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>

drivers/gpu/drm/drm_drv.c

@@ -67,6 +67,7 @@ static struct drm_ioctl_desc drm_ioctls[] = {
 	DRM_IOCTL_DEF(DRM_IOCTL_GET_MAP, drm_getmap, 0),
 	DRM_IOCTL_DEF(DRM_IOCTL_GET_CLIENT, drm_getclient, 0),
 	DRM_IOCTL_DEF(DRM_IOCTL_GET_STATS, drm_getstats, 0),
+	DRM_IOCTL_DEF(DRM_IOCTL_GET_CAP, drm_getcap, 0),
 	DRM_IOCTL_DEF(DRM_IOCTL_SET_VERSION, drm_setversion, DRM_MASTER),
 
 	DRM_IOCTL_DEF(DRM_IOCTL_SET_UNIQUE, drm_setunique, DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),

drivers/gpu/drm/drm_ioctl.c

@@ -267,6 +267,17 @@ int drm_getstats(struct drm_device *dev, void *data,
 	return 0;
 }
 
+/**
+ * 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.
  *

include/drm/drm.h

@@ -608,6 +608,12 @@ struct drm_gem_open {
 	__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 @@ struct drm_gem_open {
 #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)

include/drm/drmP.h

@@ -1276,6 +1276,8 @@ extern int drm_getclient(struct drm_device *dev, void *data,
 			 struct drm_file *file_priv);
 extern int drm_getstats(struct drm_device *dev, void *data,
 			struct drm_file *file_priv);
+extern int drm_getcap(struct drm_device *dev, void *data,
+		      struct drm_file *file_priv);
 extern int drm_setversion(struct drm_device *dev, void *data,
 			  struct drm_file *file_priv);
 extern int drm_noop(struct drm_device *dev, void *data,