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 /**
  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 }