On Mon, Jun 19, 2023 at 05:53:24PM +0200, Krzysztof Kozlowski wrote: > On 19/06/2023 17:37, Svyatoslav Ryhel wrote: > > Document device tree schema which describes hot-pluggable via GPIO > > i2c bus. > > > > Signed-off-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx> [...] > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml > > @@ -0,0 +1,65 @@ > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > > +%YAML 1.2 > > +--- > > +$id: http://devicetree.org/schemas/i2c/i2c-hotplug-gpio.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: GPIO detected hot-plugged I2C bus > > + > > +maintainers: > > + - Michał Mirosław <mirq-linux@xxxxxxxxxxxx> > > + > > +description: > > + Driver for hot-plugged I2C busses, where some devices on a bus > > "Driver" so SW? Bindings are for hardware, not for drivers. [...] > > + detect-gpios: > > + maxItems: 1 > > + > > + i2c-parent: > > + maxItems: 1 > > Discussion from v1 stands - this is a software construct, not a real device. [...] > Anyway, don't send v3, before the discussion about the entire concept > finishes. You create a software/virtual device, instead of adding these > properties to bindings for a real hardware. Hi, In this case it's hard for me to tell the difference if this is real or virtual hardware. The Transformers have a connector that's used for USB, charging or for attaching a keyboard (called a dock; it also has a battery and a touchpad). This connector probably (I don't have the means to verify that) has an I2C bus lines and a "detect" line (pulled low on the dock side) among the pins. I guess there is either no additional chip or a transparent bridge/buffer chip, but nothing that could be controlled by software. For DT this setup could be modelled like an I2C gate or 2-port mux with enable joining two I2C busses (one "closer" to the CPU -- parent). > > + > > +examples: > > + - | > > + /* > > + * Asus Transformers use I2C hotplug for attachable dock keyboard > > + */ > > + #include <dt-bindings/gpio/gpio.h> > > + #include <dt-bindings/interrupt-controller/irq.h> > > + > > + i2c-dock { > > + compatible = "i2c-hotplug-gpio"; > > + > > + #address-cells = <1>; > > + #size-cells = <0>; > > + > > + interrupts-extended = <&gpio 164 IRQ_TYPE_EDGE_BOTH>; > > + detect-gpios = <&gpio 164 GPIO_ACTIVE_LOW>; > > I don't think you can have both interrupt and GPIO on the same line. This actually works as expected. There are multiple devices (and drivers) that depend on this, e.g. matrix-keypad and gpio-keys. Best Regards Michał Mirosław
