Re: [PATCH v6 2/4] dtc: Plugin and fixup support

This patch enable the generation of symbols & local fixup information
for trees compiled with the -@ (--symbols) option.

Using this patch labels in the tree and their users emit information
in __symbols__ and __local_fixups__ nodes.

The __fixups__ node make possible the dynamic resolution of phandle
references which are present in the plugin tree but lie in the
tree that are applying the overlay against.

Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
Signed-off-by: Sascha Hauer <redacted>
Signed-off-by: Jan Luebbe <redacted>
---
 Documentation/manual.txt |  16 ++++
 checks.c                 |   8 +-
 dtc-lexer.l              |   5 ++
 dtc-parser.y             |  42 +++++++--
 dtc.c                    |  23 ++++-
 dtc.h                    |  28 +++++-
 flattree.c               |   2 +-
 fstree.c                 |   2 +-
 livetree.c               | 217 ++++++++++++++++++++++++++++++++++++++++++++++-
 9 files changed, 329 insertions(+), 14 deletions(-)

diff --git a/Documentation/manual.txt b/Documentation/manual.txt
index 398de32..3e16c24 100644
--- a/Documentation/manual.txt
+++ b/Documentation/manual.txt

@@ -119,6 +119,20 @@ Options:
 	Make space for <number> reserve map entries
 	Relevant for dtb and asm output only.
 
+    -@
+	Generates a __symbols__ node at the root node of the resulting blob
+	for any node labels used, and for any local references using phandles
+	it also generates a __local_fixups__ node that tracks them.
+
+	When using the /plugin/ tag all unresolved label references to
+	be tracked in the __fixups__ node, making dynamic resolution possible.
+
+    -A
+	Generate automatically aliases for all node labels. This is similar to
+	the -@ option (the __symbols__ node contain identical information) but
+	the semantics are slightly different since no phandles are automatically
+	generated for labeled nodes.
+
     -S <bytes>
 	Ensure the blob at least <bytes> long, adding additional
 	space if needed.

@@ -153,6 +167,8 @@ Here is a very rough overview of the layout of a DTS source file:
 
     devicetree:   '/' nodedef
 
+    plugindecl:   '/' 'plugin' '/' ';'

     nodedef:      '{' list_of_property list_of_subnode '}' ';'
 
     property:     label PROPNAME '=' propdata ';'

diff --git a/checks.c b/checks.c
index 386f956..3d4c3c6 100644
--- a/checks.c
+++ b/checks.c

@@ -490,8 +490,12 @@ static void fixup_phandle_references(struct check *c, struct node *dt,
 
 		refnode = get_node_by_ref(dt, m->ref);
 		if (! refnode) {
-			FAIL(c, "Reference to non-existent node or label \"%s\"\n",
-			     m->ref);
+			if (!(tree_get_versionflags(dt) & VF_PLUGIN))
+				FAIL(c, "Reference to non-existent node or "
+						"label \"%s\"\n", m->ref);
+			else /* mark the entry as unresolved */
+				*((cell_t *)(prop->val.val + m->offset)) =
+					cpu_to_fdt32(0xffffffff);
 			continue;
 		}
 

diff --git a/dtc-lexer.l b/dtc-lexer.l
index 790fbf6..40bbc87 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l

@@ -121,6 +121,11 @@ static void lexical_error(const char *fmt, ...);
 			return DT_V1;
 		}
 
+<*>"/plugin/"	{
+			DPRINT("Keyword: /plugin/\n");
+			return DT_PLUGIN;
+		}
+
 <*>"/memreserve/"	{
 			DPRINT("Keyword: /memreserve/\n");
 			BEGIN_DEFAULT();

diff --git a/dtc-parser.y b/dtc-parser.y
index 000873f..2d3399e 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y

@@ -19,6 +19,7 @@
  */
 %{
 #include <stdio.h>
+#include <inttypes.h>
 
 #include "dtc.h"
 #include "srcpos.h"

