jtag: add jtag_flush_queue_sleep debug command

it can be useful to throttle performance: test
differences in behavior, test performance effect
of long roundtrips.

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

src/jtag/core.c

@@ -46,6 +46,9 @@
 /// The number of JTAG queue flushes (for profiling and debugging purposes).
 static int jtag_flush_queue_count;
 
+// Sleep this # of ms after flushing the queue
+static int jtag_flush_queue_sleep = 0;
+
 static void jtag_add_scan_check(struct jtag_tap *active,
 		void (*jtag_add_scan)(struct jtag_tap *active, int in_num_fields, const struct scan_field *in_fields, tap_state_t state),
 		int in_num_fields, struct scan_field *in_fields, tap_state_t state);
@@ -129,6 +132,11 @@ static struct jtag_interface *jtag = NULL;
 /* configuration */
 struct jtag_interface *jtag_interface = NULL;
 
+void jtag_set_flush_queue_sleep(int ms)
+{
+	jtag_flush_queue_sleep = ms;
+}
+
 void jtag_set_error(int error)
 {
 	if ((error == ERROR_OK) || (jtag_error != ERROR_OK))
@@ -826,6 +834,15 @@ void jtag_execute_queue_noclear(void)
 {
 	jtag_flush_queue_count++;
 	jtag_set_error(interface_jtag_execute_queue());
+
+	if (jtag_flush_queue_sleep > 0)
+	{
+		/* For debug purposes it can be useful to test performance
+		 * or behavior when delaying after flushing the queue,
+		 * e.g. to simulate long roundtrip times.
+		 */
+		usleep(jtag_flush_queue_sleep * 1000);
+	}
 }
 
 int jtag_get_flush_queue_count(void)

src/jtag/jtag.h

@@ -311,6 +311,10 @@ int  adapter_init(struct command_context* cmd_ctx);
 /// Shutdown the debug adapter upon program exit.
 int  adapter_quit(void);
 
+/// Set ms to sleep after jtag_execute_queue() flushes queue. Debug
+/// purposes.
+void jtag_set_flush_queue_sleep(int ms);
+
 /**
  * Initialize JTAG chain using only a RESET reset. If init fails,
  * try reset + init.

src/jtag/tcl.c

@@ -1248,7 +1248,31 @@ COMMAND_HANDLER(handle_tms_sequence_command)
 	return ERROR_OK;
 }
 
+COMMAND_HANDLER(handle_jtag_flush_queue_sleep)
+{
+	if (CMD_ARGC != 1)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	int sleep_ms;
+	COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], sleep_ms);
+
+	jtag_set_flush_queue_sleep(sleep_ms);
+
+	return ERROR_OK;
+}
+
+
+
 static const struct command_registration jtag_command_handlers[] = {
+
+	{
+		.name = "jtag_flush_queue_sleep",
+		.handler = handle_jtag_flush_queue_sleep,
+		.mode = COMMAND_ANY,
+		.help = "For debug purposes(simulate long delays of interface) "
+				"to test performance or change in behavior. Default 0ms.",
+		.usage = "[sleep in ms]",
+	},
 	{
 		.name = "jtag_rclk",
 		.handler = handle_jtag_rclk_command,