[PATCH v6 1/2] dt-bindings: PCI: xilinx-cpm: Add reset-gpios for PCIe RP PERST#

[Sai Krishna Musham]

Introduce `reset-gpios` property to enable GPIO-based control of
the PCIe RP PERST# signal, generating assert and deassert signals.

Traditionally, the reset was managed in hardware and enabled during
initialization. With this patch set, the reset will be handled by the
driver. Consequently, the `reset-gpios` property must be explicitly
provided to ensure proper functionality.

Add CPM clock and reset control registers base (`cpm_crx`) to handle
PCIe IP reset along with PCIe RP PERST# to avoid Link Training errors.

Signed-off-by: Sai Krishna Musham <sai.krishna.musham@xxxxxxx>
---
Changes for v6:
- Resolve ABI break.
- Update commit message.

Changes for v5:
- Remove `reset-gpios` property from required as it is already present
  in pci-bus-common.yaml
- Update commit message

Changes for v4:
- Add CPM clock and reset control registers base to handle PCIe IP
  reset.
- Update commit message.

Changes for v3:
- None

Changes for v2:
- Add define from include/dt-bindings/gpio/gpio.h for PERST# polarity
- Update commit message
---
 .../bindings/pci/xilinx-versal-cpm.yaml       | 72 ++++++++++++++-----
 1 file changed, 55 insertions(+), 17 deletions(-)

diff --git a/Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml b/Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml
index d674a24c8ccc..26e9cea41889 100644
--- a/Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml
+++ b/Documentation/devicetree/bindings/pci/xilinx-versal-cpm.yaml
@@ -9,9 +9,6 @@ title: CPM Host Controller device tree for Xilinx Versal SoCs
 maintainers:
   - Bharat Kumar Gogada <bharat.kumar.gogada@xxxxxxx>
 
-allOf:
-  - $ref: /schemas/pci/pci-host-bridge.yaml#
-
 properties:
   compatible:
     enum:
@@ -21,18 +18,12 @@ properties:
       - xlnx,versal-cpm5nc-host
 
   reg:
-    items:
-      - description: CPM system level control and status registers.
-      - description: Configuration space region and bridge registers.
-      - description: CPM5 control and status registers.
-    minItems: 2
+    minItems: 3
+    maxItems: 4
 
   reg-names:
-    items:
-      - const: cpm_slcr
-      - const: cfg
-      - const: cpm_csr
-    minItems: 2
+    minItems: 3
+    maxItems: 4
 
   interrupts:
     maxItems: 1
@@ -72,10 +63,53 @@ required:
   - msi-map
   - interrupt-controller
 
+allOf:
+  - $ref: /schemas/pci/pci-host-bridge.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - xlnx,versal-cpm-host-1.00
+    then:
+      properties:
+        reg:
+          items:
+            - description: CPM system level control and status registers.
+            - description: Configuration space region and bridge registers.
+            - description: CPM clock and reset control registers.
+        reg-names:
+          items:
+            - const: cpm_slcr
+            - const: cfg
+            - const: cpm_crx
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - xlnx,versal-cpm5-host
+              - xlnx,versal-cpm5-host1
+    then:
+      properties:
+        reg:
+          items:
+            - description: CPM system level control and status registers.
+            - description: Configuration space region and bridge registers.
+            - description: CPM5 control and status registers.
+            - description: CPM clock and reset control registers.
+        reg-names:
+          items:
+            - const: cpm_slcr
+            - const: cfg
+            - const: cpm_csr
+            - const: cpm_crx
+
 unevaluatedProperties: false
 
 examples:
   - |
+    #include <dt-bindings/gpio/gpio.h>
 
     versal {
                #address-cells = <2>;
@@ -98,8 +132,10 @@ examples:
                                 <0x43000000 0x80 0x00000000 0x80 0x00000000 0x0 0x80000000>;
                        msi-map = <0x0 &its_gic 0x0 0x10000>;
                        reg = <0x0 0xfca10000 0x0 0x1000>,
-                             <0x6 0x00000000 0x0 0x10000000>;
-                       reg-names = "cpm_slcr", "cfg";
+                             <0x6 0x00000000 0x0 0x10000000>,
+                             <0x0 0xfca00000 0x0 10000>;
+                       reg-names = "cpm_slcr", "cfg", "cpm_crx";
+                       reset-gpios = <&gpio1 38 GPIO_ACTIVE_LOW>;
                        pcie_intc_0: interrupt-controller {
                                #address-cells = <0>;
                                #interrupt-cells = <1>;
@@ -126,8 +162,10 @@ examples:
                        msi-map = <0x0 &its_gic 0x0 0x10000>;
                        reg = <0x00 0xfcdd0000 0x00 0x1000>,
                              <0x06 0x00000000 0x00 0x1000000>,
-                             <0x00 0xfce20000 0x00 0x1000000>;
-                       reg-names = "cpm_slcr", "cfg", "cpm_csr";
+                             <0x00 0xfce20000 0x00 0x1000000>,
+                             <0x00 0xfcdc0000 0x00 0x10000>;
+                       reg-names = "cpm_slcr", "cfg", "cpm_csr", "cpm_crx";
+                       reset-gpios = <&gpio1 38 GPIO_ACTIVE_LOW>;
 
                        pcie_intc_1: interrupt-controller {
                                #address-cells = <0>;
-- 
2.44.1