shell: implement set-time command that accepts seconds since the UNIX epoch

source/shell/rtc.c

@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <stdlib.h>
 #include <time.h>
 
 #include <console.h>
@@ -36,6 +37,27 @@ int shell_time(struct console *con, size_t argc, const char **argv)
 	return 0;
 }
 
+int shell_set_time(struct console *con, size_t argc, const char **argv)
+{
+	struct tm now;
+	time_t time;
+
+	if (argc < 1) {
+		fprintf(con->fp, "usage: set-time <seconds>\n");
+		return -1;
+	}
+
+	time = (time_t)strtoul(argv[0], NULL, 0);
+	gmtime_r(&time, &now);
+	rtc_init(&now);
+
+	fprintf(con->fp, "%02d:%02d:%02d %02d-%02d-%d\n",
+		now.tm_hour, now.tm_min, now.tm_sec,
+		now.tm_mday, now.tm_mon + 1, now.tm_year + 1900);
+
+	return 0;
+}
+
 int shell_set_date(struct console *con, size_t argc, const char **argv)
 {
 	struct tm now;