serial: 8250: extract serial8250_set_fcr()

serial8250_do_set_termios() consists of many registers and up flags
settings. Extract all these into separate functions. This time, setting
of FCR.

serial8250_do_set_termios() looks sane at this point.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250611100319.186924-25-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 0f16398cc86faf89f6efbcd0f74fc7218703da4b..85b75ff0699e9c7e1d3d98dc4c8a65e889f91823 100644 (file)
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2792,6 +2792,30 @@ static void serial8250_set_efr(struct uart_port *port, struct ktermios *termios)
        serial_port_out(port, efr_reg, efr);
 }
 
+static void serial8250_set_fcr(struct uart_port *port, struct ktermios *termios)
+{
+       struct uart_8250_port *up = up_to_u8250p(port);
+       bool is_16750 = port->type == PORT_16750;
+
+       if (is_16750)
+               serial_port_out(port, UART_FCR, up->fcr);
+
+       /*
+        * LCR DLAB must be reset to enable 64-byte FIFO mode. If the FCR is written without DLAB
+        * set, this mode will be disabled.
+        */
+       serial_port_out(port, UART_LCR, up->lcr);
+
+       if (is_16750)
+               return;
+
+       /* emulated UARTs (Lucent Venus 167x) need two steps */
+       if (up->fcr & UART_FCR_ENABLE_FIFO)
+               serial_port_out(port, UART_FCR, UART_FCR_ENABLE_FIFO);
+
+       serial_port_out(port, UART_FCR, up->fcr);
+}
+
 void
 serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
                          const struct ktermios *old)
@@ -2823,22 +2847,9 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
        serial8250_set_ier(port, termios);
        serial8250_set_efr(port, termios);
        serial8250_set_divisor(port, baud, quot, frac);
-
-       /*
-        * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
-        * is written without DLAB set, this mode will be disabled.
-        */
-       if (port->type == PORT_16750)
-               serial_port_out(port, UART_FCR, up->fcr);
-
-       serial_port_out(port, UART_LCR, up->lcr);       /* reset DLAB */
-       if (port->type != PORT_16750) {
-               /* emulated UARTs (Lucent Venus 167x) need two steps */
-               if (up->fcr & UART_FCR_ENABLE_FIFO)
-                       serial_port_out(port, UART_FCR, UART_FCR_ENABLE_FIFO);
-               serial_port_out(port, UART_FCR, up->fcr);       /* set fcr */
-       }
+       serial8250_set_fcr(port, termios);
        serial8250_set_mctrl(port, port->mctrl);
+
        uart_port_unlock_irqrestore(port, flags);
        serial8250_rpm_put(up);