From cc40e67f394f5c6d1bfbc3cf49e80921c4f979d1 Mon Sep 17 00:00:00 2001
From: Amaury Pouly <amaury.pouly@lowrisc.org>
Date: Thu, 18 Jan 2024 15:52:40 +0000
Subject: [PATCH] [bazel] Convert `autogen_chip_info_src` to stamping

With this change, `autogen_chip_info_src` will only pass version
information if stamping is enabled on the command-line. This
commit changes the meaning of the `--ot_version_file` flag of
`//util:rom_chip_info`. Previously, it was a path to a file
that contains the git sha. It is now a path to the bazel version
info file which is parsed using the `version_info` library.

Note: with this change, unless stamping is enabled, the ROM will
not contained the git sha in the chip_info anymore.

Signed-off-by: Amaury Pouly <amaury.pouly@lowrisc.org>
---
 rules/autogen.bzl     | 20 ++++++++++----------
 util/rom_chip_info.py | 16 ++++++++++------
 2 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/rules/autogen.bzl b/rules/autogen.bzl
index 66a670f6b55d56..123d44157c116b 100644
--- a/rules/autogen.bzl
+++ b/rules/autogen.bzl
@@ -76,21 +76,25 @@ autogen_hjson_header = rule(
 )
 
 def _chip_info_src(ctx):
+    stamp_args = []
+    stamp_files = []
+    if stamping_enabled(ctx):
+        stamp_files = [ctx.version_file]
+        stamp_args.append("--ot_version_file")
+        stamp_args.append(ctx.version_file.path)
+
     out_source = ctx.actions.declare_file("chip_info.c")
     ctx.actions.run(
         outputs = [
             out_source,
         ],
         inputs = [
-            ctx.file.version,
             ctx.executable._tool,
-        ],
+        ] + stamp_files,
         arguments = [
             "-o",
             out_source.dirname,
-            "--ot_version_file",
-            ctx.file.version.path,
-        ],
+        ] + stamp_args,
         executable = ctx.executable._tool,
     )
 
@@ -101,16 +105,12 @@ def _chip_info_src(ctx):
 autogen_chip_info_src = rule(
     implementation = _chip_info_src,
     attrs = {
-        "version": attr.label(
-            default = "//util:scm_revision_file",
-            allow_single_file = True,
-        ),
         "_tool": attr.label(
             default = "//util:rom_chip_info",
             executable = True,
             cfg = "exec",
         ),
-    },
+    } | stamp_attr(-1, "//rules:stamp_flag"),
 )
 
 def autogen_chip_info(name):
diff --git a/util/rom_chip_info.py b/util/rom_chip_info.py
index c73fec8d339a23..9cbf6b502a9651 100755
--- a/util/rom_chip_info.py
+++ b/util/rom_chip_info.py
@@ -8,6 +8,7 @@
 import logging as log
 from pathlib import Path
 
+import version_file
 
 def generate_chip_info_c_source(scm_revision: int) -> str:
     """Return the contents of a C source file that defines `kChipInfo`.
@@ -43,11 +44,14 @@ def generate_chip_info_c_source(scm_revision: int) -> str:
 """
 
 
-def read_version_file(path: Path) -> int:
-    """Interprets the contents of `path` as a big-endian hex literal."""
+def read_version_file(version_info) -> int:
+    """
+    Search for the BUILD_SCM_REVISION variable and interprets
+    the contents as a big-endian hex literal. Return a constant
+    if the variable is not found.
+    """
 
-    with open(path, "rt") as f:
-        version = f.read().strip()
+    version = version_info.get('BUILD_SCM_REVISION', "8badF00d")
     return int(version, base=16)
 
 
@@ -73,13 +77,13 @@ def main():
                         type=Path,
                         help='Output Directory')
     parser.add_argument('--ot_version_file',
-                        required=True,
                         type=Path,
                         help='Path to a file with the OpenTitan Version')
 
     args = parser.parse_args()
 
-    version = read_version_file(args.ot_version_file)
+    # Extract version stamp from file
+    version = read_version_file(version_file.parse_version_file(args.ot_version_file))
     log.info("Version: %x" % (version, ))
 
     generated_source = generate_chip_info_c_source(version)