Merge tag 'ib-mfd-spi-tty-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd into tty-next

Immutable branch between MFD, SPI and TTY due for the v4.20 merge window

Documentation/devicetree/bindings/mfd/atmel-usart.txt

@@ -1,6 +1,6 @@
 * Atmel Universal Synchronous Asynchronous Receiver/Transmitter (USART)
 
-Required properties:
+Required properties for USART:
 - compatible: Should be "atmel,<chip>-usart" or "atmel,<chip>-dbgu"
   The compatible <chip> indicated will be the first SoC to support an
   additional mode or an USART new feature.
@@ -11,7 +11,13 @@ Required properties:
 	Required elements: "usart"
 - clocks: phandles to input clocks.
 
-Optional properties:
+Required properties for USART in SPI mode:
+- #size-cells      : Must be <0>
+- #address-cells   : Must be <1>
+- cs-gpios: chipselects (internal cs not supported)
+- atmel,usart-mode : Must be <AT91_USART_MODE_SPI> (found in dt-bindings/mfd/at91-usart.h)
+
+Optional properties in serial mode:
 - atmel,use-dma-rx: use of PDC or DMA for receiving data
 - atmel,use-dma-tx: use of PDC or DMA for transmitting data
 - {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD line respectively.
@@ -62,3 +68,18 @@ Example:
 		dma-names = "tx", "rx";
 		atmel,fifo-size = <32>;
 	};
+
+- SPI mode:
+	#include <dt-bindings/mfd/at91-usart.h>
+
+	spi0: spi@f001c000 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		compatible = "atmel,at91rm9200-usart", "atmel,at91sam9260-usart";
+		atmel,usart-mode = <AT91_USART_MODE_SPI>;
+		reg = <0xf001c000 0x100>;
+		interrupts = <12 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&usart0_clk>;
+		clock-names = "usart";
+		cs-gpios = <&pioB 3 0>;
+	};