pw_interrupt: Adds a basic interrupt module

Adds a basic interrupt module which for now only gives you the
ability to determine if you're executing in an interrupt
context.

In addition this also adds the first two backends of this module's
context facade (pw_interrupt_cortex_m:context_{armv7m,armv8m}).

Change-Id: If0056997f814b0ac33cb0209fc9b247c2599594e
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/24421
Commit-Queue: Ewout van Bekkum <[email protected]>
Reviewed-by: Keir Mierle <[email protected]>
Reviewed-by: Armando Montanez <[email protected]>

docs/BUILD.gn

@@ -72,6 +72,8 @@ group("module_docs") {
     "$dir_pw_fuzzer:docs",
     "$dir_pw_hdlc_lite:docs",
     "$dir_pw_hex_dump:docs",
+    "$dir_pw_interrupt:docs",
+    "$dir_pw_interrupt_cortex_m:docs",
     "$dir_pw_kvs:docs",
     "$dir_pw_log:docs",
     "$dir_pw_log_basic:docs",

modules.gni

@@ -41,6 +41,8 @@ declare_args() {
   dir_pw_hex_dump = get_path_info("pw_hex_dump", "abspath")
   dir_pw_env_setup = get_path_info("pw_env_setup", "abspath")
   dir_pw_hdlc_lite = get_path_info("pw_hdlc_lite", "abspath")
+  dir_pw_interrupt = get_path_info("pw_interrupt", "abspath")
+  dir_pw_interrupt_cortex_m = get_path_info("pw_interrupt_cortex_m", "abspath")
   dir_pw_kvs = get_path_info("pw_kvs", "abspath")
   dir_pw_log = get_path_info("pw_log", "abspath")
   dir_pw_log_basic = get_path_info("pw_log_basic", "abspath")

pw_interrupt/BUILD

@@ -0,0 +1,54 @@
+# Copyright 2020 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(
+    "//pw_build:pigweed.bzl",
+    "pw_cc_library",
+)
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])  # Apache License 2.0
+
+# TODO(pwbug/101): Need to add support for facades/backends to Bazel.
+PW_INTERRUPT_CONTEXT_BACKEND = "//pw_interrupt_context_cortex_m:context_armv7m"
+
+pw_cc_library(
+    name = "context_facade",
+    hdrs = [
+        "public/pw_interrupt/context.h",
+    ],
+    includes = ["public"],
+    srcs = [
+        "context.cc"
+    ],
+    deps = [
+        PW_INTERRUPT_CONTEXT_BACKEND + "_headers",
+    ],
+)
+
+pw_cc_library(
+    name = "context",
+    deps = [
+        ":context_facade",
+        PW_INTERRUPT_CONTEXT_BACKEND + "_headers",
+    ],
+)
+
+pw_cc_library(
+    name = "context_backend",
+    deps = [
+       PW_INTERRUPT_CONTEXT_BACKEND,
+    ],
+)

pw_interrupt/BUILD.gn

@@ -0,0 +1,39 @@
+# Copyright 2020 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("$dir_pw_build/facade.gni")
+import("$dir_pw_docgen/docs.gni")
+import("$dir_pw_unit_test/test.gni")
+
+declare_args() {
+  # Backend for the pw_interrupt module.
+  pw_interrupt_CONTEXT_BACKEND = ""
+}
+
+config("public_include_path") {
+  include_dirs = [ "public" ]
+  visibility = [ ":*" ]
+}
+
+pw_facade("context") {
+  backend = pw_interrupt_CONTEXT_BACKEND
+  public_configs = [ ":public_include_path" ]
+  public = [ "public/pw_interrupt/context.h" ]
+}
+
+pw_doc_group("docs") {
+  sources = [ "docs.rst" ]
+}

pw_interrupt/docs.rst

@@ -0,0 +1,12 @@
+.. _module-pw_interrupt:
+
+------------
+pw_interrupt
+------------
+Pigweed's interrupt module provides a consistent interface for to determine
+whether one is currently executing in an interrupt context (IRQ or NMI) or not.
+
+.. c:function:: bool InInterruptContext()
+  Returns true if currently executing within an interrupt service routine
+  handling an IRQ or NMI.:w!
+

