dtc: dts source location annotation

Proof of concept patch.

Annotates input source file and line number of nodes and properties as comments in output .dts file when --annotate flag is supplied.

A common dts source file convention is for a system .dts file to include default SOC and/or device .dtsi files and then add additional system specific properties or over-ride property values from the .dtsi files. It can be a time consuming and error prone exercise to determine exactly what nodes, properties, and property values are in the final .dtb binary blob and where they originated.

Modify the dtc compiler to read a (possibly cpp pre-processed) .dts file and for the output .dts annotate each node and property with the corresponding source location.

As an example, one device tree node for the dragonboard in the Linux kernel source tree is:

  sdhci@f9824900 { /* qcom-apq8074-dragonboard.dts:14 */
        compatible = "qcom,sdhci-msm-v4"; /* qcom-msm8974.dtsi:240 */
        reg = <0xf9824900 0x11c 0xf9824000 0x800>; /* qcom-msm8974.dtsi:241 */
        reg-names = "hc_mem", "core_mem"; /* qcom-msm8974.dtsi:242 */
        interrupts = <0x0 0x7b 0x0 0x0 0x8a 0x0>; /* qcom-msm8974.dtsi:243 */
        interrupt-names = "hc_irq", "pwr_irq"; /* qcom-msm8974.dtsi:244 */
        clocks = <0xd 0xd8 0xd 0xd7>; /* qcom-msm8974.dtsi:245 */
        clock-names = "core", "iface"; /* qcom-msm8974.dtsi:246 */
        status = "ok"; /* qcom-apq8074-dragonboard.dts:17 */
        bus-width = <0x8>; /* qcom-apq8074-dragonboard.dts:15 */
        non-removable; /* qcom-apq8074-dragonboard.dts:16 */
  }; /* qcom-apq8074-dragonboard.dts:18 */

qcom-apq8074-dragonboard.dts:
- last referenced the sdhci node
- changed the value of the "status" property from "disabled" to "ok"
- added two properties, "bus-width" and "non-removable"

qcom-msm8974.dtsi:
- initially set the value the "status" property to "disabled" (not visible in the annotated .dts)
- provided all of the other property values

When the dtc compiler is run within the Linux kernel build system, the path of the source files will be the full absolute path, just as seen for gcc warnings and errors. I always trim away the path leading up to the Linux kernel source tree by passing the kernel build output through a sed pipe. I have done the same to the above example to remove the excessive verbosity in the source paths.

Implementation notes:

- Added new function srcpos_string_short() which is similar to srcpos_string() but limits the location information to one line number. The fuller output of srcpos_string() adds noise to the annotation which (in my opinion) is not especially useful in this specific context.

The one downside to this choice is that the column numbers for multiple properties on the same input line will not be reported. This is unlikely to be an issue unless a .dts contains all of the properties on a single line (which might be the case for a machine generated .dts). I do not think that the extra noise for the common case justifies handling this case.

- The source location of each node and property is saved in the respective node or property during the parse phase because the source location information from current_srcfile is no longer available when the final values are written out from dt_to_source() and the functions that it calls.

- A check is added to dtc.c to ensure that input and output format are both device tree source. An alternate choice would be to turn off the --annotate flag if either the input file or the output file is not device tree source. In the alternate case, the disabling of --annotate could be silent or a warning could be issued.

TODO:
- Update "make check" tests to reflect review comments.

Changes from v2:
- v3 was not published.
- FINALLY removed the new structure "struct src". Now using the existing structure "struct srcpos"
- "make check" tests are not yet updated
- Added new patch 1 to protect against a null pointer de-reference. (The function fixed is not currently used in this patch series, but one alternative implementation would use it.)
- Properties that are generated internally are now reported as file "<no-file>" (instead of "__builtin__") to match other dtc messages.
- Changed the short form of the --annotate flag to "-A".
- The "make check" patch is not included since it is not updated.
- The Linux kernel build changes patch is not included. It was present only for the convenience of testers and is still available from v2.

< snip >

< snip >

One more TODO. Test against a wider set of .dts files. There are some rules that I did not test extensively (and some rules, such as delete that I did not test at all in this version).

-Frank

From: Frank Rowand <frank.rowand-/[email protected]>

Check for NULL pos before dereferencing is in srcpos_string().

---
 srcpos.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Index: b/srcpos.c
===================================================================
@@ -272,7 +272,9 @@ srcpos_string(struct srcpos *pos)
 		fname = pos->file->name;
 
 
-	if (pos->first_line != pos->last_line)
+	if (!pos)
+		rc = asprintf(&pos_str, "%s:0", fname);
+	else if (pos->first_line != pos->last_line)
 		rc = asprintf(&pos_str, "%s:%d.%d-%d.%d", fname,
 			      pos->first_line, pos->first_column,
 			      pos->last_line, pos->last_column);

From: Frank Rowand <frank.rowand-/[email protected]>

Proof of concept patch.

