Add i915 ioctls to configure pipes for vblank interrupt.

i915 vblanks can be generated from either pipe a or b, however a disabled
pipe generates no interrupts. This change allows the X server to select
which pipe generates vblank interrupts.

From: Keith Packard <keith.packard@intel.com> via DRM CVS
Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/i915_drm.h b/drivers/char/drm/i915_drm.h
index 4cb3da5..5aa3e0e 100644
--- a/drivers/char/drm/i915_drm.h
+++ b/drivers/char/drm/i915_drm.h
@@ -124,6 +124,8 @@
 #define DRM_I915_INIT_HEAP	0x0a
 #define DRM_I915_CMDBUFFER	0x0b
 #define DRM_I915_DESTROY_HEAP	0x0c
+#define DRM_I915_SET_VBLANK_PIPE	0x0d
+#define DRM_I915_GET_VBLANK_PIPE	0x0e
 
 #define DRM_IOCTL_I915_INIT		DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
 #define DRM_IOCTL_I915_FLUSH		DRM_IO ( DRM_COMMAND_BASE + DRM_I915_FLUSH)
@@ -138,6 +140,8 @@
 #define DRM_IOCTL_I915_INIT_HEAP        DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT_HEAP, drm_i915_mem_init_heap_t)
 #define DRM_IOCTL_I915_CMDBUFFER	DRM_IOW( DRM_COMMAND_BASE + DRM_I915_CMDBUFFER, drm_i915_cmdbuffer_t)
 #define DRM_IOCTL_I915_DESTROY_HEAP	DRM_IOW( DRM_COMMAND_BASE + DRM_I915_DESTROY_HEAP, drm_i915_mem_destroy_heap_t)
+#define DRM_IOCTL_I915_SET_VBLANK_PIPE	DRM_IOW( DRM_COMMAND_BASE + DRM_I915_SET_VBLANK_PIPE, drm_i915_vblank_pipe_t)
+#define DRM_IOCTL_I915_GET_VBLANK_PIPE	DRM_IOR( DRM_COMMAND_BASE + DRM_I915_GET_VBLANK_PIPE, drm_i915_vblank_pipe_t)
 
 /* Allow drivers to submit batchbuffers directly to hardware, relying
  * on the security mechanisms provided by hardware.
@@ -224,4 +228,13 @@
 	int region;
 } drm_i915_mem_destroy_heap_t;
 
+/* Allow X server to configure which pipes to monitor for vblank signals
+ */
+#define	DRM_I915_VBLANK_PIPE_A	1
+#define	DRM_I915_VBLANK_PIPE_B	2
+
+typedef struct drm_i915_vblank_pipe {
+	int pipe;
+} drm_i915_vblank_pipe_t;
+
 #endif				/* _I915_DRM_H_ */