u-boot/doc/device-tree-bindings/i2c/i2c.txt
Alexander Kochetkov df8dcac8a3 dm: i2c: dts: Add gpios and pinctrl device tree properties
The commit describe usage of gpios and pinctrl device tree
properties in order to enable gpio-based software deblocking.

Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
2018-04-11 11:34:17 +02:00

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U-Boot I2C
----------
U-Boot's I2C model has the concept of an offset within a chip (I2C target
device). The offset can be up to 4 bytes long, but is normally 1 byte,
meaning that offsets from 0 to 255 are supported by the chip. This often
corresponds to register numbers.
Apart from the controller-specific I2C bindings, U-Boot supports a special
property which allows the chip offset length to be selected.
Optional properties:
- u-boot,i2c-offset-len - length of chip offset in bytes. If omitted the
default value of 1 is used.
- gpios = <sda ...>, <scl ...>;
pinctrl-names = "default", "gpio";
pinctrl-0 = <&i2c_xfer>;
pinctrl-1 = <&i2c_gpio>;
Pin description for I2C bus software deblocking.
Example
-------
i2c4: i2c@12ca0000 {
cros-ec@1e {
reg = <0x1e>;
compatible = "google,cros-ec";
i2c-max-frequency = <100000>;
u-boot,i2c-offset-len = <0>;
ec-interrupt = <&gpx1 6 GPIO_ACTIVE_LOW>;
};
};
&i2c1 {
pinctrl-names = "default", "gpio";
pinctrl-0 = <&i2c1_xfer>;
pinctrl-1 = <&i2c1_gpio>;
gpios = <&gpio1 26 GPIO_ACTIVE_LOW>, /* SDA */
<&gpio1 27 GPIO_ACTIVE_LOW>; /* SCL */
};