hvc_console: Add kdb support

Add poll_get_char and poll_put_char for kdb. Enable kdb at boot with:

kgdboc=hvc0

or at runtime with:

echo hvc0 > /sys/module/kgdboc/parameters/kgdboc

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
index 59000750cc73819e9bf6c5bf0dd80757aa247d86..e1aaf4f309b3c2730dd435642bfa68cc4c6ad85b 100644 (file)
--- a/drivers/tty/hvc/hvc_console.c
+++ b/drivers/tty/hvc/hvc_console.c
@@ -39,6 +39,7 @@
 #include <linux/delay.h>
 #include <linux/freezer.h>
 #include <linux/slab.h>
+#include <linux/serial_core.h>
 
 #include <asm/uaccess.h>
 
@@ -766,6 +767,39 @@ static int hvc_tiocmset(struct tty_struct *tty,
        return hp->ops->tiocmset(hp, set, clear);
 }
 
+#ifdef CONFIG_CONSOLE_POLL
+int hvc_poll_init(struct tty_driver *driver, int line, char *options)
+{
+       return 0;
+}
+
+static int hvc_poll_get_char(struct tty_driver *driver, int line)
+{
+       struct tty_struct *tty = driver->ttys[0];
+       struct hvc_struct *hp = tty->driver_data;
+       int n;
+       char ch;
+
+       n = hp->ops->get_chars(hp->vtermno, &ch, 1);
+
+       if (n == 0)
+               return NO_POLL_CHAR;
+
+       return ch;
+}
+
+static void hvc_poll_put_char(struct tty_driver *driver, int line, char ch)
+{
+       struct tty_struct *tty = driver->ttys[0];
+       struct hvc_struct *hp = tty->driver_data;
+       int n;
+
+       do {
+               n = hp->ops->put_chars(hp->vtermno, &ch, 1);
+       } while (n <= 0);
+}
+#endif
+
 static const struct tty_operations hvc_ops = {
        .open = hvc_open,
        .close = hvc_close,
@@ -776,6 +810,11 @@ static const struct tty_operations hvc_ops = {
        .chars_in_buffer = hvc_chars_in_buffer,
        .tiocmget = hvc_tiocmget,
        .tiocmset = hvc_tiocmset,
+#ifdef CONFIG_CONSOLE_POLL
+       .poll_init = hvc_poll_init,
+       .poll_get_char = hvc_poll_get_char,
+       .poll_put_char = hvc_poll_put_char,
+#endif
 };
 
 struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,