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doc: DT: Add Generic Serial Device Tree Bindings

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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@glider.be>
Acked-by: Rob Herring <rob@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven 2016-04-22 17:22:20 +02:00 committed by Greg Kroah-Hartman
parent 28264eb6c3
commit 8d21f24416
1 changed files with 57 additions and 0 deletions
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Documentation/devicetree/bindings/serial/serial.txt Normal file
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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";
};