1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation
4 *
5 * Provide default implementations of the DMA mapping callbacks for
6 * busses using the iommu infrastructure
7 */
8
9#include <linux/dma-direct.h>
10#include <linux/pci.h>
11#include <asm/iommu.h>
12
13#ifdef CONFIG_ARCH_HAS_DMA_MAP_DIRECT
14#define can_map_direct(dev, addr) \
15 ((dev)->bus_dma_limit >= phys_to_dma((dev), (addr)))
16
17bool arch_dma_map_phys_direct(struct device *dev, phys_addr_t addr)
18{
19 if (likely(!dev->bus_dma_limit))
20 return false;
21
22 return can_map_direct(dev, addr);
23}
24
25#define is_direct_handle(dev, h) ((h) >= (dev)->archdata.dma_offset)
26
27bool arch_dma_unmap_phys_direct(struct device *dev, dma_addr_t dma_handle)
28{
29 if (likely(!dev->bus_dma_limit))
30 return false;
31
32 return is_direct_handle(dev, dma_handle);
33}
34
35bool arch_dma_map_sg_direct(struct device *dev, struct scatterlist *sg,
36 int nents)
37{
38 struct scatterlist *s;
39 int i;
40
41 if (likely(!dev->bus_dma_limit))
42 return false;
43
44 for_each_sg(sg, s, nents, i) {
45 if (!can_map_direct(dev, sg_phys(s) + s->offset + s->length))
46 return false;
47 }
48
49 return true;
50}
51
52bool arch_dma_unmap_sg_direct(struct device *dev, struct scatterlist *sg,
53 int nents)
54{
55 struct scatterlist *s;
56 int i;
57
58 if (likely(!dev->bus_dma_limit))
59 return false;
60
61 for_each_sg(sg, s, nents, i) {
62 if (!is_direct_handle(dev, s->dma_address + s->length))
63 return false;
64 }
65
66 return true;
67}
68#endif /* CONFIG_ARCH_HAS_DMA_MAP_DIRECT */
69
70/*
71 * Generic iommu implementation
72 */
73
74/* Allocates a contiguous real buffer and creates mappings over it.
75 * Returns the virtual address of the buffer and sets dma_handle
76 * to the dma address (mapping) of the first page.
77 */
78static void *dma_iommu_alloc_coherent(struct device *dev, size_t size,
79 dma_addr_t *dma_handle, gfp_t flag,
80 unsigned long attrs)
81{
82 return iommu_alloc_coherent(dev, get_iommu_table_base(dev), size,
83 dma_handle, dev->coherent_dma_mask, flag,
84 dev_to_node(dev));
85}
86
87static void dma_iommu_free_coherent(struct device *dev, size_t size,
88 void *vaddr, dma_addr_t dma_handle,
89 unsigned long attrs)
90{
91 iommu_free_coherent(get_iommu_table_base(dev), size, vaddr, dma_handle);
92}
93
94/* Creates TCEs for a user provided buffer. The user buffer must be
95 * contiguous real kernel storage (not vmalloc). The address passed here
96 * is a physical address to that page. The dma_addr_t returned will point
97 * to the same byte within the page as was passed in.
