pw_interrupt_cortex_a: Add pw_interrupt backend for A-profile processors

Change-Id: I53b570aab788eb0cde8e14c2342a31b9218938e3
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/261396
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Reviewed-by: Dave Roth <davidroth@google.com>
Commit-Queue: Randy Zhang <randyzhg@google.com>

CMakeLists.txt

@@ -109,6 +109,7 @@ add_subdirectory(pw_hex_dump EXCLUDE_FROM_ALL)
 add_subdirectory(pw_hdlc EXCLUDE_FROM_ALL)
 add_subdirectory(pw_i2c EXCLUDE_FROM_ALL)
 add_subdirectory(pw_interrupt EXCLUDE_FROM_ALL)
+add_subdirectory(pw_interrupt_cortex_a EXCLUDE_FROM_ALL)
 add_subdirectory(pw_interrupt_cortex_m EXCLUDE_FROM_ALL)
 add_subdirectory(pw_interrupt_zephyr EXCLUDE_FROM_ALL)
 add_subdirectory(pw_intrusive_ptr EXCLUDE_FROM_ALL)

PIGWEED_MODULES

@@ -80,6 +80,7 @@ pw_i2c_mcuxpresso
 pw_i2c_rp2040
 pw_ide
 pw_interrupt
+pw_interrupt_cortex_a
 pw_interrupt_cortex_m
 pw_interrupt_xtensa
 pw_interrupt_zephyr

docs/module_metadata.json

@@ -483,6 +483,10 @@
   "pw_interrupt": {
     "status": "unstable"
   },
+  "pw_interrupt_cortex_a": {
+    "status": "experimental",
+    "languages": []
+  },
   "pw_interrupt_cortex_m": {
     "status": "unstable"
   },

pw_build/generated_pigweed_modules_lists.gni

@@ -116,6 +116,8 @@ declare_args() {
   dir_pw_i2c_rp2040 = get_path_info("../pw_i2c_rp2040", "abspath")
   dir_pw_ide = get_path_info("../pw_ide", "abspath")
   dir_pw_interrupt = get_path_info("../pw_interrupt", "abspath")
+  dir_pw_interrupt_cortex_a =
+      get_path_info("../pw_interrupt_cortex_a", "abspath")
   dir_pw_interrupt_cortex_m =
       get_path_info("../pw_interrupt_cortex_m", "abspath")
   dir_pw_interrupt_xtensa = get_path_info("../pw_interrupt_xtensa", "abspath")
@@ -315,6 +317,7 @@ declare_args() {
     dir_pw_i2c_rp2040,
     dir_pw_ide,
     dir_pw_interrupt,
+    dir_pw_interrupt_cortex_a,
     dir_pw_interrupt_cortex_m,
     dir_pw_interrupt_xtensa,
     dir_pw_interrupt_zephyr,
@@ -502,6 +505,7 @@ declare_args() {
     "$dir_pw_i2c_rp2040:tests",
     "$dir_pw_ide:tests",
     "$dir_pw_interrupt:tests",
+    "$dir_pw_interrupt_cortex_a:tests",
     "$dir_pw_interrupt_cortex_m:tests",
     "$dir_pw_interrupt_xtensa:tests",
     "$dir_pw_interrupt_zephyr:tests",
@@ -689,6 +693,7 @@ declare_args() {
     "$dir_pw_i2c_rp2040:docs",
     "$dir_pw_ide:docs",
     "$dir_pw_interrupt:docs",
+    "$dir_pw_interrupt_cortex_a:docs",
     "$dir_pw_interrupt_cortex_m:docs",
     "$dir_pw_interrupt_xtensa:docs",
     "$dir_pw_interrupt_zephyr:docs",

pw_interrupt/backends.rst

@@ -8,6 +8,7 @@ Backends
 .. toctree::
    :maxdepth: 1
 
+   Cortex-A <../pw_interrupt_cortex_a/docs>
    Cortex-M <../pw_interrupt_cortex_m/docs>
    Xtensa <../pw_interrupt_xtensa/docs>
    Zephyr <../pw_interrupt_zephyr/docs>

pw_interrupt_cortex_a/BUILD.bazel

@@ -0,0 +1,56 @@
+# Copyright 2025 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+
+load("@rules_python//sphinxdocs:sphinx_docs_library.bzl", "sphinx_docs_library")
+load("//pw_build:compatibility.bzl", "incompatible_with_mcu")
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+constraint_value(
+    name = "backend",
+    constraint_setting = "//pw_interrupt:backend_constraint_setting",
+)
+
+cc_library(
+    name = "context",
+    hdrs = [
+        "public_overrides/pw_interrupt_backend/context_inline.h",
+    ],
+    strip_include_prefix = "public_overrides",
+    target_compatible_with = [":backend"],
+    deps = [
+        ":context_implementation",
+        "//pw_interrupt:context.facade",
+    ],
+)
+
+cc_library(
+    name = "context_implementation",
+    hdrs = [
+        "public/pw_interrupt_cortex_a/context_inline.h",
+    ],
+    strip_include_prefix = "public",
+    visibility = ["//visibility:private"],
+)
+
+sphinx_docs_library(
+    name = "docs",
+    srcs = [
+        "docs.rst",
+    ],
+    prefix = "pw_interrupt_cortex_a/",
+    target_compatible_with = incompatible_with_mcu(),
+)

