dtc: Implement -d option to write out a dependency file

This will allow callers to rebuild .dtb files when any of the /include/d
.dtsi files are modified, not just the top-level .dts file.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 19 insertions, 1 deletions

diff --git a/dtc.c b/dtc.c
index 15d2fc2..7a0c605 100644
--- a/dtc.c
+++ b/dtc.c
@@ -71,6 +71,7 @@ static void  __attribute__ ((noreturn)) usage(void)
 	fprintf(stderr, "\t\t\tasm - assembler source\n");
 	fprintf(stderr, "\t-V <output version>\n");
 	fprintf(stderr, "\t\tBlob version to produce, defaults to %d (relevant for dtb\n\t\tand asm output only)\n", DEFAULT_FDT_VERSION);
+	fprintf(stderr, "\t-d <output dependency file>\n");
 	fprintf(stderr, "\t-R <number>\n");
 	fprintf(stderr, "\t\tMake space for <number> reserve map entries (relevant for \n\t\tdtb and asm output only)\n");
 	fprintf(stderr, "\t-S <bytes>\n");
@@ -99,6 +100,7 @@ int main(int argc, char *argv[])
 	const char *inform = "dts";
 	const char *outform = "dts";
 	const char *outname = "-";
+	const char *depname = NULL;
 	int force = 0, sort = 0;
 	const char *arg;
 	int opt;
@@ -111,7 +113,7 @@ int main(int argc, char *argv[])
 	minsize    = 0;
 	padsize    = 0;
 
-	while ((opt = getopt(argc, argv, "hI:O:o:V:R:S:p:fqb:vH:s")) != EOF) {
+	while ((opt = getopt(argc, argv, "hI:O:o:V:d:R:S:p:fqb:vH:s")) != EOF) {
 		switch (opt) {
 		case 'I':
 			inform = optarg;
@@ -125,6 +127,9 @@ int main(int argc, char *argv[])
 		case 'V':
 			outversion = strtol(optarg, NULL, 0);
 			break;
+		case 'd':
+			depname = optarg;
+			break;
 		case 'R':
 			reservenum = strtol(optarg, NULL, 0);
 			break;
@@ -185,6 +190,14 @@ int main(int argc, char *argv[])
 	fprintf(stderr, "DTC: %s->%s  on file \"%s\"\n",
 		inform, outform, arg);
 
+	if (depname) {
+		depfile = fopen(depname, "w");
+		if (!depfile)
+			die("Couldn't open dependency file %s: %s\n", depname,
+			    strerror(errno));
+		fprintf(depfile, "%s:", outname);
+	}
+
 	if (streq(inform, "dts"))
 		bi = dt_from_source(arg);
 	else if (streq(inform, "fs"))
@@ -194,6 +207,11 @@ int main(int argc, char *argv[])
 	else
 		die("Unknown input format \"%s\"\n", inform);
 
+	if (depfile) {
+		fputc('\n', depfile);
+		fclose(depfile);
+	}
+
 	if (cmdline_boot_cpuid != -1)
 		bi->boot_cpuid_phys = cmdline_boot_cpuid;