[RFC/RFT v2 09/11] dt-bindings: pci: add lane-map to rockchip PCIe binding

[Frank Wunderlich]

From: Frank Wunderlich <frank-w at public-files.de>

Create new property for (rockchip) PCIe controller binding to
define lane mapping.

Rockchip driver uses this for bifurcation (true/false) based
on lanes should be splitted across controllers or not.

On rk3568 there are 2 PCIe Controllers which share 2 PCIe lanes.

pcie3x1: pcie at fe270000 //lane1 when using 1+1
pcie3x2: pcie at fe280000 //lane0 when using 1+1

This ends up in one Controller (pcie3x1) uses lane-map = <0 1>; and
the other lane-map = <1 0>; (pcie3x2)

This means there are 2 lanes (count of numbers), one (by position)
is mapped to the first controller, the other one is used on the other
controller.

In rockchip PCIe driver the lane-map is simply converted to the
bifurcation bool instead of direct mapping a specific lane to a
controller.

There is not yet any slot mapping below one controller.
But for binding this may be possible like:

lane-map = <1 2 3 3 4 4 4 4>;
            | | | ...
        lane0 | |
          lane1 |
            lane2

on a 8-lane phy.

This can map lane0 to port1 (number used at this position),
lane1 to port2, lanes 2+3 to port 3 and lanes 4,5,6,7 to port 4.

Signed-off-by: Frank Wunderlich <frank-w at public-files.de>
---
v2:
- new patch
---
 Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml b/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
index a992970e8b85..998b20b3a9dc 100644
--- a/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
+++ b/Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml
@@ -52,6 +52,8 @@ properties:
       - const: pclk
       - const: aux
 
+  lane-map: true
+
   msi-map: true
 
   num-lanes: true
@@ -74,8 +76,6 @@ properties:
   reset-names:
     const: pipe
 
-  bifurcation: true
-
   vpcie3v3-supply: true
 
 required:
@@ -115,6 +115,7 @@ examples:
                           "aclk_dbi", "pclk",
                           "aux";
             device_type = "pci";
+            lane-map = <0 1>;
             linux,pci-domain = <2>;
             max-link-speed = <2>;
             msi-map = <0x2000 &its 0x2000 0x1000>;
-- 
2.25.1