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/include/drm/drm.h b/include/drm/drm.h
index 8598cc9..da4efd1 100644
--- a/include/drm/drm.h
+++ b/include/drm/drm.h
@@ -608,6 +608,12 @@
 	__u64 size;
 };
 
+/** DRM_IOCTL_GET_CAP ioctl argument type */
+struct drm_get_cap {
+	__u64 capability;
+	__u64 value;
+};
+
 #include "drm_mode.h"
 
 #define DRM_IOCTL_BASE			'd'
@@ -628,6 +634,7 @@
 #define DRM_IOCTL_GEM_CLOSE		DRM_IOW (0x09, struct drm_gem_close)
 #define DRM_IOCTL_GEM_FLINK		DRM_IOWR(0x0a, struct drm_gem_flink)
 #define DRM_IOCTL_GEM_OPEN		DRM_IOWR(0x0b, struct drm_gem_open)
+#define DRM_IOCTL_GET_CAP		DRM_IOWR(0x0c, struct drm_get_cap)
 
 #define DRM_IOCTL_SET_UNIQUE		DRM_IOW( 0x10, struct drm_unique)
 #define DRM_IOCTL_AUTH_MAGIC		DRM_IOW( 0x11, struct drm_auth)