@@ -52,9 +53,11 @@ extern bool treesource_error;
 	struct node *nodelist;
 	struct reserve_info *re;
 	uint64_t integer;
+	unsigned int flags;
 }
 
 %token DT_V1
+%token DT_PLUGIN
 %token DT_MEMRESERVE
 %token DT_LSHIFT DT_RSHIFT DT_LE DT_GE DT_EQ DT_NE DT_AND DT_OR
 %token DT_BITS

@@ -71,6 +74,8 @@ extern bool treesource_error;
 
 %type <data> propdata
 %type <data> propdataprefix
+%type <flags> versioninfo
+%type <flags> plugindecl
 %type <re> memreserve
 %type <re> memreserves
 %type <array> arrayprefix

@@ -101,13 +106,31 @@ extern bool treesource_error;
 %%
 
 sourcefile:
-	  DT_V1 ';' memreserves devicetree
+	  versioninfo ';' memreserves devicetree
 		{
-			the_boot_info = build_boot_info($3, $4,
+			the_boot_info = build_boot_info($1, $3, $4,
 							guess_boot_cpuid($4));
 		}
 	;
 
+versioninfo:
+	DT_V1 plugindecl
+		{
+			$$ = VF_DT_V1 | $2;
+		}
+	;
+
+plugindecl:
+	DT_PLUGIN
+		{
+			$$ = VF_PLUGIN;
+		}
+	| /* empty */
+		{
+			$$ = 0;
+		}
+	;
+
 memreserves:
 	  /* empty */
 		{

@@ -156,10 +179,14 @@ devicetree:
 		{
 			struct node *target = get_node_by_ref($1, $2);
 
-			if (target)
+			if (target) {
 				merge_nodes(target, $3);
-			else
-				ERROR(&@2, "Label or path %s not found", $2);
+			} else {
+				if (symbol_fixup_support)

+					add_orphan_node($1, $3, $2);
+				else
+					ERROR(&@2, "Label or path %s not found", $2);
+			}
 			$$ = $1;
 		}
 	| devicetree DT_DEL_NODE DT_REF ';'

@@ -174,6 +201,11 @@ devicetree:
 
 			$$ = $1;
 		}
+	| /* empty */
+		{
+			/* build empty node */
+			$$ = name_node(build_node(NULL, NULL), "");
+		}
 	;
 
 nodedef:

diff --git a/dtc.c b/dtc.c
index 5fa23c4..f8277fb 100644
--- a/dtc.c
+++ b/dtc.c

@@ -31,6 +31,8 @@ int reservenum;		/* Number of memory reservation slots */
 int minsize;		/* Minimum blob size */
 int padsize;		/* Additional padding to blob */
 int phandle_format = PHANDLE_BOTH;	/* Use linux,phandle or phandle properties */
+int symbol_fixup_support;
+int auto_label_aliases;
 
 static void fill_fullpaths(struct node *tree, const char *prefix)
 {

@@ -53,7 +55,7 @@ static void fill_fullpaths(struct node *tree, const char *prefix)
 #define FDT_VERSION(version)	_FDT_VERSION(version)
 #define _FDT_VERSION(version)	#version
 static const char usage_synopsis[] = "dtc [options] <input file>";
-static const char usage_short_opts[] = "qI:O:o:V:d:R:S:p:fb:i:H:sW:E:hv";
+static const char usage_short_opts[] = "qI:O:o:V:d:R:S:p:fb:i:H:sW:E:@Ahv";
 static struct option const usage_long_opts[] = {
 	{"quiet",            no_argument, NULL, 'q'},
 	{"in-format",         a_argument, NULL, 'I'},

@@ -71,6 +73,8 @@ static struct option const usage_long_opts[] = {
 	{"phandle",           a_argument, NULL, 'H'},
 	{"warning",           a_argument, NULL, 'W'},
 	{"error",             a_argument, NULL, 'E'},
+	{"symbols",	     no_argument, NULL, '@'},
+	{"auto-alias",       no_argument, NULL, 'A'},
 	{"help",             no_argument, NULL, 'h'},
 	{"version",          no_argument, NULL, 'v'},
 	{NULL,               no_argument, NULL, 0x0},

