linux_sgt.c revision 1.2
1 /* $NetBSD: linux_sgt.c,v 1.2 2021/12/19 12:10:14 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2021 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #include <sys/cdefs.h> 30 __KERNEL_RCSID(0, "$NetBSD: linux_sgt.c,v 1.2 2021/12/19 12:10:14 riastradh Exp $"); 31 32 #include <sys/bus.h> 33 #include <sys/errno.h> 34 35 #include <drm/bus_dma_hacks.h> 36 37 #include <linux/dma-mapping.h> 38 #include <linux/gfp.h> 39 #include <linux/mm_types.h> 40 #include <linux/scatterlist.h> 41 #include <linux/slab.h> 42 43 int 44 sg_alloc_table(struct sg_table *sgt, unsigned npgs, gfp_t gfp) 45 { 46 47 sgt->sgl->sg_pgs = kcalloc(npgs, sizeof(sgt->sgl->sg_pgs[0]), gfp); 48 if (sgt->sgl->sg_pgs == NULL) 49 return -ENOMEM; 50 sgt->sgl->sg_npgs = sgt->nents = npgs; 51 sgt->sgl->sg_dmamap = NULL; 52 53 return 0; 54 } 55 56 int 57 __sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pgs, 58 unsigned npgs, bus_size_t offset, bus_size_t size, unsigned maxseg, 59 gfp_t gfp) 60 { 61 unsigned i; 62 int ret; 63 64 KASSERT(offset == 0); 65 KASSERT(size == (bus_size_t)npgs << PAGE_SHIFT); 66 67 ret = sg_alloc_table(sgt, npgs, gfp); 68 if (ret) 69 return ret; 70 71 for (i = 0; i < npgs; i++) 72 sgt->sgl->sg_pgs[i] = pgs[i]; 73 74 return 0; 75 } 76 77 int 78 sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pgs, 79 unsigned npgs, bus_size_t offset, bus_size_t size, gfp_t gfp) 80 { 81 82 return __sg_alloc_table_from_pages(sgt, pgs, npgs, offset, size, 83 -1, gfp); 84 } 85 86 int 87 sg_alloc_table_from_bus_dmamem(struct sg_table *sgt, bus_dma_tag_t dmat, 88 const bus_dma_segment_t *seg, int nseg, gfp_t gfp) 89 { 90 int i, npgs = 0; 91 int ret; 92 93 KASSERT(nseg >= 1); 94 95 /* 96 * Count the number of pages. Some segments may span multiple 97 * contiguous pages. 98 */ 99 for (i = 0; i < nseg; i++) { 100 bus_size_t len = seg[i].ds_len; 101 for (; len >= PAGE_SIZE; len -= PAGE_SIZE, npgs++) { 102 if (npgs == INT_MAX) 103 return -ENOMEM; 104 } 105 KASSERTMSG(len == 0, "misaligned segment length: %ju\n", 106 (uintmax_t)seg[i].ds_len); 107 } 108 109 ret = sg_alloc_table(sgt, npgs, gfp); 110 if (ret) 111 return ret; 112 113 /* XXX errno NetBSD->Linux */ 114 ret = -bus_dmamem_export_pages(dmat, seg, nseg, sgt->sgl->sg_pgs, 115 sgt->sgl->sg_npgs); 116 if (ret) 117 goto out; 118 119 /* Success! */ 120 ret = 0; 121 122 out: if (ret) 123 sg_free_table(sgt); 124 return ret; 125 } 126 127 void 128 sg_free_table(struct sg_table *sgt) 129 { 130 131 KASSERT(sgt->sgl->sg_dmamap == NULL); 132 kfree(sgt->sgl->sg_pgs); 133 sgt->sgl->sg_pgs = NULL; 134 sgt->sgl->sg_npgs = 0; 135 } 136 137 int 138 dma_map_sg(bus_dma_tag_t dmat, struct scatterlist *sg, int nents, int dir) 139 { 140 141 return dma_map_sg_attrs(dmat, sg, nents, dir, 0); 142 } 143 144 int 145 dma_map_sg_attrs(bus_dma_tag_t dmat, struct scatterlist *sg, int nents, 146 int dir, int attrs) 147 { 148 int flags = 0; 149 bool loaded = false; 150 int ret, error = 0; 151 152 KASSERT(sg->sg_dmamap == NULL); 153 KASSERT(nents >= 1); 154 155 switch (dir) { 156 case DMA_TO_DEVICE: 157 flags |= BUS_DMA_WRITE; 158 break; 159 case DMA_FROM_DEVICE: 160 flags |= BUS_DMA_READ; 161 break; 162 case DMA_BIDIRECTIONAL: 163 flags |= BUS_DMA_READ|BUS_DMA_WRITE; 164 break; 165 case DMA_NONE: 166 default: 167 panic("invalid DMA direction %d", dir); 168 } 169 170 error = bus_dmamap_create(dmat, (bus_size_t)sg->sg_npgs << PAGE_SHIFT, 171 nents, PAGE_SIZE, 0, BUS_DMA_WAITOK, &sg->sg_dmamap); 172 if (error) 173 goto out; 174 KASSERT(sg->sg_dmamap); 175 176 error = bus_dmamap_load_pages(dmat, sg->sg_dmamap, sg->sg_pgs, 177 (bus_size_t)sg->sg_npgs << PAGE_SHIFT, BUS_DMA_WAITOK|flags); 178 if (error) 179 goto out; 180 loaded = true; 181 182 /* Success! */ 183 KASSERT(sg->sg_dmamap->dm_nsegs > 0); 184 KASSERT(sg->sg_dmamap->dm_nsegs <= nents); 185 ret = sg->sg_dmamap->dm_nsegs; 186 error = 0; 187 188 out: if (error) { 189 if (loaded) 190 bus_dmamap_unload(dmat, sg->sg_dmamap); 191 loaded = false; 192 if (sg->sg_dmamap) 193 bus_dmamap_destroy(dmat, sg->sg_dmamap); 194 sg->sg_dmamap = NULL; 195 ret = 0; 196 } 197 return ret; 198 } 199 200 void 201 dma_unmap_sg(bus_dma_tag_t dmat, struct scatterlist *sg, int nents, int dir) 202 { 203 204 dma_unmap_sg_attrs(dmat, sg, nents, dir, 0); 205 } 206 207 void 208 dma_unmap_sg_attrs(bus_dma_tag_t dmat, struct scatterlist *sg, int nents, 209 int dir, int attrs) 210 { 211 212 bus_dmamap_unload(dmat, sg->sg_dmamap); 213 bus_dmamap_destroy(dmat, sg->sg_dmamap); 214 sg->sg_dmamap = NULL; 215 } 216 217 bus_addr_t 218 sg_dma_address(const struct scatterlist *sg) 219 { 220 221 KASSERT(sg->sg_dmamap->dm_nsegs == 1); 222 return sg->sg_dmamap->dm_segs[0].ds_addr; 223 } 224 225 bus_size_t 226 sg_dma_len(const struct scatterlist *sg) 227 { 228 229 KASSERT(sg->sg_dmamap->dm_nsegs == 1); 230 return sg->sg_dmamap->dm_segs[0].ds_len; 231 } 232
Indexes created Mon Sep 22 13:09:51 GMT 2025