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/module.h>
  12 #include <linux/msi.h>
  13 #include <linux/of.h>
  14 #include <linux/of_iommu.h>
  15 #include <linux/of_pci.h>
  16 #include <linux/pci.h>
  17 #include <linux/slab.h>
  18 #include <linux/fsl/mc.h>
  19
  20 #define NO_IOMMU        1
  21
  22 /**
  23  * of_get_dma_window - Parse *dma-window property and returns 0 if found.
  24  *
  25  * @dn: device node
  26  * @prefix: prefix for property name if any
  27  * @index: index to start to parse
  28  * @busno: Returns busno if supported. Otherwise pass NULL
  29  * @addr: Returns address that DMA starts
  30  * @size: Returns the range that DMA can handle
  31  *
  32  * This supports different formats flexibly. "prefix" can be
  33  * configured if any. "busno" and "index" are optionally
  34  * specified. Set 0(or NULL) if not used.
  35  */
  36 int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
  37                       unsigned long *busno, dma_addr_t *addr, size_t *size)
  38 {
  39         const __be32 *dma_window, *end;
  40         int bytes, cur_index = 0;
  41         char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
  42
  43         if (!dn || !addr || !size)
  44                 return -EINVAL;
  45
  46         if (!prefix)
  47                 prefix = "";
  48
  49         snprintf(propname, sizeof(propname), "%sdma-window", prefix);
  50         snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
  51         snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
  52
  53         dma_window = of_get_property(dn, propname, &bytes);
  54         if (!dma_window)
  55                 return -ENODEV;
  56         end = dma_window + bytes / sizeof(*dma_window);
  57
  58         while (dma_window < end) {
  59                 u32 cells;
  60                 const void *prop;
  61
  62                 /* busno is one cell if supported */
  63                 if (busno)
  64                         *busno = be32_to_cpup(dma_window++);
  65
  66                 prop = of_get_property(dn, addrname, NULL);
  67                 if (!prop)
  68                         prop = of_get_property(dn, "#address-cells", NULL);
  69
  70                 cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
  71                 if (!cells)
  72                         return -EINVAL;
  73                 *addr = of_read_number(dma_window, cells);
  74                 dma_window += cells;
  75
  76                 prop = of_get_property(dn, sizename, NULL);
  77                 cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
  78                 if (!cells)
  79                         return -EINVAL;
  80                 *size = of_read_number(dma_window, cells);
  81                 dma_window += cells;
  82
  83                 if (cur_index++ == index)
  84                         break;
  85         }
  86         return 0;
  87 }
  88 EXPORT_SYMBOL_GPL(of_get_dma_window);
  89
  90 static int of_iommu_xlate(struct device *dev,
  91                           struct of_phandle_args *iommu_spec)
  92 {
  93         const struct iommu_ops *ops;
  94         struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
  95         int ret;
  96
  97         ops = iommu_ops_from_fwnode(fwnode);
  98         if ((ops && !ops->of_xlate) ||
  99             !of_device_is_available(iommu_spec->np))
 100                 return NO_IOMMU;
 101
 102         ret = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
 103         if (ret)
 104                 return ret;
 105         /*
 106          * The otherwise-empty fwspec handily serves to indicate the specific
 107          * IOMMU device we're waiting for, which will be useful if we ever get
 108          * a proper probe-ordering dependency mechanism in future.
