build: add user_arguments to orfs_design (patch + chameleon usage)

bazel-orfs's orfs_flow already has a user_arguments parameter that
bypasses the variables.yaml validator -- intended for project-specific
env vars read only by user-supplied .tcl/.mk files. orfs_design didn't
forward to it, so config.mk vars like FP_PDN_RAIL_OFFSET (read by
chameleon's pdn.cfg, not by ORFS) were rejected.

Patch 0004 adds a user_arguments arg to orfs_design that names the
config.mk vars to lift out of the validated arguments dict and into
orfs_flow's user_arguments dict. Mirrored in flow/designs/design.bzl.

Used in flow/designs/sky130hd/chameleon to declare FP_PDN_RAIL_OFFSET
and FP_PDN_RAIL_WIDTH as user-only -- chameleon now loads.

Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

Author: oharboe

MODULE.bazel

@@ -50,6 +50,7 @@ git_override(
         "//bazel/bazel-orfs-patches:0001-stages-register-bazel-injected-vars-in-validator.patch",
         "//bazel/bazel-orfs-patches:0002-synth_partition-fix-SYNTH_SKIP_KEEP-truthy-check.patch",
         "//bazel/bazel-orfs-patches:0003-synth_partition-parse-kept_modules-json-without-greedy-sed.patch",
+        "//bazel/bazel-orfs-patches:0004-orfs_design-forward-user_arguments-to-orfs_flow.patch",
     ],
     remote = BAZEL_ORFS_REMOTE,
 )

bazel/bazel-orfs-patches/0004-orfs_design-forward-user_arguments-to-orfs_flow.patch

@@ -0,0 +1,48 @@
+diff --git a/private/orfs_design.bzl b/private/orfs_design.bzl
+index 3a0f3c2..cb607fc 100644
+--- a/private/orfs_design.bzl
++++ b/private/orfs_design.bzl
+@@ -44,7 +44,7 @@ def _convert_sources(sources, pkg):
+             result[var] = converted
+     return result
+ 
+-def orfs_design(name = None, platform = None, design = None, designs = None, mock_openroad = None, mock_yosys = None):  # buildifier: disable=unused-variable
++def orfs_design(name = None, platform = None, design = None, designs = None, mock_openroad = None, mock_yosys = None, user_arguments = []):  # buildifier: disable=unused-variable
+     """Create orfs_flow() targets for a design based on its parsed config.mk.
+ 
+     Call this from a design's BUILD.bazel:
+@@ -66,6 +66,12 @@ def orfs_design(name = None, platform = None, design = None, designs = None, moc
+         mock_yosys: Label for mock-yosys binary. When set, lint flow uses
+             this instead of real Yosys for synthesis.
+             Example: "//mock/yosys/src/bin:yosys".
++        user_arguments: List of variable names from config.mk that are
++            project-specific (read by user-supplied .tcl/.mk, not by
++            ORFS itself, e.g. FP_PDN_RAIL_OFFSET in a custom pdn.cfg).
++            Routed through orfs_flow(user_arguments=...) to bypass the
++            variables.yaml validator instead of being checked as known
++            ORFS arguments.
+     """
+     if designs == None:
+         fail("orfs_design() requires designs argument: pass DESIGNS from @orfs_designs//:designs.bzl")
+@@ -158,6 +164,13 @@ def orfs_design(name = None, platform = None, design = None, designs = None, moc
+     # Real flow — uses Docker image with real OpenROAD/Yosys
+     arguments = dict(config["arguments"])
+ 
++    # Move caller-flagged design-specific knobs out of arguments and into
++    # user_arguments so they bypass the variables.yaml validator.
++    user_args = {}
++    for var in user_arguments:
++        if var in arguments:
++            user_args[var] = arguments.pop(var)
++
+     # Default SYNTH_NUM_PARTITIONS to a static value so that the action graph
+     # is identical across machines and remote cache hits are possible.  Users
+     # who prefer local parallelism over caching can pass NUM_CPUS explicitly.
+@@ -174,6 +187,7 @@ def orfs_design(name = None, platform = None, design = None, designs = None, moc
+         verilog_files = verilog_files,
+         pdk = "//flow:" + platform,
+         arguments = arguments,
++        user_arguments = user_args,
+         sources = sources,
+         macros = macros if macros else [],
+         stage_data = {"synth": extra_data} if extra_data else {},

flow/designs/design.bzl

@@ -14,10 +14,15 @@ _GROUPS = {
     "gds": (["gds", "gds.gz"], ["gds", "gds.gz"]),
 }
 
-def design():
-    """Standard BUILD body for flow/designs/<platform>/<design>/."""
+def design(user_arguments = []):
+    """Standard BUILD body for flow/designs/<platform>/<design>/.
+
+    user_arguments: see orfs_design — list of config.mk var names that
+    are project-specific (read by the design's own .tcl/.mk, not by
+    ORFS) and should bypass the variables.yaml validator.
+    """
     native.exports_files(native.glob(["*"]))
-    orfs_design(designs = DESIGNS)
+    orfs_design(designs = DESIGNS, user_arguments = user_arguments)
 
 def files(group, extra_srcs = None):
     """Public exports_files + named filegroup over conventional extensions."""

flow/designs/sky130hd/chameleon/BUILD.bazel

@@ -1,3 +1,9 @@
 load("//flow/designs:design.bzl", "design")
 
-design()
+# FP_PDN_RAIL_{OFFSET,WIDTH} are read by chameleon's own pdn.cfg, not
+# by ORFS itself — route them through user_arguments so the validator
+# doesn't reject them as unknown ORFS variables.
+design(user_arguments = [
+    "FP_PDN_RAIL_OFFSET",
+    "FP_PDN_RAIL_WIDTH",
+])