[RFC,v2,2/4] dt-bindings: i2c: mux: demux-pinctrl: add bindings

Message ID	1452088285-6427-3-git-send-email-wsa@the-dreams.de (mailing list archive)
State	Superseded
Delegated to:	Geert Uytterhoeven
Headers	show Return-Path: <linux-sh-owner@kernel.org> From: Wolfram Sang <wsa@the-dreams.de> To: linux-i2c@vger.kernel.org Cc: Wolfram Sang <wsa@the-dreams.de>, linux-sh@vger.kernel.org, Magnus Damm <magnus.damm@gmail.com>, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Pantelis Antoniou <pantelis.antoniou@konsulko.com>, Jan Luebbe <jlu@pengutronix.de> Subject: [RFC v2 2/4] dt-bindings: i2c: mux: demux-pinctrl: add bindings Date: Wed, 6 Jan 2016 14:51:23 +0100 Message-Id: <1452088285-6427-3-git-send-email-wsa@the-dreams.de> In-Reply-To: <1452088285-6427-1-git-send-email-wsa@the-dreams.de> References: <1452088285-6427-1-git-send-email-wsa@the-dreams.de> Sender: linux-sh-owner@vger.kernel.org Precedence: bulk

diff --git a/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt new file mode 100644 index 00000000000000..de571be68f4754 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt @@ -0,0 +1,155 @@ +Pinctrl-based I2C Bus DeMux + +This binding describes an I2C bus demultiplexer that uses pin multiplexing to +route the I2C signals, and represents the pin multiplexing configuration using +the pinctrl device tree bindings. This may be used to select one I2C IP core at +runtime which may have a better feature set for a given task than another I2C +IP core on the SoC. The most simple example is to fall back to GPIO bitbanging +if your current runtime configuration hits an errata of the internal IP core. + + +-------------------------------+ + | SoC | + | | +-----+ +-----+ + | +------------+ | | dev | | dev | + | |I2C IP Core1|--\ | +-----+ +-----+ + | +------------+ \-------+ | | | + | |Pinctrl|--|------+--------+ + | +------------+ +-------+ | + | |I2C IP Core2|--/ | + | +------------+ | + | | + +-------------------------------+ + +Required properties: +- compatible: "i2c-demux-pinctrl" +- i2c-parent: List of phandles of I2C masters available for selection. The first + one will be used as default. +- i2c-bus-name: The name of this bus. Also needed as pinctrl-name for the I2C + parents. + +Furthermore, I2C mux properties and child nodes. See mux.txt in this directory. + +Example: + +Here is a snipplet for a bus to be demuxed. It contains various i2c clients for +HDMI, so the bus is named "i2c-hdmi": + + i2chdmi: i2c@8 { + + compatible = "i2c-demux-pinctrl"; + i2c-parent = <&gpioi2c>, <&iic2>, <&i2c2>; + i2c-bus-name = "i2c-hdmi"; + #address-cells = <1>; + #size-cells = <0>; + + ak4643: sound-codec@12 { + compatible = "asahi-kasei,ak4643"; + + #sound-dai-cells = <0>; + reg = <0x12>; + }; + + composite-in@20 { + compatible = "adi,adv7180"; + reg = <0x20>; + remote = <&vin1>; + + port { + adv7180: endpoint { + bus-width = <8>; + remote-endpoint = <&vin1ep0>; + }; + }; + }; + + hdmi@39 { + compatible = "adi,adv7511w"; + reg = <0x39>; + interrupt-parent = <&gpio1>; + interrupts = <15 IRQ_TYPE_LEVEL_LOW>; + + adi,input-depth = <8>; + adi,input-colorspace = "rgb"; + adi,input-clock = "1x"; + adi,input-style = <1>; + adi,input-justification = "evenly"; + + ports { + #address-cells = <1>; + #size-cells = <0>; + + port@0 { + reg = <0>; + adv7511_in: endpoint { + remote-endpoint = <&du_out_lvds0>; + }; + }; + + port@1 { + reg = <1>; + adv7511_out: endpoint { + remote-endpoint = <&hdmi_con>; + }; + }; + }; + }; + }; + +And for clarification, here are the snipplets for the i2c-parents: + + gpioi2c: i2c@9 { + #address-cells = <1>; + #size-cells = <0>; + compatible = "i2c-gpio"; + status = "disabled"; + gpios = <&gpio5 6 GPIO_ACTIVE_HIGH /* sda */ + &gpio5 5 GPIO_ACTIVE_HIGH /* scl */ + >; + i2c-gpio,delay-us = <5>; + }; + +... + +&i2c2 { + pinctrl-0 = <&i2c2_pins>; + pinctrl-names = "i2c-hdmi"; + + clock-frequency = <100000>; +}; + +... + +&iic2 { + pinctrl-0 = <&iic2_pins>; + pinctrl-names = "i2c-hdmi"; + + clock-frequency = <100000>; +}; + +Please note: + +- pinctrl properties for the parent I2C controllers need a pinctrl state + with the same name as i2c-bus-name, not "default"! + +- the i2c masters must have their status "disabled". This driver will + enable them at runtime when needed. + +Changing I2C controllers: + +The created mux-device will have a file "cur_master" in its sysfs-entry. Write +0 there for the first master listed in the "i2c-parent" property, 1 for the +second etc. Reading the file will give you a list with the active master +marked. Example from a Renesas Lager board: + +root@Lager:~# cat /sys/bus/platform/devices/i2c@8/cur_master +* 0 - /i2c@9 + 1 - /i2c@e6520000 + 2 - /i2c@e6530000 + +root@Lager:~# echo 2 > /sys/bus/platform/devices/i2c@8/cur_master + +root@Lager:~# cat /sys/bus/platform/devices/i2c@8/cur_master + 0 - /i2c@9 + 1 - /i2c@e6520000 +* 2 - /i2c@e6530000 +

[RFC,v2,2/4] dt-bindings: i2c: mux: demux-pinctrl: add bindings

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