pw_interrupt_cortex_a/BUILD.gn

@@ -0,0 +1,48 @@
+# Copyright 2025 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+
+import("//build_overrides/pigweed.gni")
+
+import("$dir_pw_build/target_types.gni")
+import("$dir_pw_docgen/docs.gni")
+import("$dir_pw_unit_test/test.gni")
+
+config("public_include_path") {
+  include_dirs = [ "public" ]
+  visibility = [ ":*" ]
+}
+
+config("backend_config") {
+  include_dirs = [ "public_overrides" ]
+  visibility = [ ":*" ]
+}
+
+pw_source_set("context") {
+  public_deps = [ "$dir_pw_interrupt:context.facade" ]
+  public_configs = [
+    ":public_include_path",
+    ":backend_config",
+  ]
+  public = [
+    "public/pw_interrupt_cortex_a/context_inline.h",
+    "public_overrides/pw_interrupt_backend/context_inline.h",
+  ]
+}
+
+pw_doc_group("docs") {
+  sources = [ "docs.rst" ]
+}
+
+pw_test_group("tests") {
+}

pw_interrupt_cortex_a/CMakeLists.txt

@@ -0,0 +1,24 @@
+# Copyright 2025 The Pigweed Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+
+include($ENV{PW_ROOT}/pw_build/pigweed.cmake)
+
+pw_add_library(pw_interrupt_cortex_a.context INTERFACE
+  HEADERS
+    public/pw_interrupt_cortex_a/context_inline.h
+    public_overrides/pw_interrupt_backend/context_inline.h
+  PUBLIC_INCLUDES
+    public
+    public_overrides
+)

pw_interrupt_cortex_a/OWNERS

@@ -0,0 +1,2 @@
+davidroth@google.com
+randyzhg@google.com

pw_interrupt_cortex_a/docs.rst

@@ -0,0 +1,11 @@
+.. _module-pw_interrupt_cortex_a:
+
+---------------------
+pw_interrupt_cortex_a
+---------------------
+.. pigweed-module::
+   :name: pw_interrupt_cortex_a
+
+Pigweed's interrupt Cortex-A module provides a set of architecture specific
+backends for ``pw_interrupt``. Currently this module only supports processors
+that implement the Aarch64 execution state.

pw_interrupt_cortex_a/public/pw_interrupt_cortex_a/context_inline.h

@@ -0,0 +1,42 @@
+// Copyright 2025 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+#pragma once
+
+#include <cstdint>
+
+namespace pw::interrupt {
+
+// This module is not preprocessor protected like pw_interrupt_cortex_m because
+// pw_preprocessor/arch.h does not have macros for Arm A-profile architectures.
+// And it is not straightforward to add them because of the "cortex_m"
+// cc_library. A more ground up refactor of pw_preprocessor is needed. For now,
+// leave the responsibility to the user this backend only for Arm A-profile
+// architectures.
+
+#if ((__ARM_ARCH_PROFILE == 'A') && (__ARM_ARCH == 8) && \
+     (__ARM_ARCH_ISA_A64 == 1))
+inline bool InInterruptContext() {
+  // Arm A-profile Architecture Registers describes if the Interrupt Status
+  // Register (ISR_EL1) is zero if there is no exception (interrupt) being
+  // processed.
+  uint32_t isr_el1;
+  asm volatile("MRS %0, ISR_EL1" : "=r"(isr_el1));
+  return isr_el1 != 0;
+}
+#else
+#error "This module is only intended for 64-bit ARMv8-A processors."
+#endif  // ((__ARM_ARCH_PROFILE == 'A') && (__ARM_ARCH == 8) &&
+        // (__ARM_ARCH_ISA_A64 == 1))
+
+}  // namespace pw::interrupt

pw_interrupt_cortex_a/public_overrides/pw_interrupt_backend/context_inline.h

@@ -0,0 +1,19 @@
+// Copyright 2025 The Pigweed Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may not
+// use this file except in compliance with the License. You may obtain a copy of
+// the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+// License for the specific language governing permissions and limitations under
+// the License.
+
+// This override header includes the main tokenized logging header and defines
+// the PW_LOG macro as the tokenized logging macro.
+#pragma once
+
+#include "pw_interrupt_cortex_a/context_inline.h"