dt-bindings: mtd: qcom_nandc: document qcom,boot-partitions binding

Document new qcom,boot-partition binding used to apply special
read/write layout to boot partitions.

QCOM apply a special layout where spare data is not protected
by ECC for some special pages (used for boot partition). Add
Documentation on how to declare these special pages.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220616001835.24393-4-ansuelsmth@gmail.com

Documentation/devicetree/bindings/mtd/qcom,nandc.yaml

@@ -102,6 +102,31 @@ allOf:
             - const: rx
             - const: cmd
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - qcom,ipq806x-nand
+
+    then:
+      properties:
+        qcom,boot-partitions:
+          $ref: /schemas/types.yaml#/definitions/uint32-matrix
+          items:
+            items:
+              - description: offset
+              - description: size
+          description:
+            Boot partition use a different layout where the 4 bytes of spare
+            data are not protected by ECC. Use this to declare these special
+            partitions by defining first the offset and then the size.
+
+            It's in the form of <offset1 size1 offset2 size2 offset3 ...>
+            and should be declared in ascending order.
+
+            Refer to the ipq8064 example on how to use this special binding.
+
 required:
   - compatible
   - reg
@@ -135,6 +160,8 @@ examples:
         nand-ecc-strength = <4>;
         nand-bus-width = <8>;
 
+        qcom,boot-partitions = <0x0 0x58a0000>;
+
         partitions {
           compatible = "fixed-partitions";
           #address-cells = <1>;