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