[RFC] dtc: add ability to make nodes conditional on them being referenced
From: heiko@sntech.de (Heiko Stübner)
Date: 2014-01-30 12:26:47
Also in:
linux-devicetree, lkml
Subsystem:
open firmware and flattened device tree, the rest · Maintainers:
Rob Herring, Saravana Kannan, Linus Torvalds
From: Heiko Stuebner <redacted>
On i.MX, which carries a lot of pin-groups of which most are unused on
individual boards, they noticed that this plehora of nodes also results
in the runtime-lookup-performance also degrading [0].
A i.MX-specific solution defining the pingroups in the board files but
using macros to reference the pingroup-data was not well received
This patch is trying to solve this issue in a more general way, by
adding the ability to mark nodes as needing to be referenced somewhere
in the tree.
To mark a node a needing to be referenced it must be prefixed with
/delete-unreferenced/. This makes dtc check the nodes reference-status
when creating the flattened tree, dropping it if unreferenced.
For example, the i.MX6SL pingroup
/delete-uneferenced/ pinctrl_ecspi1_1: ecspi1grp-1 {
fsl,pins = <
MX6SL_PAD_ECSPI1_MISO__ECSPI1_MISO 0x100b1
MX6SL_PAD_ECSPI1_MOSI__ECSPI1_MOSI 0x100b1
MX6SL_PAD_ECSPI1_SCLK__ECSPI1_SCLK 0x100b1
>;
};
would only be included in the dtb if it got referenced somewhere
as pingroup via
node {
pinctrl-0 <&pinctrl_ecscpi1_1>;
};
[0] http://thread.gmane.org/gmane.linux.ports.arm.kernel/275912/
Signed-off-by: Heiko Stuebner <redacted>
---
This is just the idea I had in [1] explored a bit more. I'm definitely
not sure if this is a valid approach to the problem.
Also this is my first venture into dtc as well as flex and bison :-) .
[1] http://www.spinics.net/lists/arm-kernel/msg303731.html
scripts/dtc/checks.c | 2 ++
scripts/dtc/dtc-lexer.l | 7 +++++++
scripts/dtc/dtc-parser.y | 5 +++++
scripts/dtc/dtc.h | 4 ++++
scripts/dtc/flattree.c | 3 +++
scripts/dtc/livetree.c | 14 ++++++++++++++
6 files changed, 35 insertions(+)
diff --git a/scripts/dtc/checks.c b/scripts/dtc/checks.c
index ee96a25..747ada8 100644
--- a/scripts/dtc/checks.c
+++ b/scripts/dtc/checks.c@@ -472,6 +472,8 @@ static void fixup_phandle_references(struct check *c, struct node *dt, phandle = get_node_phandle(dt, refnode); *((cell_t *)(prop->val.val + m->offset)) = cpu_to_fdt32(phandle); + + reference_node(refnode); } } ERROR(phandle_references, NULL, NULL, fixup_phandle_references, NULL,
diff --git a/scripts/dtc/dtc-lexer.l b/scripts/dtc/dtc-lexer.l
index 3b41bfc..3b18e97 100644
--- a/scripts/dtc/dtc-lexer.l
+++ b/scripts/dtc/dtc-lexer.l@@ -138,6 +138,13 @@ static int pop_input_file(void); return DT_DEL_NODE; } +<*>"/delete-unreferenced/" { + DPRINT("Keyword: /delete-unreferenced/\n"); + DPRINT("<PROPNODENAME>\n"); + BEGIN(PROPNODENAME); + return DT_DEL_UNREFERENCED; + } + <*>{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 f412460..ae9108b 100644
--- a/scripts/dtc/dtc-parser.y
+++ b/scripts/dtc/dtc-parser.y@@ -64,6 +64,7 @@ static unsigned char eval_char_literal(const char *s); %token DT_BITS %token DT_DEL_PROP %token DT_DEL_NODE +%token DT_DEL_UNREFERENCED %token <propnodename> DT_PROPNODENAME %token <literal> DT_LITERAL %token <literal> DT_CHAR_LITERAL
@@ -461,6 +462,10 @@ subnode: { $$ = name_node(build_node_delete(), $2); } + | DT_DEL_UNREFERENCED subnode + { + $$ = check_node_referenced($2); + } | DT_LABEL subnode { add_label(&$2->labels, $1);
diff --git a/scripts/dtc/dtc.h b/scripts/dtc/dtc.h
index 3e42a07..c10c440 100644
--- a/scripts/dtc/dtc.h
+++ b/scripts/dtc/dtc.h@@ -159,6 +159,8 @@ struct node { int addr_cells, size_cells; struct label *labels; + + int needs_reference, is_referenced; }; #define for_each_label_withdel(l0, l) \
@@ -193,6 +195,8 @@ 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 *check_node_referenced(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);
diff --git a/scripts/dtc/flattree.c b/scripts/dtc/flattree.c
index 665dad7..a327592 100644
--- a/scripts/dtc/flattree.c
+++ b/scripts/dtc/flattree.c@@ -266,6 +266,9 @@ static void flatten_tree(struct node *tree, struct emitter *emit, if (tree->deleted) return; + if (tree->needs_reference && !tree->is_referenced) + return; + emit->beginnode(etarget, tree->labels); if (vi->flags & FTF_FULLPATH)
diff --git a/scripts/dtc/livetree.c b/scripts/dtc/livetree.c
index b61465f..98bb33d 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 *check_node_referenced(struct node *node) +{ + node->needs_reference = 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;
--
1.7.10.4