| 1 | |
| 2 | |
| 3 | * Functions for dealing with DT resolution
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| 4 | *
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| 5 | * Copyright (C) 2012 Pantelis Antoniou <[email protected]>
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| 6 | * Copyright (C) 2012 Texas Instruments Inc.
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| 7 |
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| 8 |
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| 9 | #define pr_fmt(fmt) "OF: resolver: " fmt
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| 10 |
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| 11 | #include <linux/cleanup.h>
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| 12 | #include <linux/kernel.h>
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| 13 | #include <linux/module.h>
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| 14 | #include <linux/of.h>
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| 15 | #include <linux/of_device.h>
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| 16 | #include <linux/string.h>
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| 17 | #include <linux/ctype.h>
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| 18 | #include <linux/errno.h>
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| 19 | #include <linux/slab.h>
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| 20 |
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| 21 | #include "of_private.h"
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| 22 |
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| 23 | static phandle live_tree_max_phandle(void)
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| 24 | {
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| 25 | struct device_node *node;
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| 26 | phandle phandle;
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| 27 | unsigned long flags;
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| 28 |
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| 29 | raw_spin_lock_irqsave(&devtree_lock, flags);
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| 30 | phandle = 0;
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| 31 | for_each_of_allnodes(node) {
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| 32 | if (node->phandle != OF_PHANDLE_ILLEGAL &&
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| 33 | node->phandle > phandle)
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| 34 | phandle = node->phandle;
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| 35 | }
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| 36 | raw_spin_unlock_irqrestore(&devtree_lock, flags);
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| 37 |
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| 38 | return phandle;
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| 39 | }
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| 40 |
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| 41 | static void adjust_overlay_phandles(struct device_node *overlay,
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| 42 | int phandle_delta)
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| 43 | {
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| 44 | struct device_node *child;
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| 45 | const struct property *prop;
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| 46 | phandle phandle;
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| 47 |
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| 48 |
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| 49 | if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL)
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| 50 | overlay->phandle += phandle_delta;
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| 51 |
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| 52 |
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| 53 | for_each_property_of_node(overlay, prop) {
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| 54 |
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| 55 | if (of_prop_cmp(prop->name, "phandle") &&
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| 56 | of_prop_cmp(prop->name, "linux,phandle"))
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| 57 | continue;
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| 58 |
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| 59 | if (prop->length < 4)
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| 60 | continue;
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| 61 |
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| 62 | phandle = be32_to_cpup(prop->value);
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| 63 | if (phandle == OF_PHANDLE_ILLEGAL)
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| 64 | continue;
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| 65 |
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| 66 | *(__be32 *)prop->value = cpu_to_be32(overlay->phandle);
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| 67 | }
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| 68 |
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| 69 | for_each_child_of_node(overlay, child)
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| 70 | adjust_overlay_phandles(child, phandle_delta);
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| 71 | }
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| 72 |
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| 73 | static int update_usages_of_a_phandle_reference(struct device_node *overlay,
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| 74 | const struct property *prop_fixup, phandle phandle)
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| 75 | {
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| 76 | struct device_node *refnode;
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| 77 | const struct property *prop;
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| 78 | char *value __free(kfree) = kmemdup(prop_fixup->value, prop_fixup->length, GFP_KERNEL);
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| 79 | char *cur, *end, *node_path, *prop_name, *s;
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| 80 | int offset, len;
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| 81 | int err = 0;
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| 82 |
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| 83 | if (!value)
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| 84 | return -ENOMEM;
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| 85 |
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| 86 |
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| 87 | end = value + prop_fixup->length;
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| 88 | for (cur = value; cur < end; cur += len + 1) {
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| 89 | len = strlen(cur);
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| 90 |
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| 91 | node_path = cur;
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| 92 | s = strchr(cur, ':');
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| 93 | if (!s)
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| 94 | return -EINVAL;
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| 95 | *s++ = '\0';
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| 96 |
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| 97 | prop_name = s;
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| 98 | s = strchr(s, ':');
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| 99 | if (!s)
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| 100 | return -EINVAL;
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| 101 | *s++ = '\0';
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| 102 |
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| 103 | err = kstrtoint(s, 10, &offset);
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| 104 | if (err)
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| 105 | return err;
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| 106 |
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| 107 | refnode = __of_find_node_by_full_path(of_node_get(overlay), node_path);
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| 108 | if (!refnode)
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| 109 | continue;
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| 110 |
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| 111 | for_each_property_of_node(refnode, prop) {
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| 112 | if (!of_prop_cmp(prop->name, prop_name))
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| 113 | break;
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| 114 | }
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| 115 | of_node_put(refnode);
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| 116 |
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| 117 | if (!prop)
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| 118 | return -ENOENT;
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| 119 |
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| 120 | if (offset < 0 || offset + sizeof(__be32) > prop->length)
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| 121 | return -EINVAL;
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| 122 |
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| 123 | *(__be32 *)(prop->value + offset) = cpu_to_be32(phandle);
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| 124 | }
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| 125 |
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| 126 | return 0;
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| 127 | }
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| 128 |
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| 129 |
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| 130 | static int node_name_cmp(const struct device_node *dn1,
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| 131 | const struct device_node *dn2)
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| 132 | {
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| 133 | const char *n1 = kbasename(dn1->full_name);
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| 134 | const char *n2 = kbasename(dn2->full_name);
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| 135 |
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| 136 | return of_node_cmp(n1, n2);
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| 137 | }
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| 138 |
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| 139 | |
| 140 | * Adjust the local phandle references by the given phandle delta.
