serial: 8250_of: assume reg-shift of 2 for mrvl,mmp-uart

commit f4817843e39ce78aace0195a57d4e8500a65a898 upstream.

There are two other drivers that bind to mrvl,mmp-uart and both of them
assume register shift of 2 bits. There are device trees that lack the
property and rely on that assumption.

If this driver wins the race to bind to those devices, it should behave
the same as the older deprecated driver.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_of.c b/drivers/tty/serial/8250/8250_of.c
index 7a8b5fc81a192f081add58d5a1a212f9c5a41093..f89dfde934a3257ca9834342bb4fc806ae69e8c9 100644 (file)
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -97,6 +97,10 @@ static int of_platform_serial_setup(struct platform_device *ofdev,
        if (of_property_read_u32(np, "reg-offset", &prop) == 0)
                port->mapbase += prop;
 
+       /* Compatibility with the deprecated pxa driver and 8250_pxa drivers. */
+       if (of_device_is_compatible(np, "mrvl,mmp-uart"))
+               port->regshift = 2;
+
        /* Check for registers offset within the devices address range */
        if (of_property_read_u32(np, "reg-shift", &prop) == 0)
                port->regshift = prop;