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kernel/linux-imx6_3.14.28/arch/arc/mm/dma.c 2.41 KB
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6b13f685e   김민수   BSP 최초 추가 
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  /*
   * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  /*
   * DMA Coherent API Notes
   *
   * I/O is inherently non-coherent on ARC. So a coherent DMA buffer is
   * implemented by accessintg it using a kernel virtual address, with
   * Cache bit off in the TLB entry.
   *
   * The default DMA address == Phy address which is 0x8000_0000 based.
   * A platform/device can make it zero based, by over-riding
   * plat_{dma,kernel}_addr_to_{kernel,dma}
   */
  
  #include <linux/dma-mapping.h>
  #include <linux/dma-debug.h>
  #include <linux/export.h>
  #include <asm/cacheflush.h>
  
  /*
   * Helpers for Coherent DMA API.
   */
  void *dma_alloc_noncoherent(struct device *dev, size_t size,
  			    dma_addr_t *dma_handle, gfp_t gfp)
  {
  	void *paddr;
  
  	/* This is linear addr (0x8000_0000 based) */
  	paddr = alloc_pages_exact(size, gfp);
  	if (!paddr)
  		return NULL;
  
  	/* This is bus address, platform dependent */
  	*dma_handle = plat_kernel_addr_to_dma(dev, paddr);
  
  	return paddr;
  }
  EXPORT_SYMBOL(dma_alloc_noncoherent);
  
  void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr,
  			  dma_addr_t dma_handle)
  {
  	free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle),
  			 size);
  }
  EXPORT_SYMBOL(dma_free_noncoherent);
  
  void *dma_alloc_coherent(struct device *dev, size_t size,
  			 dma_addr_t *dma_handle, gfp_t gfp)
  {
  	void *paddr, *kvaddr;
  
  	/* This is linear addr (0x8000_0000 based) */
  	paddr = alloc_pages_exact(size, gfp);
  	if (!paddr)
  		return NULL;
  
  	/* This is kernel Virtual address (0x7000_0000 based) */
  	kvaddr = ioremap_nocache((unsigned long)paddr, size);
  	if (kvaddr != NULL)
  		memset(kvaddr, 0, size);
  
  	/* This is bus address, platform dependent */
  	*dma_handle = plat_kernel_addr_to_dma(dev, paddr);
  
  	return kvaddr;
  }
  EXPORT_SYMBOL(dma_alloc_coherent);
  
  void dma_free_coherent(struct device *dev, size_t size, void *kvaddr,
  		       dma_addr_t dma_handle)
  {
  	iounmap((void __force __iomem *)kvaddr);
  
  	free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle),
  			 size);
  }
  EXPORT_SYMBOL(dma_free_coherent);
  
  /*
   * Helper for streaming DMA...
   */
  void __arc_dma_cache_sync(unsigned long paddr, size_t size,
  			  enum dma_data_direction dir)
  {
  	__inline_dma_cache_sync(paddr, size, dir);
  }
  EXPORT_SYMBOL(__arc_dma_cache_sync);