@@ -101,6 +105,8 @@ static const char * const usage_opts_help[] = {
 	 "\t\tboth   - Both \"linux,phandle\" and \"phandle\" properties",
 	"\n\tEnable/disable warnings (prefix with \"no-\")",
 	"\n\tEnable/disable errors (prefix with \"no-\")",
+	"\n\tEnable symbols/fixup support",
+	"\n\tEnable auto-alias of labels",
 	"\n\tPrint this help and exit",
 	"\n\tPrint version and exit",
 	NULL,

@@ -233,7 +239,12 @@ int main(int argc, char *argv[])
 		case 'E':
 			parse_checks_option(false, true, optarg);
 			break;
-
+		case '@':
+			symbol_fixup_support = 1;
+			break;
+		case 'A':
+			auto_label_aliases = 1;
+			break;
 		case 'h':
 			usage(NULL);
 		default:

@@ -294,6 +305,14 @@ int main(int argc, char *argv[])
 	if (sort)
 		sort_tree(bi);
 
+	if (auto_label_aliases)
+		generate_label_tree(bi->dt, "aliases", false);
+
+	if (symbol_fixup_support) {
+		generate_label_tree(bi->dt, "__symbols__", true);
+		generate_fixups_tree(bi->dt);
+	}
+

 	if (streq(outname, "-")) {
 		outf = stdout;
 	} else {

diff --git a/dtc.h b/dtc.h
index 56212c8..68cb109 100644
--- a/dtc.h
+++ b/dtc.h

@@ -20,7 +20,6 @@
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
  *                                                                   USA
  */
-

 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>

@@ -54,6 +53,12 @@ extern int reservenum;		/* Number of memory reservation slots */
 extern int minsize;		/* Minimum blob size */
 extern int padsize;		/* Additional padding to blob */
 extern int phandle_format;	/* Use linux,phandle or phandle properties */
+extern int symbol_fixup_support;/* enable symbols & fixup support */
+extern int auto_label_aliases;	/* auto generate labels -> aliases */
+
+/*
+ * Tree source globals
+ */
 
 #define PHANDLE_LEGACY	0x1
 #define PHANDLE_EPAPR	0x2

@@ -158,6 +163,9 @@ struct node {
 	int addr_cells, size_cells;
 
 	struct label *labels;
+
+	/* only for the root (parent == NULL) */
+	struct boot_info *bi;

 };
 
 #define for_each_label_withdel(l0, l) \

@@ -194,6 +202,7 @@ struct node *build_node_delete(void);
 struct node *name_node(struct node *node, char *name);
 struct node *chain_node(struct node *first, struct node *list);
 struct node *merge_nodes(struct node *old_node, struct node *new_node);
+void add_orphan_node(struct node *old_node, struct node *new_node, char *ref);
 
 void add_property(struct node *node, struct property *prop);
 void delete_property_by_name(struct node *node, char *name);

@@ -236,14 +245,29 @@ struct reserve_info *add_reserve_entry(struct reserve_info *list,
 
 
 struct boot_info {
+	unsigned int versionflags;
 	struct reserve_info *reservelist;
 	struct node *dt;		/* the device tree */
 	uint32_t boot_cpuid_phys;
 };
 
-struct boot_info *build_boot_info(struct reserve_info *reservelist,
+/* version flags definitions */
+#define VF_DT_V1	0x0001	/* /dts-v1/ */

+#define VF_PLUGIN	0x0002	/* /plugin/ */
+
+static inline unsigned int tree_get_versionflags(struct node *dt)
+{
+	if (!dt || !dt->bi)
+		return 0;
+	return dt->bi->versionflags;
+}
+
+struct boot_info *build_boot_info(unsigned int versionflags,
+				  struct reserve_info *reservelist,
 				  struct node *tree, uint32_t boot_cpuid_phys);
 void sort_tree(struct boot_info *bi);
+void generate_label_tree(struct node *dt, char *gen_node_name, bool allocph);
+void generate_fixups_tree(struct node *dt);
 
