The ttyvs driver creates virtual tty devices. These devices can also be created through device tree. This commit document this. Signed-off-by: Rishi Gupta <gupt21@xxxxxxxxx> --- Changes in v3: - Rebased on top of v5.7-rc1 Changes in v2: - Made dev-num property mandatory - Removed descriptions not needed due to driver changes .../devicetree/bindings/serial/ttyvs.yaml | 165 +++++++++++++++++++++ 1 file changed, 165 insertions(+) create mode 100644 Documentation/devicetree/bindings/serial/ttyvs.yaml diff --git a/Documentation/devicetree/bindings/serial/ttyvs.yaml b/Documentation/devicetree/bindings/serial/ttyvs.yaml new file mode 100644 index 0000000..c919424 --- /dev/null +++ b/Documentation/devicetree/bindings/serial/ttyvs.yaml @@ -0,0 +1,165 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/serial/ttyvs.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Virtual multi-port serial card DT bindings + +maintainers: + - Rishi Gupta <gupt21@xxxxxxxxx> + +description: | + The ttyvs driver creates a virtual card which can have 0 to 65535 + virtual tty devices. The card is modelled as a node with zero or more + child nodes each representing a virtual tty device. These devices + can be configured to be a loop-back type device or it can be part of + a null-modem pair. + + Devices can be created by defining properties required to instantiate + a device (see examples Ex1/2/3 at the end). More information about + how to use this driver is here Documentation/virtual/tty-ttyvs.rst + +properties: + compatible: + const: ttyvs,virtual-uart-card + + max-num-vs-devs: + allOf: + - $ref: /schemas/types.yaml#/definitions/uint32 + - minimum: 0 + - maximum: 0xffff + maxItems: 1 + description: + By default, the driver can create upto 64 devices. This number can + be changed by passing 'max_num_vs_devs' module parameter to the driver + or by defining 'max-num-vs-devs' DT property. If both are used then + driver updates itself to support total number of devices as defined + by max-num-vs-devs property. + +patternProperties: + "^ttyvs@[0-9]+$": + type: object + description: + Node representing one virtual tty device. This describes, device + number and its configuration. + + properties: + dev-num: + allOf: + - $ref: /schemas/types.yaml#/definitions/uint32 + - minimum: 0 + - maximum: 65534 + maxItems: 1 + description: + Specifies index (N in /dev/ttyvsN) to use for creating device. + Valid value for dev-num is from 0 to 65534. + + rtsmap: + allOf: + - $ref: /schemas/types.yaml#/definitions/uint32-array + items: + - enum: [1, 6, 8, 9] + maxItems: 1 + description: + Specifies to which pin(s) RTS pin of this device should be + connected. Valid values are pin 1 (DCD), pin 6 (DSR), pin 8 + (CTS) and pin 9 (RI). If this is not used then RTS pin is + left unconnected. + + dtrmap: + allOf: + - $ref: /schemas/types.yaml#/definitions/uint32-array + items: + - enum: [1, 6, 8, 9] + maxItems: 1 + description: + Specifies to which pin(s) DTR pin of this device should be + connected. Valid values are pin 1 (DCD), pin 6 (DSR), pin 8 + (CTS) and pin 9 (RI). If this is not used then DTR pin is + left unconnected. + + set-dtr-at-open: + type: boolean + description: + If used, DTR signal will be asserted by driver when device + node is opened by user space application. + + peer-dev: + $ref: /schemas/types.yaml#definitions/phandle + description: + Phandle to the peer DT node if this node is part of a null + modem pair. + +required: + - compatible + - dev-num + +examples: + - | + # Ex1; Null-modem pair only TX/RX connected + # /dev/ttvs0 <---> /dev/ttyvs1 + # TX (3) ----> (2) RX + # RX (2) <---- (3) TX + + ttyvs-card@0 { + compatible = "ttyvs,virtual-uart-card"; + + ttyvs0: ttyvs0 { + dev-num = <0>; + peer-dev = <&ttyvs1>; + }; + + ttyvs1: ttyvs1 { + dev-num = <1>; + peer-dev = <&ttyvs0>; + }; + }; + + - | + # Ex2; Standard loop-back device + # TX (3) -->| + # RX (2) <--| + + ttyvs-card@0 { + compatible = "ttyvs,virtual-uart-card"; + ttyvs2 { + dev-num = <2>; + rtsmap = <8>; + dtrmap = <1 6>; + set-dtr-at-open; + }; + }; + + - | + # Ex3; Standard null-modem pair for hardware flow control + # TX (3) ----> (2) RX + # RX (2) <---- (3) TX + # RTS (7) ----> (8) CTS + # DTR (4) --+-> (1) DCD + # +-> (6) DSR + # CTS (8) <---- (7) RTS + # DCD (1) <-+-- (4) DTR + # DSR (6) <-+ + + ttyvs-card@0 { + compatible = "ttyvs,virtual-uart-card"; + max-num-vs-devs = <128>; + + ttyvs3: ttyvs3 { + dev-num = <3>; + rtsmap = <8>; + dtrmap = <1 6>; + set-dtr-at-open; + peer-dev = <&ttyvs4>; + }; + + ttyvs4: ttyvs4 { + dev-num = <4>; + rtsmap = <8>; + dtrmap = <1 6>; + set-dtr-at-open; + peer-dev = <&ttyvs3>; + }; + }; +... -- 2.7.4
