1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * OF helpers for IOMMU 4 * 5 * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved. 6 */ 7 8 #include <linux/export.h> 9 #include <linux/iommu.h> 10 #include <linux/limits.h> 11 #include <linux/module.h> 12 #include <linux/msi.h> 13 #include <linux/of.h> 14 #include <linux/of_iommu.h> 15 #include <linux/of_pci.h> 16 #include <linux/pci.h> 17 #include <linux/slab.h> 18 #include <linux/fsl/mc.h> 19 20 #define NO_IOMMU 1 21 22 /** 23 * of_get_dma_window - Parse *dma-window property and returns 0 if found. 24 * 25 * @dn: device node 26 * @prefix: prefix for property name if any 27 * @index: index to start to parse 28 * @busno: Returns busno if supported. Otherwise pass NULL 29 * @addr: Returns address that DMA starts 30 * @size: Returns the range that DMA can handle 31 * 32 * This supports different formats flexibly. "prefix" can be 33 * configured if any. "busno" and "index" are optionally 34 * specified. Set 0(or NULL) if not used. 35 */ 36 int of_get_dma_window(struct device_node *dn, const char *prefix, int index, 37 unsigned long *busno, dma_addr_t *addr, size_t *size) 38 { 39 const __be32 *dma_window, *end; 40 int bytes, cur_index = 0; 41 char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX]; 42 43 if (!dn || !addr || !size) 44 return -EINVAL; 45 46 if (!prefix) 47 prefix = ""; 48 49 snprintf(propname, sizeof(propname), "%sdma-window", prefix); 50 snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix); 51 snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix); 52 53 dma_window = of_get_property(dn, propname, &bytes); 54 if (!dma_window) 55 return -ENODEV; 56 end = dma_window + bytes / sizeof(*dma_window); 57 58 while (dma_window < end) { 59 u32 cells; 60 const void *prop; 61 62 /* busno is one cell if supported */ 63 if (busno) 64 *busno = be32_to_cpup(dma_window++); 65 66 prop = of_get_property(dn, addrname, NULL); 67 if (!prop) 68 prop = of_get_property(dn, "#address-cells", NULL); 69 70 cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn); 71 if (!cells) 72 return -EINVAL; 73 *addr = of_read_number(dma_window, cells); 74 dma_window += cells; 75 76 prop = of_get_property(dn, sizename, NULL); 77 cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn); 78 if (!cells) 79 return -EINVAL; 80 *size = of_read_number(dma_window, cells); 81 dma_window += cells; 82 83 if (cur_index++ == index) 84 break; 85 } 86 return 0; 87 } 88 EXPORT_SYMBOL_GPL(of_get_dma_window); 89 90 static int of_iommu_xlate(struct device *dev, 91 struct of_phandle_args *iommu_spec) 92 { 93 const struct iommu_ops *ops; 94 struct fwnode_handle *fwnode = &iommu_spec->np->fwnode; 95 int ret; 96 97 ops = iommu_ops_from_fwnode(fwnode); 98 if ((ops && !ops->of_xlate) || 99 !of_device_is_available(iommu_spec->np)) 100 return NO_IOMMU; 101 102 ret = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops); 103 if (ret) 104 return ret; 105 /* 106 * The otherwise-empty fwspec handily serves to indicate the specific 107 * IOMMU device we're waiting for, which will be useful if we ever get 108 * a proper probe-ordering dependency mechanism in future. 109 */ 110 if (!ops) 111 return driver_deferred_probe_check_state(dev); 112 113 if (!try_module_get(ops->owner)) 114 return -ENODEV; 115 116 ret = ops->of_xlate(dev, iommu_spec); 117 module_put(ops->owner); 118 return ret; 119 } 120 121 struct of_pci_iommu_alias_info { 122 struct device *dev; 123 struct device_node *np; 124 }; 125 126 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data) 127 { 128 struct of_pci_iommu_alias_info *info = data; 129 struct of_phandle_args iommu_spec = { .args_count = 1 }; 130 int err; 131 132 err = of_map_rid(info->np, alias, "iommu-map", "iommu-map-mask", 133 &iommu_spec.np, iommu_spec.args); 134 if (err) 135 return err == -ENODEV ? NO_IOMMU : err; 136 137 err = of_iommu_xlate(info->dev, &iommu_spec); 138 of_node_put(iommu_spec.np); 139 return err; 140 } 141 142 static int of_fsl_mc_iommu_init(struct fsl_mc_device *mc_dev, 143 struct device_node *master_np) 144 { 145 struct of_phandle_args iommu_spec = { .args_count = 1 }; 146 int err; 147 148 err = of_map_rid(master_np, mc_dev->icid, "iommu-map", 149 "iommu-map-mask", &iommu_spec.np, 150 iommu_spec.args); 151 if (err) 152 return err == -ENODEV ? NO_IOMMU : err; 153 154 err = of_iommu_xlate(&mc_dev->dev, &iommu_spec); 155 of_node_put(iommu_spec.np); 156 return err; 157 } 158 159 const struct iommu_ops *of_iommu_configure(struct device *dev, 160 struct device_node *master_np) 161 { 162 const struct iommu_ops *ops = NULL; 163 struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); 164 int err = NO_IOMMU; 165 166 if (!master_np) 167 return NULL; 168 169 if (fwspec) { 170 if (fwspec->ops) 171 return fwspec->ops; 172 173 /* In the deferred case, start again from scratch */ 174 iommu_fwspec_free(dev); 175 } 176 177 /* 178 * We don't currently walk up the tree looking for a parent IOMMU. 179 * See the `Notes:' section of 180 * Documentation/devicetree/bindings/iommu/iommu.txt 181 */ 182 if (dev_is_pci(dev)) { 183 struct of_pci_iommu_alias_info info = { 184 .dev = dev, 185 .np = master_np, 186 }; 187 188 pci_request_acs(); 189 err = pci_for_each_dma_alias(to_pci_dev(dev), 190 of_pci_iommu_init, &info); 191 } else if (dev_is_fsl_mc(dev)) { 192 err = of_fsl_mc_iommu_init(to_fsl_mc_device(dev), master_np); 193 } else { 194 struct of_phandle_args iommu_spec; 195 int idx = 0; 196 197 while (!of_parse_phandle_with_args(master_np, "iommus", 198 "#iommu-cells", 199 idx, &iommu_spec)) { 200 err = of_iommu_xlate(dev, &iommu_spec); 201 of_node_put(iommu_spec.np); 202 idx++; 203 if (err) 204 break; 205 } 206 207 fwspec = dev_iommu_fwspec_get(dev); 208 if (!err && fwspec) 209 of_property_read_u32(master_np, "pasid-num-bits", 210 &fwspec->num_pasid_bits); 211 } 212 213 /* 214 * Two success conditions can be represented by non-negative err here: 215 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons 216 * 0 : we found an IOMMU, and dev->fwspec is initialised appropriately 217 * <0 : any actual error 218 */ 219 if (!err) { 220 /* The fwspec pointer changed, read it again */ 221 fwspec = dev_iommu_fwspec_get(dev); 222 ops = fwspec->ops; 223 } 224 /* 225 * If we have reason to believe the IOMMU driver missed the initial 226 * probe for dev, replay it to get things in order. 227 */ 228 if (!err && dev->bus && !device_iommu_mapped(dev)) 229 err = iommu_probe_device(dev); 230 231 /* Ignore all other errors apart from EPROBE_DEFER */ 232 if (err == -EPROBE_DEFER) { 233 ops = ERR_PTR(err); 234 } else if (err < 0) { 235 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err); 236 ops = NULL; 237 } 238 239 return ops; 240 } 241