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 3613a6aabfb37db7abf529bcb034d300b579d7b8..ec510e342e06cf86eb5ebb118263cac5a0c58de2 100644 (file)
--- a/drivers/tty/serial/8250/8250_of.c
+++ b/drivers/tty/serial/8250/8250_of.c
@@ -105,6 +105,10 @@ 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;