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 #include <linux/fsl/mc.h> 28 29 #define NO_IOMMU 1 30 31 /** 32 * of_get_dma_window - Parse *dma-window property and returns 0 if found. 33 * 34 * @dn: device node 35 * @prefix: prefix for property name if any 36 * @index: index to start to parse 37 * @busno: Returns busno if supported. Otherwise pass NULL 38 * @addr: Returns address that DMA starts 39 * @size: Returns the range that DMA can handle 40 * 41 * This supports different formats flexibly. "prefix" can be 42 * configured if any. "busno" and "index" are optionally 43 * specified. Set 0(or NULL) if not used. 44 */ 45 int of_get_dma_window(struct device_node *dn, const char *prefix, int index, 46 unsigned long *busno, dma_addr_t *addr, size_t *size) 47 { 48 const __be32 *dma_window, *end; 49 int bytes, cur_index = 0; 50 char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX]; 51 52 if (!dn || !addr || !size) 53 return -EINVAL; 54 55 if (!prefix) 56 prefix = ""; 57 58 snprintf(propname, sizeof(propname), "%sdma-window", prefix); 59 snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix); 60 snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix); 61 62 dma_window = of_get_property(dn, propname, &bytes); 63 if (!dma_window) 64 return -ENODEV; 65 end = dma_window + bytes / sizeof(*dma_window); 66 67 while (dma_window < end) { 68 u32 cells; 69 const void *prop; 70 71 /* busno is one cell if supported */ 72 if (busno) 73 *busno = be32_to_cpup(dma_window++); 74 75 prop = of_get_property(dn, addrname, NULL); 76 if (!prop) 77 prop = of_get_property(dn, "#address-cells", NULL); 78 79 cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn); 80 if (!cells) 81 return -EINVAL; 82 *addr = of_read_number(dma_window, cells); 83 dma_window += cells; 84 85 prop = of_get_property(dn, sizename, NULL); 86 cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn); 87 if (!cells) 88 return -EINVAL; 89 *size = of_read_number(dma_window, cells); 90 dma_window += cells; 91 92 if (cur_index++ == index) 93 break; 94 } 95 return 0; 96 } 97 EXPORT_SYMBOL_GPL(of_get_dma_window); 98 99 static int of_iommu_xlate(struct device *dev, 100 struct of_phandle_args *iommu_spec) 101 { 102 const struct iommu_ops *ops; 103 struct fwnode_handle *fwnode = &iommu_spec->np->fwnode; 104 int err; 105 106 ops = iommu_ops_from_fwnode(fwnode); 107 if ((ops && !ops->of_xlate) || 108 !of_device_is_available(iommu_spec->np)) 109 return NO_IOMMU; 110 111 err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops); 112 if (err) 113 return err; 114 /* 115 * The otherwise-empty fwspec handily serves to indicate the specific 116 * IOMMU device we're waiting for, which will be useful if we ever get 117 * a proper probe-ordering dependency mechanism in future. 118 */ 119 if (!ops) 120 return driver_deferred_probe_check_state(dev); 121 122 return ops->of_xlate(dev, iommu_spec); 123 } 124 125 struct of_pci_iommu_alias_info { 126 struct device *dev; 127 struct device_node *np; 128 }; 129 130 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data) 131 { 132 struct of_pci_iommu_alias_info *info = data; 133 struct of_phandle_args iommu_spec = { .args_count = 1 }; 134 int err; 135 136 err = of_map_rid(info->np, alias, "iommu-map", "iommu-map-mask", 137 &iommu_spec.np, 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 static int of_fsl_mc_iommu_init(struct fsl_mc_device *mc_dev, 147 struct device_node *master_np) 148 { 149 struct of_phandle_args iommu_spec = { .args_count = 1 }; 150 int err; 151 152 err = of_map_rid(master_np, mc_dev->icid, "iommu-map", 153 "iommu-map-mask", &iommu_spec.np, 154 iommu_spec.args); 155 if (err) 156 return err == -ENODEV ? NO_IOMMU : err; 157 158 err = of_iommu_xlate(&mc_dev->dev, &iommu_spec); 159 of_node_put(iommu_spec.np); 160 return err; 161 } 162 163 const struct iommu_ops *of_iommu_configure(struct device *dev, 164 struct device_node *master_np) 165 { 166 const struct iommu_ops *ops = NULL; 167 struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); 168 int err = NO_IOMMU; 169 170 if (!master_np) 171 return NULL; 172 173 if (fwspec) { 174 if (fwspec->ops) 175 return fwspec->ops; 176 177 /* In the deferred case, start again from scratch */ 178 iommu_fwspec_free(dev); 179 } 180 181 /* 182 * We don't currently walk up the tree looking for a parent IOMMU. 183 * See the `Notes:' section of 184 * Documentation/devicetree/bindings/iommu/iommu.txt 185 */ 186 if (dev_is_pci(dev)) { 187 struct of_pci_iommu_alias_info info = { 188 .dev = dev, 189 .np = master_np, 190 }; 191 192 err = pci_for_each_dma_alias(to_pci_dev(dev), 193 of_pci_iommu_init, &info); 194 } else if (dev_is_fsl_mc(dev)) { 195 err = of_fsl_mc_iommu_init(to_fsl_mc_device(dev), master_np); 196 } else { 197 struct of_phandle_args iommu_spec; 198 int idx = 0; 199 200 while (!of_parse_phandle_with_args(master_np, "iommus", 201 "#iommu-cells", 202 idx, &iommu_spec)) { 203 err = of_iommu_xlate(dev, &iommu_spec); 204 of_node_put(iommu_spec.np); 205 idx++; 206 if (err) 207 break; 208 } 209 } 210 211 212 /* 213 * Two success conditions can be represented by non-negative err here: 214 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons 215 * 0 : we found an IOMMU, and dev->fwspec is initialised appropriately 216 * <0 : any actual error 217 */ 218 if (!err) { 219 /* The fwspec pointer changed, read it again */ 220 fwspec = dev_iommu_fwspec_get(dev); 221 ops = fwspec->ops; 222 } 223 /* 224 * If we have reason to believe the IOMMU driver missed the initial 225 * probe for dev, replay it to get things in order. 226 */ 227 if (dev->bus && !device_iommu_mapped(dev)) 228 err = iommu_probe_device(dev); 229 230 /* Ignore all other errors apart from EPROBE_DEFER */ 231 if (err == -EPROBE_DEFER) { 232 ops = ERR_PTR(err); 233 } else if (err < 0) { 234 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err); 235 ops = NULL; 236 } 237 238 return ops; 239 } 240