It was noticed that polling drivers (like KGDB) are not able to use
serial ports if the ports were not previously initialized via console.
I.e. when booting with console=ttyAMA0 kgdboc=ttyAMA0, everything works
fine, but with console=ttyFOO kgdboc=ttyAMA0, the kgdboc doesn't work.
This is because we don't initialize the hardware. Calling ->startup() is
not an option, because drivers request interrupts there, and drivers
fail to handle situations when tty isn't opened with interrupts enabled.
So, we have to implement a new callback (actually, tty_ops already have
a similar callback), which does everything needed to initialize just the
hardware.
Signed-off-by: Anton Vorontsov <anton.voront...@linaro.org>
---
drivers/tty/serial/serial_core.c | 15 +++++++++++++++
include/linux/serial_core.h | 1 +
2 files changed, 16 insertions(+)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index a21dc8e..cba8443 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2108,11 +2108,13 @@ static int uart_poll_init(struct tty_driver *driver,
int line, char *options)
{
struct uart_driver *drv = driver->driver_state;
struct uart_state *state = drv->state + line;
+ struct tty_port *tport;
struct uart_port *port;
int baud = 9600;
int bits = 8;
int parity = 'n';
int flow = 'n';
+ int ret;
if (!state || !state->uart_port)
return -1;
@@ -2121,6 +2123,19 @@ static int uart_poll_init(struct tty_driver *driver, int
line, char *options)
if (!(port->ops->poll_get_char && port->ops->poll_put_char))
return -1;
+ tport = &state->port;
+ if (!(tport->flags & ASYNC_INITIALIZED) && port->ops->poll_init) {
+ mutex_lock(&tport->mutex);
+ ret = port->ops->poll_init(port);
+ /*
+ * We don't set ASYNCB_INITIALIZED as we only initialized the
+ * hw, e.g. state->xmit is still uninitialized.
+ */
+ mutex_unlock(&tport->mutex);
+ if (ret)
+ return ret;
+ }
+
if (options) {
uart_parse_options(options, &baud, &parity, &bits, &flow);
return uart_set_options(port, NULL, baud, parity, bits, flow);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 0253c20..3642710 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -274,6 +274,7 @@ struct uart_ops {
int (*verify_port)(struct uart_port *, struct serial_struct
*);
int (*ioctl)(struct uart_port *, unsigned int, unsigned
long);
#ifdef CONFIG_CONSOLE_POLL
+ int (*poll_init)(struct uart_port *);
void (*poll_put_char)(struct uart_port *, unsigned char);
int (*poll_get_char)(struct uart_port *);
#endif
--
1.7.11.5
--
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