arch/arc/mm/dma.c

   1 /*
   2  * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 /*
  10  * DMA Coherent API Notes
  11  *
  12  * I/O is inherently non-coherent on ARC. So a coherent DMA buffer is
  13  * implemented by accessintg it using a kernel virtual address, with
  14  * Cache bit off in the TLB entry.
  15  *
  16  * The default DMA address == Phy address which is 0x8000_0000 based.
  17  * A platform/device can make it zero based, by over-riding
  18  * plat_{dma,kernel}_addr_to_{kernel,dma}
  19  */
  20
  21 #include <linux/dma-mapping.h>
  22 #include <linux/dma-debug.h>
  23 #include <linux/export.h>
  24 #include <asm/cacheflush.h>
  25
  26 /*
  27  * Helpers for Coherent DMA API.
  28  */
  29 void *dma_alloc_noncoherent(struct device *dev, size_t size,
  30                             dma_addr_t *dma_handle, gfp_t gfp)
  31 {
  32         void *paddr;
  33
  34         /* This is linear addr (0x8000_0000 based) */
  35         paddr = alloc_pages_exact(size, gfp);
  36         if (!paddr)
  37                 return NULL;
  38
  39         /* This is bus address, platform dependent */
  40         *dma_handle = plat_kernel_addr_to_dma(dev, paddr);
  41
  42         return paddr;
  43 }
  44 EXPORT_SYMBOL(dma_alloc_noncoherent);
  45
  46 void dma_free_noncoherent(struct device *dev, size_t size, void *vaddr,
  47                           dma_addr_t dma_handle)
  48 {
  49         free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle),
  50                          size);
  51 }
  52 EXPORT_SYMBOL(dma_free_noncoherent);
  53
  54 void *dma_alloc_coherent(struct device *dev, size_t size,
  55                          dma_addr_t *dma_handle, gfp_t gfp)
  56 {
  57         void *paddr, *kvaddr;
  58
  59         /* This is linear addr (0x8000_0000 based) */
  60         paddr = alloc_pages_exact(size, gfp);
  61         if (!paddr)
  62                 return NULL;
  63
  64         /* This is kernel Virtual address (0x7000_0000 based) */
  65         kvaddr = ioremap_nocache((unsigned long)paddr, size);
  66         if (kvaddr != NULL)
  67                 memset(kvaddr, 0, size);
  68
  69         /* This is bus address, platform dependent */
  70         *dma_handle = plat_kernel_addr_to_dma(dev, paddr);
  71
  72         return kvaddr;
  73 }
  74 EXPORT_SYMBOL(dma_alloc_coherent);
  75
  76 void dma_free_coherent(struct device *dev, size_t size, void *kvaddr,
  77                        dma_addr_t dma_handle)
  78 {
  79         iounmap((void __force __iomem *)kvaddr);
  80
  81         free_pages_exact((void *)plat_dma_addr_to_kernel(dev, dma_handle),
  82                          size);
  83 }
  84 EXPORT_SYMBOL(dma_free_coherent);
  85
  86 /*
  87  * Helper for streaming DMA...
  88  */
  89 void __arc_dma_cache_sync(unsigned long paddr, size_t size,
  90                           enum dma_data_direction dir)
  91 {
  92         __inline_dma_cache_sync(paddr, size, dir);
  93 }
  94 EXPORT_SYMBOL(__arc_dma_cache_sync);