serial/pmac_zilog: Add console polling support

This implements poll_get_char and poll_put_char for console polling,
which enables kgdb to work on machines that use the pmac_zilog serial
driver, for example the Apple PowerMac G5.

Signed-off-by: Chris J Arges <arges@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

drivers/serial/pmac_zilog.c

@@ -1383,6 +1383,29 @@ static int pmz_verify_port(struct uart_port *port, struct serial_struct *ser)
 	return -EINVAL;
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+
+static int pmz_poll_get_char(struct uart_port *port)
+{
+	struct uart_pmac_port *uap = (struct uart_pmac_port *)port;
+
+	while ((read_zsreg(uap, R0) & Rx_CH_AV) == 0)
+		udelay(5);
+	return read_zsdata(uap);
+}
+
+static void pmz_poll_put_char(struct uart_port *port, unsigned char c)
+{
+	struct uart_pmac_port *uap = (struct uart_pmac_port *)port;
+
+	/* Wait for the transmit buffer to empty. */
+	while ((read_zsreg(uap, R0) & Tx_BUF_EMP) == 0)
+		udelay(5);
+	write_zsdata(uap, c);
+}
+
+#endif
+
 static struct uart_ops pmz_pops = {
 	.tx_empty	=	pmz_tx_empty,
 	.set_mctrl	=	pmz_set_mctrl,
@@ -1400,6 +1423,10 @@ static struct uart_ops pmz_pops = {
 	.request_port	=	pmz_request_port,
 	.config_port	=	pmz_config_port,
 	.verify_port	=	pmz_verify_port,
+#ifdef CONFIG_CONSOLE_POLL
+	.poll_get_char	=	pmz_poll_get_char,
+	.poll_put_char	=	pmz_poll_put_char,
+#endif
 };
 
 /*