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[RFC/PATCH 0/4] New style overlay and /expansion/ support

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  [RFC/PATCH 0/4] New style overlay and /expansion/ support Stephen Boyd <stephen.boyd@linaro.org> - 2017-01-31 01:10 +0100
    [RFC/PATCH 2/4] dtc: Add syntactic sugar version of overlays Stephen Boyd <stephen.boyd@linaro.org> - 2017-01-31 01:10 +0100

#1570197 — [RFC/PATCH 0/4] New style overlay and /expansion/ support

This series revives the new style of overlay syntax that never got
merged. David said he wanted to handle it outside of the parse
phase[1], and he proposed a patch to move overlay application to the
livetree phase. I've applied that patch and reworked Pantelis' last
two patches for the new style "syntactic sugar" on top[2].

In addition, I've included the new /expansion/ keyword support for
overlays that don't reference any labels that are outside of the
input file. The new expansion keyword just transforms the unresolved
references into strings that go into a new 'target-alias' property
instead of the 'target' property. This is in line with what David
has proposed on the mailing list a few months ago[3].

RFC part: The current syntax requires a root node or overlays are rejected.
Making the root node optional would require some non-trivial rework of the
grammar to support it. This means the proposed 'new style' syntax doesn't
work without the root node.

[1] https://lkml.kernel.org/r/20161125041124.GB12287@umbus.fritz.box
[2] https://lkml.kernel.org/r/1481114903-8197-7-git-send-email-pantelis.antoniou@konsulko.com
[3] https://lkml.kernel.org/r/20160718142037.GS16769@voom.fritz.box

David Gibson (1):
  Start moving overlay handling from parser into dtc core

Pantelis Antoniou (1):
  tests: Add a test for overlays syntactic sugar

Stephen Boyd (2):
  dtc: Add syntactic sugar version of overlays
  dtc: Add /expansion/ support

 checks.c                         |  2 +-
 dtc-lexer.l                      |  6 +++
 dtc-parser.y                     | 68 +++++++++++++++++-----------------
 dtc.c                            | 16 +++++++-
 dtc.h                            | 20 +++++++++-
 flattree.c                       |  2 +-
 fstree.c                         |  2 +-
 livetree.c                       | 80 +++++++++++++++++++++++++++++++++++++++-
 tests/overlay_overlay_simple.dts |  3 ++
 tests/run_tests.sh               |  6 +++
 10 files changed, 163 insertions(+), 42 deletions(-)

-- 
2.10.0.297.gf6727b0

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#1570198 — [RFC/PATCH 2/4] dtc: Add syntactic sugar version of overlays

Instead of writing overlays with the target property and
__overlay__ node, i.e.

	fragment@0 {
		target = <&foo>;
		__overlay__ {
			bar-property = <0x200>;
		};
	}

support the syntactic sugar version of overlays where this can
be written as

&foo {
	bar-property = <0x200>;
};

and have dtc convert that into a fragment node.

Based on a patch by Pantelis Antoniou.

Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
---
 dtc.c      |  2 +-
 dtc.h      |  3 ++-
 livetree.c | 40 ++++++++++++++++++++++++++++++++++++----
 3 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/dtc.c b/dtc.c
index 91e4c18b891e..d52d6c77a8cd 100644
--- a/dtc.c
+++ b/dtc.c
@@ -63,7 +63,7 @@ static void resolve_overlays(struct dt_info *dti)
 	struct overlay *o = dti->overlays;
 
 	while (o) {
-		apply_overlay(dti->dt, o);
+		apply_overlay(dti->dt, o, dti->dtsflags);
 		o = o->next;
 	}
 }
diff --git a/dtc.h b/dtc.h
index c4eb6421eabf..be75aac1f185 100644
--- a/dtc.h
+++ b/dtc.h
@@ -216,7 +216,8 @@ void append_to_property(struct node *node,
 
 struct overlay *build_overlay(char *target, struct node *dt);
 struct overlay *chain_overlay(struct overlay *first, struct overlay *list);
-void apply_overlay(struct node *base, struct overlay *overlay);
+void apply_overlay(struct node *base, struct overlay *overlay,
+		   unsigned int dtsflags);
 
 const char *get_unitname(struct node *node);
 struct property *get_property(struct node *node, const char *propname);
diff --git a/livetree.c b/livetree.c
index dd51223d1e61..798a87ed587e 100644
--- a/livetree.c
+++ b/livetree.c
@@ -331,14 +331,46 @@ struct overlay *chain_overlay(struct overlay *first, struct overlay *list)
 	return first;
 }
 
-void apply_overlay(struct node *base, struct overlay *overlay)
+static void add_fragment(struct node *base, struct overlay *overlay)
 {
-	struct node *target = get_node_by_ref(base, overlay->target);
+	static unsigned int next_fragment = 0;
+	struct node *node;
+	struct property *p;
+	struct data d = empty_data;
+	char *name;
 
-	if (!target)
-		die("Couldn't find label or path %s for overlay\n",
+	if (!overlay->dt)
+		die("Deletions not supported at runtime for %s\n",
 		    overlay->target);
 
+	/* Insert a target = <&phandle> property */
+	d = data_add_marker(d, REF_PHANDLE, overlay->target);
+	d = data_append_integer(d, 0xffffffff, 32);
+
+	p = build_property("target", d);
+
+	xasprintf(&name, "fragment@%u", next_fragment++);
+	name_node(overlay->dt, "__overlay__");
+	node = build_node(p, overlay->dt);
+	name_node(node, name);
+
+	add_child(base, node);
+}
+
+void apply_overlay(struct node *base, struct overlay *overlay,
+		   unsigned int dtsflags)
+{
+	struct node *target = get_node_by_ref(base, overlay->target);
+
+	if (!target) {
+		if (dtsflags & DTSF_PLUGIN) {
+			add_fragment(base, overlay);
+			return;
+		} else
+			die("Couldn't find label or path %s for overlay\n",
+			    overlay->target);
+	}
+
 	if (!overlay->dt)
 		/* Deletion */
 		delete_node(target);
-- 
2.10.0.297.gf6727b0

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