8250: use callbacks to access UART_DLL/UART_DLM

commit 0b41ce991052022c030fd868e03877700220b090 upstream.

Some UART HW has a single register combining UART_DLL/UART_DLM
(this was probably forgotten in the change that introduced the
callbacks, commit b32b19b8ffc05cbd3bf91c65e205f6a912ca15d9)

Fixes: b32b19b8ffc0 ("[SERIAL] 8250: set divisor register correctly ...")

Signed-off-by: Sebastian Frias <sf84@laposte.net>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2:
 - Adjust filename
 - We're using serial_{in,out}p for 8-bit I/O]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/tty/serial/8250.c b/drivers/tty/serial/8250.c
index 33601f8..07cfec5 100644 (file)
--- a/drivers/tty/serial/8250.c
+++ b/drivers/tty/serial/8250.c
@@ -777,22 +777,16 @@ static int size_fifo(struct uart_8250_port *up)
  */
 static unsigned int autoconfig_read_divisor_id(struct uart_8250_port *p)
 {
-       unsigned char old_dll, old_dlm, old_lcr;
-       unsigned int id;
+       unsigned char old_lcr;
+       unsigned int id, old_dl;
 
        old_lcr = serial_inp(p, UART_LCR);
        serial_outp(p, UART_LCR, UART_LCR_CONF_MODE_A);
+       old_dl = serial_dl_read(p);
+       serial_dl_write(p, 0);
+       id = serial_dl_read(p);
+       serial_dl_write(p, old_dl);
 
-       old_dll = serial_inp(p, UART_DLL);
-       old_dlm = serial_inp(p, UART_DLM);
-
-       serial_outp(p, UART_DLL, 0);
-       serial_outp(p, UART_DLM, 0);
-
-       id = serial_inp(p, UART_DLL) | serial_inp(p, UART_DLM) << 8;
-
-       serial_outp(p, UART_DLL, old_dll);
-       serial_outp(p, UART_DLM, old_dlm);
        serial_outp(p, UART_LCR, old_lcr);
 
        return id;