On 2016-06-23 17:59, Jon Hunter wrote:
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 Acked-by: Thierry Reding treding@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..71bea55d4c1b 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. If the 'i2c-bus'
- subnode is present, only subnodes of this will be considered as I2C
- slaves. The properties, '#address-cells' and '#size-cells' must be
- defined under this subnode if present.
Hmmm, those #-properties are listed above, under "Required properties", which is no longer 100% true. Maybe rephrase to
slaves. The required properties '#address-cells' and '#size-cells' must be defined under this subnode instead, if this subnode is present.
to make the rules (even) clearer?
Cheers, Peter
- i2c-scl-falling-time-ns Number of nanoseconds the SCL signal takes to fall; t(f) in the I2C specification.