Annotates input source file and line number of nodes and properties as comments in output .dts file when --annotate flag is supplied.

A common dts source file convention is for a system .dts file to include default SOC and/or device .dtsi files and then add additional system specific properties or over-ride property values from the .dtsi files. It can be a time consuming and error prone exercise to determine exactly what nodes, properties, and property values are in the final .dtb binary blob and where they originated.

Modify the dtc compiler to read a (possibly cpp pre-processed) .dts file and for the output .dts annotate each node and property with the corresponding source location.

As an example, one device tree node for the dragonboard in the Linux kernel source tree is:

  sdhci@f9824900 { /* qcom-apq8074-dragonboard.dts:14 */
        compatible = "qcom,sdhci-msm-v4"; /* qcom-msm8974.dtsi:240 */
        reg = <0xf9824900 0x11c 0xf9824000 0x800>; /* qcom-msm8974.dtsi:241 */
        reg-names = "hc_mem", "core_mem"; /* qcom-msm8974.dtsi:242 */
        interrupts = <0x0 0x7b 0x0 0x0 0x8a 0x0>; /* qcom-msm8974.dtsi:243 */
        interrupt-names = "hc_irq", "pwr_irq"; /* qcom-msm8974.dtsi:244 */
        clocks = <0xd 0xd8 0xd 0xd7>; /* qcom-msm8974.dtsi:245 */
        clock-names = "core", "iface"; /* qcom-msm8974.dtsi:246 */
        status = "ok"; /* qcom-apq8074-dragonboard.dts:17 */
        bus-width = <0x8>; /* qcom-apq8074-dragonboard.dts:15 */
        non-removable; /* qcom-apq8074-dragonboard.dts:16 */
  }; /* qcom-apq8074-dragonboard.dts:18 */

qcom-apq8074-dragonboard.dts:
- last referenced the sdhci node
- changed the value of the "status" property from "disabled" to "ok"
- added two properties, "bus-width" and "non-removable"

qcom-msm8974.dtsi:
- initially set the value the "status" property to "disabled" (not visible in the annotated .dts)
- provided all of the other property values

When the dtc compiler is run within the Linux kernel build system, the path of the source files will be the full absolute path, just as seen for gcc warnings and errors. I always trim away the path leading up to the Linux kernel source tree by passing the kernel build output through a sed pipe. I have done the same to the above example to remove the excessive verbosity in the source paths.

Implementation notes:

- The source location of each node and property is saved in the respective node or property during the parse phase because the source location information is no longer
available when the final values are written out from dt_to_source() and the functions that it calls.

- A check is added to dtc.c to ensure that input and output format are both device tree source. An alternate choice would be to turn off the --annotate flag if either the input file or the output file is not device tree source. In the alternate case, the disabling of --annotate could be silent or a warning could be issued.

---
 dtc-parser.y |   23 +++++++++++++++++++----
 dtc.c        |    9 +++++++++
 dtc.h        |    7 +++++++
 livetree.c   |   20 ++++++++++++++++++++
 srcpos.c     |   42 ++++++++++++++++++++++++++++++++++++++++++
 srcpos.h     |    2 ++
 treesource.c |   38 +++++++++++++++++++++++++++++++++-----
 7 files changed, 132 insertions(+), 9 deletions(-)

Index: b/dtc.h
===================================================================
@@ -54,6 +54,7 @@ extern int reservenum;		/* Number of mem
 extern int minsize;		/* Minimum blob size */
 extern int padsize;		/* Additional padding to blob */
 extern int phandle_format;	/* Use linux,phandle or phandle properties */
+extern bool annotate;		/* annotate .dts with input source location */
 
 #define PHANDLE_LEGACY	0x1
 #define PHANDLE_EPAPR	0x2

@@ -140,6 +141,7 @@ struct property {
 	struct property *next;
 
 	struct label *labels;
+	struct srcpos *srcpos;
 };
 
 struct node {

@@ -158,6 +160,8 @@ struct node {
 	int addr_cells, size_cells;
 
 	struct label *labels;
+	struct srcpos *begin_srcpos;
+	struct srcpos *end_srcpos;
 };
 
 #define for_each_label_withdel(l0, l) \

@@ -185,6 +189,7 @@ void add_label(struct label **labels, ch
 void delete_labels(struct label **labels);
 
 struct property *build_property(char *name, struct data val);
+void srcpos_property(struct property *prop, struct srcpos *srcpos);
 struct property *build_property_delete(char *name);
 struct property *chain_property(struct property *first, struct property *list);
 struct property *reverse_properties(struct property *first);

