[PATCH v3 1/7] dt-bindings: connector: add GE SUNH hotplug addon connector

Luca Ceresoli
2024-08-09T15:35:47Z

Add bindings for the GE SUNH add-on connector. This is a physical,
hot-pluggable connector that allows to attach and detach at runtime an
add-on adding peripherals on non-discoverable busses.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

---

Changed in v3:
- change the layout to only add subnodes, not properties
- add the 'nobus-devices' node description to hold devices not on any bus
- add 'i2c-*' nodes for the I2C busses, using a i2c-parent phandle
- and the 'dsi' node for the DSI bus
- move the entire port@1 node to the overlay (not only the remote-endpoint
property)
- remove the overlay examples (Overlays in examples are not supported)
- add more clarifying descriptions and comments for examples
- some rewording

This patch was added in v2.
---
.../connector/ge,sunh-addon-connector.yaml | 185 +++++++++++++++++++++
MAINTAINERS | 5 +
2 files changed, 190 insertions(+)

diff --git a/Documentation/devicetree/bindings/connector/ge,sunh-addon-connector.yaml b/Documentation/devicetree/bindings/connector/ge,sunh-addon-connector.yaml
new file mode 100644
index 000000000000..2a0b4e0fd089
--- /dev/null
+++ b/Documentation/devicetree/bindings/connector/ge,sunh-addon-connector.yaml
@@ -0,0 +1,185 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/connector/ge,sunh-addon-connector.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: GE SUNH hotplug add-on connector
+
+maintainers:
+ - Luca Ceresoli <luca.ceresoli@bootlin.com>
+
+description:
+ Represent the physical connector present on GE SUNH devices that allows
+ to attach and detach at runtime an add-on adding peripherals on
+ non-discoverable busses. Peripherals on the add-on include I2C sensors
+ and a video bridge controlled via I2C.
+
+ The connector has status GPIOs to notify the connection status to the CPU
+ and a reset GPIO to allow the CPU to reset all the peripherals on the
+ add-on. It also has I2C busses and a 4-lane MIPI DSI bus.
+
+ Different add-on models can be connected, each having different
+ peripherals. For this reason each add-on has a model ID stored in a
+ non-volatile memory, which is accessed in the same way on all add-ons.
+
+ Add-on removal can happen at any moment under user control and without
+ prior notice to the CPU, making all of its components not usable
+ anymore. Later on, the same or a different add-on model can be connected.
+
+properties:
+ compatible:
+ const: ge,sunh-addon-connector
+
+ reset-gpios:
+ description: An output GPIO to reset the peripherals on the add-on.
+ maxItems: 1
+
+ plugged-gpios:
+ description: An input GPIO that is asserted if and only if an add-on is
+ physically connected.
+ maxItems: 1
+
+ powergood-gpios:
+ description: An input GPIO that is asserted if and only if power rails
+ on the add-on are stable.
+ maxItems: 1
+
+ nobus-devices:
+ description:
+ A container for devices not accessible via any data bus. Common use
+ cases include fixed and GPIO regulators, simple video panels and LED
+ or GPIO backlight devices. When not hot-pluggable, nodes such devices
+ are children of the root node.
+
+ This node should not be present in the connector description in the
+ base device tree. It should be added by overlays along with a subnode
+ per device.
+
+ type: object
+ additionalProperties: false
+
+ dsi:
+ type: object
+ additionalProperties: false
+
+ properties:
+ ports:
+ $ref: /schemas/graph.yaml#/properties/ports
+
+ description:
+ OF graph bindings modeling the MIPI DSI bus across the connector. The
+ connector splits the video pipeline in a fixed part and a removable
+ part.
+
+ The fixed part of the video pipeline includes all components up to
+ the display controller and 0 or more bridges. The removable part
+ includes any bridges and any other components up to the panel.
+
+ properties:
+ port@0:
+ $ref: /schemas/graph.yaml#/properties/port
+ description:
+ The last point of the non-removable part of the MIPI DSI bus
+ line. The remote-endpoint sub-node must point to the last
+ non-removable video component of the video pipeline.
+
+ port@1:
+ $ref: /schemas/graph.yaml#/properties/port
+ description:
+ The first point of the removable part of the MIPI DSI bus
+ line. The remote-endpoint sub-node must point to the first
+ video pipeline component on the add-on. As it describes the
+ hot-pluggable hardware, the endpoint node cannot be filled
+ until an add-on is detected, so this node needs to be added
+ by a device tree overlay at runtime.
+
+ required:
+ - port@0
+ # port@1 is added by the overlay for any add-on using the DSI lines
+
+ required:
+ - ports
+
+patternProperties:
+ '^i2c-(dbat|gp|btp)$':
+ description:
+ An I2C bus that goes through the connector. The adapter (and possibly
+ some clients) are on the fixed side. Add-ons that have any clients on
+ this bus have to be added by the add-on overlay, inside this node.
+
+ $ref: /schemas/i2c/i2c-controller.yaml#
+ unevaluatedProperties: false
+ type: object
+
+ properties:
+ i2c-parent:
+ $ref: /schemas/types.yaml#/definitions/phandle
+ description:
+ Phandle pointing to the I2C bus controller on the fixed side that
+ drives this bus
+
+required:
+ - compatible
+ - i2c-dbat
+ - i2c-gp
+ - i2c-btp
+ - dsi
+
+unevaluatedProperties: false
+
+examples:
+ # This is the description of the connector as it should appear in the
+ # main DTS describing the "main" board up to the connector. This is
+ # supposed to be used together with the overlays in the two following
+ # examples. The addon_connector and hotplug_conn_dsi_out labels are
+ # referenced by the overlays in those examples.
+ - |
+ / {
+ #include <dt-bindings/gpio/gpio.h>
+
+ addon_connector: addon-connector {
+ compatible = "ge,sunh-addon-connector";
+ reset-gpios = <&gpio1 1 GPIO_ACTIVE_LOW>;
+ plugged-gpios = <&gpio1 2 GPIO_ACTIVE_LOW>;
+ powergood-gpios = <&gpio1 3 GPIO_ACTIVE_HIGH>;
+
+ i2c-dbat {
+ i2c-parent = <&i2c5_ch2>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ // device subnodes to be added by overlays
+ };
+
+ i2c-gp {
+ i2c-parent = <&i2c4>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ // device subnodes to be added by overlays
+ };
+
+ i2c-btp {
+ i2c-parent = <&i2c3>;
+ #address-cells = <1>;
+ #size-cells = <0>;
+ // device subnodes to be added by overlays
+ };
+
+ dsi {
+ ports {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ port@0 {
+ reg = <0>;
+
+ endpoint {
+ remote-endpoint = <&previous_bridge_out>;
+ };
+ };
+
+ // port@1 to be added by overlay
+ };
+ };
+ };
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index 42decde38320..9e902db825d7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10254,6 +10254,11 @@ S: Maintained
F: Documentation/devicetree/bindings/iio/pressure/honeywell,mprls0025pa.yaml
F: drivers/iio/pressure/mprls0025pa*

+HOTPLUG CONNECTOR FOR GE SUNH ADDONS
+M: Luca Ceresoli <luca.ceresoli@bootlin.com>
+S: Maintained
+F: Documentation/devicetree/bindings/connector/ge,sunh-addon-connector.yaml
+
HP BIOSCFG DRIVER
M: Jorge Lopez <jorge.lopez2@hp.com>
L: platform-driver-x86@vger.kernel.org

--
2.34.1