devicetree: Add support for fixed-partitions

Add DT_NODE_BY_FIXED_PARTITION_LABEL that given a "label" in any
fixed-partitions map will return the node_id for that partition node.

Add DT_NODE_HAS_FIXED_PARTITION_LABEL that will test if a given
fixed-partitions "label" is valid.

Add DT_FIXED_PARTITION_ID that will return an unique ordinal value for
the partition give a node_id to the partition.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>

doc/guides/dts/macros.bnf

@@ -39,6 +39,8 @@ node-macro =/ %s"DT_N" path-id %s"_IRQ_IDX_" DIGIT
               %s"_VAL_" dt-name [ %s"_EXISTS" ]
 node-macro =/ %s"DT_N" path-id %s"_IRQ_NAME_" dt-name
               %s"_VAL_" dt-name [ %s"_EXISTS" ]
+; For fixed-partitions give a unique ordinal value for each partition */
+node-macro =/ %s"DT_N" path-id %s"_PARTITION_ID" DIGIT
 ; Macros are generated for each of the node's compatibles.
 node-macro =/ %s"DT_N" path-id %s"_COMPAT_MATCHES_" dt-name
 ; The node identifier for the node's parent in the devicetree.
@@ -148,7 +150,8 @@ other-macro =/ %s"DT_CHOSEN_" dt-name
 other-macro =/ %s"DT_COMPAT_" dt-name %s"_BUS_" dt-name
 ;   #define DT_COMPAT_HAS_OKAY_vnd_dev 1
 other-macro =/ %s"DT_COMPAT_HAS_OKAY_" dt-name
-
+; Allows mapping a "label" property to a compatible node
+other-macro =/ %s"DT_COMPAT_" dt-name %s"_LABEL" dt-name
 ; --------------------------------------------------------------------
 ; alternate-id: another way to specify a node besides a path-id
 ;

include/devicetree.h

@@ -1585,6 +1585,7 @@
 #include <devicetree/spi.h>
 #include <devicetree/dma.h>
 #include <devicetree/pwms.h>
+#include <devicetree/fixed-partitions.h>
 #include <devicetree/zephyr.h>
 
 #endif /* DEVICETREE_H */

include/devicetree/fixed-partitions.h

@@ -0,0 +1,57 @@
+/**
+ * @file
+ * @brief Flash Devicetree macro public API header file.
+ */
+
+/*
+ * Copyright (c) 2020, Linaro Ltd.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_DEVICETREE_FIXED_PARTITION_H_
+#define ZEPHYR_INCLUDE_DEVICETREE_FIXED_PARTITION_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup devicetree-fixed-partition Devicetree Fixed Partition API
+ * @ingroup devicetree
+ * @{
+ */
+
+/**
+ * @brief Get fixed partition with "label" property that matches label
+ * @param label lowercase-and-underscores value for "label" property
+ * @return a node identifier for the partition that matches label
+ */
+#define DT_NODE_BY_FIXED_PARTITION_LABEL(label) \
+	DT_CAT(DT_COMPAT_fixed_partitions_LABEL_, label)
+
+/**
+ * @brief Test if a fixed partition with the "label" property exists
+ * @param label lowercase-and-underscores value for "label" property
+ * @return 1 if the label exists across all 'fixed-partitions' nodes
+ *         0 otherwise.
+ */
+#define DT_HAS_FIXED_PARTITION_LABEL(label) \
+	IS_ENABLED(DT_COMPAT_fixed_partitions_LABEL_##label##_EXISTS)
+
+/**
+ * @brief 'fixed-partitions' ID
+ * @param node_id node identifier
+ * @return unique fixed partition id for given partition referenced by node_id
+ */
+#define DT_FIXED_PARTITION_ID(node_id) DT_CAT(node_id, _PARTITION_ID)
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* ZEPHYR_INCLUDE_DEVICETREE_FIXED_PARTITION_H_ */

scripts/dts/gen_defines.py

@@ -29,6 +29,7 @@ import edtlib
 
 def main():
     global header_file
+    global flash_area_num
 
     args = parse_args()
 
@@ -41,6 +42,8 @@ def main():
     except edtlib.EDTError as e:
         sys.exit(f"devicetree error: {e}")
 
+    flash_area_num = 0
+
     # Save merged DTS source, as a debugging aid
     with open(args.dts_out, "w", encoding="utf-8") as f:
         print(edt.dts_source, file=f)
@@ -254,6 +257,8 @@ def write_special_props(node):
     # data cannot otherwise be obtained from write_vanilla_props()
     # results
 
+    global flash_area_num
+
     out_comment("Special property macros:")
 
     # Macros that are special to the devicetree specification
@@ -262,6 +267,10 @@ def write_special_props(node):
     write_compatibles(node)
     write_status(node)
 
+    if node.parent and "fixed-partitions" in node.parent.compats:
+        macro = f"{node.z_path_id}_PARTITION_ID"
+        out_dt_define(macro, flash_area_num)
+        flash_area_num += 1
 
 def write_regs(node):
     # reg property: edtlib knows the right #address-cells and
@@ -586,6 +595,18 @@ def write_global_compat_info(edt):
             " ".join(f"fn({edt.compat2nodes[compat].index(node)})"
                      for node in okay_nodes)
 
+    for compat, nodes in edt.compat2nodes.items():
+        for node in nodes:
+            if compat == "fixed-partitions":
+                for child in node.children.values():
+                    if "label" in child.props:
+                        label = child.props["label"].val
+                        macro = f"COMPAT_{str2ident(compat)}_LABEL_{str2ident(label)}"
+                        val = f"DT_{child.z_path_id}"
+
+                        out_dt_define(macro, val)
+                        out_dt_define(macro + "_EXISTS", 1)
+
     out_comment('Macros for compatibles with status "okay" nodes\n')
     for compat, okay_nodes in edt.compat2okay.items():
         if okay_nodes: