tty: of_serial: support for 32 bit accesses

Some platforms e.g. TI Davinci require 32-bit accesses to the UARTs.
The of_serial driver currently registers all UARTs as UPIO_MEM.  Add a
new attribute "reg-io-width" to allow the port to be registered with
different IO width requirements.

Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

2 files changed, 20 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/tty/serial/of-serial.txt b/Documentation/devicetree/bindings/tty/serial/of-serial.txt
index 35e53ae85eec..337a7e51faca 100644
--- a/Documentation/devicetree/bindings/tty/serial/of-serial.txt
+++ b/Documentation/devicetree/bindings/tty/serial/of-serial.txt
@@ -19,6 +19,9 @@ Optional properties:
 - current-speed : the current active speed of the UART.
 - reg-offset : offset to apply to the mapbase from the start of the registers.
 - reg-shift : quantity to shift the register offsets by.
+- reg-io-width : the size (in bytes) of the IO accesses that should be
+  performed on the device.  There are some systems that require 32-bit
+  accesses to the UART (e.g. TI davinci).
 - used-by-rtas : set to indicate that the port is in use by the OpenFirmware
   RTAS and should not be registered.
 
diff --git a/drivers/tty/serial/of_serial.c b/drivers/tty/serial/of_serial.c
index c911b2419abb..36038ed8f09a 100644
--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c
@@ -65,6 +65,23 @@ static int __devinit of_platform_serial_setup(struct platform_device *ofdev,
 
         port->irq = irq_of_parse_and_map(np, 0);
         port->iotype = UPIO_MEM;
+        prop = of_get_property(np, "reg-io-width", &prop_size);
+        if (prop && (prop_size == sizeof(u32))) {
+                switch (be32_to_cpup(prop)) {
+                case 1:
+                        port->iotype = UPIO_MEM;
+                        break;
+                case 4:
+                        port->iotype = UPIO_MEM32;
+                        break;
+                default:
+                        dev_warn(&ofdev->dev,
+                                 "unsupported io width (%d bytes)\n",
+                                 be32_to_cpup(prop));
+                        return -EINVAL;
+                }
+        }
+
         port->type = type;
         port->uartclk = be32_to_cpup(clk);
         port->flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF | UPF_IOREMAP