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[PATCH 3/5 v2] powerpc/dma: implement per-platform dma_get_page_shift

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The IOMMU page size is not always stored in struct iommu on Power.
Specifically if a device is configured for DDW (Dynamic DMA Windows aka.
64-bit direct DMA), the used TCE (Translation Control Entry) size is
stored in a special device property created at run-time by the DDW
configuration code. DDW is a pseries-specific feature, so allow
platforms to override the implementation of dma_get_page_shift if
desired.

Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index cab6753..5c372e3 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -78,9 +78,10 @@ struct machdep_calls {
 #endif
 #endif /* CONFIG_PPC64 */
 
-	/* Platform set_dma_mask and dma_get_required_mask overrides */
+	/* Platform overrides */
 	int		(*dma_set_mask)(struct device *dev, u64 dma_mask);
 	u64		(*dma_get_required_mask)(struct device *dev);
+	unsigned long	(*dma_get_page_shift)(struct device *dev);
 
 	int		(*probe)(void);
 	void		(*setup_arch)(void); /* Optional, may be NULL */
diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c
index e805af2..c363896 100644
--- a/arch/powerpc/kernel/dma.c
+++ b/arch/powerpc/kernel/dma.c
@@ -338,6 +338,8 @@ EXPORT_SYMBOL(dma_set_mask);
 unsigned long dma_get_page_shift(struct device *dev)
 {
 	struct iommu_table *tbl = get_iommu_table_base(dev);
+	if (ppc_md.dma_get_page_shift)
+		return ppc_md.dma_get_page_shift(dev);
 	if (tbl)
 		return tbl->it_page_shift;
 	return PAGE_SHIFT;

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[PATCH 0/2] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 19:20 +0200
  [PATCH 1/2] powerpc/iommu: expose IOMMU page shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 19:20 +0200
    [PATCH 2/2] drivers/nvme: default to the IOMMU page size on Power Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 19:30 +0200
      Re: [PATCH 2/2] drivers/nvme: default to the IOMMU page size on Power Christoph Hellwig <hch@infradead.org> - 2015-10-02 19:30 +0200
        Re: [PATCH 2/2] drivers/nvme: default to the IOMMU page size on Power Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 19:50 +0200
          Re: [PATCH 2/2] drivers/nvme: default to the IOMMU page size on Power Christoph Hellwig <hch@infradead.org> - 2015-10-02 19:50 +0200
  [PATCH 2/5 v2] powerpc/dma-mapping: override dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 22:20 +0200
    [PATCH 3/5 v2] powerpc/dma: implement per-platform dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 22:20 +0200
      [PATCH 4/5 v2] pseries/iommu: implement DDW-aware dma_get_page_shift Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 22:30 +0200
        [PATCH 5/5 v2] drivers/nvme: default to the IOMMU page size Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 22:40 +0200
        Re: [PATCH 4/5 v2] pseries/iommu: implement DDW-aware  dma_get_page_shift kbuild test robot <lkp@intel.com> - 2015-10-02 22:40 +0200
  [PATCH 1/5 v2] dma-mapping: add generic dma_get_page_shift API Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 22:20 +0200
  [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 22:20 +0200
    Re: [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-02 23:10 +0200
      Re: [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-10-02 23:40 +0200
        Re: [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Nishanth Aravamudan <nacc@linux.vnet.ibm.com> - 2015-10-03 00:00 +0200
    Re: [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-10-02 23:30 +0200
      Re: [PATCH 0/5 v2] Fix NVMe driver support on Power with 32-bit DMA Christoph Hellwig <hch@infradead.org> - 2015-10-03 10:30 +0200

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