Document device tree schema which describes hot-pluggable via GPIO
i2c bus.
Signed-off-by: Svyatoslav Ryhel <[email protected]>
---
.../bindings/i2c/i2c-hotplug-gpio.yaml | 65 +++++++++++++++++++
1 file changed, 65 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml
diff --git a/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml b/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml
new file mode 100644
index 000000000000..21f2b74ca6c1
--- /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 <[email protected]>
+
+description:
+ Driver for hot-plugged I2C busses, where some devices on a bus
+ are hot-pluggable and their presence is indicated by GPIO line.
+
+properties:
+ compatible:
+ items:
+ - const: i2c-hotplug-gpio
+
+ '#address-cells':
+ const: 1
+
+ '#size-cells':
+ const: 0
+
+ interrupts-extended:
+ minItems: 1
+
+ detect-gpios:
+ maxItems: 1
+
+ i2c-parent:
+ maxItems: 1
+
+required:
+ - compatible
+ - '#address-cells'
+ - '#size-cells'
+ - interrupts-extended
+ - detect-gpios
+ - i2c-parent
+
+unevaluatedProperties: false
+
+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>;
+
+ i2c-parent = <&gen2_i2c>;
+ };
+...
--
2.39.2
On 29/07/2023 18:08, Svyatoslav Ryhel wrote:
> Document device tree schema which describes hot-pluggable via GPIO
> i2c bus.
>
A nit, subject: drop second/last, redundant "binding for". The
"dt-bindings" prefix is already stating that these are bindings.
> Signed-off-by: Svyatoslav Ryhel <[email protected]>
> ---
> .../bindings/i2c/i2c-hotplug-gpio.yaml | 65 +++++++++++++++++++
> 1 file changed, 65 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml b/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml
> new file mode 100644
> index 000000000000..21f2b74ca6c1
> --- /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 <[email protected]>
> +
> +description:
> + Driver for hot-plugged I2C busses, where some devices on a bus
> + are hot-pluggable and their presence is indicated by GPIO line.
> +
> +properties:
> + compatible:
> + items:
Drop items.
> + - const: i2c-hotplug-gpio
> +
> + '#address-cells':
> + const: 1
> +
> + '#size-cells':
> + const: 0
Why do you need these two? You do not have any children.
> +
> + interrupts-extended:
Just interrupts.
> + minItems: 1
maxItems instead
> +
> + detect-gpios:
> + maxItems: 1
> +
> + i2c-parent:
> + maxItems: 1
Where is the type defined? Why this has maxItems? Is it an array?
> +
> +required:
> + - compatible
> + - '#address-cells'
> + - '#size-cells'
> + - interrupts-extended
> + - detect-gpios
> + - i2c-parent
> +
> +unevaluatedProperties: false
Without any $ref, this should be additionalProperties: false.
> +
> +examples:
> + - |
> + /*
> + * Asus Transformers use I2C hotplug for attachable dock keyboard
> + */
> + #include <dt-bindings/gpio/gpio.h>
> + #include <dt-bindings/interrupt-controller/irq.h>
> +
> + i2c-dock {
> + compatible = "i2c-hotplug-gpio";
> +
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + interrupts-extended = <&gpio 164 IRQ_TYPE_EDGE_BOTH>;
> + detect-gpios = <&gpio 164 GPIO_ACTIVE_LOW>;
> +
> + i2c-parent = <&gen2_i2c>;
So do you expect here any children or not?
> + };
> +...
Best regards,
Krzysztof
On Sat, Jul 29, 2023 at 07:08:56PM +0300, Svyatoslav Ryhel wrote:
> Document device tree schema which describes hot-pluggable via GPIO
> i2c bus.
What's that? 'hot-pluggable via GPIO i2c bus' is not coherent.
>
> Signed-off-by: Svyatoslav Ryhel <[email protected]>
> ---
> .../bindings/i2c/i2c-hotplug-gpio.yaml | 65 +++++++++++++++++++
> 1 file changed, 65 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml b/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml
> new file mode 100644
> index 000000000000..21f2b74ca6c1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml
> @@ -0,0 +1,65 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$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 <[email protected]>
> +
> +description:
> + Driver for hot-plugged I2C busses, where some devices on a bus
Bindings are for h/w, not a driver.
> + are hot-pluggable and their presence is indicated by GPIO line.
> +
> +properties:
> + compatible:
> + items:
> + - const: i2c-hotplug-gpio
> +
> + '#address-cells':
> + const: 1
> +
> + '#size-cells':
> + const: 0
What are these for? You don't have any child nodes.
> +
> + interrupts-extended:
> + minItems: 1
> +
> + detect-gpios:
> + maxItems: 1
> +
> + i2c-parent:
> + maxItems: 1
> +
> +required:
> + - compatible
> + - '#address-cells'
> + - '#size-cells'
> + - interrupts-extended
> + - detect-gpios
> + - i2c-parent
> +
> +unevaluatedProperties: false
> +
> +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>;
Looks like the same signal. You should only need one of them. Probably
'detect-gpios' as I guess you need to read the state of the line.
> +
> + i2c-parent = <&gen2_i2c>;
Couldn't you just add 'detect-gpios' to the existing bus node? It's
really part of that bus and there's not a separate bus. That would be a
lot simpler. I suppose you want to instantiate a driver, but that's not
DT's problem.
Rob
On Fri, Aug 11, 2023 at 11:37:52AM -0600, Rob Herring wrote:
> On Sat, Jul 29, 2023 at 07:08:56PM +0300, Svyatoslav Ryhel wrote:
[...]
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-hotplug-gpio.yaml
[...]
> > + - |
> > + /*
> > + * 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>;
[...]
> > + i2c-parent = <&gen2_i2c>;
>
> Couldn't you just add 'detect-gpios' to the existing bus node? It's
> really part of that bus and there's not a separate bus. That would be a
> lot simpler. I suppose you want to instantiate a driver, but that's not
> DT's problem.
Not a driver but a group of devices (possibly discovered dynamically)
behind a passive gate (like e.g. PCA9517A with EN tied to a connector pin).
It's not much different to a I2C gate or mux with a single child bus
(i2c-mux-gpio that has only a single child). For ASUS Transformers with
only the dock plugged-in it could work with a 'detect-gpios' extension
(I'll take a look at how this way would work). I think there were also
different attachments made you could connect instead of the dock.
Best Regards
Micha? Miros?aw
> Not a driver but a group of devices (possibly discovered dynamically)
> behind a passive gate (like e.g. PCA9517A with EN tied to a connector pin).
> It's not much different to a I2C gate or mux with a single child bus
> (i2c-mux-gpio that has only a single child).
I agree. To prevent the the bus from spikes when connecting /
disconnecting something like PCA9517A should be in place. And this one
can be considered a 1:1 mux. Just with the exception that Linux cannot
control the gate, but can only react to changes to the enable pin.
Can't we have a driver for the PCA9517 which gets interrupts when the
enable pin changes and then adds / removes the child i2c adapter?