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 static int of_iommu_configure_dev_id(struct device_node *master_np, 122 struct device *dev, 123 const u32 *id) 124 { 125 struct of_phandle_args iommu_spec = { .args_count = 1 }; 126 int err; 127 128 err = of_map_id(master_np, *id, "iommu-map", 129 "iommu-map-mask", &iommu_spec.np, 130 iommu_spec.args); 131 if (err) 132 return err == -ENODEV ? NO_IOMMU : err; 133 134 err = of_iommu_xlate(dev, &iommu_spec); 135 of_node_put(iommu_spec.np); 136 return err; 137 } 138 139 static int of_iommu_configure_dev(struct device_node *master_np, 140 struct device *dev) 141 { 142 struct of_phandle_args iommu_spec; 143 int err = NO_IOMMU, idx = 0; 144 145 while (!of_parse_phandle_with_args(master_np, "iommus", 146 "#iommu-cells", 147 idx, &iommu_spec)) { 148 err = of_iommu_xlate(dev, &iommu_spec); 149 of_node_put(iommu_spec.np); 150 idx++; 151 if (err) 152 break; 153 } 154 155 return err; 156 } 157 158 struct of_pci_iommu_alias_info { 159 struct device *dev; 160 struct device_node *np; 161 }; 162 163 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data) 164 { 165 struct of_pci_iommu_alias_info *info = data; 166 u32 input_id = alias; 167 168 return of_iommu_configure_dev_id(info->np, info->dev, &input_id); 169 } 170 171 static int of_iommu_configure_device(struct device_node *master_np, 172 struct device *dev, const u32 *id) 173 { 174 return (id) ? of_iommu_configure_dev_id(master_np, dev, id) : 175 of_iommu_configure_dev(master_np, dev); 176 } 177 178 const struct iommu_ops *of_iommu_configure(struct device *dev, 179 struct device_node *master_np, 180 const u32 *id) 181 { 182 const struct iommu_ops *ops = NULL; 183 struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); 184 int err = NO_IOMMU; 185 186 if (!master_np) 187 return NULL; 188 189 if (fwspec) { 190 if (fwspec->ops) 191 return fwspec->ops; 192 193 /* In the deferred case, start again from scratch */ 194 iommu_fwspec_free(dev); 195 } 196 197 /* 198 * We don't currently walk up the tree looking for a parent IOMMU. 199 * See the `Notes:' section of 200 * Documentation/devicetree/bindings/iommu/iommu.txt 201 */ 202 if (dev_is_pci(dev)) { 203 struct of_pci_iommu_alias_info info = { 204 .dev = dev, 205 .np = master_np, 206 }; 207 208 pci_request_acs(); 209 err = pci_for_each_dma_alias(to_pci_dev(dev), 210 of_pci_iommu_init, &info); 211 } else { 212 err = of_iommu_configure_device(master_np, dev, id); 213 } 214 215 /* 216 * Two success conditions can be represented by non-negative err here: 217 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons 218 * 0 : we found an IOMMU, and dev->fwspec is initialised appropriately 219 * <0 : any actual error 220 */ 221 if (!err) { 222 /* The fwspec pointer changed, read it again */ 223 fwspec = dev_iommu_fwspec_get(dev); 224 ops = fwspec->ops; 225 } 226 /* 227 * If we have reason to believe the IOMMU driver missed the initial 228 * probe for dev, replay it to get things in order. 229 */ 230 if (!err && dev->bus && !device_iommu_mapped(dev)) 231 err = iommu_probe_device(dev); 232 233 /* Ignore all other errors apart from EPROBE_DEFER */ 234 if (err == -EPROBE_DEFER) { 235 ops = ERR_PTR(err); 236 } else if (err < 0) { 237 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err); 238 ops = NULL; 239 } 240 241 return ops; 242 } 243