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 static int of_iommu_xlate(struct device *dev, 23 struct of_phandle_args *iommu_spec) 24 { 25 const struct iommu_ops *ops; 26 struct fwnode_handle *fwnode = &iommu_spec->np->fwnode; 27 int ret; 28 29 ops = iommu_ops_from_fwnode(fwnode); 30 if ((ops && !ops->of_xlate) || 31 !of_device_is_available(iommu_spec->np)) 32 return NO_IOMMU; 33 34 ret = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops); 35 if (ret) 36 return ret; 37 /* 38 * The otherwise-empty fwspec handily serves to indicate the specific 39 * IOMMU device we're waiting for, which will be useful if we ever get 40 * a proper probe-ordering dependency mechanism in future. 41 */ 42 if (!ops) 43 return driver_deferred_probe_check_state(dev); 44 45 if (!try_module_get(ops->owner)) 46 return -ENODEV; 47 48 ret = ops->of_xlate(dev, iommu_spec); 49 module_put(ops->owner); 50 return ret; 51 } 52 53 static int of_iommu_configure_dev_id(struct device_node *master_np, 54 struct device *dev, 55 const u32 *id) 56 { 57 struct of_phandle_args iommu_spec = { .args_count = 1 }; 58 int err; 59 60 err = of_map_id(master_np, *id, "iommu-map", 61 "iommu-map-mask", &iommu_spec.np, 62 iommu_spec.args); 63 if (err) 64 return err == -ENODEV ? NO_IOMMU : err; 65 66 err = of_iommu_xlate(dev, &iommu_spec); 67 of_node_put(iommu_spec.np); 68 return err; 69 } 70 71 static int of_iommu_configure_dev(struct device_node *master_np, 72 struct device *dev) 73 { 74 struct of_phandle_args iommu_spec; 75 int err = NO_IOMMU, idx = 0; 76 77 while (!of_parse_phandle_with_args(master_np, "iommus", 78 "#iommu-cells", 79 idx, &iommu_spec)) { 80 err = of_iommu_xlate(dev, &iommu_spec); 81 of_node_put(iommu_spec.np); 82 idx++; 83 if (err) 84 break; 85 } 86 87 return err; 88 } 89 90 struct of_pci_iommu_alias_info { 91 struct device *dev; 92 struct device_node *np; 93 }; 94 95 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data) 96 { 97 struct of_pci_iommu_alias_info *info = data; 98 u32 input_id = alias; 99 100 return of_iommu_configure_dev_id(info->np, info->dev, &input_id); 101 } 102 103 static int of_iommu_configure_device(struct device_node *master_np, 104 struct device *dev, const u32 *id) 105 { 106 return (id) ? of_iommu_configure_dev_id(master_np, dev, id) : 107 of_iommu_configure_dev(master_np, dev); 108 } 109 110 const struct iommu_ops *of_iommu_configure(struct device *dev, 111 struct device_node *master_np, 112 const u32 *id) 113 { 114 const struct iommu_ops *ops = NULL; 115 struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); 116 int err = NO_IOMMU; 117 118 if (!master_np) 119 return NULL; 120 121 if (fwspec) { 122 if (fwspec->ops) 123 return fwspec->ops; 124 125 /* In the deferred case, start again from scratch */ 126 iommu_fwspec_free(dev); 127 } 128 129 /* 130 * We don't currently walk up the tree looking for a parent IOMMU. 131 * See the `Notes:' section of 132 * Documentation/devicetree/bindings/iommu/iommu.txt 133 */ 134 if (dev_is_pci(dev)) { 135 struct of_pci_iommu_alias_info info = { 136 .dev = dev, 137 .np = master_np, 138 }; 139 140 pci_request_acs(); 141 err = pci_for_each_dma_alias(to_pci_dev(dev), 142 of_pci_iommu_init, &info); 143 } else { 144 err = of_iommu_configure_device(master_np, dev, id); 145 } 146 147 /* 148 * Two success conditions can be represented by non-negative err here: 149 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons 150 * 0 : we found an IOMMU, and dev->fwspec is initialised appropriately 151 * <0 : any actual error 152 */ 153 if (!err) { 154 /* The fwspec pointer changed, read it again */ 155 fwspec = dev_iommu_fwspec_get(dev); 156 ops = fwspec->ops; 157 } 158 /* 159 * If we have reason to believe the IOMMU driver missed the initial 160 * probe for dev, replay it to get things in order. 161 */ 162 if (!err && dev->bus && !device_iommu_mapped(dev)) 163 err = iommu_probe_device(dev); 164 165 /* Ignore all other errors apart from EPROBE_DEFER */ 166 if (err == -EPROBE_DEFER) { 167 ops = ERR_PTR(err); 168 } else if (err < 0) { 169 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err); 170 ops = NULL; 171 } 172 173 return ops; 174 } 175