The export symbols node adds some additional symbols that can be used in the symbols resolution. The resolver tries to match unresolved symbols first using the export symbols node and, if a match is not found, it tries the normal route and walks the tree. Contrary to symbols available in the global __symbols__ node, symbols listed in the export symbols node can be considered as local symbols. Indeed, they can be changed depending on the node the overlay is going to be applied to and are only visible from the current node properties. export-symbols are phandle based as opposed to global __symbols__. This allows for much simpler use with overlays as opposed to __symbols__ where paths require resizing of overlays as show in [0]. [0]: https://lore.kernel.org/devicetree-compiler/6b2dba90-3c52-4933-88f3-b47f96dc7710@xxxxxxxxxxxxxxx/T/#m8259c8754f680b9da7b91f7b7dd89f10da91d8ed Signed-off-by: Ayush Singh <ayush@xxxxxxxxxxxxxxx> --- As discussed in the export-symbols kernel patch series [0], the following patch series adds support for export-symbols in the base devicetree compiler. This patch series is mostly a prototype for the functionality. Depending on the direction, next revision of the patch will add tests. Support for export-symbols in overlays will be part of a seperate patch series. [0]: https://lore.kernel.org/all/20241209151830.95723-1-herve.codina@xxxxxxxxxxx/ --- checks.c | 42 ++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 40 insertions(+), 2 deletions(-) diff --git a/checks.c b/checks.c index 123f2eb425f4a2f8ac22bfe10a842bf08e296ba1..e577f30a3ed9b762aee073fa1ff9d866f5de60b6 100644 --- a/checks.c +++ b/checks.c @@ -600,11 +600,37 @@ ERROR(name_properties, check_name_properties, NULL, &name_is_string); * Reference fixup functions */ +static const char *fixup_export_symbol(struct node *export_symbols, + struct marker *m) +{ + struct property *prop; + struct marker *em; + + for_each_property(export_symbols, prop) { + if (streq(m->ref, prop->name)) { + em = prop->val.markers; + for_each_marker_of_type(em, REF_PHANDLE) { + return em->ref; + } + } + } + + return NULL; +} + static void fixup_phandle_references(struct check *c, struct dt_info *dti, struct node *node) { struct node *dt = dti->dt; struct property *prop; + struct node *child, *export_symbols = NULL; + + for_each_child(node, child) { + if (streq(child->name, "export-symbols")) { + export_symbols = child; + break; + } + } for_each_property(node, prop) { struct marker *m = prop->val.markers; @@ -612,13 +638,25 @@ static void fixup_phandle_references(struct check *c, struct dt_info *dti, cell_t phandle; for_each_marker_of_type(m, REF_PHANDLE) { + const char *ref = NULL; + assert(m->offset + sizeof(cell_t) <= prop->val.len); - refnode = get_node_by_ref(dt, m->ref); + /* Check export-symbols if present */ + if (export_symbols) + ref = fixup_export_symbol(export_symbols, m); + + /* If entry not found in export-symbols (or export-symbols not present), + * search the normal way. + */ + if (!ref) + ref = m->ref; + + refnode = get_node_by_ref(dt, ref); if (! refnode) { if (!(dti->dtsflags & DTSF_PLUGIN)) FAIL(c, dti, node, "Reference to non-existent node or " - "label \"%s\"\n", m->ref); + "label \"%s\"\n", ref); else /* mark the entry as unresolved */ *((fdt32_t *)(prop->val.val + m->offset)) = cpu_to_fdt32(0xffffffff); --- base-commit: 18f4f305fdd7e14c8941658a29c7b85c27d41de4 change-id: 20250110-export-symbols-e2ea3df01ea9 Best regards, -- Ayush Singh <ayush@xxxxxxxxxxxxxxx>
