linux-kernel - [PATCH 1/7] dt-bindings: i2c: add support for 'i2c-mux' subnode

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Message-ID: <1469609010-23049-2-git-send-email-peda@axentia.se>
Date:	Wed, 27 Jul 2016 10:43:24 +0200
From:	Peter Rosin <peda@...ntia.se>
To:	<linux-kernel@...r.kernel.org>
CC:	Peter Rosin <peda@...ntia.se>, Wolfram Sang <wsa@...-dreams.de>,
	Rob Herring <robh+dt@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Guenter Roeck <linux@...ck-us.net>,
	"David S. Miller" <davem@...emloft.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kalle Valo <kvalo@...eaurora.org>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Emil Velikov <emil.l.velikov@...il.com>,
	<linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
	Crestez Dan Leonard <leonard.crestez@...el.com>
Subject: [PATCH 1/7] dt-bindings: i2c: add support for 'i2c-mux' subnode

Similar to the new optional 'i2c-bus' subnode from Jon Hunter, this
adds an optional 'i2c-mux' subnode, for similar reasons. I.e. it is
bad of the i2c mux core to assume that any subnode of an i2c mux device
is a potential (when the 'reg' property matches) i2c-mux child bus,
given that i2c mux devices might do more than mux i2c traffic.

So, if an 'i2c-mux' subnode is present, dictate that all i2c-mux child
buses exist beneath that subnode.

Signed-off-by: Peter Rosin <peda@...ntia.se>
---
 Documentation/devicetree/bindings/i2c/i2c-mux.txt | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux.txt b/Documentation/devicetree/bindings/i2c/i2c-mux.txt
index af84cce5cd7b..212e6779dc5c 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-mux.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-mux.txt
@@ -2,19 +2,32 @@ Common i2c bus multiplexer/switch properties.
 
 An i2c bus multiplexer/switch will have several child busses that are
 numbered uniquely in a device dependent manner.  The nodes for an i2c bus
-multiplexer/switch will have one child node for each child
-bus.
+multiplexer/switch will have one child node for each child bus.
 
-Required properties:
+Optional properties:
+- #address-cells = <1>;
+   This property is required is the i2c-mux child node does not exist.
+
+- #size-cells = <0>;
+   This property is required is the i2c-mux child node does not exist.
+
+- i2c-mux
+   For i2c multiplexers/switches that have child nodes that are a mixture
+   of both i2c child busses and other child nodes, the 'i2c-mux' subnode
+   can be used for populating the i2c child busses.  If an 'i2c-mux'
+   subnode is present, only subnodes of this will be considered as i2c
+   child busses.
+
+Required properties for the i2c-mux child node:
 - #address-cells = <1>;
 - #size-cells = <0>;
 
-Required properties for child nodes:
+Required properties for i2c child bus nodes:
 - #address-cells = <1>;
 - #size-cells = <0>;
 - reg : The sub-bus number.
 
-Optional properties for child nodes:
+Optional properties for i2c child bus nodes:
 - Other properties specific to the multiplexer/switch hardware.
 - Child nodes conforming to i2c bus binding
 
-- 
2.1.4