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/slab.h>
  26
  27 static const struct of_device_id __iommu_of_table_sentinel
  28         __used __section(__iommu_of_table_end);
  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 struct of_iommu_node {
  99         struct list_head list;
 100         struct device_node *np;
 101         struct iommu_ops *ops;
 102 };
 103 static LIST_HEAD(of_iommu_list);
 104 static DEFINE_SPINLOCK(of_iommu_lock);
 105
 106 void of_iommu_set_ops(struct device_node *np, struct iommu_ops *ops)
 107 {
 108         struct of_iommu_node *iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
 109
 110         if (WARN_ON(!iommu))
 111                 return;
 112
 113         INIT_LIST_HEAD(&iommu->list);
 114         iommu->np = np;
 115         iommu->ops = ops;
 116         spin_lock(&of_iommu_lock);
 117         list_add_tail(&iommu->list, &of_iommu_list);
 118         spin_unlock(&of_iommu_lock);
 119 }
 120
 121 struct iommu_ops *of_iommu_get_ops(struct device_node *np)
 122 {
 123         struct of_iommu_node *node;
 124         struct iommu_ops *ops = NULL;
 125
 126         spin_lock(&of_iommu_lock);
 127         list_for_each_entry(node, &of_iommu_list, list)
 128                 if (node->np == np) {
 129                         ops = node->ops;
 130                         break;
 131                 }
 132         spin_unlock(&of_iommu_lock);
 133         return ops;
 134 }
 135
 136 struct iommu_ops *of_iommu_configure(struct device *dev,
 137                                      struct device_node *master_np)
 138 {
 139         struct of_phandle_args iommu_spec;
 140         struct device_node *np;
 141         struct iommu_ops *ops = NULL;
 142         int idx = 0;
 143
 144         /*
 145          * We can't do much for PCI devices without knowing how
 146          * device IDs are wired up from the PCI bus to the IOMMU.
 147          */
 148         if (dev_is_pci(dev))
 149                 return NULL;
 150
 151         /*
 152          * We don't currently walk up the tree looking for a parent IOMMU.
 153          * See the `Notes:' section of
 154          * Documentation/devicetree/bindings/iommu/iommu.txt
 155          */
 156         while (!of_parse_phandle_with_args(master_np, "iommus",
 157                                            "#iommu-cells", idx,
 158                                            &iommu_spec)) {
 159                 np = iommu_spec.np;
 160                 ops = of_iommu_get_ops(np);
 161
 162                 if (!ops || !ops->of_xlate || ops->of_xlate(dev, &iommu_spec))
 163                         goto err_put_node;
 164
 165                 of_node_put(np);
 166                 idx++;
 167         }
 168
 169         return ops;
 170
 171 err_put_node:
 172         of_node_put(np);
 173         return NULL;
 174 }
 175
 176 void __init of_iommu_init(void)
 177 {
 178         struct device_node *np;
 179         const struct of_device_id *match, *matches = &__iommu_of_table;
 180
 181         for_each_matching_node_and_match(np, matches, &match) {
 182                 const of_iommu_init_fn init_fn = match->data;
 183
 184                 if (init_fn(np))
 185                         pr_err("Failed to initialise IOMMU %s\n",
 186                                 of_node_full_name(np));
 187         }
 188 }