drivers/iommu/of_iommu.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * OF helpers for IOMMU
   4  *
   5  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
   6  */
   7
   8 #include <linux/export.h>
   9 #include <linux/iommu.h>
  10 #include <linux/limits.h>
  11 #include <linux/of.h>
  12 #include <linux/of_iommu.h>
  13 #include <linux/of_pci.h>
  14 #include <linux/slab.h>
  15 #include <linux/fsl/mc.h>
  16
  17 #define NO_IOMMU        1
  18
  19 /**
  20  * of_get_dma_window - Parse *dma-window property and returns 0 if found.
  21  *
  22  * @dn: device node
  23  * @prefix: prefix for property name if any
  24  * @index: index to start to parse
  25  * @busno: Returns busno if supported. Otherwise pass NULL
  26  * @addr: Returns address that DMA starts
  27  * @size: Returns the range that DMA can handle
  28  *
  29  * This supports different formats flexibly. "prefix" can be
  30  * configured if any. "busno" and "index" are optionally
  31  * specified. Set 0(or NULL) if not used.
  32  */
  33 int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
  34                       unsigned long *busno, dma_addr_t *addr, size_t *size)
  35 {
  36         const __be32 *dma_window, *end;
  37         int bytes, cur_index = 0;
  38         char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
  39
  40         if (!dn || !addr || !size)
  41                 return -EINVAL;
  42
  43         if (!prefix)
  44                 prefix = "";
  45
  46         snprintf(propname, sizeof(propname), "%sdma-window", prefix);
  47         snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
  48         snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
  49
  50         dma_window = of_get_property(dn, propname, &bytes);
  51         if (!dma_window)
  52                 return -ENODEV;
  53         end = dma_window + bytes / sizeof(*dma_window);
  54
  55         while (dma_window < end) {
  56                 u32 cells;
  57                 const void *prop;
  58
  59                 /* busno is one cell if supported */
  60                 if (busno)
  61                         *busno = be32_to_cpup(dma_window++);
  62
  63                 prop = of_get_property(dn, addrname, NULL);
  64                 if (!prop)
  65                         prop = of_get_property(dn, "#address-cells", NULL);
  66
  67                 cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
  68                 if (!cells)
  69                         return -EINVAL;
  70                 *addr = of_read_number(dma_window, cells);
  71                 dma_window += cells;
  72
  73                 prop = of_get_property(dn, sizename, NULL);
  74                 cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
  75                 if (!cells)
  76                         return -EINVAL;
  77                 *size = of_read_number(dma_window, cells);
  78                 dma_window += cells;
  79
  80                 if (cur_index++ == index)
  81                         break;
  82         }
  83         return 0;
  84 }
  85 EXPORT_SYMBOL_GPL(of_get_dma_window);
  86
  87 static int of_iommu_xlate(struct device *dev,
  88                           struct of_phandle_args *iommu_spec)
  89 {
  90         const struct iommu_ops *ops;
  91         struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
  92         int err;
  93
  94         ops = iommu_ops_from_fwnode(fwnode);
  95         if ((ops && !ops->of_xlate) ||
  96             !of_device_is_available(iommu_spec->np))
  97                 return NO_IOMMU;
  98
  99         err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
 100         if (err)
 101                 return err;
 102         /*
 103          * The otherwise-empty fwspec handily serves to indicate the specific
 104          * IOMMU device we're waiting for, which will be useful if we ever get
 105          * a proper probe-ordering dependency mechanism in future.