@@ -192,6 +197,8 @@ struct property *reverse_properties(stru
 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);
+void begin_srcpos_node(struct node *node, struct srcpos *srcpos);
+void end_srcpos_node(struct node *node, struct srcpos *srcpos);
 struct node *chain_node(struct node *first, struct node *list);
 struct node *merge_nodes(struct node *old_node, struct node *new_node);
 

Index: b/livetree.c
===================================================================
@@ -19,6 +19,7 @@
  */
 
 #include "dtc.h"
+#include "srcpos.h"
 
 /*
  * Tree building functions

@@ -74,6 +75,11 @@ struct property *build_property_delete(c
 	return new;
 }
 
+void srcpos_property(struct property *prop, struct srcpos *srcpos)
+{
+	prop->srcpos = srcpos_copy_all(srcpos);
+}
+
 struct property *chain_property(struct property *first, struct property *list)
 {
 	assert(first->next == NULL);

@@ -134,6 +140,16 @@ struct node *name_node(struct node *node
 	return node;
 }
 
+void begin_srcpos_node(struct node *node, struct srcpos *srcpos)
+{
+	node->begin_srcpos = srcpos_copy_all(srcpos);
+}
+
+void end_srcpos_node(struct node *node, struct srcpos *srcpos)
+{
+	node->end_srcpos = srcpos_copy_all(srcpos);
+}
+
 struct node *merge_nodes(struct node *old_node, struct node *new_node)
 {
 	struct property *new_prop, *old_prop;

@@ -169,6 +185,7 @@ struct node *merge_nodes(struct node *ol
 
 				old_prop->val = new_prop->val;
 				old_prop->deleted = 0;
+				old_prop->srcpos = new_prop->srcpos;
 				free(new_prop);
 				new_prop = NULL;
 				break;

@@ -209,6 +226,9 @@ struct node *merge_nodes(struct node *ol
 			add_child(old_node, new_child);
 	}
 
+	old_node->begin_srcpos = new_node->begin_srcpos;
+	old_node->end_srcpos = new_node->end_srcpos;
+
 	/* The new node contents are now merged into the old node.  Free
 	 * the new node. */
 	free(new_node);

Index: b/treesource.c
===================================================================
@@ -200,9 +200,16 @@ static void write_propval(FILE *f, struc
 	int nnotstring = 0, nnul = 0;
 	int nnotstringlbl = 0, nnotcelllbl = 0;
 	int i;
+	char *srcstr;
 
 	if (len == 0) {
-		fprintf(f, ";\n");
+		if (annotate) {
+			srcstr = srcpos_string_short(prop->srcpos);
+			fprintf(f, "; /* %s */\n", srcstr);
+			free(srcstr);
+		} else {
+			fprintf(f, ";\n");
+		}
 		return;
 	}
 

@@ -230,7 +237,13 @@ static void write_propval(FILE *f, struc
 		write_propval_bytes(f, prop->val);
 	}
 
-	fprintf(f, ";\n");
+	if (annotate) {
+		srcstr = srcpos_string_short(prop->srcpos);
+		fprintf(f, "; /* %s */\n", srcstr);
+		free(srcstr);
+	} else {
+		fprintf(f, ";\n");
+	}
 }
 
 static void write_tree_source_node(FILE *f, struct node *tree, int level)

@@ -238,14 +251,23 @@ static void write_tree_source_node(FILE
 	struct property *prop;
 	struct node *child;
 	struct label *l;
+	char *srcstr;
 
 	write_prefix(f, level);
 	for_each_label(tree->labels, l)
 		fprintf(f, "%s: ", l->label);
+
 	if (tree->name && (*tree->name))
-		fprintf(f, "%s {\n", tree->name);
+		fprintf(f, "%s {", tree->name);
 	else
-		fprintf(f, "/ {\n");
+		fprintf(f, "/ {");
+	if (annotate) {
+		srcstr = srcpos_string_short(tree->begin_srcpos);
+		fprintf(f, " /* %s */\n", srcstr);
+		free(srcstr);
+	} else {
+		fprintf(f, "\n");
+	}
 
 	for_each_property(tree, prop) {
 		write_prefix(f, level+1);

@@ -259,7 +281,13 @@ static void write_tree_source_node(FILE
 		write_tree_source_node(f, child, level+1);
 	}
 	write_prefix(f, level);
-	fprintf(f, "};\n");
+	if (annotate) {
+		srcstr = srcpos_string_short(tree->end_srcpos);
+		fprintf(f, "}; /* %s */\n", srcstr);
+		free(srcstr);
+	} else {
+		fprintf(f, "};\n");
+	}
 }
 
 

