drm/core: add ioctl to query device/driver capabilities

We're coming to see a need to have a set of generic capability checks in
the core DRM, in addition to the driver-specific ioctls that already
exist.

This patch defines an ioctl to do as such, but does not yet define any
capabilities.

[airlied: drop the driver callback for now.]

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 1174905..d6de9d0 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -268,6 +268,17 @@
 }
 
 /**
+ * Get device/driver capabilities
+ */
+int drm_getcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
+{
+	struct drm_get_cap *req = data;
+
+	req->value = 0;
+	return 0;
+}
+
+/**
  * Setversion ioctl.
  *
  * \param inode device inode.