serial: 8250: introduce up_to_u8250p() helper

It helps to cast struct uart_port to struct uart_8250_port at runtime.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index af47a8a..730ab4b 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -100,6 +100,11 @@ struct uart_8250_port {
 	void			(*dl_write)(struct uart_8250_port *, int);
 };
 
+static inline struct uart_8250_port *up_to_u8250p(struct uart_port *up)
+{
+	return container_of(up, struct uart_8250_port, port);
+}
+
 int serial8250_register_8250_port(struct uart_8250_port *);
 void serial8250_unregister_port(int line);
 void serial8250_suspend_port(int line);