* Atmel Universal Synchronous Asynchronous Receiver/Transmitter (USART) Required properties: - compatible: Should be "atmel,-usart" or "atmel,-dbgu" The compatible indicated will be the first SoC to support an additional mode or an USART new feature. For the dbgu UART, use "atmel,-dbgu", "atmel,-usart" - reg: Should contain registers location and length - interrupts: Should contain interrupt - clock-names: tuple listing input clock names. Required elements: "usart" - clocks: phandles to input clocks. Optional properties: - 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. It will use specified PIO instead of the peripheral function pin for the USART feature. If unsure, don't specify this property. - add dma bindings for dma transfer: - dmas: DMA specifier, consisting of a phandle to DMA controller node, memory peripheral interface and USART DMA channel ID, FIFO configuration. Refer to dma.txt and atmel-dma.txt for details. - dma-names: "rx" for RX channel, "tx" for TX channel. - atmel,fifo-size: maximum number of data the RX and TX FIFOs can store for FIFO capable USARTs. - rs485-rts-delay, rs485-rx-during-tx, linux,rs485-enabled-at-boot-time: see rs485.txt compatible description: - at91rm9200: legacy USART support - at91sam9260: generic USART implementation for SAM9 SoCs Example: - use PDC: usart0: serial@fff8c000 { compatible = "atmel,at91sam9260-usart"; reg = <0xfff8c000 0x4000>; interrupts = <7>; clocks = <&usart0_clk>; clock-names = "usart"; atmel,use-dma-rx; atmel,use-dma-tx; rts-gpios = <&pioD 15 GPIO_ACTIVE_LOW>; cts-gpios = <&pioD 16 GPIO_ACTIVE_LOW>; dtr-gpios = <&pioD 17 GPIO_ACTIVE_LOW>; dsr-gpios = <&pioD 18 GPIO_ACTIVE_LOW>; dcd-gpios = <&pioD 20 GPIO_ACTIVE_LOW>; rng-gpios = <&pioD 19 GPIO_ACTIVE_LOW>; }; - use DMA: usart0: serial@f001c000 { compatible = "atmel,at91sam9260-usart"; reg = <0xf001c000 0x100>; interrupts = <12 4 5>; clocks = <&usart0_clk>; clock-names = "usart"; atmel,use-dma-rx; atmel,use-dma-tx; dmas = <&dma0 2 0x3>, <&dma0 2 0x204>; dma-names = "tx", "rx"; atmel,fifo-size = <32>; };