[bazel,top] Rework top selection mecanism to use string_flag

Signed-off-by: Amaury Pouly <[email protected]>
lowRISC · Nov 25, 2024 · e017fb5 · e017fb5
1 parent 7fdb846
commit e017fb5
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Showing 3 changed files with 52 additions and 19 deletions.
diff --git a/hw/top/BUILD b/hw/top/BUILD
@@ -2,6 +2,7 @@
 # Licensed under the Apache License, Version 2.0, see LICENSE for details.
 # SPDX-License-Identifier: Apache-2.0
 
+load("@bazel_skylib//rules:common_settings.bzl", "string_flag")
 load(
     "//rules:autogen.bzl",
     "opentitan_ip_c_header",
@@ -14,42 +15,56 @@ load("//hw/top:defs.bzl", IPS = "OPENTITAN_ALL_IPS")
 
 package(default_visibility = ["//visibility:public"])
 
-# FIXME rework that properly with platforms
-constraint_setting(
-    name = "top_setting",
-    default_constraint_value = ":top_earlgrey",
-)
+ALL_TOPS = [
+    "earlgrey",
+    "darjeeling",
+]
 
-constraint_value(
-    name = "top_earlgrey",
-    constraint_setting = ":top_setting",
+# Use this flag to select the top.
+string_flag(
+    name = "top",
+    build_setting_default = "earlgrey",
+    values = ALL_TOPS,
 )
 
+# Config settings to test against tops.
+[
+    config_setting(
+        name = "is_{}".format(top),
+        flag_values = {
+            ":top": top,
+        },
+    )
+    for top in ALL_TOPS
+]
+
 alias(
-    name = "top",
+    name = "top_desc",
     actual = select(
         {
-            ":top_earlgrey": "//hw/top_earlgrey",
+            ":is_earlgrey": "//hw/top_earlgrey",
+            ":is_darjeeling": "//hw/top_darjeeling",
         },
-        no_match_error = "no top selected",
+        no_match_error = "unknown top",
     ),
 )
 
 alias(
     name = "top_lib",
     actual = select(
         {
-            ":top_earlgrey": "//hw/top_earlgrey/sw/autogen:top_earlgrey",
+            ":is_earlgrey": "//hw/top_earlgrey/sw/autogen:top_earlgrey",
+            ":is_darjeeling": "//hw/top_darjeeling/sw/autogen:top_darjeeling",
         },
-        no_match_error = "no top selected",
+        no_match_error = "unknown top",
     ),
 )
 
 [
     opentitan_ip_c_header(
         name = "{}_c_regs".format(ip),
         ip = ip,
-        top = ":top",
+        top = ":top_desc",
     )
     for ip in IPS
 ]
@@ -58,22 +73,22 @@ alias(
     opentitan_ip_rust_header(
         name = "{}_rust_regs".format(ip),
         ip = ip,
-        top = ":top",
+        top = ":top_desc",
     )
     for ip in IPS
 ]
 
 opentitan_top_dt_api(
     name = "dt_api",
-    top = ":top",
+    top = ":top_desc",
     deps = [":top_lib"],
 )
 
 [
     opentitan_ip_dt_header(
         name = "dt_{}".format(ip),
         ip = ip,
-        top = ":top",
+        top = ":top_desc",
         deps = [":dt_api"],
     )
     for ip in IPS
@@ -87,6 +102,6 @@ cc_library(
 
 opentitan_top_devicetables(
     name = "devicetables",
-    top = ":top",
+    top = ":top_desc",
     deps = [":dt_headers"],
 )
diff --git a/hw/top/defs.bzl b/hw/top/defs.bzl
@@ -43,3 +43,21 @@ OPENTITAN_ALL_IPS = [
     "uart",
     "usbdev",
 ]
+
+def opentitan_require_top(top_name):
+    """
+    Use this macro in the `target_compatible_with` attribute of
+    a rule to express the requirement that this target should only
+    be considered for a particular top.
+
+    Example:
+    cc_library(
+      name = "bla",
+      ...
+      target_compatible_with = opentitan_require_top("earlgrey"),
+    )
+    """
+    return select({
+        "//hw/top:is_{}".format(top_name): [],
+        "//conditions:default": ["@platforms//:incompatible"],
+    })
diff --git a/sw/device/lib/dif/autogen/BUILD b/sw/device/lib/dif/autogen/BUILD
@@ -11,7 +11,7 @@ package(default_visibility = ["//visibility:public"])
     opentitan_autogen_dif(
         name = ip,
         ip = ip,
-        top = "//hw/top",
+        top = "//hw/top:top_desc",
     )
     for ip in OPENTITAN_ALL_IPS
 ]