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 #define NO_IOMMU 1 29 30 static const struct of_device_id __iommu_of_table_sentinel 31 __used __section(__iommu_of_table_end); 32 33 /** 34 * of_get_dma_window - Parse *dma-window property and returns 0 if found. 35 * 36 * @dn: device node 37 * @prefix: prefix for property name if any 38 * @index: index to start to parse 39 * @busno: Returns busno if supported. Otherwise pass NULL 40 * @addr: Returns address that DMA starts 41 * @size: Returns the range that DMA can handle 42 * 43 * This supports different formats flexibly. "prefix" can be 44 * configured if any. "busno" and "index" are optionally 45 * specified. Set 0(or NULL) if not used. 46 */ 47 int of_get_dma_window(struct device_node *dn, const char *prefix, int index, 48 unsigned long *busno, dma_addr_t *addr, size_t *size) 49 { 50 const __be32 *dma_window, *end; 51 int bytes, cur_index = 0; 52 char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX]; 53 54 if (!dn || !addr || !size) 55 return -EINVAL; 56 57 if (!prefix) 58 prefix = ""; 59 60 snprintf(propname, sizeof(propname), "%sdma-window", prefix); 61 snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix); 62 snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix); 63 64 dma_window = of_get_property(dn, propname, &bytes); 65 if (!dma_window) 66 return -ENODEV; 67 end = dma_window + bytes / sizeof(*dma_window); 68 69 while (dma_window < end) { 70 u32 cells; 71 const void *prop; 72 73 /* busno is one cell if supported */ 74 if (busno) 75 *busno = be32_to_cpup(dma_window++); 76 77 prop = of_get_property(dn, addrname, NULL); 78 if (!prop) 79 prop = of_get_property(dn, "#address-cells", NULL); 80 81 cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn); 82 if (!cells) 83 return -EINVAL; 84 *addr = of_read_number(dma_window, cells); 85 dma_window += cells; 86 87 prop = of_get_property(dn, sizename, NULL); 88 cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn); 89 if (!cells) 90 return -EINVAL; 91 *size = of_read_number(dma_window, cells); 92 dma_window += cells; 93 94 if (cur_index++ == index) 95 break; 96 } 97 return 0; 98 } 99 EXPORT_SYMBOL_GPL(of_get_dma_window); 100 101 static bool of_iommu_driver_present(struct device_node *np) 102 { 103 /* 104 * If the IOMMU still isn't ready by the time we reach init, assume 105 * it never will be. We don't want to defer indefinitely, nor attempt 106 * to dereference __iommu_of_table after it's been freed. 107 */ 108 if (system_state >= SYSTEM_RUNNING) 109 return false; 110 111 return of_match_node(&__iommu_of_table, np); 112 } 113 114 static int of_iommu_xlate(struct device *dev, 115 struct of_phandle_args *iommu_spec) 116 { 117 const struct iommu_ops *ops; 118 struct fwnode_handle *fwnode = &iommu_spec->np->fwnode; 119 int err; 120 121 ops = iommu_ops_from_fwnode(fwnode); 122 if ((ops && !ops->of_xlate) || 123 !of_device_is_available(iommu_spec->np) || 124 (!ops && !of_iommu_driver_present(iommu_spec->np))) 125 return NO_IOMMU; 126 127 err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops); 128 if (err) 129 return err; 130 /* 131 * The otherwise-empty fwspec handily serves to indicate the specific 132 * IOMMU device we're waiting for, which will be useful if we ever get 133 * a proper probe-ordering dependency mechanism in future. 134 */ 135 if (!ops) 136 return -EPROBE_DEFER; 137 138 return ops->of_xlate(dev, iommu_spec); 139 } 140 141 struct of_pci_iommu_alias_info { 142 struct device *dev; 143 struct device_node *np; 144 }; 145 146 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data) 147 { 148 struct of_pci_iommu_alias_info *info = data; 149 struct of_phandle_args iommu_spec = { .args_count = 1 }; 150 int err; 151 152 err = of_pci_map_rid(info->np, alias, "iommu-map", 153 "iommu-map-mask", &iommu_spec.np, 154 iommu_spec.args); 155 if (err) 156 return err == -ENODEV ? NO_IOMMU : err; 157 158 err = of_iommu_xlate(info->dev, &iommu_spec); 159 of_node_put(iommu_spec.np); 160 return err; 161 } 162 163 const struct iommu_ops *of_iommu_configure(struct device *dev, 164 struct device_node *master_np) 165 { 166 const struct iommu_ops *ops = NULL; 167 struct iommu_fwspec *fwspec = dev->iommu_fwspec; 168 int err = NO_IOMMU; 169 170 if (!master_np) 171 return NULL; 172 173 if (fwspec) { 174 if (fwspec->ops) 175 return fwspec->ops; 176 177 /* In the deferred case, start again from scratch */ 178 iommu_fwspec_free(dev); 179 } 180 181 /* 182 * We don't currently walk up the tree looking for a parent IOMMU. 183 * See the `Notes:' section of 184 * Documentation/devicetree/bindings/iommu/iommu.txt 185 */ 186 if (dev_is_pci(dev)) { 187 struct of_pci_iommu_alias_info info = { 188 .dev = dev, 189 .np = master_np, 190 }; 191 192 err = pci_for_each_dma_alias(to_pci_dev(dev), 193 of_pci_iommu_init, &info); 194 } else { 195 struct of_phandle_args iommu_spec; 196 int idx = 0; 197 198 while (!of_parse_phandle_with_args(master_np, "iommus", 199 "#iommu-cells", 200 idx, &iommu_spec)) { 201 err = of_iommu_xlate(dev, &iommu_spec); 202 of_node_put(iommu_spec.np); 203 idx++; 204 if (err) 205 break; 206 } 207 } 208 209 /* 210 * Two success conditions can be represented by non-negative err here: 211 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons 212 * 0 : we found an IOMMU, and dev->fwspec is initialised appropriately 213 * <0 : any actual error 214 */ 215 if (!err) 216 ops = dev->iommu_fwspec->ops; 217 /* 218 * If we have reason to believe the IOMMU driver missed the initial 219 * add_device callback for dev, replay it to get things in order. 220 */ 221 if (ops && ops->add_device && dev->bus && !dev->iommu_group) 222 err = ops->add_device(dev); 223 224 /* Ignore all other errors apart from EPROBE_DEFER */ 225 if (err == -EPROBE_DEFER) { 226 ops = ERR_PTR(err); 227 } else if (err < 0) { 228 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err); 229 ops = NULL; 230 } 231 232 return ops; 233 } 234