 /* Checks */
 

diff --git a/flattree.c b/flattree.c
index ec14954..5dde832 100644
--- a/flattree.c
+++ b/flattree.c

@@ -929,5 +929,5 @@ struct boot_info *dt_from_blob(const char *fname)
 
 	fclose(f);
 
-	return build_boot_info(reservelist, tree, boot_cpuid_phys);
+	return build_boot_info(VF_DT_V1, reservelist, tree, boot_cpuid_phys);
 }

diff --git a/fstree.c b/fstree.c
index 6d1beec..54f520b 100644
--- a/fstree.c
+++ b/fstree.c

@@ -86,6 +86,6 @@ struct boot_info *dt_from_fs(const char *dirname)
 	tree = read_fstree(dirname);
 	tree = name_node(tree, "");
 
-	return build_boot_info(NULL, tree, guess_boot_cpuid(tree));
+	return build_boot_info(VF_DT_V1, NULL, tree, guess_boot_cpuid(tree));
 }
 

diff --git a/livetree.c b/livetree.c
index e229b84..e7d0fe5 100644
--- a/livetree.c
+++ b/livetree.c

@@ -18,6 +18,7 @@
  *                                                                   USA
  */
 
+#define _GNU_SOURCE

 #include "dtc.h"
 
 /*

@@ -216,6 +217,34 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 	return old_node;
 }
 
+void add_orphan_node(struct node *dt, struct node *new_node, char *ref)
+{
+	static unsigned int next_orphan_fragment = 0;
+	struct node *node = xmalloc(sizeof(*node));
+	struct property *p;
+	struct data d = empty_data;
+	char *name;
+	int ret;
+
+	memset(node, 0, sizeof(*node));
+
+	d = data_add_marker(d, REF_PHANDLE, ref);
+	d = data_append_integer(d, 0xffffffff, 32);
+
+	p = build_property("target", d);
+	add_property(node, p);
+
+	ret = asprintf(&name, "fragment@%u",
+			next_orphan_fragment++);
+	if (ret == -1)
+		die("asprintf() failed\n");
+	name_node(node, name);
+	name_node(new_node, "__overlay__");
+
+	add_child(dt, node);
+	add_child(node, new_node);
+}

 struct node *chain_node(struct node *first, struct node *list)
 {
 	assert(first->next_sibling == NULL);

@@ -335,15 +364,19 @@ struct reserve_info *add_reserve_entry(struct reserve_info *list,
 	return list;
 }
 
-struct boot_info *build_boot_info(struct reserve_info *reservelist,
+struct boot_info *build_boot_info(unsigned int versionflags,
+				  struct reserve_info *reservelist,
 				  struct node *tree, uint32_t boot_cpuid_phys)
 {
 	struct boot_info *bi;
 
 	bi = xmalloc(sizeof(*bi));
+	bi->versionflags = versionflags;
 	bi->reservelist = reservelist;
 	bi->dt = tree;
 	bi->boot_cpuid_phys = boot_cpuid_phys;
+	/* link back */
+	tree->bi = bi;
 
 	return bi;
 }

@@ -709,3 +742,185 @@ void sort_tree(struct boot_info *bi)
 	sort_reserve_entries(bi);
 	sort_node(bi->dt);
 }
+
+/* utility helper to avoid code duplication */
+static struct node *build_and_name_child_node(struct node *parent, char *name)
+{
+	struct node *node;
+
+	node = build_node(NULL, NULL);
+	name_node(node, xstrdup(name));
+	add_child(parent, node);
+
+	return node;
+}
+
+static void generate_label_tree_internal(struct node *dt, struct node *node,
+					 char *gen_node_name, bool allocph)
+{
+	struct node *c, *an;
+	struct property *p;
+	struct label *l;
+
+	/* if if there are labels */
+	if (node->labels) {
+		/* an is the aliases/__symbols__ node */
+		an = get_subnode(dt, gen_node_name);