drm/i915/context: create & destroy ioctls

Add the interfaces to allow user space to create and destroy contexts.
Contexts are destroyed automatically if the file descriptor for the dri
device is closed.

Following convention as usual here causes checkpatch warnings.

v2: with is_initialized, no longer need to init at create
drop the context switch on create (daniel)

v3: Use interruptible lock (Chris)
return -ENODEV in !GEM case (Chris)

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 6a7b67d..5642c40 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -489,3 +489,58 @@
 		drm_gem_object_unreference(&from_obj->base);
 	return ret;
 }
+
+int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
+				  struct drm_file *file)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_gem_context_create *args = data;
+	struct drm_i915_file_private *file_priv = file->driver_priv;
+	struct i915_hw_context *ctx;
+	int ret;
+
+	if (!(dev->driver->driver_features & DRIVER_GEM))
+		return -ENODEV;
+
+	ret = i915_mutex_lock_interruptible(dev);
+	if (ret)
+		return ret;
+
+	ret = create_hw_context(dev, file_priv, &ctx);
+	mutex_unlock(&dev->struct_mutex);
+
+	args->ctx_id = ctx->id;
+	DRM_DEBUG_DRIVER("HW context %d created\n", args->ctx_id);
+
+	return ret;
+}
+
+int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
+				   struct drm_file *file)
+{
+	struct drm_i915_gem_context_destroy *args = data;
+	struct drm_i915_file_private *file_priv = file->driver_priv;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct i915_hw_context *ctx;
+	int ret;
+
+	if (!(dev->driver->driver_features & DRIVER_GEM))
+		return -ENODEV;
+
+	ret = i915_mutex_lock_interruptible(dev);
+	if (ret)
+		return ret;
+
+	ctx = i915_gem_context_get(file_priv, args->ctx_id);
+	if (!ctx) {
+		mutex_unlock(&dev->struct_mutex);
+		return -EINVAL;
+	}
+
+	do_destroy(ctx);
+
+	mutex_unlock(&dev->struct_mutex);
+
+	DRM_DEBUG_DRIVER("HW context %d destroyed\n", args->ctx_id);
+	return 0;
+}