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 #define NO_IOMMU        1
  29
  30 static const struct of_device_id __iommu_of_table_sentinel
  31         __used __section(__iommu_of_table_end);
  32
  33 /**
  34  * of_get_dma_window - Parse *dma-window property and returns 0 if found.
  35  *
  36  * @dn: device node
  37  * @prefix: prefix for property name if any
  38  * @index: index to start to parse
  39  * @busno: Returns busno if supported. Otherwise pass NULL
  40  * @addr: Returns address that DMA starts
  41  * @size: Returns the range that DMA can handle
  42  *
  43  * This supports different formats flexibly. "prefix" can be
  44  * configured if any. "busno" and "index" are optionally
  45  * specified. Set 0(or NULL) if not used.
  46  */
  47 int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
  48                       unsigned long *busno, dma_addr_t *addr, size_t *size)
  49 {
  50         const __be32 *dma_window, *end;
  51         int bytes, cur_index = 0;
  52         char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
  53
  54         if (!dn || !addr || !size)
  55                 return -EINVAL;
  56
  57         if (!prefix)
  58                 prefix = "";
  59
  60         snprintf(propname, sizeof(propname), "%sdma-window", prefix);
  61         snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
  62         snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
  63
  64         dma_window = of_get_property(dn, propname, &bytes);
  65         if (!dma_window)
  66                 return -ENODEV;
  67         end = dma_window + bytes / sizeof(*dma_window);
  68
  69         while (dma_window < end) {
  70                 u32 cells;
  71                 const void *prop;
  72
  73                 /* busno is one cell if supported */
  74                 if (busno)
  75                         *busno = be32_to_cpup(dma_window++);
  76
  77                 prop = of_get_property(dn, addrname, NULL);
  78                 if (!prop)
  79                         prop = of_get_property(dn, "#address-cells", NULL);
  80
  81                 cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
  82                 if (!cells)
  83                         return -EINVAL;
  84                 *addr = of_read_number(dma_window, cells);
  85                 dma_window += cells;
  86
  87                 prop = of_get_property(dn, sizename, NULL);
  88                 cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
  89                 if (!cells)
  90                         return -EINVAL;
  91                 *size = of_read_number(dma_window, cells);
  92                 dma_window += cells;
  93
  94                 if (cur_index++ == index)
  95                         break;
  96         }
  97         return 0;
  98 }
  99 EXPORT_SYMBOL_GPL(of_get_dma_window);
 100
 101 static bool of_iommu_driver_present(struct device_node *np)
 102 {
 103         /*
 104          * If the IOMMU still isn't ready by the time we reach init, assume
 105          * it never will be. We don't want to defer indefinitely, nor attempt
 106          * to dereference __iommu_of_table after it's been freed.
 107          */
 108         if (system_state >= SYSTEM_RUNNING)
 109                 return false;
 110
 111         return of_match_node(&__iommu_of_table, np);
 112 }
 113
 114 static int of_iommu_xlate(struct device *dev,
 115                           struct of_phandle_args *iommu_spec)
 116 {
 117         const struct iommu_ops *ops;
 118         struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
 119         int err;
 120
 121         ops = iommu_ops_from_fwnode(fwnode);
 122         if ((ops && !ops->of_xlate) ||
 123             !of_device_is_available(iommu_spec->np) ||
 124             (!ops && !of_iommu_driver_present(iommu_spec->np)))
 125                 return NO_IOMMU;
 126
 127         err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
 128         if (err)
 129                 return err;
 130         /*
 131          * The otherwise-empty fwspec handily serves to indicate the specific
 132          * IOMMU device we're waiting for, which will be useful if we ever get
 133          * a proper probe-ordering dependency mechanism in future.
 134          */
 135         if (!ops)
 136                 return -EPROBE_DEFER;
 137
 138         return ops->of_xlate(dev, iommu_spec);
 139 }
 140
 141 struct of_pci_iommu_alias_info {
 142         struct device *dev;
 143         struct device_node *np;
 144 };
 145
 146 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
 147 {
 148         struct of_pci_iommu_alias_info *info = data;
 149         struct of_phandle_args iommu_spec = { .args_count = 1 };
 150         int err;
 151
 152         err = of_pci_map_rid(info->np, alias, "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(info->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;
 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 {
 195                 struct of_phandle_args iommu_spec;
 196                 int idx = 0;
 197
 198                 while (!of_parse_phandle_with_args(master_np, "iommus",
 199                                                    "#iommu-cells",
 200                                                    idx, &iommu_spec)) {
 201                         err = of_iommu_xlate(dev, &iommu_spec);
 202                         of_node_put(iommu_spec.np);
 203                         idx++;
 204                         if (err)
 205                                 break;
 206                 }
 207         }
 208
 209         /*
 210          * Two success conditions can be represented by non-negative err here:
 211          * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
 212          *  0 : we found an IOMMU, and dev->fwspec is initialised appropriately
 213          * <0 : any actual error
 214          */
 215         if (!err)
 216                 ops = dev->iommu_fwspec->ops;
 217         /*
 218          * If we have reason to believe the IOMMU driver missed the initial
 219          * add_device callback for dev, replay it to get things in order.
 220          */
 221         if (ops && ops->add_device && dev->bus && !dev->iommu_group)
 222                 err = ops->add_device(dev);
 223
 224         /* Ignore all other errors apart from EPROBE_DEFER */
 225         if (err == -EPROBE_DEFER) {
 226                 ops = ERR_PTR(err);
 227         } else if (err < 0) {
 228                 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
 229                 ops = NULL;
 230         }
 231
 232         return ops;
 233 }