--- /dev/null
+#include "libfdt_env.h"
+
+#include <fdt.h>
+#include <libfdt.h>
+
+#include "libfdt_internal.h"
+
+static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
+{
+ const uint32_t *val;
+ int len;
+
+ val = fdt_getprop(fdto, fragment, "target", &len);
+ if (!val)
+ return 0;
+
+ if ((*val == 0xffffffff) || (len != sizeof(*val)))
+ return 0xffffffff;
+
+ return fdt32_to_cpu(*val);
+}
+
+static int overlay_get_target(const void *fdt, const void *fdto,
+ int fragment)
+{
+ uint32_t phandle;
+ const char *path;
+
+ /* Try first to do a phandle based lookup */
+ phandle = overlay_get_target_phandle(fdto, fragment);
+ if (phandle == -1)
+ return -FDT_ERR_BADPHANDLE;
+
+ if (phandle)
+ return fdt_node_offset_by_phandle(fdt, phandle);
+
+ /* And then a path based lookup */
+ path = fdt_getprop(fdto, fragment, "target-path", NULL);
+ if (!path)
+ return -FDT_ERR_NOTFOUND;
+
+ return fdt_path_offset(fdt, path);
+}
+
+static int overlay_phandle_add_offset(void *fdt, int node,
+ const char *name, uint32_t delta)
+{
+ const uint32_t *val;
+ uint32_t adj_val;
+ int len;
+
+ val = fdt_getprop(fdt, node, name, &len);
+ if (!val)
+ return len;
+
+ if (len != sizeof(*val))
+ return -FDT_ERR_BADSTRUCTURE;
+
+ adj_val = fdt32_to_cpu(*val);
+ if ((adj_val + delta) < adj_val)
+ return -FDT_ERR_BADPHANDLE;
+
+ adj_val += delta;
+ return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
+}
+
+static int overlay_adjust_node_phandles(void *fdto, int node,
+ uint32_t delta)
+{
+ bool found = false;
+ int child;
+ int ret;
+
+ ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
+ if (ret && ret != -FDT_ERR_NOTFOUND)
+ return ret;
+
+ if (!ret)
+ found = true;
+
+ ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
+ if (ret && ret != -FDT_ERR_NOTFOUND)
+ return ret;
+
+ /*
+ * If neither phandle nor linux,phandle have been found return
+ * an error.
+ */
+ if (!found && !ret)
+ return ret;
+
+ fdt_for_each_subnode(fdto, child, node)
+ overlay_adjust_node_phandles(fdto, child, delta);
+
+ return 0;
+}
+
+static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
+{
+ /*
+ * Start adjusting the phandles from the overlay root
+ */
+ return overlay_adjust_node_phandles(fdto, 0, delta);
+}
+
+static int overlay_update_local_node_references(void *fdto,
+ int tree_node,
+ int fixup_node,
+ uint32_t delta)
+{
+ int fixup_prop;
+ int fixup_child;
+ int ret;
+
+ fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
+ const uint32_t *val = NULL;
+ uint32_t adj_val, index;
+ const char *name;
+ int fixup_len;
+ int tree_len;
+
+ val = fdt_getprop_by_offset(fdto, fixup_prop,
+ &name, &fixup_len);
+ if (!val)
+ return fixup_len;
+ index = fdt32_to_cpu(*val);
+
+ val = fdt_getprop(fdto, tree_node, name, &tree_len);
+ if (!val)
+ return tree_len;
+
+ /*
+ * The index can be unaligned.
+ *
+ * Use a memcpy for the architectures that do not
+ * support unaligned accesses.
+ */
+ memcpy(&adj_val, (unsigned char *)val + index,
+ sizeof(uint32_t));
+
+ adj_val = fdt32_to_cpu(adj_val);
+ adj_val += delta;
+ adj_val = cpu_to_fdt32(adj_val);
+
+ ret = fdt_setprop_inplace_namelen_by_index(fdto, tree_node,
+ name, strlen(name),
+ index, &adj_val,
+ sizeof(adj_val));
+ if (ret)
+ return ret;
+ }
+
+ fdt_for_each_subnode(fdto, fixup_child, fixup_node) {
+ const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
+ NULL);
+ int tree_child;
+
+ tree_child = fdt_subnode_offset(fdto, tree_node,
+ fixup_child_name);
+ if (tree_child < 0)
+ return tree_child;
+
+ ret = overlay_update_local_node_references(fdto,
+ tree_child,
+ fixup_child,
+ delta);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int overlay_update_local_references(void *dto, uint32_t delta)
+{
+ int fixups;
+
+ fixups = fdt_path_offset(dto, "/__local_fixups__");
+ if (fixups < 0) {
+ /* There's no local phandles to adjust, bail out */
+ if (fixups == -FDT_ERR_NOTFOUND)
+ return 0;
+
+ return fixups;
+ }
+
+ /*
+ * Update our local references from the root of the tree
+ */
+ return overlay_update_local_node_references(dto, 0, fixups,
+ delta);
+}
+
+static int overlay_fixup_one_phandle(void *fdt, void *fdto,
+ int symbols_off,
+ const char *path, uint32_t path_len,
+ const char *name, uint32_t name_len,