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| 141 | *
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| 142 | * Subtree @local_fixups, which is overlay node __local_fixups__,
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| 143 | * mirrors the fragment node structure at the root of the overlay.
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| 144 | *
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| 145 | * For each property in the fragments that contains a phandle reference,
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| 146 | * @local_fixups has a property of the same name that contains a list
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| 147 | * of offsets of the phandle reference(s) within the respective property
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| 148 | * value(s). The values at these offsets will be fixed up.
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| 149 |
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| 150 | static int adjust_local_phandle_references(const struct device_node *local_fixups,
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| 151 | const struct device_node *overlay, int phandle_delta)
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| 152 | {
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| 153 | struct device_node *overlay_child;
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| 154 | const struct property *prop_fix, *prop;
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| 155 | int err, i, count;
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| 156 | unsigned int off;
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| 157 |
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| 158 | if (!local_fixups)
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| 159 | return 0;
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| 160 |
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| 161 | for_each_property_of_node(local_fixups, prop_fix) {
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| 162 |
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| 163 |
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| 164 | if (is_pseudo_property(prop_fix->name))
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| 165 | continue;
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| 166 |
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| 167 | if ((prop_fix->length % 4) != 0 || prop_fix->length == 0)
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| 168 | return -EINVAL;
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| 169 | count = prop_fix->length / sizeof(__be32);
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| 170 |
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| 171 | for_each_property_of_node(overlay, prop) {
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| 172 | if (!of_prop_cmp(prop->name, prop_fix->name))
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| 173 | break;
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| 174 | }
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| 175 |
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| 176 | if (!prop)
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| 177 | return -EINVAL;
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| 178 |
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| 179 | for (i = 0; i < count; i++) {
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| 180 | off = be32_to_cpu(((__be32 *)prop_fix->value)[i]);
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| 181 | if ((off + 4) > prop->length)
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| 182 | return -EINVAL;
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| 183 |
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| 184 | be32_add_cpu(prop->value + off, phandle_delta);
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| 185 | }
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| 186 | }
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| 187 |
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| 188 | |
| 189 | * These nested loops recurse down two subtrees in parallel, where the
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| 190 | * node names in the two subtrees match.
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| 191 | *
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| 192 | * The roots of the subtrees are the overlay's __local_fixups__ node
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| 193 | * and the overlay's root node.
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| 194 |
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| 195 | for_each_child_of_node_scoped(local_fixups, child) {
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| 196 |
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| 197 | for_each_child_of_node(overlay, overlay_child)
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| 198 | if (!node_name_cmp(child, overlay_child)) {
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| 199 | of_node_put(overlay_child);
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| 200 | break;
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| 201 | }
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| 202 |
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| 203 | if (!overlay_child)
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| 204 | return -EINVAL;
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| 205 |
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| 206 | err = adjust_local_phandle_references(child, overlay_child,
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| 207 | phandle_delta);
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| 208 | if (err)
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| 209 | return err;
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| 210 | }
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| 211 |
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| 212 | return 0;
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| 213 | }
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| 214 |
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| 215 | |
| 216 | * of_resolve_phandles - Relocate and resolve overlay against live tree
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| 217 | *
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| 218 | * @overlay: Pointer to devicetree overlay to relocate and resolve
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| 219 | *
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| 220 | * Modify (relocate) values of local phandles in @overlay to a range that
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| 221 | * does not conflict with the live expanded devicetree. Update references
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| 222 | * to the local phandles in @overlay. Update (resolve) phandle references
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| 223 | * in @overlay that refer to the live expanded devicetree.
