serial: sh-sci: console drainage

Modify the serial console code to wait for the transmit FIFO,
make sure all bits have been put on the wire before returning.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/serial/sh-sci.c b/drivers/serial/sh-sci.c
index 557b54ab2f25..d3ccce0bfd44 100644
--- a/drivers/serial/sh-sci.c
+++ b/drivers/serial/sh-sci.c
@@ -139,7 +139,7 @@ static void sci_poll_put_char(struct uart_port *port, unsigned char c)
         } while (!(status & SCxSR_TDxE(port)));
 
         sci_in(port, SCxSR);            /* Dummy read */
-        sci_out(port, SCxSR, SCxSR_TDxE_CLEAR(port));
+        sci_out(port, SCxSR, SCxSR_TDxE_CLEAR(port) & ~SCxSR_TEND(port));
         sci_out(port, SCxTDR, c);
 }
 #endif /* CONFIG_CONSOLE_POLL || CONFIG_SERIAL_SH_SCI_CONSOLE */
@@ -1095,6 +1095,7 @@ static void serial_console_write(struct console *co, const char *s,
                                  unsigned count)
 {
         struct uart_port *port = &serial_console_port->port;
+        unsigned short bits;
         int i;
 
         for (i = 0; i < count; i++) {
@@ -1103,6 +1104,11 @@ static void serial_console_write(struct console *co, const char *s,
 
                 sci_poll_put_char(port, *s++);
         }
+
+        /* wait until fifo is empty and last bit has been transmitted */
+        bits = SCxSR_TDxE(port) | SCxSR_TEND(port);
+        while ((sci_in(port, SCxSR) & bits) != bits)
+                cpu_relax();
 }
 
 static int __init serial_console_setup(struct console *co, char *options)