tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
8Optional properties:
9- rs485-rts-delay: prop-encoded-array <a b> where:
10 * a is the delay between 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 If this property is not specified, <0 0> is assumed.
15- rs485-rts-active-low: drive RTS low when sending (default is high).
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