[PATCH v5 06/20] dt-bindings: PCI: dwc: Add max-link-speed common property

[Serge Semin <Sergey.Semin@baikalelectronics.ru>]

In accordance with [1] DW PCIe controllers support up to Gen5 link speed.
Let's add the max-link-speed property upper bound to 5 then. The DT
bindings of the particular devices are expected to setup more strict
constraint on that parameter.

[1] Synopsys DesignWare Cores PCI Express Controller Databook, Version
5.40a, March 2019, p. 27

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Rob Herring <robh@kernel.org>

---

Changelog v3:
- This is a new patch unpinned from the next one:
  https://lore.kernel.org/linux-pci/20220503214638.1895-2-Sergey.Semin@baikalelectronics.ru/
  by the Rob' request. (@Rob)
---
 Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml | 3 +++
 Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml     | 2 ++
 Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml        | 1 +
 3 files changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
index e8d610d63ae2..5fc704138677 100644
--- a/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
+++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
@@ -49,6 +49,9 @@ properties:
       the peripheral devices available on the PCIe bus.
     maxItems: 1
 
+  max-link-speed:
+    maximum: 5
+
   num-lanes:
     description:
       Number of PCIe link lanes to use. Can be omitted if the already brought
diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml
index dcd521aed213..fc3b5d4ac245 100644
--- a/Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml
+++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml
@@ -55,4 +55,6 @@ examples:
 
       phys = <&pcie_phy0>, <&pcie_phy1>, <&pcie_phy2>, <&pcie_phy3>;
       phy-names = "pcie0", "pcie1", "pcie2", "pcie3";
+
+      max-link-speed = <3>;
     };
diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
index d9512f7f7124..e787b9727589 100644
--- a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
+++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
@@ -74,4 +74,5 @@ examples:
       phy-names = "pcie";
 
       num-lanes = <1>;
+      max-link-speed = <3>;
     };
-- 
2.35.1