tty/8250_early: Turn serial_in/serial_out into weak symbols.

Allows overriding default methods serial_in/serial_out.

In such platform specific replacement it is possible to use
other regshift, biased register offset, any other manipulation
that is not covered with common default methods.

Overriding default methods may be useful for platforms which got
serial peripheral with registers represented in big endian.
In this situation and assuming that 32 bit operations / alignment
is required then it may be useful to swab words before/after
accessing the serial registers.

Signed-off-by: Noam Camus <noamc@ezchip.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index c174c90fb3fb..c490d20b3fb8 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -105,6 +105,8 @@ extern int early_serial_setup(struct uart_port *port);
 
 extern int serial8250_find_port(struct uart_port *p);
 extern int serial8250_find_port_for_earlycon(void);
+extern unsigned int serial8250_early_in(struct uart_port *port, int offset);
+extern void serial8250_early_out(struct uart_port *port, int offset, int value);
 extern int setup_early_serial8250_console(char *cmdline);
 extern void serial8250_do_set_termios(struct uart_port *port,
                 struct ktermios *termios, struct ktermios *old);