diff options
| -rw-r--r-- | drivers/of/resolver.c | 66 |
1 files changed, 47 insertions, 19 deletions
diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c index 76c09cb..f842dbd 100644 --- a/drivers/of/resolver.c +++ b/drivers/of/resolver.c @@ -50,9 +50,6 @@ static struct device_node *find_node_by_full_name(struct device_node *node, return NULL; } -/* - * Find live tree's maximum phandle value. - */ static phandle live_tree_max_phandle(void) { struct device_node *node; @@ -71,9 +68,6 @@ static phandle live_tree_max_phandle(void) return phandle; } -/* - * Adjust a subtree's phandle values by a given delta. - */ static void adjust_overlay_phandles(struct device_node *overlay, int phandle_delta) { @@ -81,9 +75,11 @@ static void adjust_overlay_phandles(struct device_node *overlay, struct property *prop; phandle phandle; + /* adjust node's phandle in node */ if (overlay->phandle != 0 && overlay->phandle != OF_PHANDLE_ILLEGAL) overlay->phandle += phandle_delta; + /* copy adjusted phandle into *phandle properties */ for_each_property_of_node(overlay, prop) { if (of_prop_cmp(prop->name, "phandle") && @@ -118,6 +114,7 @@ static int update_usages_of_a_phandle_reference(struct device_node *overlay, return -ENOMEM; memcpy(value, prop_fixup->value, prop_fixup->length); + /* prop_fixup contains a list of tuples of path:property_name:offset */ end = value + prop_fixup->length; for (cur = value; cur < end; cur += len + 1) { len = strlen(cur); @@ -177,10 +174,14 @@ static int node_name_cmp(const struct device_node *dn1, /* * Adjust the local phandle references by the given phandle delta. - * Assumes the existances of a __local_fixups__ node at the root. - * Assumes that __of_verify_tree_phandle_references has been called. - * Does not take any devtree locks so make sure you call this on a tree - * which is at the detached state. + * + * Subtree @local_fixups, which is overlay node __local_fixups__, + * mirrors the fragment node structure at the root of the overlay. + * + * For each property in the fragments that contains a phandle reference, + * @local_fixups has a property of the same name that contains a list + * of offsets of the phandle reference(s) within the respective property + * value(s). The values at these offsets will be fixed up. */ static int adjust_local_phandle_references(struct device_node *local_fixups, struct device_node *overlay, int phandle_delta) @@ -225,6 +226,13 @@ static int adjust_local_phandle_references(struct device_node *local_fixups, } } + /* + * These nested loops recurse down two subtrees in parallel, where the + * node names in the two subtrees match. + * + * The roots of the subtrees are the overlay's __local_fixups__ node + * and the overlay's root node. + */ for_each_child_of_node(local_fixups, child) { for_each_child_of_node(overlay, overlay_child) @@ -244,17 +252,37 @@ static int adjust_local_phandle_references(struct device_node *local_fixups, } /** - * of_resolve - Resolve the given node against the live tree. + * of_resolve_phandles - Relocate and resolve overlay against live tree + * + * @overlay: Pointer to devicetree overlay to relocate and resolve + * + * Modify (relocate) values of local phandles in @overlay to a range that + * does not conflict with the live expanded devicetree. Update references + * to the local phandles in @overlay. Update (resolve) phandle references + * in @overlay that refer to the live expanded devicetree. + * + * Phandle values in the live tree are in the range of + * 1 .. live_tree_max_phandle(). The range of phandle values in the overlay + * also begin with at 1. Adjust the phandle values in the overlay to begin + * at live_tree_max_phandle() + 1. Update references to the phandles to + * the adjusted phandle values. + * + * The name of each property in the "__fixups__" node in the overlay matches + * the name of a symbol (a label) in the live tree. The values of each + * property in the "__fixups__" node is a list of the property values in the + * overlay that need to be updated to contain the phandle reference + * corresponding to that symbol in the live tree. Update the references in + * the overlay with the phandle values in the live tree. + * + * @overlay must be detached. * - * @resolve: Node to resolve + * Resolving and applying @overlay to the live expanded devicetree must be + * protected by a mechanism to ensure that multiple overlays are processed + * in a single threaded manner so that multiple overlays will not relocate + * phandles to overlapping ranges. The mechanism to enforce this is not + * yet implemented. * - * Perform dynamic Device Tree resolution against the live tree - * to the given node to resolve. This depends on the live tree - * having a __symbols__ node, and the resolve node the __fixups__ & - * __local_fixups__ nodes (if needed). - * The result of the operation is a resolve node that it's contents - * are fit to be inserted or operate upon the live tree. - * Returns 0 on success or a negative error value on error. + * Return: %0 on success or a negative error value on error. */ int of_resolve_phandles(struct device_node *overlay) { |
