LXR linux/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 */
  29void *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}
  44EXPORT_SYMBOL(dma_alloc_noncoherent);
  45
  46void 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}
  52EXPORT_SYMBOL(dma_free_noncoherent);
  53
  54void *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}
  74EXPORT_SYMBOL(dma_alloc_coherent);
  75
  76void 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}
  84EXPORT_SYMBOL(dma_free_coherent);
  85
  86/*
  87 * Helper for streaming DMA...
  88 */
  89void __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}
  94EXPORT_SYMBOL(__arc_dma_cache_sync);
  95