[PATCH v5 02/17] spi: dt-bindings: add spi-phy-pattern-partition property

[Santhosh Kumar K]

Add spi-phy-pattern-partition, a per-device phandle property on the
flash sub-node that allows the DT author to directly reference the
partition holding the SPI PHY tuning pattern. Used to locate the
pattern data during PHY tuning when the device cannot load the
pattern dynamically.

PHY tuning works by reading a known data pattern from the device
repeatedly while sweeping controller delay parameters until the
capture window is stable. For SPI NAND, the driver loads the pattern
into the page cache once using write-to-cache opcodes, then reads it
during the sweep. SPI NOR devices have no equivalent opcode, so the
pattern must be pre-programmed in a dedicated flash partition. One
partition per device is required to keep the procedure unambiguous
when multiple devices share a bus.

Signed-off-by: Santhosh Kumar K <s-k6@xxxxxx>
---
 .../devicetree/bindings/spi/cdns,qspi-nor.yaml  | 17 +++++++++++++++++
 .../bindings/spi/spi-peripheral-props.yaml      |  7 +++++++
 2 files changed, 24 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/cdns,qspi-nor.yaml b/Documentation/devicetree/bindings/spi/cdns,qspi-nor.yaml
index 891f578b5ac4..277dedcd4246 100644
--- a/Documentation/devicetree/bindings/spi/cdns,qspi-nor.yaml
+++ b/Documentation/devicetree/bindings/spi/cdns,qspi-nor.yaml
@@ -209,5 +209,22 @@ examples:
             cdns,tsd2d-ns = <60>;
             cdns,tchsh-ns = <60>;
             cdns,tslch-ns = <60>;
+            spi-phy-pattern-partition = <&phy_pattern>;
+
+            partitions {
+                compatible = "fixed-partitions";
+                #address-cells = <1>;
+                #size-cells = <1>;
+
+                partition@0 {
+                    label = "data";
+                    reg = <0x0 0x3fc0000>;
+                };
+
+                phy_pattern: partition@3fc0000 {
+                    label = "phy-pattern";
+                    reg = <0x3fc0000 0x40000>;
+                };
+            };
         };
     };
diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
index 12211f8c9f7d..d506807c128a 100644
--- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
+++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml
@@ -122,6 +122,13 @@ properties:
     description:
       Delay, in microseconds, after a write transfer.
 
+  spi-phy-pattern-partition:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Phandle to the flash partition holding the pre-programmed SPI PHY tuning
+      pattern. Used when the device cannot load the pattern dynamically during
+      PHY tuning.
+
   stacked-memories:
     description: Several SPI memories can be wired in stacked mode.
       This basically means that either a device features several chip
-- 
2.34.1