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>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/serial/pmac_zilog.c b/drivers/serial/pmac_zilog.c
index 317b061f7641..ad3488504010 100644
--- a/drivers/serial/pmac_zilog.c
+++ b/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
 };
 
 /*