arch/powerpc/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 #include <asm/ppc-pci.h>
  31
  32 static void *pci_direct_alloc_coherent(struct device *hwdev, size_t size,
  33                                    dma_addr_t *dma_handle, gfp_t flag)
  34 {
  35         void *ret;
  36
  37         ret = (void *)__get_free_pages(flag, get_order(size));
  38         if (ret != NULL) {
  39                 memset(ret, 0, size);
  40                 *dma_handle = virt_to_abs(ret);
  41         }
  42         return ret;
  43 }
  44
  45 static void pci_direct_free_coherent(struct device *hwdev, size_t size,
  46                                  void *vaddr, dma_addr_t dma_handle)
  47 {
  48         free_pages((unsigned long)vaddr, get_order(size));
  49 }
  50
  51 static dma_addr_t pci_direct_map_single(struct device *hwdev, void *ptr,
  52                 size_t size, enum dma_data_direction direction)
  53 {
  54         return virt_to_abs(ptr);
  55 }
  56
  57 static void pci_direct_unmap_single(struct device *hwdev, dma_addr_t dma_addr,
  58                 size_t size, enum dma_data_direction direction)
  59 {
  60 }
  61
  62 static int pci_direct_map_sg(struct device *hwdev, struct scatterlist *sg,
  63                 int nents, enum dma_data_direction direction)
  64 {
  65         int i;
  66
  67         for (i = 0; i < nents; i++, sg++) {
  68                 sg->dma_address = page_to_phys(sg->page) + sg->offset;
  69                 sg->dma_length = sg->length;
  70         }
  71
  72         return nents;
  73 }
  74
  75 static void pci_direct_unmap_sg(struct device *hwdev, struct scatterlist *sg,
  76                 int nents, enum dma_data_direction direction)
  77 {
  78 }
  79
  80 static int pci_direct_dma_supported(struct device *dev, u64 mask)
  81 {
  82         return mask < 0x100000000ull;
  83 }
  84
  85 static struct dma_mapping_ops pci_direct_ops = {
  86         .alloc_coherent = pci_direct_alloc_coherent,
  87         .free_coherent = pci_direct_free_coherent,
  88         .map_single = pci_direct_map_single,
  89         .unmap_single = pci_direct_unmap_single,
  90         .map_sg = pci_direct_map_sg,
  91         .unmap_sg = pci_direct_unmap_sg,
  92         .dma_supported = pci_direct_dma_supported,
  93 };
  94
  95 void __init pci_direct_iommu_init(void)
  96 {
  97         pci_dma_ops = pci_direct_ops;
  98 }