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