Generic bindings for RS485 feature included in some UARTs.
Those bindings have to be used withing an UART device tree node.
Documentation updated to link to the bindings definition.
Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
---
Hi all,
1/ I have used the "linux" vendor definition: tell me if it makes sense...
2/ I have the feeling that the SER_RS485_RTS_ON_SEND flag can easily deduced
from a zero value on both "before" and "after" data delays.
Tell me what you think about this...
Bye,
Documentation/devicetree/bindings/serial/rs485.txt | 28 ++++++++++++++++++++
Documentation/serial/serial-rs485.txt | 5 +++
2 files changed, 33 insertions(+), 0 deletions(-)
create mode 100644 Documentation/devicetree/bindings/serial/rs485.txt
diff --git a/Documentation/devicetree/bindings/serial/rs485.txt b/Documentation/devicetree/bindings/serial/rs485.txt
new file mode 100644
index 0000000..6514be8
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/rs485.txt
@@ -0,0 +1,28 @@
+* 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.
+
+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.
+- linux,rs485-rts-delay: prop-encoded-array <a b> 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.
+
+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;
+ linux,rs485-rts-delay = <0 200>; // in milliseconds
+ };
+
diff --git a/Documentation/serial/serial-rs485.txt b/Documentation/serial/serial-rs485.txt
index a493238..d11e5eb 100644
--- a/Documentation/serial/serial-rs485.txt
+++ b/Documentation/serial/serial-rs485.txt
@@ -28,6 +28,10 @@
RS485 communications. This data structure is used to set and configure RS485
parameters in the platform data and in ioctls.
+ The device tree can also provide RS485 boot time parameters (see [2]
+ for bindings). The driver is in charge of filling this data structure from
+ the values given by the device tree.
+
Any driver for devices capable of working both as RS232 and RS485 should
provide at least the following ioctls:
@@ -118,3 +122,4 @@
5. REFERENCES
[1] include/linux/serial.h
+ [2] Documentation/devicetree/bindings/serial/rs485.txt
--
1.7.5.4
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