devicetree: fixed-partition: Add sub-partition macros

Adds some macros for usage with sub-partitions

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

Author: nordicjm

include/zephyr/devicetree/fixed-partitions.h

@@ -133,6 +133,82 @@ extern "C" {
 #define DT_FIXED_PARTITION_ADDR(node_id)                                                           \
 	(DT_REG_ADDR(DT_MEM_FROM_FIXED_PARTITION(node_id)) + DT_REG_ADDR(node_id))
 
+/**
+ * @brief Test if fixed-subpartitions compatible node exists
+ *
+ * @param node_id DTS node to test
+ * @return 1 if node exists and is fixed-subpartitions compatible, 0 otherwise.
+ */
+#define DT_FIXED_SUBPARTITION_EXISTS(node_id)		\
+	DT_NODE_HAS_COMPAT(DT_PARENT(node_id), fixed_subpartitions)
+
+/**
+ * @brief Get the node identifier of the flash memory for a subpartition
+ * @param node_id node identifier for a fixed-subpartitions child node
+ * @return the node identifier of the internal memory that contains the
+ * fixed-subpartitions node, or @ref DT_INVALID_NODE if it doesn't exist.
+ */
+#define DT_MEM_FROM_FIXED_SUBPARTITION(node_id)                                                    \
+	COND_CODE_1(DT_NODE_HAS_COMPAT(DT_GPARENT(DT_PARENT(node_id)), soc_nv_flash),              \
+		    (DT_GPARENT(DT_PARENT(node_id))), (DT_INVALID_NODE))
+
+/**
+ * @brief Get the node identifier of the flash controller for a subpartition
+ * @param node_id node identifier for a fixed-subpartitions child node
+ * @return the node identifier of the memory technology device that
+ * contains the fixed-subpartitions node.
+ */
+#define DT_MTD_FROM_FIXED_SUBPARTITION(node_id)                                                    \
+	COND_CODE_1(DT_NODE_EXISTS(DT_MEM_FROM_FIXED_SUBPARTITION(node_id)),                       \
+		    (DT_PARENT(DT_MEM_FROM_FIXED_SUBPARTITION(node_id))), (DT_GPARENT(node_id)))
+
+/**
+ * @brief Get the absolute address of a fixed subpartition
+ *
+ * Example devicetree fragment:
+ *
+ *     &flash_controller {
+ *             flash@1000000 {
+ *                     compatible = "soc-nv-flash";
+ *
+ *                     partitions {
+ *                             compatible = "fixed-partitions";
+ *
+ *                             slot0_partition: partition@10000 {
+ *                                     compatible = "fixed-subpartitions";
+ *                                     reg = <0x00010000 0x40000>;
+ *                                     ranges = <0x0 0x10000 0x40000>;
+ *                                     #address-cells = <1>;
+ *                                     #size-cells = <1>;
+ *
+ *                                     storage_partition: partition@0 {
+ *                                             label = "storage";
+ *                                             reg = <0x00000000 0x40000>;
+ *                                     };
+ *                             };
+ *                     };
+ *             };
+ *     };
+ *
+ * Here, the "storage" partition is seen to belong to flash memory
+ * starting at address 0x1000000. The partition's unit address of
+ * 0x10000 represents an offset inside that flash memory.
+ *
+ * Example usage:
+ *
+ *     DT_FIXED_SUBPARTITION_ADDR(DT_NODELABEL(storage_partition)) // 0x1010000
+ *
+ * This macro can only be used with subpartitions of internal memory
+ * addressable by the CPU. Otherwise, it may produce a compile-time
+ * error, such as: `'__REG_IDX_0_VAL_ADDRESS' undeclared`.
+ *
+ * @param node_id node identifier for a fixed-subpartitions child node
+ * @return the subpartition's offset plus the base address of the flash
+ * node containing it.
+ */
+#define DT_FIXED_SUBPARTITION_ADDR(node_id)                                                        \
+	(DT_REG_ADDR(DT_MEM_FROM_FIXED_SUBPARTITION(node_id)) + DT_REG_ADDR(node_id))
+
 /**
  * @}
  */