[RFC PATCH 07/13] dt-bindings: i2c: Add support for 'i2c-bus' subnode

[Jon Hunter <jonathanh@nvidia.com>]

The I2C driver core for boards using device-tree assumes any subnode of
an I2C adapter in the device-tree blob as being a I2C slave device.
Although this makes complete sense, some I2C adapters may have subnodes
which are not I2C slaves but subnodes presenting other features. For
example some Tegra devices have an I2C interface which may share its
pins with other devices and to share these pins subnodes for
representing these pins so they have be shared via the pinctrl framework
are needed.

To allow I2C adapters to have non-I2C specific subnodes in device-tree
that are not parsed by the I2C driver core by adding support for a
'i2c-bus' subnode where I2C slaves can be placed. If the 'i2c-bus'
subnode is present then all I2C slaves must be placed under this subnode.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
---
 Documentation/devicetree/bindings/i2c/i2c.txt | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c.txt b/Documentation/devicetree/bindings/i2c/i2c.txt
index f31b2ad1552b..ed56b08c7e6e 100644
--- a/Documentation/devicetree/bindings/i2c/i2c.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c.txt
@@ -32,6 +32,14 @@ wants to support one of the below features, it should adapt the bindings below.
 - clock-frequency
 	frequency of bus clock in Hz.
 
+- i2c-bus
+	For I2C adapters that have child nodes that are a mixture of both I2C
+	devices and non-I2C devices (such as a pin controller), the 'i2c-bus'
+	subnode can be used for populating I2C devices to prevent the I2C core
+	from attempting to add any non-i2c nodes as I2C devices. If 'i2c-bus'
+	subnode is present then all I2C slaves must be added under this
+	subnode.
+
 - i2c-scl-falling-time-ns
 	Number of nanoseconds the SCL signal takes to fall; t(f) in the I2C
 	specification.
-- 
2.1.4