Document a set of generic properties for describing UARTs in a
device tree:
1. The GPIO modem control properties are currently duplicated across
hardware-specific binding documentation,
2. The property for dedicated RTS/CTS hardware flow control lines is
already supported by several drivers, albeit with a vendor-specific
prefix, hence make it generic.
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Acked-by: Rob Herring <rob@xxxxxxxxxx>
---
v2:
- Add Acked-by,
- Drop out[12]-gpios.
---
.../devicetree/bindings/serial/serial.txt | 57 ++++++++++++++++++++++
1 file changed, 57 insertions(+)
create mode 100644 Documentation/devicetree/bindings/serial/serial.txt
diff --git a/Documentation/devicetree/bindings/serial/serial.txt b/Documentation/devicetree/bindings/serial/serial.txt
new file mode 100644
index 0000000000000000..fd970f76a7b8ef0c
--- /dev/null
+++ b/Documentation/devicetree/bindings/serial/serial.txt
@@ -0,0 +1,57 @@
+Generic Serial DT Bindings
+
+This document lists a set of generic properties for describing UARTs in a
+device tree. Whether these properties apply to a particular device depends on
+the DT bindings for the actual device.
+
+Optional properties:
+ - cts-gpios: Must contain a GPIO specifier, referring to the GPIO pin to be
+ used as the UART's CTS line.
+ - dcd-gpios: Must contain a GPIO specifier, referring to the GPIO pin to be
+ used as the UART's DCD line.
+ - dsr-gpios: Must contain a GPIO specifier, referring to the GPIO pin to be
+ used as the UART's DSR line.
+ - dtr-gpios: Must contain a GPIO specifier, referring to the GPIO pin to be
+ used as the UART's DTR line.
+ - rng-gpios: Must contain a GPIO specifier, referring to the GPIO pin to be
+ used as the UART's RNG line.
+ - rts-gpios: Must contain a GPIO specifier, referring to the GPIO pin to be
+ used as the UART's RTS line.
+
+ - uart-has-rtscts: The presence of this property indicates that the
+ UART has dedicated lines for RTS/CTS hardware flow control, and that
+ they are available for use (wired and enabled by pinmux configuration).
+ This depends on both the UART hardware and the board wiring.
+ Note that this property is mutually-exclusive with "cts-gpios" and
+ "rts-gpios" above.
+
+
+Examples:
+
+ uart1: serial@48022000 {
+ compatible = "ti,am3352-uart", "ti,omap3-uart";
+ ti,hwmods = "uart2";
+ clock-frequency = <48000000>;
+ reg = <0x48022000 0x2000>;
+ interrupts = <73>;
+ dmas = <&edma 28 0>, <&edma 29 0>;
+ dma-names = "tx", "rx";
+ dtr-gpios = <&gpio2 22 GPIO_ACTIVE_LOW>;
+ dsr-gpios = <&gpio2 23 GPIO_ACTIVE_LOW>;
+ dcd-gpios = <&gpio2 24 GPIO_ACTIVE_LOW>;
+ rng-gpios = <&gpio2 25 GPIO_ACTIVE_LOW>;
+ cts-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>;
+ rts-gpios = <&gpio0 13 GPIO_ACTIVE_LOW>;
+ status = "okay";
+ };
+
+ scifa4: serial@e6c80000 {
+ compatible = "renesas,scifa-sh73a0", "renesas,scifa";
+ reg = <0xe6c80000 0x100>;
+ interrupts = <GIC_SPI 78 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&mstp2_clks SH73A0_CLK_SCIFA4>;
+ clock-names = "fck";
+ power-domains = <&pd_a3sp>;
+ uart-has-rtscts;
+ status = "okay";
+ };
--
1.9.1
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