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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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94 lines
2.4 KiB
C
94 lines
2.4 KiB
C
/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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/*
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* DMA Coherent API Notes
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*
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* I/O is inherently non-coherent on ARC. So a coherent DMA buffer is
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* implemented by accessintg it using a kernel virtual address, with
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* Cache bit off in the TLB entry.
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*
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* The default DMA address == Phy address which is 0x8000_0000 based.
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* A platform/device can make it zero based, by over-riding
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* plat_{dma,kernel}_addr_to_{kernel,dma}
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*/
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#include <linux/dma-mapping.h>
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#include <linux/dma-debug.h>
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#include <linux/export.h>
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#include <asm/cacheflush.h>
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/*
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* Helpers for Coherent DMA API.
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*/
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void *dma_alloc_noncoherent(struct device *dev, size_t size,
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dma_addr_t *dma_handle, gfp_t gfp)
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{
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void *paddr;
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/* This is linear addr (0x8000_0000 based) */
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paddr = alloc_pages_exact(size, gfp);
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if (!paddr)
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return NULL;
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/* This is bus address, platform dependent */
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*dma_handle = plat_kernel_addr_to_dma(dev, paddr);
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return paddr;
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}
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EXPORT_SYMBOL(dma_alloc_noncoherent);
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void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr,
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dma_addr_t dma_handle)
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{
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free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle),
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size);
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}
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EXPORT_SYMBOL(dma_free_noncoherent);
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void *dma_alloc_coherent(struct device *dev, size_t size,
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dma_addr_t *dma_handle, gfp_t gfp)
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{
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void *paddr, *kvaddr;
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/* This is linear addr (0x8000_0000 based) */
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paddr = alloc_pages_exact(size, gfp);
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if (!paddr)
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return NULL;
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/* This is kernel Virtual address (0x7000_0000 based) */
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kvaddr = ioremap_nocache((unsigned long)paddr, size);
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if (kvaddr != NULL)
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memset(kvaddr, 0, size);
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/* This is bus address, platform dependent */
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*dma_handle = plat_kernel_addr_to_dma(dev, paddr);
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return kvaddr;
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}
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EXPORT_SYMBOL(dma_alloc_coherent);
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void dma_free_coherent(struct device *dev, size_t size, void *kvaddr,
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dma_addr_t dma_handle)
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{
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iounmap((void __force __iomem *)kvaddr);
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free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle),
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size);
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}
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EXPORT_SYMBOL(dma_free_coherent);
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/*
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* Helper for streaming DMA...
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*/
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void __arc_dma_cache_sync(unsigned long paddr, size_t size,
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enum dma_data_direction dir)
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{
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__inline_dma_cache_sync(paddr, size, dir);
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}
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EXPORT_SYMBOL(__arc_dma_cache_sync);
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