dts: edtlib/gen_defines: Fix API design re. dtc flags

It's better to allow per-instance EDT configuration than to set a global
variable on the edtlib module. Enable/disable the warning for reg/unit
address mismatches via a flag to EDT.__init__(), instead of via a global
variable. That makes it consistent too.

Another option would be to pass the 'dtc' flags to EDT.__init__(), but
it makes the interface a bit ugly. Maybe if it needs to emulate lots of
other flags later.

Clarify that edtlib itself isn't meant to have any state in the comment
at the top of the module.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>

scripts/dts/edtlib.py

@@ -34,6 +34,11 @@ a .dts file to parse and a list of paths to directories containing bindings.
 # Please do not access private things. Instead, think of what API you need, and
 # add it.
 #
+# This module is not meant to have any global state. It should be possible to
+# create several EDT objects with independent binding paths and flags. If you
+# need to add a configuration parameter or the like, store it in the EDT
+# instance, and initialize it e.g. with a constructor argument.
+#
 # This library is layered on top of dtlib, and is not meant to expose it to
 # clients. This keeps the header generation script simple.
 #
@@ -83,8 +88,6 @@ from dtlib import DT, DTError, to_num, to_nums, TYPE_EMPTY, TYPE_NUMS, \
 from grutils import Graph
 
 
-dtc_flags = ""
-
 #
 # Public classes
 #
@@ -128,7 +131,8 @@ class EDT:
     bindings_dirs:
       The bindings directory paths passed to __init__()
     """
-    def __init__(self, dts, bindings_dirs, warn_file=None):
+    def __init__(self, dts, bindings_dirs, warn_file=None,
+                 warn_reg_unit_address_mismatch=True):
         """
         EDT constructor. This is the top-level entry point to the library.
 
@@ -139,13 +143,20 @@ class EDT:
           List of paths to directories containing bindings, in YAML format.
           These directories are recursively searched for .yaml files.
 
-        warn_file:
+        warn_file (default: None):
           'file' object to write warnings to. If None, sys.stderr is used.
+
+        warn_reg_unit_address_mismatch (default: True):
+          If True, a warning is printed if a node has a 'reg' property where
+          the address of the first entry does not match the unit address of the
+          node
         """
         # Do this indirection with None in case sys.stderr is deliberately
         # overridden
         self._warn_file = sys.stderr if warn_file is None else warn_file
 
+        self._warn_reg_unit_address_mismatch = warn_reg_unit_address_mismatch
+
         self.dts_path = dts
         self.bindings_dirs = bindings_dirs
 
@@ -779,8 +790,6 @@ class Node:
       The flash controller for the node. Only meaningful for nodes representing
       flash partitions.
     """
-    global dtc_flags
-
     @property
     def name(self):
         "See the class docstring"
@@ -802,12 +811,12 @@ class Node:
 
         addr = _translate(addr, self._node)
 
-        # This code is redundant, it checks the same thing as simple_bus_reg in
-        # dtc, we disable it in python if it's suppressed in dtc.
-        if "-Wno-simple_bus_reg" not in dtc_flags:
-            if self.regs and self.regs[0].addr != addr:
-                self.edt._warn("unit-address and first reg (0x{:x}) don't match "
-                               "for {}".format(self.regs[0].addr, self.name))
+        # Matches the simple_bus_reg warning in dtc
+        if self.edt._warn_reg_unit_address_mismatch and \
+           self.regs and self.regs[0].addr != addr:
+            self.edt._warn("unit address and first address in 'reg' "
+                           f"(0x{self.regs[0].addr:x}) don't match for "
+                           f"{self.path}")
 
         return addr
 

scripts/dts/gen_defines.py

@@ -34,7 +34,10 @@ def main():
     args = parse_args()
 
     try:
-        edt = edtlib.EDT(args.dts, args.bindings_dirs)
+        edt = edtlib.EDT(args.dts, args.bindings_dirs,
+                         # Suppress this warning if it's suppressed in dtc
+                         warn_reg_unit_address_mismatch=
+                             "-Wno-simple_bus_reg" not in args.dtc_flags)
     except edtlib.EDTError as e:
         sys.exit(f"devicetree error: {e}")
 
@@ -45,7 +48,6 @@ def main():
     conf_file = open(args.conf_out, "w", encoding="utf-8")
     header_file = open(args.header_out, "w", encoding="utf-8")
     flash_area_num = 0
-    edtlib.dtc_flags = args.dtc_flags
 
     write_top_comment(edt)
 
@@ -90,7 +92,9 @@ def parse_args():
 
     parser = argparse.ArgumentParser()
     parser.add_argument("--dts", required=True, help="DTS file")
-    parser.add_argument("--dtc-flags", help="extra device tree parameters")
+    parser.add_argument("--dtc-flags",
+                        help="'dtc' devicetree compiler flags, some of which "
+                             "might be respected here")
     parser.add_argument("--bindings-dirs", nargs='+', required=True,
                         help="directory with bindings in YAML format, "
                         "we allow multiple")