REG_GCRBTR
(gc_readl(priv, REG_GCRBTR) - base) / 4); \
gc_writel(priv, REG_GCRBTR, priv->shared_phys);
(gc_readl(priv, REG_GCRBTR) - base) / 4);
gc_writel(priv, REG_GCRBTR, shared->buffer_phys + num * 4);