1 /* 2 * OF helpers for IOMMU 3 * 4 * Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved. 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms and conditions of the GNU General Public License, 8 * version 2, as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 13 * more details. 14 * 15 * You should have received a copy of the GNU General Public License along with 16 * this program; if not, write to the Free Software Foundation, Inc., 17 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. 18 */ 19 20 #include <linux/export.h> 21 #include <linux/iommu.h> 22 #include <linux/limits.h> 23 #include <linux/of.h> 24 #include <linux/of_iommu.h> 25 #include <linux/of_pci.h> 26 #include <linux/slab.h> 27 28 #define NO_IOMMU 1 29 30 /** 31 * of_get_dma_window - Parse *dma-window property and returns 0 if found. 32 * 33 * @dn: device node 34 * @prefix: prefix for property name if any 35 * @index: index to start to parse 36 * @busno: Returns busno if supported. Otherwise pass NULL 37 * @addr: Returns address that DMA starts 38 * @size: Returns the range that DMA can handle 39 * 40 * This supports different formats flexibly. "prefix" can be 41 * configured if any. "busno" and "index" are optionally 42 * specified. Set 0(or NULL) if not used. 43 */ 44 int of_get_dma_window(struct device_node *dn, const char *prefix, int index, 45 unsigned long *busno, dma_addr_t *addr, size_t *size) 46 { 47 const __be32 *dma_window, *end; 48 int bytes, cur_index = 0; 49 char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX]; 50 51 if (!dn || !addr || !size) 52 return -EINVAL; 53 54 if (!prefix) 55 prefix = ""; 56 57 snprintf(propname, sizeof(propname), "%sdma-window", prefix); 58 snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix); 59 snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix); 60 61 dma_window = of_get_property(dn, propname, &bytes); 62 if (!dma_window) 63 return -ENODEV; 64 end = dma_window + bytes / sizeof(*dma_window); 65 66 while (dma_window < end) { 67 u32 cells; 68 const void *prop; 69 70 /* busno is one cell if supported */ 71 if (busno) 72 *busno = be32_to_cpup(dma_window++); 73 74 prop = of_get_property(dn, addrname, NULL); 75 if (!prop) 76 prop = of_get_property(dn, "#address-cells", NULL); 77 78 cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn); 79 if (!cells) 80 return -EINVAL; 81 *addr = of_read_number(dma_window, cells); 82 dma_window += cells; 83 84 prop = of_get_property(dn, sizename, NULL); 85 cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn); 86 if (!cells) 87 return -EINVAL; 88 *size = of_read_number(dma_window, cells); 89 dma_window += cells; 90 91 if (cur_index++ == index) 92 break; 93 } 94 return 0; 95 } 96 EXPORT_SYMBOL_GPL(of_get_dma_window); 97 98 static int of_iommu_xlate(struct device *dev, 99 struct of_phandle_args *iommu_spec) 100 { 101 const struct iommu_ops *ops; 102 struct fwnode_handle *fwnode = &iommu_spec->np->fwnode; 103 int err; 104 105 ops = iommu_ops_from_fwnode(fwnode); 106 if ((ops && !ops->of_xlate) || 107 !of_device_is_available(iommu_spec->np)) 108 return NO_IOMMU; 109 110 err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops); 111 if (err) 112 return err; 113 /* 114 * The otherwise-empty fwspec handily serves to indicate the specific 115 * IOMMU device we're waiting for, which will be useful if we ever get 116 * a proper probe-ordering dependency mechanism in future. 117 */ 118 if (!ops) 119 return driver_deferred_probe_check_state(dev); 120 121 return ops->of_xlate(dev, iommu_spec); 122 } 123 124 struct of_pci_iommu_alias_info { 125 struct device *dev; 126 struct device_node *np; 127 }; 128 129 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data) 130 { 131 struct of_pci_iommu_alias_info *info = data; 132 struct of_phandle_args iommu_spec = { .args_count = 1 }; 133 int err; 134 135 err = of_pci_map_rid(info->np, alias, "iommu-map", 136 "iommu-map-mask", &iommu_spec.np, 137 iommu_spec.args); 138 if (err) 139 return err == -ENODEV ? NO_IOMMU : err; 140 141 err = of_iommu_xlate(info->dev, &iommu_spec); 142 of_node_put(iommu_spec.np); 143 return err; 144 } 145 146 const struct iommu_ops *of_iommu_configure(struct device *dev, 147 struct device_node *master_np) 148 { 149 const struct iommu_ops *ops = NULL; 150 struct iommu_fwspec *fwspec = dev->iommu_fwspec; 151 int err = NO_IOMMU; 152 153 if (!master_np) 154 return NULL; 155 156 if (fwspec) { 157 if (fwspec->ops) 158 return fwspec->ops; 159 160 /* In the deferred case, start again from scratch */ 161 iommu_fwspec_free(dev); 162 } 163 164 /* 165 * We don't currently walk up the tree looking for a parent IOMMU. 166 * See the `Notes:' section of 167 * Documentation/devicetree/bindings/iommu/iommu.txt 168 */ 169 if (dev_is_pci(dev)) { 170 struct of_pci_iommu_alias_info info = { 171 .dev = dev, 172 .np = master_np, 173 }; 174 175 err = pci_for_each_dma_alias(to_pci_dev(dev), 176 of_pci_iommu_init, &info); 177 } else { 178 struct of_phandle_args iommu_spec; 179 int idx = 0; 180 181 while (!of_parse_phandle_with_args(master_np, "iommus", 182 "#iommu-cells", 183 idx, &iommu_spec)) { 184 err = of_iommu_xlate(dev, &iommu_spec); 185 of_node_put(iommu_spec.np); 186 idx++; 187 if (err) 188 break; 189 } 190 } 191 192 /* 193 * Two success conditions can be represented by non-negative err here: 194 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons 195 * 0 : we found an IOMMU, and dev->fwspec is initialised appropriately 196 * <0 : any actual error 197 */ 198 if (!err) 199 ops = dev->iommu_fwspec->ops; 200 /* 201 * If we have reason to believe the IOMMU driver missed the initial 202 * add_device callback for dev, replay it to get things in order. 203 */ 204 if (ops && ops->add_device && dev->bus && !dev->iommu_group) 205 err = ops->add_device(dev); 206 207 /* Ignore all other errors apart from EPROBE_DEFER */ 208 if (err == -EPROBE_DEFER) { 209 ops = ERR_PTR(err); 210 } else if (err < 0) { 211 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err); 212 ops = NULL; 213 } 214 215 return ops; 216 } 217