[U-Boot] [PATCH v2] ns16550: Add WATCHDOG_RESET to putc for short watchdog timeout boards

[Stefan Roese]

This is needed for board with a very short watchdog timeout, like the
lwmon5 with a 100ms timeout. Without this patch this board resets in the
commands with long outputs, like "printenv" or "fdt print".

Note that the image size is not increased with this patch when
CONFIG_HW_WATCHDOG or CONFIG_WATCHDOG are not defined since the compiler
optimizes this additional code away.

Signed-off-by: Stefan Roese <sr at denx.de>
---
v2:
- Move declaration and assignment of "count" out of loop
  as pointed out by Wolfgang (thanks).

 drivers/serial/ns16550.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index 7e833fd..5dc18f4 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -5,6 +5,7 @@
  */
 
 #include <config.h>
+#include <common.h>
 #include <ns16550.h>
 #include <watchdog.h>
 #include <linux/types.h>
@@ -68,7 +69,13 @@ void NS16550_reinit (NS16550_t com_port, int baud_divisor)
 
 void NS16550_putc (NS16550_t com_port, char c)
 {
-	while ((serial_in(&com_port->lsr) & UART_LSR_THRE) == 0);
+	int count = 0;
+
+	while ((serial_in(&com_port->lsr) & UART_LSR_THRE) == 0) {
+		/* reset watchdog from time to time */
+		if ((count++ % (256 << 10)) == 0)
+			WATCHDOG_RESET();
+	}
 	serial_out(c, &com_port->thr);
 }
 
-- 
1.7.3.1