altera_jtag_uart: bypass when no jtag connection
This patch adds an option to bypass output waiting when there
is no jtag connection. This allows the jtag uart work similar
to a serial uart, ie, boot even without connection.
This option is enabled with CONFIG_ALTERA_JTAG_UART_BYPASS
Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Scott McNutt <smcnutt@psyent.com>
diff --git a/drivers/serial/altera_jtag_uart.c b/drivers/serial/altera_jtag_uart.c
index fb28aa9..2980e4d 100644
--- a/drivers/serial/altera_jtag_uart.c
+++ b/drivers/serial/altera_jtag_uart.c
@@ -38,8 +38,16 @@
void serial_putc (char c)
{
- while (NIOS_JTAG_WSPACE ( readl (&jtag->control)) == 0)
- WATCHDOG_RESET ();
+ while (1) {
+ unsigned st = readl(&jtag->control);
+ if (NIOS_JTAG_WSPACE(st))
+ break;
+#ifdef CONFIG_ALTERA_JTAG_UART_BYPASS
+ if (!(st & NIOS_JTAG_AC)) /* no connection */
+ return;
+#endif
+ WATCHDOG_RESET();
+ }
writel ((unsigned char)c, &jtag->data);
}