+ int index, const char *label)
+{
+ const char *symbol_path;
+ uint32_t phandle;
+ int symbol_off, fixup_off;
+ int prop_len;
+
+ symbol_path = fdt_getprop(fdt, symbols_off, label,
+ &prop_len);
+ if (!symbol_path)
+ return -FDT_ERR_NOTFOUND;
+
+ symbol_off = fdt_path_offset(fdt, symbol_path);
+ if (symbol_off < 0)
+ return symbol_off;
+
+ phandle = fdt_get_phandle(fdt, symbol_off);
+ if (!phandle)
+ return -FDT_ERR_NOTFOUND;
+
+ fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
+ if (fixup_off < 0)
+ return fixup_off;
+
+ phandle = cpu_to_fdt32(phandle);
+ return fdt_setprop_inplace_namelen_by_index(fdto, fixup_off,
+ name, name_len, index,
+ &phandle, sizeof(phandle));
+};
+
+static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
+ int property)
+{
+ const char *value;
+ const char *label;
+ int len;
+
+ value = fdt_getprop_by_offset(fdto, property,
+ &label, &len);
+ if (!value)
+ return len;
+
+ do {
+ const char *prop_string = value;
+ const char *path, *name;
+ uint32_t prop_len = strlen(value);
+ uint32_t path_len, name_len;
+ char *sep, *endptr;
+ int index;
+ int ret;
+
+ path = prop_string;
+ sep = memchr(prop_string, ':', prop_len);
+ if (*sep != ':')
+ return -FDT_ERR_BADSTRUCTURE;
+ path_len = sep - path;
+
+ name = sep + 1;
+ sep = memchr(name, ':', prop_len);
+ if (*sep != ':')
+ return -FDT_ERR_BADSTRUCTURE;
+ name_len = sep - name;
+
+ index = strtoul(sep + 1, &endptr, 10);
+ if ((*endptr != '\0') || (endptr <= (sep + 1)))
+ return -FDT_ERR_BADSTRUCTURE;
+
+ len -= prop_len + 1;
+ value += prop_len + 1;
+
+ ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
+ path, path_len, name, name_len,
+ index, label);
+ if (ret)
+ return ret;
+ } while (len > 0);
+
+ return 0;
+}
+
+static int overlay_fixup_phandles(void *dt, void *dto)
+{
+ int fixups_off, symbols_off;
+ int property;
+
+ symbols_off = fdt_path_offset(dt, "/__symbols__");
+ fixups_off = fdt_path_offset(dto, "/__fixups__");
+
+ fdt_for_each_property_offset(property, dto, fixups_off)
+ overlay_fixup_phandle(dt, dto, symbols_off, property);
+
+ return 0;
+}
+
+static int apply_overlay_node(void *dt, int target,
+ void *dto, int fragment)
+{
+ int property;
+ int node;
+
+ fdt_for_each_property_offset(property, dto, fragment) {
+ const char *name;
+ const void *prop;
+ int prop_len;
+ int ret;
+
+ prop = fdt_getprop_by_offset(dto, property, &name,
+ &prop_len);
+ if (prop_len == -FDT_ERR_NOTFOUND)
+ return -FDT_ERR_INTERNAL;
+ if (prop_len < 0)
+ return prop_len;
+
+ ret = fdt_setprop(dt, target, name, prop, prop_len);
+ if (ret)
+ return ret;
+ }
+
+ fdt_for_each_subnode(dto, node, fragment) {
+ const char *name = fdt_get_name(dto, node, NULL);
+ int nnode;
+ int ret;
+
+ nnode = fdt_add_subnode(dt, target, name);
+ if (nnode == -FDT_ERR_EXISTS)
+ nnode = fdt_subnode_offset(dt, target, name);
+
+ if (nnode < 0)
+ return nnode;
+
+ ret = apply_overlay_node(dt, nnode, dto, node);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int overlay_merge(void *dt, void *dto)
+{
+ int fragment;
+
+ fdt_for_each_subnode(dto, fragment, 0) {
+ int overlay;
+ int target;
+ int ret;
+
+ target = overlay_get_target(dt, dto, fragment);
+ if (target < 0)
+ continue;
+
+ overlay = fdt_subnode_offset(dto, fragment, "__overlay__");
+ if (overlay < 0)
+ return overlay;
+
+ ret = apply_overlay_node(dt, target, dto, overlay);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+int fdt_overlay_apply(void *fdt, void *fdto)
+{
+ uint32_t delta = fdt_get_max_phandle(fdt) + 1;
+ int ret;
+
+ FDT_CHECK_HEADER(fdt);
+ FDT_CHECK_HEADER(fdto);
+
+ ret = overlay_adjust_local_phandles(fdto, delta);
+ if (ret)
+ goto err;
+
+ ret = overlay_update_local_references(fdto, delta);
+ if (ret)
+ goto err;
+
+ ret = overlay_fixup_phandles(fdt, fdto);
+ if (ret)
+ goto err;
+
+ ret = overlay_merge(fdt, fdto);
+ if (ret)
+ goto err;
+
+ /*
+ * The overlay has been damaged, erase its magic.
+ */
+ fdt_set_magic(fdto, ~0);
+
+ return 0;
+
+err:
+ /*
+ * The overlay might have been damaged, erase its magic.
+ */
+ fdt_set_magic(fdto, ~0);
+
+ /*
+ * The base device tree might have been damaged, erase its
+ * magic.
+ */
+ fdt_set_magic(fdt, ~0);
+
+ return ret;
+}
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