 106          */
 107         if (!ops)
 108                 return driver_deferred_probe_check_state(dev);
 109
 110         return ops->of_xlate(dev, iommu_spec);
 111 }
 112
 113 struct of_pci_iommu_alias_info {
 114         struct device *dev;
 115         struct device_node *np;
 116 };
 117
 118 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
 119 {
 120         struct of_pci_iommu_alias_info *info = data;
 121         struct of_phandle_args iommu_spec = { .args_count = 1 };
 122         int err;
 123
 124         err = of_map_rid(info->np, alias, "iommu-map", "iommu-map-mask",
 125                          &iommu_spec.np, iommu_spec.args);
 126         if (err)
 127                 return err == -ENODEV ? NO_IOMMU : err;
 128
 129         err = of_iommu_xlate(info->dev, &iommu_spec);
 130         of_node_put(iommu_spec.np);
 131         return err;
 132 }
 133
 134 static int of_fsl_mc_iommu_init(struct fsl_mc_device *mc_dev,
 135                                 struct device_node *master_np)
 136 {
 137         struct of_phandle_args iommu_spec = { .args_count = 1 };
 138         int err;
 139
 140         err = of_map_rid(master_np, mc_dev->icid, "iommu-map",
 141                          "iommu-map-mask", &iommu_spec.np,
 142                          iommu_spec.args);
 143         if (err)
 144                 return err == -ENODEV ? NO_IOMMU : err;
 145
 146         err = of_iommu_xlate(&mc_dev->dev, &iommu_spec);
 147         of_node_put(iommu_spec.np);
 148         return err;
 149 }
 150
 151 const struct iommu_ops *of_iommu_configure(struct device *dev,
 152                                            struct device_node *master_np)
 153 {
 154         const struct iommu_ops *ops = NULL;
 155         struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 156         int err = NO_IOMMU;
 157
 158         if (!master_np)
 159                 return NULL;
 160
 161         if (fwspec) {
 162                 if (fwspec->ops)
 163                         return fwspec->ops;
 164
 165                 /* In the deferred case, start again from scratch */
 166                 iommu_fwspec_free(dev);
 167         }
 168
 169         /*
 170          * We don't currently walk up the tree looking for a parent IOMMU.
 171          * See the `Notes:' section of
 172          * Documentation/devicetree/bindings/iommu/iommu.txt
 173          */
 174         if (dev_is_pci(dev)) {
 175                 struct of_pci_iommu_alias_info info = {
 176                         .dev = dev,
 177                         .np = master_np,
 178                 };
 179
 180                 err = pci_for_each_dma_alias(to_pci_dev(dev),
 181                                              of_pci_iommu_init, &info);
 182         } else if (dev_is_fsl_mc(dev)) {
 183                 err = of_fsl_mc_iommu_init(to_fsl_mc_device(dev), master_np);
 184         } else {
 185                 struct of_phandle_args iommu_spec;
 186                 int idx = 0;
 187
 188                 while (!of_parse_phandle_with_args(master_np, "iommus",
 189                                                    "#iommu-cells",
 190                                                    idx, &iommu_spec)) {
 191                         err = of_iommu_xlate(dev, &iommu_spec);
 192                         of_node_put(iommu_spec.np);
 193                         idx++;
 194                         if (err)
 195                                 break;
 196                 }
 197         }
 198
 199
 200         /*
 201          * Two success conditions can be represented by non-negative err here:
 202          * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
 203          *  0 : we found an IOMMU, and dev->fwspec is initialised appropriately
 204          * <0 : any actual error
 205          */
 206         if (!err) {
 207                 /* The fwspec pointer changed, read it again */
 208                 fwspec = dev_iommu_fwspec_get(dev);
 209                 ops    = fwspec->ops;
 210         }
 211         /*
 212          * If we have reason to believe the IOMMU driver missed the initial
 213          * probe for dev, replay it to get things in order.
 214          */
 215         if (!err && dev->bus && !device_iommu_mapped(dev))
 216                 err = iommu_probe_device(dev);
 217
 218         /* Ignore all other errors apart from EPROBE_DEFER */
 219         if (err == -EPROBE_DEFER) {
 220                 ops = ERR_PTR(err);
 221         } else if (err < 0) {
 222                 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
 223                 ops = NULL;
 224         }
 225
 226         return ops;
 227 }