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Commit 9de66db4 authored by Mitchel Humpherys's avatar Mitchel Humpherys Committed by Patrick Daly
Browse files

iommu: dma-mapping-fast: Only flush non-coherent page tables 



Some SMMUs can walk page tables in the CPU cache, avoiding the need to
do cache maintenance operations on the page table memory.  Don't do
cache maintenance on SMMUs with coherent page tables.

Change-Id: I47e00e72548212209b59c13a0d7d59cb0ab964ff
Signed-off-by: default avatarMitchel Humpherys <mitchelh@codeaurora.org>
Signed-off-by: default avatarPatrick Daly <pdaly@codeaurora.org>
parent 05314f32

drivers/iommu/dma-mapping-fast.c

+16 −7
Original line number Diff line number Diff line
@@ -25,6 +25,13 @@ 
#define FAST_PAGE_MASK (~(PAGE_SIZE - 1))

#define FAST_PTE_ADDR_MASK		((av8l_fast_iopte)0xfffffffff000)



static void fast_dmac_clean_range(struct dma_fast_smmu_mapping *mapping,

				  void *start, void *end)

{

	if (!mapping->is_smmu_pt_coherent)

		dmac_clean_range(start, end);

}



/*

 * Checks if the allocated range (ending at @end) covered the upcoming

 * stale bit.  We don't need to know exactly where the range starts since
@@ -302,8 +309,7 @@ static dma_addr_t fast_smmu_map_page(struct device *dev, struct page *page, 
	if (unlikely(av8l_fast_map_public(pmd, phys_to_map, len, prot)))

		goto fail_free_iova;



	if (!skip_sync)		/* TODO: should ask SMMU if coherent */

		dmac_clean_range(pmd, pmd + nptes);

	fast_dmac_clean_range(mapping, pmd, pmd + nptes);



	spin_unlock_irqrestore(&mapping->lock, flags);

	return iova + offset_from_phys_to_map;
@@ -333,8 +339,7 @@ static void fast_smmu_unmap_page(struct device *dev, dma_addr_t iova, 


	spin_lock_irqsave(&mapping->lock, flags);

	av8l_fast_unmap_public(pmd, len);

	if (!skip_sync)		/* TODO: should ask SMMU if coherent */

		dmac_clean_range(pmd, pmd + nptes);

	fast_dmac_clean_range(mapping, pmd, pmd + nptes);

	__fast_smmu_free_iova(mapping, iova, len);

	spin_unlock_irqrestore(&mapping->lock, flags);

}
@@ -489,7 +494,7 @@ static void *fast_smmu_alloc(struct device *dev, size_t size, 
			/* TODO: unwind previously successful mappings */

			goto out_free_iova;

		}

		dmac_clean_range(ptep, ptep + nptes);

		fast_dmac_clean_range(mapping, ptep, ptep + nptes);

		iova_iter += miter.length;

	}

	sg_miter_stop(&miter);
@@ -511,7 +516,7 @@ static void *fast_smmu_alloc(struct device *dev, size_t size, 
	spin_lock_irqsave(&mapping->lock, flags);

	ptep = iopte_pmd_offset(mapping->pgtbl_pmds, dma_addr);

	av8l_fast_unmap_public(ptep, size);

	dmac_clean_range(ptep, ptep + count);

	fast_dmac_clean_range(mapping, ptep, ptep + count);

out_free_iova:

	__fast_smmu_free_iova(mapping, dma_addr, size);

	spin_unlock_irqrestore(&mapping->lock, flags);
@@ -544,7 +549,7 @@ static void fast_smmu_free(struct device *dev, size_t size, 
	ptep = iopte_pmd_offset(mapping->pgtbl_pmds, dma_handle);

	spin_lock_irqsave(&mapping->lock, flags);

	av8l_fast_unmap_public(ptep, size);

	dmac_clean_range(ptep, ptep + count);

	fast_dmac_clean_range(mapping, ptep, ptep + count);

	__fast_smmu_free_iova(mapping, dma_handle, size);

	spin_unlock_irqrestore(&mapping->lock, flags);

	__fast_smmu_free_pages(pages, count);
@@ -719,6 +724,10 @@ int fast_smmu_attach_device(struct device *dev, 
	}

	mapping->fast->pgtbl_pmds = info.pmds;



	if (iommu_domain_get_attr(domain, DOMAIN_ATTR_PAGE_TABLE_IS_COHERENT,

				  &mapping->fast->is_smmu_pt_coherent))

		return -EINVAL;



	mapping->fast->notifier.notifier_call = fast_smmu_notify;

	av8l_register_notify(&mapping->fast->notifier);

include/linux/dma-mapping-fast.h

+2 −0
Original line number Diff line number Diff line
@@ -36,6 +36,8 @@ struct dma_fast_smmu_mapping { 


	spinlock_t	lock;

	struct notifier_block notifier;



	int		is_smmu_pt_coherent;

};



#ifdef CONFIG_IOMMU_IO_PGTABLE_FAST