj = NULL;
+	}
+
+exit:
+	mutex_unlock(&dev_priv->perf.lock);
+}
+
+void i915_perf_unregister(struct drm_i915_private *dev_priv)
+{
+	if (!IS_HASWELL(dev_priv))
+		return;
+
+	if (!dev_priv->perf.metrics_kobj)
+		return;
+
+	i915_perf_unregister_sysfs_hsw(dev_priv);
+
+	kobject_put(dev_priv->perf.metrics_kobj);
+	dev_priv->perf.metrics_kobj = NULL;
+}
+
 void i915_perf_init(struct drm_i915_private *dev_priv)
 {
 	if (!IS_HASWELL(dev_priv))