[PATCH v10 15/19] serial: amba-pl011: Pass FIQ information to KGDB.

Daniel Thompson daniel.thompson at linaro.org
Tue Aug 19 09:46:05 PDT 2014

Speculatively register a FIQ resource with KGDB. KGDB will only
accept it if the kgdb/fiq feature is enabled (both with compile time and
runtime switches) and the interrupt controller supports FIQ.

By providing this information to KGDB the serial driver offers
"permission" for KGDB to route the UART interrupt signal from the
drivers own handler to KGDBs FIQ handler (which will eventually use the
UART's polled I/O callbacks to interact with the user). This permission
also implies the amba-pl011 driver has already unmasked RX interrupts
(otherwise the FIQ handler will never trigger).

Signed-off-by: Daniel Thompson <daniel.thompson at linaro.org>
Cc: Russell King <linux at arm.linux.org.uk>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Jiri Slaby <jslaby at suse.cz>
Cc: linux-serial at vger.kernel.org
 drivers/tty/serial/amba-pl011.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 0b06dcf..63c67b0 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -58,6 +58,7 @@
 #include <linux/pinctrl/consumer.h>
 #include <linux/sizes.h>
 #include <linux/io.h>
+#include <linux/kgdb.h>
 #define UART_NR			14
@@ -1466,6 +1467,18 @@ static int pl011_hwinit(struct uart_port *port)
+static int pl011_poll_init(struct uart_port *port)
+	int retval = pl011_hwinit(port);
+	if (retval == 0)
+		kgdb_register_fiq(port->irq);
+	return retval;
 static void pl011_quiesce_irqs(struct uart_port *port)
 	struct uart_amba_port *uap =
@@ -1905,7 +1918,7 @@ static struct uart_ops amba_pl011_pops = {
 	.config_port	= pl011_config_port,
 	.verify_port	= pl011_verify_port,
-	.poll_init     = pl011_hwinit,
+	.poll_init     = pl011_poll_init,
 	.poll_get_char = pl011_get_poll_char,
 	.poll_put_char = pl011_put_poll_char,

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