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/of.h> 13 #include <linux/of_iommu.h> 14 #include <linux/of_pci.h> 15 #include <linux/pci.h> 16 #include <linux/slab.h> 17 #include <linux/fsl/mc.h> 18 19 #define NO_IOMMU 1 20 21 static int of_iommu_xlate(struct device *dev, 22 struct of_phandle_args *iommu_spec) 23 { 24 const struct iommu_ops *ops; 25 struct fwnode_handle *fwnode = &iommu_spec->np->fwnode; 26 int ret; 27 28 ops = iommu_ops_from_fwnode(fwnode); 29 if ((ops && !ops->of_xlate) || 30 !of_device_is_available(iommu_spec->np)) 31 return NO_IOMMU; 32 33 ret = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops); 34 if (ret) 35 return ret; 36 /* 37 * The otherwise-empty fwspec handily serves to indicate the specific 38 * IOMMU device we're waiting for, which will be useful if we ever get 39 * a proper probe-ordering dependency mechanism in future. 40 */ 41 if (!ops) 42 return driver_deferred_probe_check_state(dev); 43 44 if (!try_module_get(ops->owner)) 45 return -ENODEV; 46 47 ret = ops->of_xlate(dev, iommu_spec); 48 module_put(ops->owner); 49 return ret; 50 } 51 52 static int of_iommu_configure_dev_id(struct device_node *master_np, 53 struct device *dev, 54 const u32 *id) 55 { 56 struct of_phandle_args iommu_spec = { .args_count = 1 }; 57 int err; 58 59 err = of_map_id(master_np, *id, "iommu-map", 60 "iommu-map-mask", &iommu_spec.np, 61 iommu_spec.args); 62 if (err) 63 return err == -ENODEV ? NO_IOMMU : err; 64 65 err = of_iommu_xlate(dev, &iommu_spec); 66 of_node_put(iommu_spec.np); 67 return err; 68 } 69 70 static int of_iommu_configure_dev(struct device_node *master_np, 71 struct device *dev) 72 { 73 struct of_phandle_args iommu_spec; 74 int err = NO_IOMMU, idx = 0; 75 76 while (!of_parse_phandle_with_args(master_np, "iommus", 77 "#iommu-cells", 78 idx, &iommu_spec)) { 79 err = of_iommu_xlate(dev, &iommu_spec); 80 of_node_put(iommu_spec.np); 81 idx++; 82 if (err) 83 break; 84 } 85 86 return err; 87 } 88 89 struct of_pci_iommu_alias_info { 90 struct device *dev; 91 struct device_node *np; 92 }; 93 94 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data) 95 { 96 struct of_pci_iommu_alias_info *info = data; 97 u32 input_id = alias; 98 99 return of_iommu_configure_dev_id(info->np, info->dev, &input_id); 100 } 101 102 static int of_iommu_configure_device(struct device_node *master_np, 103 struct device *dev, const u32 *id) 104 { 105 return (id) ? of_iommu_configure_dev_id(master_np, dev, id) : 106 of_iommu_configure_dev(master_np, dev); 107 } 108 109 const struct iommu_ops *of_iommu_configure(struct device *dev, 110 struct device_node *master_np, 111 const u32 *id) 112 { 113 const struct iommu_ops *ops = NULL; 114 struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); 115 int err = NO_IOMMU; 116 117 if (!master_np) 118 return NULL; 119 120 if (fwspec) { 121 if (fwspec->ops) 122 return fwspec->ops; 123 124 /* In the deferred case, start again from scratch */ 125 iommu_fwspec_free(dev); 126 } 127 128 /* 129 * We don't currently walk up the tree looking for a parent IOMMU. 130 * See the `Notes:' section of 131 * Documentation/devicetree/bindings/iommu/iommu.txt 132 */ 133 if (dev_is_pci(dev)) { 134 struct of_pci_iommu_alias_info info = { 135 .dev = dev, 136 .np = master_np, 137 }; 138 139 pci_request_acs(); 140 err = pci_for_each_dma_alias(to_pci_dev(dev), 141 of_pci_iommu_init, &info); 142 } else { 143 err = of_iommu_configure_device(master_np, dev, id); 144 } 145 146 /* 147 * Two success conditions can be represented by non-negative err here: 148 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons 149 * 0 : we found an IOMMU, and dev->fwspec is initialised appropriately 150 * <0 : any actual error 151 */ 152 if (!err) { 153 /* The fwspec pointer changed, read it again */ 154 fwspec = dev_iommu_fwspec_get(dev); 155 ops = fwspec->ops; 156 } 157 /* 158 * If we have reason to believe the IOMMU driver missed the initial 159 * probe for dev, replay it to get things in order. 160 */ 161 if (!err && dev->bus && !device_iommu_mapped(dev)) 162 err = iommu_probe_device(dev); 163 164 /* Ignore all other errors apart from EPROBE_DEFER */ 165 if (err == -EPROBE_DEFER) { 166 ops = ERR_PTR(err); 167 } else if (err < 0) { 168 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err); 169 ops = NULL; 170 } 171 172 return ops; 173 } 174