[Intel-gfx] [PATCH 4/4] drm/i915: expose engine availability through sysfs

[Lionel Landwerlin]

This enables userspace to discover the engines available on the GPU.
Here is the layout :

/sys/devices/pci0000:00/0000:00:02.0/drm/card0/engines
├── bcs0
│   ├── class
│   └── instance
├── rcs0
│   ├── class
│   └── instance
├── vcs0
│   ├── class
│   ├── hevc
│   └── instance
├── vcs1
│   ├── class
│   └── instance
└── vecs0
    ├── class
    └── instance

Further capabilities can be added later as attributes of each engine.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h         |  1 +
 drivers/gpu/drm/i915/i915_sysfs.c       | 92 +++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/intel_ringbuffer.h |  2 +
 3 files changed, 95 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 44b807421af8..c4f6e8ecf212 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2749,6 +2749,7 @@ struct drm_i915_private {
 
 	struct {
 		struct intel_topology_kobject kobj;
+		struct kobject engines_kobj;
 
 		struct sysfs_slice {
 			struct intel_slice_kobject kobj;
diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index 1d835f164d80..992aeaa91565 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -712,6 +712,92 @@ static void i915_teardown_topology_sysfs(struct drm_i915_private *dev_priv)
 	kobject_del(&topology_kobj->kobj);
 }
 
+static struct attribute engine_instance_attr = {
+	.name = "instance",
+	.mode = 0444,
+};
+
+static struct attribute engine_class_attr = {
+	.name = "class",
+	.mode = 0444,
+};
+
+static struct attribute engine_hevc_attr = {
+	.name = "hevc",
+	.mode = 0444,
+};
+
+static ssize_t
+show_engine_attr(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+	struct intel_engine_cs *engine =
+		container_of(kobj, struct intel_engine_cs, kobj);
+
+	if (attr == &engine_instance_attr)
+		return sprintf(buf, "%hhu\n", engine->uabi_id);
+	if (attr == &engine_class_attr)
+		return sprintf(buf, "%hhu\n", engine->uabi_class);
+	if (attr == &engine_hevc_attr)
+		return sprintf(buf, "%i\n", INTEL_GEN(engine->i915) >= 8);
+	return sprintf(buf, "\n");
+}
+
+static const struct sysfs_ops engine_ops = {
+	.show = show_engine_attr,
+};
+
+static struct kobj_type engine_type = {
+	.sysfs_ops = &engine_ops,
+};
+
+static int i915_setup_engines_sysfs(struct drm_i915_private *dev_priv)
+{
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+
+	kobject_init_and_add(&dev_priv->topology.engines_kobj,
+			     dev_priv->drm.primary->kdev->kobj.ktype,
+			     &dev_priv->drm.primary->kdev->kobj,
+			     "engines");
+
+	for_each_engine(engine, dev_priv, id) {
+		int ret;
+
+		kobject_init_and_add(&engine->kobj, &engine_type,
+				     &dev_priv->topology.engines_kobj,
+				     engine->name);
+
+		ret = sysfs_create_file(&engine->kobj, &engine_instance_attr);
+		if (ret)
+			return ret;
+		ret = sysfs_create_file(&engine->kobj, &engine_class_attr);
+		if (ret)
+			return ret;
+		if (engine->id == VCS) {
+			ret = sysfs_create_file(&engine->kobj, &engine_hevc_attr);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+
+static void i915_teardown_engines_sysfs(struct drm_i915_private *dev_priv)
+{
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+
+	for_each_engine(engine, dev_priv, id) {
+		sysfs_remove_file(&engine->kobj, &engine_instance_attr);
+		sysfs_remove_file(&engine->kobj, &engine_class_attr);
+		sysfs_remove_file(&engine->kobj, &engine_hevc_attr);
+	}
+
+	kobject_get(&dev_priv->topology.engines_kobj);
+	kobject_del(&dev_priv->topology.engines_kobj);
+}
+
 void i915_setup_sysfs(struct drm_i915_private *dev_priv)
 {
 	struct device *kdev = dev_priv->drm.primary->kdev;
@@ -762,6 +848,10 @@ void i915_setup_sysfs(struct drm_i915_private *dev_priv)
 	if (ret)
 		DRM_ERROR("Topology sysfs setup failed\n");
 
+	ret = i915_setup_engines_sysfs(dev_priv);
+	if (ret)
+		DRM_ERROR("Engines sysfs setup failed\n");
+
 	i915_setup_error_capture(kdev);
 }
 
@@ -771,6 +861,8 @@ void i915_teardown_sysfs(struct drm_i915_private *dev_priv)
 
 	i915_teardown_error_capture(kdev);
 
+	i915_teardown_engines_sysfs(dev_priv);
+
 	i915_teardown_topology_sysfs(dev_priv);
 
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
index 5f96533e5341..0243a9e620da 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.h
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
@@ -290,6 +290,8 @@ struct intel_engine_cs {
 	struct drm_i915_private *i915;
 	char name[INTEL_ENGINE_CS_MAX_NAME];
 
+	struct kobject kobj;
+
 	enum intel_engine_id id;
 	unsigned int hw_id;
 	unsigned int guc_id;
-- 
2.15.0