Add a command to access the system timer

Two sub-commands... start and get.
 * start sets the reference.
 * get prints out the time since the last start (in "<sec>.<msec>" format).
If get is called without start, returns time since boot.
Simple way to benchmark an operation: "timer start;<commands-to-measure>;timer get"

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

README

@@ -858,7 +858,8 @@ The following options need to be configured:
 		CONFIG_CMD_SPI		* SPI serial bus support
 		CONFIG_CMD_TFTPSRV	* TFTP transfer in server mode
 		CONFIG_CMD_TFTPPUT	* TFTP put command (upload)
-		CONFIG_CMD_TIME		* run command and report execution time
+		CONFIG_CMD_TIME		* run command and report execution time (ARM specific)
+		CONFIG_CMD_TIMER	* access to the system tick timer
 		CONFIG_CMD_USB		* USB support
 		CONFIG_CMD_CDP		* Cisco Discover Protocol support
 		CONFIG_CMD_MFSL		* Microblaze FSL support

common/cmd_misc.c

@@ -53,3 +53,30 @@ U_BOOT_CMD(
 	"N\n"
 	"    - delay execution for N seconds (N is _decimal_ !!!)"
 );
+
+#ifdef CONFIG_CMD_TIMER
+static int do_timer(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	static ulong start;
+
+	if (argc != 2)
+		return CMD_RET_USAGE;
+
+	if (!strcmp(argv[1], "start"))
+		start = get_timer(0);
+
+	if (!strcmp(argv[1], "get")) {
+		ulong msecs = get_timer(start) * 1000 / CONFIG_SYS_HZ;
+		printf("%ld.%03d\n", msecs / 1000, (int)(msecs % 1000));
+	}
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	timer,    2,    1,     do_timer,
+	"access the system timer",
+	"start - Reset the timer reference.\n"
+	"timer get   - Print the time since 'start'."
+);
+#endif