Index: b/dtc.c
===================================================================
@@ -29,6 +29,7 @@ int reservenum;		/* Number of memory res
 int minsize;		/* Minimum blob size */
 int padsize;		/* Additional padding to blob */
 int phandle_format = PHANDLE_BOTH;	/* Use linux,phandle or phandle properties */
+bool annotate = false;	/* annotate .dts with input source location */
 
 static void fill_fullpaths(struct node *tree, const char *prefix)
 {

@@ -71,6 +72,7 @@ static struct option const usage_long_op
 	{"error",             a_argument, NULL, 'E'},
 	{"help",             no_argument, NULL, 'h'},
 	{"version",          no_argument, NULL, 'v'},
+	{"annotate",         no_argument, NULL, 'A'},
 	{NULL,               no_argument, NULL, 0x0},
 };
 static const char * const usage_opts_help[] = {

@@ -101,6 +103,7 @@ static const char * const usage_opts_hel
 	"\n\tEnable/disable errors (prefix with \"no-\")",
 	"\n\tPrint this help and exit",
 	"\n\tPrint version and exit",
+	"\n\tAnnotate output .dts with input source file and line",
 	NULL,
 };
 

@@ -125,6 +128,9 @@ int main(int argc, char *argv[])
 
 	while ((opt = util_getopt_long()) != EOF) {
 		switch (opt) {
+		case 'A':
+			annotate = true;
+			break;
 		case 'I':
 			inform = optarg;
 			break;

@@ -213,6 +219,9 @@ int main(int argc, char *argv[])
 		fprintf(depfile, "%s:", outname);
 	}
 
+	if (annotate && (!streq(inform, "dts") || !streq(outform, "dts")))
+		die("--annotate requires -I dts -O dts\n");
+
 	if (streq(inform, "dts"))
 		bi = dt_from_source(arg);
 	else if (streq(inform, "fs"))

Index: b/dtc-parser.y
===================================================================
@@ -134,10 +134,13 @@ memreserve:
 devicetree:
 	  '/' nodedef
 		{
+			begin_srcpos_node($2, &@1);
 			$$ = name_node($2, "");
 		}
 	| devicetree '/' nodedef
 		{
+			begin_srcpos_node($3, &@2);
+			name_node($3, "");
 			$$ = merge_nodes($1, $3);
 		}
 

@@ -146,20 +149,27 @@ devicetree:
 			struct node *target = get_node_by_ref($1, $3);
 
 			add_label(&target->labels, $2);
-			if (target)
+			if (target) {
+				begin_srcpos_node($4, &@3);
+				name_node($4, target->name);
 				merge_nodes(target, $4);
-			else
+			} else {
 				ERROR(&@3, "Label or path %s not found", $3);
+			}
 			$$ = $1;
 		}
 	| devicetree DT_REF nodedef
 		{
 			struct node *target = get_node_by_ref($1, $2);
 
-			if (target)
+
+			if (target) {
+				begin_srcpos_node($3, &@2);
+				name_node($3, target->name);
 				merge_nodes(target, $3);
-			else
+			} else {
 				ERROR(&@2, "Label or path %s not found", $2);
+			}
 			$$ = $1;
 		}
 	| devicetree DT_DEL_NODE DT_REF ';'

@@ -180,6 +190,7 @@ nodedef:
 	  '{' proplist subnodes '}' ';'
 		{
 			$$ = build_node($2, $3);
+			end_srcpos_node($$, &@4);
 		}
 	;
 

@@ -198,10 +209,12 @@ propdef:
 	  DT_PROPNODENAME '=' propdata ';'
 		{
 			$$ = build_property($1, $3);
+			srcpos_property($$, &@1);
 		}
 	| DT_PROPNODENAME ';'
 		{
 			$$ = build_property($1, empty_data);
+			srcpos_property($$, &@1);
 		}
 	| DT_DEL_PROP DT_PROPNODENAME ';'
 		{

@@ -456,11 +469,13 @@ subnodes:
 subnode:
 	  DT_PROPNODENAME nodedef
 		{
+			begin_srcpos_node($2, &@1);
 			$$ = name_node($2, $1);
 		}
 	| DT_DEL_NODE DT_PROPNODENAME ';'
 		{
 			$$ = name_node(build_node_delete(), $2);
+			begin_srcpos_node($$, &@2);
 		}
 	| DT_LABEL subnode
 		{

Index: b/srcpos.h
===================================================================
@@ -104,7 +104,9 @@ extern struct srcpos srcpos_empty;
 
 extern void srcpos_update(struct srcpos *pos, const char *text, int len);
 extern struct srcpos *srcpos_copy(struct srcpos *pos);
+extern struct srcpos *srcpos_copy_all(struct srcpos *pos);
 extern char *srcpos_string(struct srcpos *pos);
+extern char *srcpos_string_short(struct srcpos *pos);
 extern void srcpos_dump(struct srcpos *pos);
 
 extern void srcpos_verror(struct srcpos *pos, const char *prefix,

Please ignore v4. Version v5 will be out in a few minutes.

-Frank