linux/Documentation/devicetree/bindings/serial/rs485.txt
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   1* RS485 serial communications
   2
   3The RTS signal is capable of automatically controlling line direction for
   4the built-in half-duplex mode.
   5The properties described hereafter shall be given to a half-duplex capable
   6UART node.
   7
   8Required properties:
   9- rs485-rts-delay: prop-encoded-array <a b> where:
  10  * a is the delay beteween rts signal and beginning of data sent in milliseconds.
  11      it corresponds to the delay before sending data.
  12  * b is the delay between end of data sent and rts signal in milliseconds
  13      it corresponds to the delay after sending data and actual release of the line.
  14
  15Optional properties:
  16- linux,rs485-enabled-at-boot-time: empty property telling to enable the rs485
  17  feature at boot time. It can be disabled later with proper ioctl.
  18- rs485-rx-during-tx: empty property that enables the receiving of data even
  19  whilst sending data.
  20
  21RS485 example for Atmel USART:
  22        usart0: serial@fff8c000 {
  23                compatible = "atmel,at91sam9260-usart";
  24                reg = <0xfff8c000 0x4000>;
  25                interrupts = <7>;
  26                atmel,use-dma-rx;
  27                atmel,use-dma-tx;
  28                linux,rs485-enabled-at-boot-time;
  29                rs485-rts-delay = <0 200>;              // in milliseconds
  30        };
  31
  32