Commit c30700db authored by Christoph Hellwig's avatar Christoph Hellwig
Browse files

dma-direct: provide generic support for uncached kernel segments 



A few architectures support uncached kernel segments.  In that case we get
an uncached mapping for a given physica address by using an offset in the
uncached segement.  Implement support for this scheme in the generic
dma-direct code instead of duplicating it in arch hooks.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 67f30ad1

arch/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -260,6 +260,14 @@ config ARCH_HAS_SET_MEMORY 
config ARCH_HAS_SET_DIRECT_MAP

	bool



#

# Select if arch has an uncached kernel segment and provides the

# uncached_kernel_address / cached_kernel_address symbols to use it

#

config ARCH_HAS_UNCACHED_SEGMENT

	select ARCH_HAS_DMA_PREP_COHERENT

	bool



# Select if arch init_task must go in the __init_task_data section

config ARCH_TASK_STRUCT_ON_STACK

       bool

include/linux/dma-noncoherent.h

+3 −0
Original line number Diff line number Diff line
@@ -80,4 +80,7 @@ static inline void arch_dma_prep_coherent(struct page *page, size_t size) 
}

#endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */



void *uncached_kernel_address(void *addr);

void *cached_kernel_address(void *addr);



#endif /* _LINUX_DMA_NONCOHERENT_H */

kernel/dma/direct.c

+15 −2
Original line number Diff line number Diff line
@@ -158,6 +158,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, 
		*dma_handle = phys_to_dma(dev, page_to_phys(page));

	}

	memset(ret, 0, size);



	if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&

	    !dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT)) {

		arch_dma_prep_coherent(page, size);

		ret = uncached_kernel_address(ret);

	}



	return ret;

}
@@ -173,13 +180,18 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, 


	if (force_dma_unencrypted())

		set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);



	if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&

	    !dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT))

		cpu_addr = cached_kernel_address(cpu_addr);

	__dma_direct_free_pages(dev, size, virt_to_page(cpu_addr));

}



void *dma_direct_alloc(struct device *dev, size_t size,

		dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)

{

	if (!dev_is_dma_coherent(dev))

	if (!IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&

	    !dev_is_dma_coherent(dev))

		return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);

	return dma_direct_alloc_pages(dev, size, dma_handle, gfp, attrs);

}
@@ -187,7 +199,8 @@ void *dma_direct_alloc(struct device *dev, size_t size, 
void dma_direct_free(struct device *dev, size_t size,

		void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs)

{

	if (!dev_is_dma_coherent(dev))

	if (!IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&

	    !dev_is_dma_coherent(dev))

		arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);

	else

		dma_direct_free_pages(dev, size, cpu_addr, dma_addr, attrs);

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