serial/serial_arc: add work-around of ISS bug

Explanation is in in-lined comment.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Tom Rini <trini@ti.com>

diff --git a/drivers/serial/serial_arc.c b/drivers/serial/serial_arc.c
index e63d25d7949a47bbd73efc97e80685d162215c19..55d07691fcf227a65eebfee94f9710b096c57c6b 100644 (file)
--- a/drivers/serial/serial_arc.c
+++ b/drivers/serial/serial_arc.c
@@ -39,7 +39,23 @@ static void arc_serial_setbrg(void)
 
        arc_console_baud = gd->cpu_clk / (gd->baudrate * 4) - 1;
        writel(arc_console_baud & 0xff, &regs->baudl);
+
+#ifdef CONFIG_ARC
+       /*
+        * UART ISS(Instruction Set simulator) emulation has a subtle bug:
+        * A existing value of Baudh = 0 is used as a indication to startup
+        * it's internal state machine.
+        * Thus if baudh is set to 0, 2 times, it chokes.
+        * This happens with BAUD=115200 and the formaula above
+        * Until that is fixed, when running on ISS, we will set baudh to !0
+        */
+       if (gd->arch.running_on_hw)
+               writel((arc_console_baud & 0xff00) >> 8, &regs->baudh);
+       else
+               writel(1, &regs->baudh);
+#else
        writel((arc_console_baud & 0xff00) >> 8, &regs->baudh);
+#endif
 }
 
 static int arc_serial_init(void)