tty: poll_nmi_wrap/unwrap

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>

3 files changed, 46 insertions, 0 deletions

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 984605bb5bf1..69df4ac7bb2f 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2305,6 +2305,36 @@ static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
 		port->ops->poll_put_char(port, '\r');
 	port->ops->poll_put_char(port, ch);
 }
+
+static int uart_poll_request_nmi(struct tty_driver *driver, int line,
+				 irq_handler_t handler)
+{
+	struct uart_driver *drv = driver->driver_state;
+	struct uart_state *state = drv->state + line;
+	struct uart_port *port;
+
+	if (!state || !state->uart_port)
+		return -1;
+
+	port = state->uart_port;
+	if (!port->ops->poll_request_nmi || !port->ops->poll_free_nmi)
+		return -1;
+
+	return port->ops->poll_request_nmi(port, handler);
+}
+
+static void uart_poll_free_nmi(struct tty_driver *driver, int line)
+{
+	struct uart_driver *drv = driver->driver_state;
+	struct uart_state *state = drv->state + line;
+	struct uart_port *port;
+
+	if (!state || !state->uart_port)
+		return;
+
+	port = state->uart_port;
+	port->ops->poll_free_nmi(port);
+}
 #endif
 
 static const struct tty_operations uart_ops = {
@@ -2337,6 +2367,8 @@ static const struct tty_operations uart_ops = {
 	.poll_init	= uart_poll_init,
 	.poll_get_char	= uart_poll_get_char,
 	.poll_put_char	= uart_poll_put_char,
+	.poll_request_nmi = uart_poll_request_nmi,
+	.poll_free_nmi  = uart_poll_free_nmi,
 #endif
 };
 
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 3dff1a7437b8..9132048c5880 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -90,6 +90,8 @@ struct uart_ops {
 	int		(*poll_init)(struct uart_port *);
 	void		(*poll_put_char)(struct uart_port *, unsigned char);
 	int		(*poll_get_char)(struct uart_port *);
+	int		(*poll_request_nmi)(struct uart_port *, irq_handler_t);
+	void		(*poll_free_nmi)(struct uart_port *);
 #endif
 };
 
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 92e337c18839..8eace29ecc6f 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -240,6 +240,7 @@
 
 #include <linux/export.h>
 #include <linux/fs.h>
+#include <linux/interrupt.h>
 #include <linux/list.h>
 #include <linux/cdev.h>
 #include <linux/termios.h>
@@ -289,6 +290,17 @@ struct tty_operations {
 	int (*poll_init)(struct tty_driver *driver, int line, char *options);
 	int (*poll_get_char)(struct tty_driver *driver, int line);
 	void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
+
+	/*
+	 * Request that the NMI be poked when there is data available.
+	 * This forms part of the polling API because the NMI handler will use
+	 * the polling API to service the interrupt. If hardware cannot
+	 * easily clearing the interrupt source using the polling API
+	 * the pointers should be set to NULL.
+	 */
+	int (*poll_request_nmi)(struct tty_driver *driver, int line,
+				irq_handler_t handler);
+	void (*poll_free_nmi)(struct tty_driver *driver, int line);
 #endif
 	const struct file_operations *proc_fops;
 };