Kernel-3.10.0-957.el7_rs485

• RS485 serial communications

The RTS signal is capable of automatically controlling line direction for
the built-in half-duplex mode.
The properties described hereafter shall be given to a half-duplex capable
UART node.

Required properties:

• rs485-rts-delay: prop-encoded-array where:
  • a is the delay beteween rts signal and beginning of data sent in milliseconds.
    it corresponds to the delay before sending data.
  • b is the delay between end of data sent and rts signal in milliseconds
    it corresponds to the delay after sending data and actual release of the line.

Optional properties:

• linux,rs485-enabled-at-boot-time: empty property telling to enable the rs485
  feature at boot time. It can be disabled later with proper ioctl.
• rs485-rx-during-tx: empty property that enables the receiving of data even
  whilst sending data.

RS485 example for Atmel USART:
usart0: serial@fff8c000 {
compatible = “atmel,at91sam9260-usart”;
reg = <0xfff8c000 0x4000>;
interrupts = <7>;
atmel,use-dma-rx;
atmel,use-dma-tx;
linux,rs485-enabled-at-boot-time;
rs485-rts-delay = <0 200>; // in milliseconds
};