mm: re-architect the VM_UNPAGED logic
[linux-2.6] / 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 void __init pci_direct_iommu_init(void)
86 {
87         pci_dma_ops.alloc_coherent = pci_direct_alloc_coherent;
88         pci_dma_ops.free_coherent = pci_direct_free_coherent;
89         pci_dma_ops.map_single = pci_direct_map_single;
90         pci_dma_ops.unmap_single = pci_direct_unmap_single;
91         pci_dma_ops.map_sg = pci_direct_map_sg;
92         pci_dma_ops.unmap_sg = pci_direct_unmap_sg;
93         pci_dma_ops.dma_supported = pci_direct_dma_supported;
94 }