drivers/iommu/of_iommu.c

   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 static const struct of_device_id __iommu_of_table_sentinel
  29         __used __section(__iommu_of_table_end);
  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 bool of_iommu_driver_present(struct device_node *np)
 100 {
 101         /*
 102          * If the IOMMU still isn't ready by the time we reach init, assume
 103          * it never will be. We don't want to defer indefinitely, nor attempt
 104          * to dereference __iommu_of_table after it's been freed.
 105          */
 106         if (system_state > SYSTEM_BOOTING)
 107                 return false;
 108
 109         return of_match_node(&__iommu_of_table, np);
 110 }
 111
 112 static const struct iommu_ops
 113 *of_iommu_xlate(struct device *dev, struct of_phandle_args *iommu_spec)
 114 {
 115         const struct iommu_ops *ops;
 116         struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
 117         int err;
 118
 119         ops = iommu_ops_from_fwnode(fwnode);
 120         if ((ops && !ops->of_xlate) ||
 121             (!ops && !of_iommu_driver_present(iommu_spec->np)))
 122                 return NULL;
 123
 124         err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
 125         if (err)
 126                 return ERR_PTR(err);
 127         /*
 128          * The otherwise-empty fwspec handily serves to indicate the specific
 129          * IOMMU device we're waiting for, which will be useful if we ever get
 130          * a proper probe-ordering dependency mechanism in future.
 131          */
 132         if (!ops)
 133                 return ERR_PTR(-EPROBE_DEFER);
 134
 135         err = ops->of_xlate(dev, iommu_spec);
 136         if (err)
 137                 return ERR_PTR(err);
 138
 139         return ops;
 140 }
 141
 142 static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
 143 {
 144         struct of_phandle_args *iommu_spec = data;
 145
 146         iommu_spec->args[0] = alias;
 147         return iommu_spec->np == pdev->bus->dev.of_node;
 148 }
 149
 150 static const struct iommu_ops
 151 *of_pci_iommu_init(struct pci_dev *pdev, struct device_node *bridge_np)
 152 {
 153         const struct iommu_ops *ops;
 154         struct of_phandle_args iommu_spec;
 155         int err;
 156
 157         /*
 158          * Start by tracing the RID alias down the PCI topology as
 159          * far as the host bridge whose OF node we have...
 160          * (we're not even attempting to handle multi-alias devices yet)
 161          */
 162         iommu_spec.args_count = 1;
 163         iommu_spec.np = bridge_np;
 164         pci_for_each_dma_alias(pdev, __get_pci_rid, &iommu_spec);
 165         /*
 166          * ...then find out what that becomes once it escapes the PCI
 167          * bus into the system beyond, and which IOMMU it ends up at.
 168          */
 169         iommu_spec.np = NULL;
 170         err = of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
 171                              "iommu-map-mask", &iommu_spec.np,
 172                              iommu_spec.args);
 173         if (err)
 174                 return err == -ENODEV ? NULL : ERR_PTR(err);
 175
 176         ops = of_iommu_xlate(&pdev->dev, &iommu_spec);
 177
 178         of_node_put(iommu_spec.np);
 179         return ops;
 180 }
 181
 182 static const struct iommu_ops
 183 *of_platform_iommu_init(struct device *dev, struct device_node *np)
 184 {
 185         struct of_phandle_args iommu_spec;
 186         const struct iommu_ops *ops = NULL;
 187         int idx = 0;
 188
 189         /*
 190          * We don't currently walk up the tree looking for a parent IOMMU.
 191          * See the `Notes:' section of
 192          * Documentation/devicetree/bindings/iommu/iommu.txt
 193          */
 194         while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells",
 195                                            idx, &iommu_spec)) {
 196                 ops = of_iommu_xlate(dev, &iommu_spec);
 197                 of_node_put(iommu_spec.np);
 198                 idx++;
 199                 if (IS_ERR_OR_NULL(ops))
 200                         break;
 201         }
 202
 203         return ops;
 204 }
 205
 206 const struct iommu_ops *of_iommu_configure(struct device *dev,
 207                                            struct device_node *master_np)
 208 {
 209         const struct iommu_ops *ops;
 210         struct iommu_fwspec *fwspec = dev->iommu_fwspec;
 211
 212         if (!master_np)
 213                 return NULL;
 214
 215         if (fwspec) {
 216                 if (fwspec->ops)
 217                         return fwspec->ops;
 218
 219                 /* In the deferred case, start again from scratch */
 220                 iommu_fwspec_free(dev);
 221         }
 222
 223         if (dev_is_pci(dev))
 224                 ops = of_pci_iommu_init(to_pci_dev(dev), master_np);
 225         else
 226                 ops = of_platform_iommu_init(dev, master_np);
 227         /*
 228          * If we have reason to believe the IOMMU driver missed the initial
 229          * add_device callback for dev, replay it to get things in order.
 230          */
 231         if (!IS_ERR_OR_NULL(ops) && ops->add_device &&
 232             dev->bus && !dev->iommu_group) {
 233                 int err = ops->add_device(dev);
 234
 235                 if (err)
 236                         ops = ERR_PTR(err);
 237         }
 238
 239         return ops;
 240 }
 241
 242 static int __init of_iommu_init(void)
 243 {
 244         struct device_node *np;
 245         const struct of_device_id *match, *matches = &__iommu_of_table;
 246
 247         for_each_matching_node_and_match(np, matches, &match) {
 248                 const of_iommu_init_fn init_fn = match->data;
 249
 250                 if (init_fn && init_fn(np))
 251                         pr_err("Failed to initialise IOMMU %s\n",
 252                                 of_node_full_name(np));
 253         }
 254
 255         return 0;
 256 }
 257 postcore_initcall_sync(of_iommu_init);