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| 224 | *
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| 225 | * Phandle values in the live tree are in the range of
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| 226 | * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay
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| 227 | * also begin with at 1. Adjust the phandle values in the overlay to begin
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| 228 | * at live_tree_max_phandle() + 1. Update references to the phandles to
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| 229 | * the adjusted phandle values.
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| 230 | *
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| 231 | * The name of each property in the "__fixups__" node in the overlay matches
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| 232 | * the name of a symbol (a label) in the live tree. The values of each
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| 233 | * property in the "__fixups__" node is a list of the property values in the
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| 234 | * overlay that need to be updated to contain the phandle reference
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| 235 | * corresponding to that symbol in the live tree. Update the references in
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| 236 | * the overlay with the phandle values in the live tree.
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| 237 | *
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| 238 | * @overlay must be detached.
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| 239 | *
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| 240 | * Resolving and applying @overlay to the live expanded devicetree must be
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| 241 | * protected by a mechanism to ensure that multiple overlays are processed
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| 242 | * in a single threaded manner so that multiple overlays will not relocate
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| 243 | * phandles to overlapping ranges. The mechanism to enforce this is not
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| 244 | * yet implemented.
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| 245 | *
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| 246 | * Return: %0 on success or a negative error value on error.
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| 247 |
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| 248 | int of_resolve_phandles(struct device_node *overlay)
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| 249 | {
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| 250 | struct device_node *child, *refnode;
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| 251 | struct device_node *overlay_fixups;
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| 252 | struct device_node __free(device_node) *local_fixups = NULL;
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| 253 | struct property *prop;
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| 254 | const char *refpath;
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| 255 | phandle phandle, phandle_delta;
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| 256 | int err;
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| 257 |
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| 258 | if (!overlay) {
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| 259 | pr_err("null overlay\n");
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| 260 | return -EINVAL;
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| 261 | }
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| 262 |
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| 263 | if (!of_node_check_flag(overlay, OF_DETACHED)) {
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| 264 | pr_err("overlay not detached\n");
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| 265 | return -EINVAL;
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| 266 | }
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| 267 |
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| 268 | phandle_delta = live_tree_max_phandle() + 1;
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| 269 | adjust_overlay_phandles(overlay, phandle_delta);
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| 270 |
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| 271 | for_each_child_of_node(overlay, local_fixups)
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| 272 | if (of_node_name_eq(local_fixups, "__local_fixups__"))
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| 273 | break;
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| 274 |
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| 275 | err = adjust_local_phandle_references(local_fixups, overlay, phandle_delta);
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| 276 | if (err)
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| 277 | return err;
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| 278 |
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| 279 | overlay_fixups = NULL;
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| 280 |
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| 281 | for_each_child_of_node(overlay, child) {
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| 282 | if (of_node_name_eq(child, "__fixups__"))
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| 283 | overlay_fixups = child;
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| 284 | }
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| 285 |
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| 286 | if (!overlay_fixups)
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| 287 | return 0;
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| 288 |
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| 289 | struct device_node __free(device_node) *tree_symbols = of_find_node_by_path("/__symbols__");
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| 290 | if (!tree_symbols) {
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| 291 | pr_err("no symbols in root of device tree.\n");
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| 292 | return -EINVAL;
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| 293 | }
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| 294 |
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| 295 | for_each_property_of_node(overlay_fixups, prop) {
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| 296 |
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| 297 |
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| 298 | if (!of_prop_cmp(prop->name, "name"))
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| 299 | continue;
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| 300 |
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| 301 | err = of_property_read_string(tree_symbols,
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| 302 | prop->name, &refpath);
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| 303 | if (err) {
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| 304 | pr_err("node label '%s' not found in live devicetree symbols table\n",
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| 305 | prop->name);
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| 306 | return err;
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| 307 | }
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| 308 |
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| 309 | refnode = of_find_node_by_path(refpath);
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| 310 | if (!refnode)
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| 311 | return -ENOENT;
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| 312 |
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| 313 | phandle = refnode->phandle;
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| 314 | of_node_put(refnode);
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| 315 |
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| 316 | err = update_usages_of_a_phandle_reference(overlay, prop, phandle);
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| 317 | if (err)
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| 318 | break;
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| 319 | }
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| 320 |
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| 321 | if (err)
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| 322 | pr_err("overlay phandle fixup failed: %d\n", err);
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| 323 | return err;
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| 324 | }
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| 325 | EXPORT_SYMBOL_GPL(of_resolve_phandles);
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