1 /* 2 * OF helpers for IOMMU 3 * 4 * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved. 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms and conditions of the GNU General Public License, 8 * version 2, as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 13 * more details. 14 * 15 * You should have received a copy of the GNU General Public License along with 16 * this program; if not, write to the Free Software Foundation, Inc., 17 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. 18 */ 19 20 #include <linux/export.h> 21 #include <linux/iommu.h> 22 #include <linux/limits.h> 23 #include <linux/of.h> 24 #include <linux/of_iommu.h> 25 #include <linux/of_pci.h> 26 #include <linux/slab.h> 27 28 static const struct of_device_id __iommu_of_table_sentinel 29 __used __section(__iommu_of_table_end); 30 31 /** 32 * of_get_dma_window - Parse *dma-window property and returns 0 if found. 33 * 34 * @dn: device node 35 * @prefix: prefix for property name if any 36 * @index: index to start to parse 37 * @busno: Returns busno if supported. Otherwise pass NULL 38 * @addr: Returns address that DMA starts 39 * @size: Returns the range that DMA can handle 40 * 41 * This supports different formats flexibly. "prefix" can be 42 * configured if any. "busno" and "index" are optionally 43 * specified. Set 0(or NULL) if not used. 44 */ 45 int of_get_dma_window(struct device_node *dn, const char *prefix, int index, 46 unsigned long *busno, dma_addr_t *addr, size_t *size) 47 { 48 const __be32 *dma_window, *end; 49 int bytes, cur_index = 0; 50 char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX]; 51 52 if (!dn || !addr || !size) 53 return -EINVAL; 54 55 if (!prefix) 56 prefix = ""; 57 58 snprintf(propname, sizeof(propname), "%sdma-window", prefix); 59 snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix); 60 snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix); 61 62 dma_window = of_get_property(dn, propname, &bytes); 63 if (!dma_window) 64 return -ENODEV; 65 end = dma_window + bytes / sizeof(*dma_window); 66 67 while (dma_window < end) { 68 u32 cells; 69 const void *prop; 70 71 /* busno is one cell if supported */ 72 if (busno) 73 *busno = be32_to_cpup(dma_window++); 74 75 prop = of_get_property(dn, addrname, NULL); 76 if (!prop) 77 prop = of_get_property(dn, "#address-cells", NULL); 78 79 cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn); 80 if (!cells) 81 return -EINVAL; 82 *addr = of_read_number(dma_window, cells); 83 dma_window += cells; 84 85 prop = of_get_property(dn, sizename, NULL); 86 cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn); 87 if (!cells) 88 return -EINVAL; 89 *size = of_read_number(dma_window, cells); 90 dma_window += cells; 91 92 if (cur_index++ == index) 93 break; 94 } 95 return 0; 96 } 97 EXPORT_SYMBOL_GPL(of_get_dma_window); 98 99 static bool of_iommu_driver_present(struct device_node *np) 100 { 101 /* 102 * If the IOMMU still isn't ready by the time we reach init, assume 103 * it never will be. We don't want to defer indefinitely, nor attempt 104 * to dereference __iommu_of_table after it's been freed. 105 */ 106 if (system_state >= SYSTEM_RUNNING) 107 return false; 108 109 return of_match_node(&__iommu_of_table, np); 110 } 111 112 static const struct iommu_ops 113 *of_iommu_xlate(struct device *dev, struct of_phandle_args *iommu_spec) 114 { 115 const struct iommu_ops *ops; 116 struct fwnode_handle *fwnode = &iommu_spec->np->fwnode; 117 int err; 118 119 ops = iommu_ops_from_fwnode(fwnode); 120 if ((ops && !ops->of_xlate) || 121 !of_device_is_available(iommu_spec->np) || 122 (!ops && !of_iommu_driver_present(iommu_spec->np))) 123 return NULL; 124 125 err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops); 126 if (err) 127 return ERR_PTR(err); 128 /* 129 * The otherwise-empty fwspec handily serves to indicate the specific 130 * IOMMU device we're waiting for, which will be useful if we ever get 131 * a proper probe-ordering dependency mechanism in future. 