arch/ppc64/kernel/pci_direct_iommu.c

   1 /*
   2  * Support for DMA from PCI devices to main memory on
   3  * machines without an iommu or with directly addressable
   4  * RAM (typically a pmac with 2Gb of RAM or less)
   5  *
   6  * Copyright (C) 2003 Benjamin Herrenschmidt (benh@kernel.crashing.org)
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the License, or (at your option) any later version.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/pci.h>
  16 #include <linux/delay.h>
  17 #include <linux/string.h>
  18 #include <linux/init.h>
  19 #include <linux/bootmem.h>
  20 #include <linux/mm.h>
  21 #include <linux/dma-mapping.h>
  22
  23 #include <asm/sections.h>
  24 #include <asm/io.h>
  25 #include <asm/prom.h>
  26 #include <asm/pci-bridge.h>
  27 #include <asm/machdep.h>
  28 #include <asm/pmac_feature.h>
  29 #include <asm/abs_addr.h>
  30
  31 #include "pci.h"
  32
  33 static void *pci_direct_alloc_coherent(struct device *hwdev, size_t size,
  34                                    dma_addr_t *dma_handle, unsigned int __nocast flag)
  35 {
  36         void *ret;
  37
  38         ret = (void *)__get_free_pages(flag, get_order(size));
  39         if (ret != NULL) {
  40                 memset(ret, 0, size);
  41                 *dma_handle = virt_to_abs(ret);
  42         }
  43         return ret;
  44 }
  45
  46 static void pci_direct_free_coherent(struct device *hwdev, size_t size,
  47                                  void *vaddr, dma_addr_t dma_handle)
  48 {
  49         free_pages((unsigned long)vaddr, get_order(size));
  50 }
  51
  52 static dma_addr_t pci_direct_map_single(struct device *hwdev, void *ptr,
  53                 size_t size, enum dma_data_direction direction)
  54 {
  55         return virt_to_abs(ptr);
  56 }
  57
  58 static void pci_direct_unmap_single(struct device *hwdev, dma_addr_t dma_addr,
  59                 size_t size, enum dma_data_direction direction)
  60 {
  61 }
  62
  63 static int pci_direct_map_sg(struct device *hwdev, struct scatterlist *sg,
  64                 int nents, enum dma_data_direction direction)
  65 {
  66         int i;
  67
  68         for (i = 0; i < nents; i++, sg++) {
  69                 sg->dma_address = page_to_phys(sg->page) + sg->offset;
  70                 sg->dma_length = sg->length;
  71         }
  72
  73         return nents;
  74 }
  75
  76 static void pci_direct_unmap_sg(struct device *hwdev, struct scatterlist *sg,
  77                 int nents, enum dma_data_direction direction)
  78 {
  79 }
  80
  81 static int pci_direct_dma_supported(struct device *dev, u64 mask)
  82 {
  83         return mask < 0x100000000ull;
  84 }
  85
  86 void __init pci_direct_iommu_init(void)
  87 {
  88         pci_dma_ops.alloc_coherent = pci_direct_alloc_coherent;
  89         pci_dma_ops.free_coherent = pci_direct_free_coherent;
  90         pci_dma_ops.map_single = pci_direct_map_single;
  91         pci_dma_ops.unmap_single = pci_direct_unmap_single;
  92         pci_dma_ops.map_sg = pci_direct_map_sg;
  93         pci_dma_ops.unmap_sg = pci_direct_unmap_sg;
  94         pci_dma_ops.dma_supported = pci_direct_dma_supported;
  95 }