1 files changed, 77 insertions, 0 deletions
diff --git a/commands/devlookup.c b/commands/devlookup.c
new file mode 100644
index 0000000000..ffd6afbaba
--- /dev/null
+++ b/commands/devlookup.c
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <common.h>
+#include <command.h>
+#include <fs.h>
+#include <getopt.h>
+#include <malloc.h>
+#include <linux/stat.h>
+#include <linux/ctype.h>
+#include <environment.h>
+
+static int report(const char *variable, const char *val)
+{
+	if (!val)
+		return -(errno ?: EINVAL);
+
+	if (variable)
+		return setenv(variable, val);
+
+	printf("%s\n", val);
+	return 0;
+}
+
+static int do_devlookup(int argc, char *argv[])
+{
+	const char *variable = NULL, *devicefile, *paramname;
+	struct cdev *cdev;
+	int opt;
+
+	while ((opt = getopt(argc, argv, "v:")) > 0) {
+		switch(opt) {
+		case 'v':
+			variable = optarg;
+			break;
+		}
+	}
+
+	if (argc - optind == 0 || argc - optind > 2)
+		return COMMAND_ERROR_USAGE;
+
+	devicefile = argv[optind];
+	paramname  = argv[optind + 1];
+
+	devicefile = devpath_to_name(devicefile);
+
+	cdev = cdev_by_name(devicefile);
+	if (!cdev) {
+		printf("devlookup: cdev %s not found\n", devicefile);
+		return -ENOENT;
+	}
+
+	if (!cdev->dev) {
+		printf("devlookup: cdev %s not associated with a device\n", devicefile);
+		return -ENODEV;
+	}
+
+	if (paramname)
+		return report(variable, dev_get_param(cdev->dev, paramname));
+
+	return report(variable, dev_name(cdev->dev));
+}
+
+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_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_GROUP(CMD_GRP_SCRIPT)
+	BAREBOX_CMD_HELP(cmd_devlookup_help)
+BAREBOX_CMD_END
+