[PATCH 1/2] dt-bindings: mmc: sdhci-msm: Document bindings for Nord SDCC

[Anjana Hari]

Add Device Tree binding for the Nord SDHCI variant of the Qualcomm
sdhci-msm controller, where platform resources are managed by firmware
through the SCMI power protocol rather than being directly accessible
to Linux.

Unlike existing sdhci-msm variants, this binding does not require
clock, interconnect, reset, or regulator properties. Instead, platform
resource control is abstracted behind two logical power domains:

  - "power": controls the SDCC rail power state. The kernel requests
    power-on and power-off transitions via the runtime PM framework;
    these are forwarded to firmware as SCMI power-state messages.

  - "perf": exposes the supported clock frequencies as OPPs populated
    dynamically by the SCMI perf domain driver at probe time via the
    SCMI performance protocol. The driver selects operating points via
    dev_pm_opp_find_freq_floor() and dev_pm_opp_set_opp().

Both domains must be listed under power-domains with their names
declared in power-domain-names.

The compatible string "qcom,nord-sdhci" selects this variant at probe
time and causes the driver to attach the two power domains via
dev_pm_domain_attach_list() with PD_FLAG_DEV_LINK_ON, ensuring correct
suspend/resume ordering between the SDCC controller and the firmware
power domain devices.

Signed-off-by: Anjana Hari <anjana.hari@xxxxxxxxxxxxxxxx>
---
 .../devicetree/bindings/mmc/qcom,nord-sdhci.yaml   | 89 ++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/qcom,nord-sdhci.yaml b/Documentation/devicetree/bindings/mmc/qcom,nord-sdhci.yaml
new file mode 100644
index 000000000000..c512628617b0
--- /dev/null
+++ b/Documentation/devicetree/bindings/mmc/qcom,nord-sdhci.yaml
@@ -0,0 +1,89 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mmc/qcom,nord-sdhci.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Nord SDHCI Controller
+
+maintainers:
+  - Anjana Hari <anjana.hari@xxxxxxxxxxxxxxxx>
+
+description:
+  SDHCI (SD Host Controller Interface) present on Qualcomm Nord SoC.
+  Clock and power resources are managed by firmware through an SCMI
+  server, so no clock entries are required in the device tree node.
+
+properties:
+  compatible:
+    const: qcom,nord-sdhci
+
+  reg:
+    maxItems: 1
+
+  reg-names:
+    items:
+      - const: hc
+
+  interrupts:
+    maxItems: 2
+
+  interrupt-names:
+    items:
+      - const: hc_irq
+      - const: pwr_irq
+
+  iommus:
+    maxItems: 1
+    description: phandle to the apps SMMU node with SID mask.
+
+  dma-coherent: true
+
+  power-domains:
+    maxItems: 2
+
+  power-domain-names:
+    items:
+      - const: power
+      - const: perf
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - interrupts
+  - interrupt-names
+  - iommus
+  - dma-coherent
+  - power-domains
+  - power-domain-names
+
+allOf:
+  - $ref: sdhci-common.yaml#
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    mmc@b84000 {
+        compatible = "qcom,nord-sdhci";
+        reg = <0x000b84000 0x1000>;
+        reg-names = "hc";
+
+        interrupts = <GIC_SPI 261 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 227 IRQ_TYPE_LEVEL_HIGH>;
+        interrupt-names = "hc_irq", "pwr_irq";
+
+        bus-width = <4>;
+        no-sd;
+        no-mmc;
+        non-removable;
+
+        iommus = <&apps_smmu 0x1580 0x0>;
+        dma-coherent;
+
+        power-domains = <&scmi34_pd 0>, <&scmi34_dvfs 0>;
+        power-domain-names = "power", "perf";
+    };

-- 
2.34.1