[PATCH v2 1/4] dt-bindings: connector: Add PCIe M.2 Mechanical Key M connector

[Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>]

Add the devicetree binding for PCIe M.2 Mechanical Key M connector defined
in the PCI Express M.2 Specification, r4.0, sec 5.3. This connector
provides interfaces like PCIe and SATA to attach the Solid State Drives
(SSDs) to the host machine along with additional interfaces like USB, and
SMB for debugging and supplementary features. At any point of time, the
connector can only support either PCIe or SATA as the primary host
interface.

The connector provides a primary power supply of 3.3v, along with an
optional 1.8v VIO supply for the Adapter I/O buffer circuitry operating at
1.8v sideband signaling.

The connector also supplies optional signals in the form of GPIOs for fine
grained power management.

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 .../bindings/connector/pcie-m2-m-connector.yaml    | 122 +++++++++++++++++++++
 1 file changed, 122 insertions(+)

diff --git a/Documentation/devicetree/bindings/connector/pcie-m2-m-connector.yaml b/Documentation/devicetree/bindings/connector/pcie-m2-m-connector.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..be0a3b43e8fd2a2a3b76cad4808ddde79dceaa21
--- /dev/null
+++ b/Documentation/devicetree/bindings/connector/pcie-m2-m-connector.yaml
@@ -0,0 +1,122 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/connector/pcie-m2-m-connector.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: PCIe M.2 Mechanical Key M Connector
+
+maintainers:
+  - Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
+
+description:
+  A PCIe M.2 M connector node represents a physical PCIe M.2 Mechanical Key M
+  connector. The Mechanical Key M connectors are used to connect SSDs to the
+  host system over PCIe/SATA interfaces. These connectors also offer optional
+  interfaces like USB, SMB.
+
+properties:
+  compatible:
+    const: pcie-m2-m-connector
+
+  vpcie3v3-supply:
+    description: A phandle to the regulator for 3.3v supply.
+
+  vio1v8-supply:
+    description: A phandle to the regulator for VIO 1.8v supply.
+
+  ports:
+    $ref: /schemas/graph.yaml#/properties/ports
+    description: OF graph bindings modeling the interfaces exposed on the
+      connector. Since a single connector can have multiple interfaces, every
+      interface has an assigned OF graph port number as described below.
+
+    properties:
+      port@0:
+        $ref: /schemas/graph.yaml#/properties/port
+        description: PCIe/SATA interface
+
+      port@1:
+        $ref: /schemas/graph.yaml#/properties/port
+        description: USB interface
+
+      port@2:
+        $ref: /schemas/graph.yaml#/properties/port
+        description: SMB interface
+
+    required:
+      - port@0
+
+  clocks:
+    description: 32.768 KHz Suspend Clock (SUSCLK) input from the host system to
+      the M.2 card. Refer, PCI Express M.2 Specification r4.0, sec 3.1.12.1 for
+      more details.
+    maxItems: 1
+
+  pedet-gpios:
+    description: GPIO controlled connection to PEDET signal. This signal is used
+      by the host systems to determine the communication protocol that the M.2
+      card uses; SATA signaling (low) or PCIe signaling (high). Refer, PCI
+      Express M.2 Specification r4.0, sec 3.3.4.2 for more details.
+    maxItems: 1
+
+  led1-gpios:
+    description: GPIO controlled connection to LED_1# signal. This signal is
+      used by the M.2 card to indicate the card status via the system mounted
+      LED. Refer, PCI Express M.2 Specification r4.0, sec 3.1.12.2 for more
+      details.
+    maxItems: 1
+
+  viocfg-gpios:
+    description: GPIO controlled connection to IO voltage configuration
+      (VIO_CFG) signal. This signal is used by the M.2 card to indicate to the
+      host system that the card supports an independent IO voltage domain for
+      the sideband signals. Refer, PCI Express M.2 Specification r4.0, sec
+      3.1.15.1 for more details.
+    maxItems: 1
+
+  pwrdis-gpios:
+    description: GPIO controlled connection to Power Disable (PWRDIS) signal.
+      This signal is used by the host system to disable power on the M.2 card.
+      Refer, PCI Express M.2 Specification r4.0, sec 3.3.5.2 for more details.
+    maxItems: 1
+
+  pln-gpios:
+    description: GPIO controlled connection to Power Loss Notification (PLN#)
+      signal. This signal is use to notify the M.2 card by the host system that
+      the power loss event is expected to occur. Refer, PCI Express M.2
+      Specification r4.0, sec 3.2.17.1 for more details.
+    maxItems: 1
+
+  plas3-gpios:
+    description: GPIO controlled connection to Power Loss Acknowledge (PLA_S3#)
+      signal. This signal is used by the M.2 card to notify the host system, the
+      status of the M.2 card's preparation for power loss.
+    maxItems: 1
+
+required:
+  - compatible
+  - vpcie3v3-supply
+
+additionalProperties: false
+
+examples:
+  # PCI M.2 Key M connector for SSDs with PCIe interface
+  - |
+    connector {
+        compatible = "pcie-m2-m-connector";
+        vpcie3v3-supply = <&vreg_nvme>;
+
+        ports {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            port@0 {
+                reg = <0>;
+
+                endpoint {
+                    remote-endpoint = <&pcie6_port0_ep>;
+                };
+            };
+        };
+    };

-- 
2.48.1