powerpc/cell: use the generic iommu bypass code

This gets rid of a lot of clumsy code and finally allows us to mark
dma_iommu_ops const.

Includes fixes from Michael Ellerman.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/dma-mapping.h

@@ -74,7 +74,7 @@ static inline unsigned long device_to_mask(struct device *dev)
  * Available generic sets of operations
  */
 #ifdef CONFIG_PPC64
-extern struct dma_map_ops dma_iommu_ops;
+extern const struct dma_map_ops dma_iommu_ops;
 #endif
 extern const struct dma_map_ops dma_nommu_ops;
 

arch/powerpc/include/asm/iommu.h

@@ -319,5 +319,11 @@ extern void iommu_release_ownership(struct iommu_table *tbl);
 extern enum dma_data_direction iommu_tce_direction(unsigned long tce);
 extern unsigned long iommu_direction_to_tce_perm(enum dma_data_direction dir);
 
+#ifdef CONFIG_PPC_CELL_NATIVE
+extern bool iommu_fixed_is_weak;
+#else
+#define iommu_fixed_is_weak false
+#endif
+
 #endif /* __KERNEL__ */
 #endif /* _ASM_IOMMU_H */