132 */ 133 if (!ops) 134 return ERR_PTR(-EPROBE_DEFER); 135 136 err = ops->of_xlate(dev, iommu_spec); 137 if (err) 138 return ERR_PTR(err); 139 140 return ops; 141 } 142 143 static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data) 144 { 145 struct of_phandle_args *iommu_spec = data; 146 147 iommu_spec->args[0] = alias; 148 return iommu_spec->np == pdev->bus->dev.of_node; 149 } 150 151 static const struct iommu_ops 152 *of_pci_iommu_init(struct pci_dev *pdev, struct device_node *bridge_np) 153 { 154 const struct iommu_ops *ops; 155 struct of_phandle_args iommu_spec; 156 int err; 157 158 /* 159 * Start by tracing the RID alias down the PCI topology as 160 * far as the host bridge whose OF node we have... 161 * (we're not even attempting to handle multi-alias devices yet) 162 */ 163 iommu_spec.args_count = 1; 164 iommu_spec.np = bridge_np; 165 pci_for_each_dma_alias(pdev, __get_pci_rid, &iommu_spec); 166 /* 167 * ...then find out what that becomes once it escapes the PCI 168 * bus into the system beyond, and which IOMMU it ends up at. 169 */ 170 iommu_spec.np = NULL; 171 err = of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map", 172 "iommu-map-mask", &iommu_spec.np, 173 iommu_spec.args); 174 if (err) 175 return err == -ENODEV ? NULL : ERR_PTR(err); 176 177 ops = of_iommu_xlate(&pdev->dev, &iommu_spec); 178 179 of_node_put(iommu_spec.np); 180 return ops; 181 } 182 183 static const struct iommu_ops 184 *of_platform_iommu_init(struct device *dev, struct device_node *np) 185 { 186 struct of_phandle_args iommu_spec; 187 const struct iommu_ops *ops = NULL; 188 int idx = 0; 189 190 /* 191 * We don't currently walk up the tree looking for a parent IOMMU. 192 * See the `Notes:' section of 193 * Documentation/devicetree/bindings/iommu/iommu.txt 194 */ 195 while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", 196 idx, &iommu_spec)) { 197 ops = of_iommu_xlate(dev, &iommu_spec); 198 of_node_put(iommu_spec.np); 199 idx++; 200 if (IS_ERR_OR_NULL(ops)) 201 break; 202 } 203 204 return ops; 205 } 206 207 const struct iommu_ops *of_iommu_configure(struct device *dev, 208 struct device_node *master_np) 209 { 210 const struct iommu_ops *ops; 211 struct iommu_fwspec *fwspec = dev->iommu_fwspec; 212 213 if (!master_np) 214 return NULL; 215 216 if (fwspec) { 217 if (fwspec->ops) 218 return fwspec->ops; 219 220 /* In the deferred case, start again from scratch */ 221 iommu_fwspec_free(dev); 222 } 223 224 if (dev_is_pci(dev)) 225 ops = of_pci_iommu_init(to_pci_dev(dev), master_np); 226 else 227 ops = of_platform_iommu_init(dev, master_np); 228 /* 229 * If we have reason to believe the IOMMU driver missed the initial 230 * add_device callback for dev, replay it to get things in order. 231 */ 232 if (!IS_ERR_OR_NULL(ops) && ops->add_device && 233 dev->bus && !dev->iommu_group) { 234 int err = ops->add_device(dev); 235 236 if (err) 237 ops = ERR_PTR(err); 238 } 239 240 /* Ignore all other errors apart from EPROBE_DEFER */ 241 if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) { 242 dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops)); 243 ops = NULL; 244 } 245 246 return ops; 247 } 248 249 static int __init of_iommu_init(void) 250 { 251 struct device_node *np; 252 const struct of_device_id *match, *matches = &__iommu_of_table; 253 254 for_each_matching_node_and_match(np, matches, &match) { 255 const of_iommu_init_fn init_fn = match->data; 256 257 if (init_fn && init_fn(np)) 258 pr_err("Failed to initialise IOMMU %s\n", 259 of_node_full_name(np)); 260 } 261 262 return 0; 263 } 264 postcore_initcall_sync(of_iommu_init); 265