linux-kernel - [RFC v1 1/4] dt-bindings: pinctrl: document polarfire soc mssio pin controller

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Message-ID: <20251112-reappear-margarita-83b9d6c04dd6@spud>
Date: Wed, 12 Nov 2025 14:31:12 +0000
From: Conor Dooley <conor@...nel.org>
To: linus.walleij@...aro.org
Cc: conor@...nel.org,
	Conor Dooley <conor.dooley@...rochip.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org,
	devicetree@...r.kernel.org,
	Valentina.FernandezAlanis@...rochip.com
Subject: [RFC v1 1/4] dt-bindings: pinctrl: document polarfire soc mssio pin controller

From: Conor Dooley <conor.dooley@...rochip.com>

On Polarfire SoC, the Bank 2 and Bank 4 IOs connected to the
Multiprocessor Subsystem (MSS) are controlled by IOMUX_CRs 1 through 6,
which determine what function in routed to them, and
MSSIO_BANK#_IO_CFG_CRs, which determine the configuration of each pin.

Document it, including several custom configuration options that stem
from MSS Configurator options (the MSS Configurator is part of the FPGA
tooling for this device). "ibufmd" unfortunately is not a 1:1 mapping
with an MSS Configurator option, unlike clamp-diode or lockdown, and I
do not know the effect of any bits in the field. I have no been able to
find an explanation for these bits in documentation.

Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
---
 .../pinctrl/microchip,mpfs-pinctrl-mssio.yaml | 108 ++++++++++++++++++
 .../microchip,mpfs-mss-top-sysreg.yaml        |   4 +
 2 files changed, 112 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pinctrl/microchip,mpfs-pinctrl-mssio.yaml

diff --git a/Documentation/devicetree/bindings/pinctrl/microchip,mpfs-pinctrl-mssio.yaml b/Documentation/devicetree/bindings/pinctrl/microchip,mpfs-pinctrl-mssio.yaml
new file mode 100644
index 000000000000..32d7a31d669f
--- /dev/null
+++ b/Documentation/devicetree/bindings/pinctrl/microchip,mpfs-pinctrl-mssio.yaml
@@ -0,0 +1,108 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pinctrl/microchip,mpfs-pinctrl-mssio.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip Polarfire SoC MSSIO pinctrl
+
+maintainers:
+  - Conor Dooley <conor.dooley@...rochip.com>
+
+properties:
+  compatible:
+    const: microchip,mpfs-pinctrl-mssio
+
+  reg:
+    maxItems: 1
+
+  pinctrl-use-default: true
+
+patternProperties:
+  '-cfg$':
+    type: object
+    additionalProperties: false
+
+    patternProperties:
+      '-pins$':
+        type: object
+        additionalProperties: false
+
+        allOf:
+          - $ref: pincfg-node.yaml#
+          - $ref: pinmux-node.yaml#
+
+        properties:
+          pins:
+            description: |
+              The list of IOs that properties in the pincfg node apply to.
+
+          function:
+            description:
+              A string containing the name of the function to mux for these
+              pins. The "reserved" function tristates a pin.
+            enum: [ sd, emmc, qspi, spi, usb, uart, i2c, can, mdio, misc
+                    reserved, gpio, fabric-test, tied-low, tied-high, tristate ]
+
+          bias-bus-hold: true
+          bias-disable: true
+          bias-pull-down: true
+          bias-pull-up: true
+          input-schmitt-enable: true
+          low-power-enable: true
+
+          drive-strength:
+            enum: [ 2, 4, 6, 8, 10, 12, 16, 20 ]
+
+          microchip,clamp-diode:
+            $ref: /schemas/types.yaml#/definitions/flag
+            description: |
+              Reflects the "Clamp Diode" setting in the MSS Configurator for
+              this pin.
+
+          microchip,bank-lockdown:
+            $ref: /schemas/types.yaml#/definitions/flag
+            description: |
+              Reflects the "Lock Down Bank{2,4} I/Os" setting in the MSS
+              Configurator for this pin.
+
+          microchip,ibufmd:
+            $ref: /schemas/types.yaml#/definitions/uint32
+            default: 0
+            description: |
+              Reflects the "IBUFMD" bits in the MSS Configurator output files
+              for this pin.
+
+        required:
+          - pins
+          - function
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    pinctrl@204 {
+      compatible = "microchip,mpfs-pinctrl-mssio";
+      reg = <0x204 0x7c>;
+
+      irkd_sd_cfg: irkd-sd-cfg {
+        sd-10ma-pins {
+          pins = <0>, <1>, <2>, <3>, <4>, <5>, <8>, <9>, <10>, <11>, <12>, <13>;
+          function = "sd";
+          bias-pull-up;
+          drive-strength = <10>;
+        };
+
+        sd-8ma-pins {
+          pins = <6>, <7>;
+          function = "sd";
+          bias-pull-up;
+          drive-strength = <8>;
+        };
+      };
+    };
+...
diff --git a/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-mss-top-sysreg.yaml b/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-mss-top-sysreg.yaml
index 39987f722411..44e4a50c3155 100644
--- a/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-mss-top-sysreg.yaml
+++ b/Documentation/devicetree/bindings/soc/microchip/microchip,mpfs-mss-top-sysreg.yaml
@@ -42,6 +42,10 @@ properties:
     type: object
     $ref: /schemas/pinctrl/microchip,mpfs-pinctrl-iomux0.yaml
 
+  pinctrl@204:
+    type: object
+    $ref: /schemas/pinctrl/microchip,mpfs-pinctrl-mssio.yaml
+
 required:
   - compatible
   - reg
-- 
2.51.0