[PATCH v2 3/3] commands: devlookup: add option to print kernel root option

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

There exists currently no way to view the kernel root option that
barebox would generate when instructed to via global.bootm.root_dev,
but without actually mounting the file system.

Add a new -k option that can print this. This can be useful in scripts
that want to fixup the root line, so it's interpreted by the rdinit, but
not by the kernel.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 commands/devlookup.c | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

diff --git a/commands/devlookup.c b/commands/devlookup.c
index 4a2c9b773661..0d4c6e808b60 100644
--- a/commands/devlookup.c
+++ b/commands/devlookup.c
@@ -8,26 +8,36 @@
 #include <linux/stat.h>
 #include <linux/ctype.h>
 #include <environment.h>
+#include <block.h>
 
 static int do_devlookup(int argc, char *argv[])
 {
 	const char *variable = NULL, *devicefile, *paramname;
 	struct cdev *cdev;
 	int opt, ret;
+	bool kernelopt = false;
+	const char *val;
+	char *buf = NULL;
 
-	while ((opt = getopt(argc, argv, "v:")) > 0) {
+	while ((opt = getopt(argc, argv, "v:k")) > 0) {
 		switch(opt) {
 		case 'v':
 			variable = optarg;
 			break;
+		case 'k':
+			kernelopt = true;
+			break;
 		}
 	}
 
-	if (argc - optind == 0 || argc - optind > 2)
+	argv += optind;
+	argc -= optind;
+
+	if (argc == 0 || argc > 2 || (kernelopt && argc != 1))
 		return COMMAND_ERROR_USAGE;
 
-	devicefile = argv[optind];
-	paramname  = argv[optind + 1];
+	devicefile = argv[0];
+	paramname  = argv[1];
 
 	devicefile = devpath_to_name(devicefile);
 
@@ -43,11 +53,16 @@ static int do_devlookup(int argc, char *argv[])
 		goto out;
 	}
 
-	if (paramname)
-		ret = cmd_export_val(variable, dev_get_param(cdev->dev, paramname));
+	if (kernelopt)
+		val = buf = cdev_get_linux_rootarg(cdev);
+	else if (paramname)
+		val = dev_get_param(cdev->dev, paramname);
 	else
-		ret = cmd_export_val(variable, dev_name(cdev->dev));
+		val = dev_name(cdev->dev);
+
+	ret = cmd_export_val(variable, val);
 out:
+	free(buf);
 	cdev_close(cdev);
 
 	return ret;
@@ -56,14 +71,17 @@ static int do_devlookup(int argc, char *argv[])
 BAREBOX_CMD_HELP_START(devlookup)
 BAREBOX_CMD_HELP_TEXT("Detects the device behind a device file and outputs it,")
 BAREBOX_CMD_HELP_TEXT("unless a second argument is given. In that case the device")
-BAREBOX_CMD_HELP_TEXT("parameter with that name is looked up. Specifying -v VARIABLE")
-BAREBOX_CMD_HELP_TEXT("will write output to VARIABLE instead of printing it")
+BAREBOX_CMD_HELP_TEXT("parameter with that name is looked up.")
+BAREBOX_CMD_HELP_TEXT("")
+BAREBOX_CMD_HELP_TEXT("Options:")
+BAREBOX_CMD_HELP_OPT ("-v",  "write output to VARIABLE instead of printing it")
+BAREBOX_CMD_HELP_OPT ("-k",  "output kernel rootarg line")
 BAREBOX_CMD_HELP_END
 
 BAREBOX_CMD_START(devlookup)
 	.cmd		= do_devlookup,
 	BAREBOX_CMD_DESC("look up device behind device file and its parameters")
-	BAREBOX_CMD_OPTS("[-v VAR] /dev/DEVICE [parameter]")
+	BAREBOX_CMD_OPTS("[-v VAR] [-k] /dev/DEVICE [parameter]")
 	BAREBOX_CMD_GROUP(CMD_GRP_SCRIPT)
 	BAREBOX_CMD_HELP(cmd_devlookup_help)
 BAREBOX_CMD_END
-- 
2.39.5