dt-bindings: PCI: dwc: Add max-functions EP property

In accordance with [1] the CX_NFUNC IP-core synthesize parameter is
responsible for the number of physical functions to support in the EP
mode. Its upper limit is 32. Let's use it to constrain the number of
PCIe functions the DW PCIe EP DT-nodes can advertise.

[1] Synopsys DesignWare Cores PCI Express Controller Databook - DWC PCIe
Endpoint, Version 5.40a, March 2019, p. 887.

Link: https://lore.kernel.org/r/20221113191301.5526-9-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>

diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml
index d04001248b53d5ec76e50ab264f69e20719abfec..71dd19ae1060cef552165bb5a4a1fa557e3184fe 100644 (file)
--- a/Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml
+++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie-ep.yaml
@@ -41,6 +41,9 @@ properties:
     items:
       enum: [dbi, dbi2, config, atu, addr_space, link, atu_dma, appl]
 
+  max-functions:
+    maximum: 32
+
 required:
   - compatible
   - reg
@@ -61,4 +64,5 @@ examples:
       phy-names = "pcie0", "pcie1", "pcie2", "pcie3";
 
       max-link-speed = <3>;
+      max-functions = /bits/ 8 <4>;
     };