exa: add a pixmap private pointer for drivers to retrieve.

exa/exa.c

@@ -74,6 +74,14 @@ exaGetPixmapOffset(PixmapPtr pPix)
 	    (unsigned long)pExaScr->info->memoryBase);
 }
 
+void *
+exaGetPixmapDriverPrivate(PixmapPtr pPix)
+{
+    ExaPixmapPriv(pPix);
+
+    return pExaPixmap->driverPriv;
+}
+
 /**
  * exaGetPixmapPitch() returns the pitch (in bytes) of the given pixmap.
  *

exa/exa.h

@@ -773,6 +773,9 @@ exaMoveInPixmap (PixmapPtr pPixmap);
 void
 exaMoveOutPixmap (PixmapPtr pPixmap);
 
+void *
+exaGetPixmapDriverPrivate(PixmapPtr p);
+
 /**
  * Returns TRUE if the given planemask covers all the significant bits in the
  * pixel values for pDrawable.

exa/exa_priv.h

@@ -192,6 +192,10 @@ typedef struct {
      * damage, which may be overreported) of a pixmap's system and FB copies.
      */
     RegionRec	    validSys, validFB;
+    /**
+     * Driver private storage per EXA pixmap
+     */
+    void *driverPriv;
 } ExaPixmapPrivRec, *ExaPixmapPrivPtr;
  
 typedef struct _ExaMigrationRec {