tty: add a DesignWare 8250 driver

The Synopsys DesignWare 8250 is an 8250 that has an extra interrupt that
gets raised when writing to the LCR when busy.  To handle this we need
special serial_out, serial_in and handle_irq methods.  Add a new
platform driver that uses these accessors.

Cc: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 25 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/tty/serial/snps-dw-apb-uart.txt b/Documentation/devicetree/bindings/tty/serial/snps-dw-apb-uart.txt
new file mode 100644
index 000000000000..f13f1c5be91c
--- /dev/null
+++ b/Documentation/devicetree/bindings/tty/serial/snps-dw-apb-uart.txt
@@ -0,0 +1,25 @@
+* Synopsys DesignWare ABP UART
+
+Required properties:
+- compatible : "snps,dw-apb-uart"
+- reg : offset and length of the register set for the device.
+- interrupts : should contain uart interrupt.
+- clock-frequency : the input clock frequency for the UART.
+
+Optional properties:
+- reg-shift : quantity to shift the register offsets by.  If this property is
+  not present then the register offsets are not shifted.
+- reg-io-width : the size (in bytes) of the IO accesses that should be
+  performed on the device.  If this property is not present then single byte
+  accesses are used.
+
+Example:
+
+        uart@80230000 {
+                compatible = "snps,dw-apb-uart";
+                reg = <0x80230000 0x100>;
+                clock-frequency = <3686400>;
+                interrupts = <10>;
+                reg-shift = <2>;
+                reg-io-width = <4>;
+        };