mirror of
https://github.com/torvalds/linux.git
synced 2024-12-26 12:52:30 +00:00
ae58d1e406
This is useful for SoCs whose I2C module's signals can be routed to
different sets of pins at run-time, using the pinctrl API.
+-----+ +-----+
| dev | | dev |
+------------------------+ +-----+ +-----+
| SoC | | |
| /----|------+--------+
| +---+ +------+ | child bus A, on first set of pins
| |I2C|---|Pinmux| |
| +---+ +------+ | child bus B, on second set of pins
| \----|------+--------+--------+
| | | | |
+------------------------+ +-----+ +-----+ +-----+
| dev | | dev | | dev |
+-----+ +-----+ +-----+
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
94 lines
2.8 KiB
Plaintext
94 lines
2.8 KiB
Plaintext
Pinctrl-based I2C Bus Mux
|
|
|
|
This binding describes an I2C bus multiplexer that uses pin multiplexing to
|
|
route the I2C signals, and represents the pin multiplexing configuration
|
|
using the pinctrl device tree bindings.
|
|
|
|
+-----+ +-----+
|
|
| dev | | dev |
|
|
+------------------------+ +-----+ +-----+
|
|
| SoC | | |
|
|
| /----|------+--------+
|
|
| +---+ +------+ | child bus A, on first set of pins
|
|
| |I2C|---|Pinmux| |
|
|
| +---+ +------+ | child bus B, on second set of pins
|
|
| \----|------+--------+--------+
|
|
| | | | |
|
|
+------------------------+ +-----+ +-----+ +-----+
|
|
| dev | | dev | | dev |
|
|
+-----+ +-----+ +-----+
|
|
|
|
Required properties:
|
|
- compatible: i2c-mux-pinctrl
|
|
- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
|
|
port is connected to.
|
|
|
|
Also required are:
|
|
|
|
* Standard pinctrl properties that specify the pin mux state for each child
|
|
bus. See ../pinctrl/pinctrl-bindings.txt.
|
|
|
|
* Standard I2C mux properties. See mux.txt in this directory.
|
|
|
|
* I2C child bus nodes. See mux.txt in this directory.
|
|
|
|
For each named state defined in the pinctrl-names property, an I2C child bus
|
|
will be created. I2C child bus numbers are assigned based on the index into
|
|
the pinctrl-names property.
|
|
|
|
The only exception is that no bus will be created for a state named "idle". If
|
|
such a state is defined, it must be the last entry in pinctrl-names. For
|
|
example:
|
|
|
|
pinctrl-names = "ddc", "pta", "idle" -> ddc = bus 0, pta = bus 1
|
|
pinctrl-names = "ddc", "idle", "pta" -> Invalid ("idle" not last)
|
|
pinctrl-names = "idle", "ddc", "pta" -> Invalid ("idle" not last)
|
|
|
|
Whenever an access is made to a device on a child bus, the relevant pinctrl
|
|
state will be programmed into hardware.
|
|
|
|
If an idle state is defined, whenever an access is not being made to a device
|
|
on a child bus, the idle pinctrl state will be programmed into hardware.
|
|
|
|
If an idle state is not defined, the most recently used pinctrl state will be
|
|
left programmed into hardware whenever no access is being made of a device on
|
|
a child bus.
|
|
|
|
Example:
|
|
|
|
i2cmux {
|
|
compatible = "i2c-mux-pinctrl";
|
|
#address-cells = <1>;
|
|
#size-cells = <0>;
|
|
|
|
i2c-parent = <&i2c1>;
|
|
|
|
pinctrl-names = "ddc", "pta", "idle";
|
|
pinctrl-0 = <&state_i2cmux_ddc>;
|
|
pinctrl-1 = <&state_i2cmux_pta>;
|
|
pinctrl-2 = <&state_i2cmux_idle>;
|
|
|
|
i2c@0 {
|
|
reg = <0>;
|
|
#address-cells = <1>;
|
|
#size-cells = <0>;
|
|
|
|
eeprom {
|
|
compatible = "eeprom";
|
|
reg = <0x50>;
|
|
};
|
|
};
|
|
|
|
i2c@1 {
|
|
reg = <1>;
|
|
#address-cells = <1>;
|
|
#size-cells = <0>;
|
|
|
|
eeprom {
|
|
compatible = "eeprom";
|
|
reg = <0x50>;
|
|
};
|
|
};
|
|
};
|
|
|