 109          */
 110         if (!ops)
 111                 return driver_deferred_probe_check_state(dev);
 112
 113         if (!try_module_get(ops->owner))
 114                 return -ENODEV;
 115
 116         ret = ops->of_xlate(dev, iommu_spec);
 117         module_put(ops->owner);
 118         return ret;
 119 }
 120
 121 static int of_iommu_configure_dev_id(struct device_node *master_np,
 122                                      struct device *dev,
 123                                      const u32 *id)
 124 {
 125         struct of_phandle_args iommu_spec = { .args_count = 1 };
 126         int err;
 127
 128         err = of_map_id(master_np, *id, "iommu-map",
 129                          "iommu-map-mask", &iommu_spec.np,
 130                          iommu_spec.args);
 131         if (err)
 132                 return err == -ENODEV ? NO_IOMMU : err;
 133
 134         err = of_iommu_xlate(dev, &iommu_spec);
 135         of_node_put(iommu_spec.np);
 136         return err;
 137 }
 138
 139 static int of_iommu_configure_dev(struct device_node *master_np,
 140                                   struct device *dev)
 141 {
 142         struct of_phandle_args iommu_spec;
 143         int err = NO_IOMMU, idx = 0;
 144
 145         while (!of_parse_phandle_with_args(master_np, "iommus",
 146                                            "#iommu-cells",
 147                                            idx, &iommu_spec)) {
 148                 err = of_iommu_xlate(dev, &iommu_spec);
 149                 of_node_put(iommu_spec.np);
 150                 idx++;
 151                 if (err)
 152                         break;
 153         }
 154
 155         return err;
 156 }
 157
 158 struct of_pci_iommu_alias_info {
 159         struct device *dev;
 160         struct device_node *np;
 161 };
 162
 163 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
 164 {
 165         struct of_pci_iommu_alias_info *info = data;
 166         u32 input_id = alias;
 167
 168         return of_iommu_configure_dev_id(info->np, info->dev, &input_id);
 169 }
 170
 171 static int of_iommu_configure_device(struct device_node *master_np,
 172                                      struct device *dev, const u32 *id)
 173 {
 174         return (id) ? of_iommu_configure_dev_id(master_np, dev, id) :
 175                       of_iommu_configure_dev(master_np, dev);
 176 }
 177
 178 const struct iommu_ops *of_iommu_configure(struct device *dev,
 179                                            struct device_node *master_np,
 180                                            const u32 *id)
 181 {
 182         const struct iommu_ops *ops = NULL;
 183         struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 184         int err = NO_IOMMU;
 185
 186         if (!master_np)
 187                 return NULL;
 188
 189         if (fwspec) {
 190                 if (fwspec->ops)
 191                         return fwspec->ops;
 192
 193                 /* In the deferred case, start again from scratch */
 194                 iommu_fwspec_free(dev);
 195         }
 196
 197         /*
 198          * We don't currently walk up the tree looking for a parent IOMMU.
 199          * See the `Notes:' section of
 200          * Documentation/devicetree/bindings/iommu/iommu.txt
 201          */
 202         if (dev_is_pci(dev)) {
 203                 struct of_pci_iommu_alias_info info = {
 204                         .dev = dev,
 205                         .np = master_np,
 206                 };
 207
 208                 pci_request_acs();
 209                 err = pci_for_each_dma_alias(to_pci_dev(dev),
 210                                              of_pci_iommu_init, &info);
 211         } else {
 212                 err = of_iommu_configure_device(master_np, dev, id);
 213
 214                 fwspec = dev_iommu_fwspec_get(dev);
 215                 if (!err && fwspec)
 216                         of_property_read_u32(master_np, "pasid-num-bits",
 217                                              &fwspec->num_pasid_bits);
 218         }
 219
 220         /*
 221          * Two success conditions can be represented by non-negative err here:
 222          * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
 223          *  0 : we found an IOMMU, and dev->fwspec is initialised appropriately
 224          * <0 : any actual error
 225          */
 226         if (!err) {
 227                 /* The fwspec pointer changed, read it again */
 228                 fwspec = dev_iommu_fwspec_get(dev);
 229                 ops    = fwspec->ops;
 230         }
 231         /*
 232          * If we have reason to believe the IOMMU driver missed the initial
 233          * probe for dev, replay it to get things in order.
 234          */
 235         if (!err && dev->bus && !device_iommu_mapped(dev))
 236                 err = iommu_probe_device(dev);
 237
 238         /* Ignore all other errors apart from EPROBE_DEFER */
 239         if (err == -EPROBE_DEFER) {
 240                 ops = ERR_PTR(err);
 241         } else if (err < 0) {
 242                 dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
 243                 ops = NULL;
 244         }
 245
 246         return ops;
 247 }