98 */
99static dma_addr_t dma_iommu_map_phys(struct device *dev, phys_addr_t phys,
100 size_t size,
101 enum dma_data_direction direction,
102 unsigned long attrs)
103{
104 return iommu_map_phys(dev, get_iommu_table_base(dev), phys, size,
105 dma_get_mask(dev), direction, attrs);
106}
107
108static void dma_iommu_unmap_phys(struct device *dev, dma_addr_t dma_handle,
109 size_t size, enum dma_data_direction direction,
110 unsigned long attrs)
111{
112 iommu_unmap_phys(get_iommu_table_base(dev), dma_handle, size, direction,
113 attrs);
114}
115
116static int dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
117 int nelems, enum dma_data_direction direction,
118 unsigned long attrs)
119{
120 return ppc_iommu_map_sg(dev, get_iommu_table_base(dev), sglist, nelems,
121 dma_get_mask(dev), direction, attrs);
122}
123
124static void dma_iommu_unmap_sg(struct device *dev, struct scatterlist *sglist,
125 int nelems, enum dma_data_direction direction,
126 unsigned long attrs)
127{
128 ppc_iommu_unmap_sg(get_iommu_table_base(dev), sglist, nelems,
129 direction, attrs);
130}
131
132static bool dma_iommu_bypass_supported(struct device *dev, u64 mask)
133{
134 struct pci_dev *pdev = to_pci_dev(dev);
135 struct pci_controller *phb = pci_bus_to_host(pdev->bus);
136
137 if (!phb->controller_ops.iommu_bypass_supported)
138 return false;
139 return phb->controller_ops.iommu_bypass_supported(pdev, mask);
140}
141
142/* We support DMA to/from any memory page via the iommu */
143int dma_iommu_dma_supported(struct device *dev, u64 mask)
144{
145 struct iommu_table *tbl;
146
147 if (dev_is_pci(dev) && dma_iommu_bypass_supported(dev, mask)) {
148 /*
149 * dma_iommu_bypass_supported() sets dma_max when there is
150 * 1:1 mapping but it is somehow limited.
151 * ibm,pmemory is one example.
152 */
153 dev->dma_ops_bypass = dev->bus_dma_limit == 0;
154 if (!dev->dma_ops_bypass)
155 dev_warn(dev,
156 "iommu: 64-bit OK but direct DMA is limited by %llx\n",
157 dev->bus_dma_limit);
158 else
159 dev_dbg(dev, "iommu: 64-bit OK, using fixed ops\n");
160 return 1;
161 }
162
163 tbl = get_iommu_table_base(dev);
164
165 if (!tbl) {
166 dev_err(dev, "Warning: IOMMU dma not supported: mask 0x%08llx, table unavailable\n", mask);
167 return 0;
168 }
169
170 if (tbl->it_offset > (mask >> tbl->it_page_shift)) {
171 dev_info(dev, "Warning: IOMMU offset too big for device mask\n");
172 dev_info(dev, "mask: 0x%08llx, table offset: 0x%08lx\n",
173 mask, tbl->it_offset << tbl->it_page_shift);
174 return 0;
175 }
176
177 dev_dbg(dev, "iommu: not 64-bit, using default ops\n");
178 dev->dma_ops_bypass = false;
179 return 1;
180}
181
182u64 dma_iommu_get_required_mask(struct device *dev)
183{
184 struct iommu_table *tbl = get_iommu_table_base(dev);
185 u64 mask;
186
187 if (dev_is_pci(dev)) {
188 u64 bypass_mask = dma_direct_get_required_mask(dev);
189
190 if (dma_iommu_dma_supported(dev, mask: bypass_mask)) {
191 dev_info(dev, "%s: returning bypass mask 0x%llx\n", __func__, bypass_mask);
192 return bypass_mask;
193 }
194 }
195
196 if (!tbl)
197 return 0;
198
199 mask = 1ULL << (fls_long(l: tbl->it_offset + tbl->it_size) +
200 tbl->it_page_shift - 1);
201 mask += mask - 1;
202
203 return mask;
204}
205
206const struct dma_map_ops dma_iommu_ops = {
207 .alloc = dma_iommu_alloc_coherent,
208 .free = dma_iommu_free_coherent,
209 .map_sg = dma_iommu_map_sg,
210 .unmap_sg = dma_iommu_unmap_sg,
211 .dma_supported = dma_iommu_dma_supported,
212 .map_phys = dma_iommu_map_phys,
213 .unmap_phys = dma_iommu_unmap_phys,
214 .get_required_mask = dma_iommu_get_required_mask,
215 .mmap = dma_common_mmap,
216 .get_sgtable = dma_common_get_sgtable,
217 .alloc_pages_op = dma_common_alloc_pages,
218 .free_pages = dma_common_free_pages,
219};
220

source code of linux/arch/powerpc/kernel/dma-iommu.c