From 5ed2dc5623b45ebd51d71f7daffd0cbcbc441186 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Tue, 21 Jan 2020 10:23:17 +0000 Subject: [PATCH] dtc: add ability to make nodes conditional on them being referenced This is needed when importing mainline DTs into U-Boot, as some started using this /omit-if-no-ref/ tag, so won't compile with U-Boot's current dtc copy. This is just a cherry-pick of the patch introducing this feature. Original commit message from Maxime: ------------------ A number of platforms have a need to reduce the number of DT nodes, mostly because of two similar constraints: the size of the DT blob, and the time it takes to parse it. As the DT is used in more and more SoCs, and by more projects, some constraints start to appear in bootloaders running from SRAM with an order of magnitude of 10kB. A typical DT is in the same order of magnitude, so any effort to reduce the blob size is welcome in such an environment. Some platforms also want to reach very fast boot time, and the time it takes to parse a typical DT starts to be noticeable. Both of these issues can be mitigated by reducing the number of nodes in the DT. The biggest provider of nodes is usually the pin controller and its subnodes, usually one for each valid pin configuration in a given SoC. Obviously, a single, fixed, set of these nodes will be used by a given board, so we can introduce a node property that will tell the DT compiler to drop the nodes when they are not referenced in the tree, and as such wouldn't be useful in the targetted system. Signed-off-by: Maxime Ripard Reviewed-by: Rob Herring Signed-off-by: Andre Przywara Reviewed-by: Simon Glass --- scripts/dtc/checks.c | 13 +++++++++++++ scripts/dtc/dtc-lexer.l | 7 +++++++ scripts/dtc/dtc-parser.y | 17 +++++++++++++++++ scripts/dtc/dtc.h | 4 ++++ scripts/dtc/livetree.c | 14 ++++++++++++++ 5 files changed, 55 insertions(+) diff --git a/scripts/dtc/checks.c b/scripts/dtc/checks.c index c07ba4d..4087967 100644 --- a/scripts/dtc/checks.c +++ b/scripts/dtc/checks.c @@ -579,6 +579,8 @@ static void fixup_phandle_references(struct check *c, struct dt_info *dti, phandle = get_node_phandle(dt, refnode); *((fdt32_t *)(prop->val.val + m->offset)) = cpu_to_fdt32(phandle); + + reference_node(refnode); } } } @@ -609,11 +611,21 @@ static void fixup_path_references(struct check *c, struct dt_info *dti, path = refnode->fullpath; prop->val = data_insert_at_marker(prop->val, m, path, strlen(path) + 1); + + reference_node(refnode); } } } ERROR(path_references, fixup_path_references, NULL, &duplicate_node_names); +static void fixup_omit_unused_nodes(struct check *c, struct dt_info *dti, + struct node *node) +{ + if (node->omit_if_unused && !node->is_referenced) + delete_node(node); +} +ERROR(omit_unused_nodes, fixup_omit_unused_nodes, NULL, &phandle_references, &path_references); + /* * Semantic checks */ @@ -1367,6 +1379,7 @@ static struct check *check_table[] = { &explicit_phandles, &phandle_references, &path_references, + &omit_unused_nodes, &address_cells_is_cell, &size_cells_is_cell, &interrupt_cells_is_cell, &device_type_is_string, &model_is_string, &status_is_string, diff --git a/scripts/dtc/dtc-lexer.l b/scripts/dtc/dtc-lexer.l index 24af549..d3694d6 100644 --- a/scripts/dtc/dtc-lexer.l +++ b/scripts/dtc/dtc-lexer.l @@ -152,6 +152,13 @@ static void PRINTF(1, 2) lexical_error(const char *fmt, ...); return DT_DEL_NODE; } +<*>"/omit-if-no-ref/" { + DPRINT("Keyword: /omit-if-no-ref/\n"); + DPRINT("\n"); + BEGIN(PROPNODENAME); + return DT_OMIT_NO_REF; + } + <*>{LABEL}: { DPRINT("Label: %s\n", yytext); yylval.labelref = xstrdup(yytext); diff --git a/scripts/dtc/dtc-parser.y b/scripts/dtc/dtc-parser.y index 44af170..66ff7f7 100644 --- a/scripts/dtc/dtc-parser.y +++ b/scripts/dtc/dtc-parser.y @@ -63,6 +63,7 @@ extern bool treesource_error; %token DT_BITS %token DT_DEL_PROP %token DT_DEL_NODE +%token DT_OMIT_NO_REF %token DT_PROPNODENAME %token DT_LITERAL %token DT_CHAR_LITERAL @@ -219,6 +220,18 @@ devicetree: $$ = $1; } + | devicetree DT_OMIT_NO_REF DT_REF ';' + { + struct node *target = get_node_by_ref($1, $3); + + if (target) + omit_node_if_unused(target); + else + ERROR(&@3, "Label or path %s not found", $3); + + + $$ = $1; + } ; nodedef: @@ -523,6 +536,10 @@ subnode: { $$ = name_node(build_node_delete(), $2); } + | DT_OMIT_NO_REF subnode + { + $$ = omit_node_if_unused($2); + } | DT_LABEL subnode { add_label(&$2->labels, $1); diff --git a/scripts/dtc/dtc.h b/scripts/dtc/dtc.h index 3b18a42..6d66770 100644 --- a/scripts/dtc/dtc.h +++ b/scripts/dtc/dtc.h @@ -168,6 +168,8 @@ struct node { struct label *labels; const struct bus_type *bus; + + bool omit_if_unused, is_referenced; }; #define for_each_label_withdel(l0, l) \ @@ -202,6 +204,8 @@ struct property *reverse_properties(struct property *first); struct node *build_node(struct property *proplist, struct node *children); struct node *build_node_delete(void); struct node *name_node(struct node *node, char *name); +struct node *omit_node_if_unused(struct node *node); +struct node *reference_node(struct node *node); struct node *chain_node(struct node *first, struct node *list); struct node *merge_nodes(struct node *old_node, struct node *new_node); struct node *add_orphan_node(struct node *old_node, struct node *new_node, char *ref); diff --git a/scripts/dtc/livetree.c b/scripts/dtc/livetree.c index 57b7db2..81b6c48 100644 --- a/scripts/dtc/livetree.c +++ b/scripts/dtc/livetree.c @@ -134,6 +134,20 @@ struct node *name_node(struct node *node, char *name) return node; } +struct node *omit_node_if_unused(struct node *node) +{ + node->omit_if_unused = 1; + + return node; +} + +struct node *reference_node(struct node *node) +{ + node->is_referenced = 1; + + return node; +} + struct node *merge_nodes(struct node *old_node, struct node *new_node) { struct property *new_prop, *old_prop; -- 2.7.4