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dma-direct: provide a arch_dma_clear_uncached hook

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This allows the arch code to reset the page tables to cached access when
freeing a dma coherent allocation that was set to uncached using
arch_dma_set_uncached.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
This commit is contained in:
Christoph Hellwig 2020-02-21 12:35:05 -08:00
parent fa7e2247c5
commit 999a5d1203
3 changed files with 10 additions and 0 deletions
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7
arch/Kconfig
View File

@ -255,6 +255,13 @@ config ARCH_HAS_SET_DIRECT_MAP
config ARCH_HAS_DMA_SET_UNCACHED
bool
#
# Select if the architectures provides the arch_dma_clear_uncached symbol
# to undo an in-place page table remap for uncached access.
#
config ARCH_HAS_DMA_CLEAR_UNCACHED
bool
# Select if arch init_task must go in the __init_task_data section
config ARCH_TASK_STRUCT_ON_STACK
bool

1
include/linux/dma-noncoherent.h
View File

@ -109,5 +109,6 @@ static inline void arch_dma_prep_coherent(struct page *page, size_t size)
#endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */
void *arch_dma_set_uncached(void *addr, size_t size);
void arch_dma_clear_uncached(void *addr, size_t size);
#endif /* _LINUX_DMA_NONCOHERENT_H */

2
kernel/dma/direct.c
View File

@ -231,6 +231,8 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr))
vunmap(cpu_addr);
else if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED))
arch_dma_clear_uncached(cpu_addr, size);
dma_free_contiguous(dev, dma_direct_to_page(dev, dma_addr), size);
}