[PATCH v8 1/2] dt-bindings: PCI: xilinx-versal-cpm: Add PERST# and reset support

[Sai Krishna Musham <sai.krishna.musham@amd.com>]

Add the optional 'resets' property to manage the PCIe IP reset, and the
'reset-gpios' property on the Root Port child node for GPIO-based control
of the PCIe RP PERST# signal (assert/deassert). Both are optional to keep
backward compatibility with existing device trees.

Update the examples to show the reset controller and PERST# GPIO wiring.

Signed-off-by: Sai Krishna Musham <sai.krishna.musham@amd.com>
---
Changes in v8:
- Add resets property.
- Move reset-gpios property to child node and update the example.

v1: https://lore.kernel.org/all/20250224063046.1438006-2-sai.krishna.musham@amd.com/
v2: https://lore.kernel.org/all/20250226124358.88227-2-sai.krishna.musham@amd.com/
v3: https://lore.kernel.org/all/20250227042454.907182-2-sai.krishna.musham@amd.com/
v4: https://lore.kernel.org/all/20250318092648.2298280-2-sai.krishna.musham@amd.com/
v5: https://lore.kernel.org/all/20250321114211.2185782-2-sai.krishna.musham@amd.com/
v6: https://lore.kernel.org/all/20250326022811.3090688-2-sai.krishna.musham@amd.com/
v7: https://lore.kernel.org/all/20250414032304.862779-2-sai.krishna.musham@amd.com/
---
 .../bindings/pci/xilinx-versal-cpm.yaml       | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml b/Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml
index 9823456addea..a28a88dc8e88 100644
--- a/Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml
+++ b/Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml
@@ -41,6 +41,10 @@ properties:
     description:
       Maps a Requester ID to an MSI controller and associated MSI sideband data.
 
+  resets:
+    description: Reset for the PCIe controller.
+    maxItems: 1
+
   ranges:
     maxItems: 2
 
@@ -61,6 +65,17 @@ properties:
 
       interrupt-controller: true
 
+patternProperties:
+  '^pcie@[0-2],0$':
+    type: object
+    $ref: /schemas/pci/pci-pci-bridge.yaml#
+
+    properties:
+      reg:
+        maxItems: 1
+
+    unevaluatedProperties: false
+
 required:
   - reg
   - reg-names
@@ -76,6 +91,9 @@ unevaluatedProperties: false
 
 examples:
   - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/reset/xlnx-versal-resets.h>
+
     versal {
         #address-cells = <2>;
         #size-cells = <2>;
@@ -99,6 +117,16 @@ examples:
             reg = <0x0 0xfca10000 0x0 0x1000>,
                   <0x6 0x00000000 0x0 0x10000000>;
             reg-names = "cpm_slcr", "cfg";
+            resets = <&versal_reset VERSAL_RST_PCIE_CORE0>;
+
+            pcie@0,0 {
+                device_type = "pci";
+                reg = <0x0 0x0 0x0 0x0 0x0>;
+                reset-gpios = <&gpio1 38 GPIO_ACTIVE_LOW>;
+                #address-cells = <3>;
+                #size-cells = <2>;
+                ranges;
+            };
             pcie_intc_0: interrupt-controller {
                     #address-cells = <0>;
                     #interrupt-cells = <1>;
@@ -127,6 +155,16 @@ examples:
                   <0x06 0x00000000 0x00 0x1000000>,
                   <0x00 0xfce20000 0x00 0x1000000>;
             reg-names = "cpm_slcr", "cfg", "cpm_csr";
+            resets = <&versal_reset VERSAL_RST_PCIE_CORE0>;
+
+            pcie@0,0 {
+                device_type = "pci";
+                reg = <0x0 0x0 0x0 0x0 0x0>;
+                reset-gpios = <&gpio1 38 GPIO_ACTIVE_LOW>;
+                #address-cells = <3>;
+                #size-cells = <2>;
+                ranges;
+            };
 
             pcie_intc_1: interrupt-controller {
                 #address-cells = <0>;
-- 
2.44.4