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 
arch_dma_map_page_direct(struct device * dev,phys_addr_t addr)17 bool arch_dma_map_page_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 
arch_dma_unmap_page_direct(struct device * dev,dma_addr_t dma_handle)27 bool arch_dma_unmap_page_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 
arch_dma_map_sg_direct(struct device * dev,struct scatterlist * sg,int nents)35 bool 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 
arch_dma_unmap_sg_direct(struct device * dev,struct scatterlist * sg,int nents)52 bool 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  */
dma_iommu_alloc_coherent(struct device * dev,size_t size,dma_addr_t * dma_handle,gfp_t flag,unsigned long attrs)78 static 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 
dma_iommu_free_coherent(struct device * dev,size_t size,void * vaddr,dma_addr_t dma_handle,unsigned long attrs)87 static 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  * comprises a page address and offset into that page. The dma_addr_t
97  * returned will point to the same byte within the page as was passed in.
98  */
dma_iommu_map_page(struct device * dev,struct page * page,unsigned long offset,size_t size,enum dma_data_direction direction,unsigned long attrs)99 static dma_addr_t dma_iommu_map_page(struct device *dev, struct page *page,
100 				     unsigned long offset, size_t size,
101 				     enum dma_data_direction direction,
102 				     unsigned long attrs)
103 {
104 	return iommu_map_page(dev, get_iommu_table_base(dev), page, offset,
105 			      size, dma_get_mask(dev), direction, attrs);
106 }
107 
108 
dma_iommu_unmap_page(struct device * dev,dma_addr_t dma_handle,size_t size,enum dma_data_direction direction,unsigned long attrs)109 static void dma_iommu_unmap_page(struct device *dev, dma_addr_t dma_handle,
110 				 size_t size, enum dma_data_direction direction,
111 				 unsigned long attrs)
112 {
113 	iommu_unmap_page(get_iommu_table_base(dev), dma_handle, size, direction,
114 			 attrs);
115 }
116 
117 
dma_iommu_map_sg(struct device * dev,struct scatterlist * sglist,int nelems,enum dma_data_direction direction,unsigned long attrs)118 static int dma_iommu_map_sg(struct device *dev, struct scatterlist *sglist,
119 			    int nelems, enum dma_data_direction direction,
120 			    unsigned long attrs)
121 {
122 	return ppc_iommu_map_sg(dev, get_iommu_table_base(dev), sglist, nelems,
123 				dma_get_mask(dev), direction, attrs);
124 }
125 
dma_iommu_unmap_sg(struct device * dev,struct scatterlist * sglist,int nelems,enum dma_data_direction direction,unsigned long attrs)126 static void dma_iommu_unmap_sg(struct device *dev, struct scatterlist *sglist,
127 		int nelems, enum dma_data_direction direction,
128 		unsigned long attrs)
129 {
130 	ppc_iommu_unmap_sg(get_iommu_table_base(dev), sglist, nelems,
131 			   direction, attrs);
132 }
133 
dma_iommu_bypass_supported(struct device * dev,u64 mask)134 static bool dma_iommu_bypass_supported(struct device *dev, u64 mask)
135 {
136 	struct pci_dev *pdev = to_pci_dev(dev);
137 	struct pci_controller *phb = pci_bus_to_host(pdev->bus);
138 
139 	if (iommu_fixed_is_weak || !phb->controller_ops.iommu_bypass_supported)
140 		return false;
141 	return phb->controller_ops.iommu_bypass_supported(pdev, mask);
142 }
143 
144 /* We support DMA to/from any memory page via the iommu */
dma_iommu_dma_supported(struct device * dev,u64 mask)145 int dma_iommu_dma_supported(struct device *dev, u64 mask)
146 {
147 	struct iommu_table *tbl = get_iommu_table_base(dev);
148 
149 	if (dev_is_pci(dev) && dma_iommu_bypass_supported(dev, mask)) {
150 		/*
151 		 * dma_iommu_bypass_supported() sets dma_max when there is
152 		 * 1:1 mapping but it is somehow limited.
153 		 * ibm,pmemory is one example.
154 		 */
155 		dev->dma_ops_bypass = dev->bus_dma_limit == 0;
156 		if (!dev->dma_ops_bypass)
157 			dev_warn(dev,
158 				 "iommu: 64-bit OK but direct DMA is limited by %llx\n",
159 				 dev->bus_dma_limit);
160 		else
161 			dev_dbg(dev, "iommu: 64-bit OK, using fixed ops\n");
162 		return 1;
163 	}
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 
dma_iommu_get_required_mask(struct device * dev)182 u64 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, 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(tbl->it_offset + tbl->it_size) +
200 			tbl->it_page_shift - 1);
201 	mask += mask - 1;
202 
203 	return mask;
204 }
205 
206 const 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_page		= dma_iommu_map_page,
213 	.unmap_page		= dma_iommu_unmap_page,
214 	.get_required_mask	= dma_iommu_get_required_mask,
215 	.mmap			= dma_common_mmap,
216 	.get_sgtable		= dma_common_get_sgtable,
217 	.alloc_pages		= dma_common_alloc_pages,
218 	.free_pages		= dma_common_free_pages,
219 };
220