pw_interrupt/public/pw_interrupt/context.h

@@ -0,0 +1,24 @@
+// Copyright 2020 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 "pw_interrupt_backend/context_backend.h"
+
+namespace pw::interrupt {
+
+// Returns true if currently executing within an interrupt service routine
+// handling an IRQ or NMI.
+bool InInterruptContext();
+
+}  // namespace pw::interrupt

pw_interrupt_cortex_m/BUILD

@@ -0,0 +1,66 @@
+# Copyright 2020 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(
+    "//pw_build:pigweed.bzl",
+    "pw_cc_library",
+)
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])  # Apache License 2.0
+
+pw_cc_library(
+    name = "context_armv7m_headers",
+    hdrs = [
+        "public/pw_interrupt_cortex_m/context.h",
+        "public_overrides/pw_interrupt_backend/context_backend.h",
+    ],
+    copts = [ "-DPW_INTERRUPT_CORTEX_M_ARMV7M=1" ],
+    includes = [
+        "public",
+        "public_overrides",
+    ],
+)
+
+pw_cc_library(
+    name = "context_armv7m",
+    copts = [ "-DPW_INTERRUPT_CORTEX_M_ARMV7M=1" ],
+    deps = [
+        ":context_armv7m_headers",
+        "//pw_interrupt:context_facade",
+    ],
+)
+
+pw_cc_library(
+    name = "context_armv8m_headers",
+    hdrs = [
+        "public/pw_interrupt_cortex_m/context.h",
+        "public_overrides/pw_interrupt_backend/context_backend.h",
+    ],
+    copts = [ "-DPW_INTERRUPT_CORTEX_M_ARMV8M=1" ],
+    includes = [
+        "public",
+        "public_overrides",
+    ],
+)
+
+pw_cc_library(
+    name = "context_armv8m",
+    copts = [ "-DPW_INTERRUPT_CORTEX_M_ARMV8M=1" ],
+    deps = [
+        ":context_armv8m_headers",
+        "//pw_interrupt:context_facade",
+    ],
+)

pw_interrupt_cortex_m/BUILD.gn

@@ -0,0 +1,64 @@
+# Copyright 2020 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")
+
+config("public_include_path") {
+  include_dirs = [ "public" ]
+  visibility = [ ":*" ]
+}
+
+config("backend_config") {
+  include_dirs = [ "public_overrides" ]
+  visibility = [ ":*" ]
+}
+
+config("armv7m") {
+  defines = [ "PW_INTERRUPT_CORTEX_M_ARMV7M=1" ]
+}
+
+config("armv8m") {
+  defines = [ "PW_INTERRUPT_CORTEX_M_ARMV8M=1" ]
+}
+
+_context_common = {
+  public_deps = [ "$dir_pw_interrupt:context.facade" ]
+  public_configs = [
+    ":public_include_path",
+    ":backend_config",
+  ]
+  public = [
+    "public/pw_interrupt_cortex_m/context.h",
+    "public_overrides/pw_interrupt_backend/context_backend.h",
+  ]
+}
+
+# This targets provides the ARMv7-M backend for pw_interrupt's context facade.
+pw_source_set("context_armv7m") {
+  forward_variables_from(_context_common, "*")
+  public_configs += [ ":armv7m" ]
+}
+
+# This targets provides the ARMv8-M backend for pw_interrupt's context facade.
+pw_source_set("context_armv8m") {
+  forward_variables_from(_context_common, "*")
+  public_configs += [ ":armv8m" ]
+}
+
+pw_doc_group("docs") {
+  sources = [ "docs.rst" ]
+}

pw_interrupt_cortex_m/docs.rst

@@ -0,0 +1,7 @@
+.. _module-pw_interrupt_cortex_m:
+
+---------------------
+pw_interrupt_cortex_m
+---------------------
+Pigweed's interrupt Cortex-M module provides a set of architecture specific
+backends for ``pw_interrupt``.

pw_interrupt_cortex_m/public/pw_interrupt_cortex_m/context.h

@@ -0,0 +1,34 @@
+// Copyright 2020 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
+
+namespace pw::interrupt {
+
+#include <cstdint>
+
+#if defined(PW_INTERRUPT_CORTEX_M_ARMV7M) || \
+    defined(PW_INTERRUPT_CORTEX_M_ARMV8M)
+inline bool InInterruptContext() {
+  // ARMv7M Reference manual section B1.4.2 describes how the Interrupt
+  // Program Status Register (IPSR) is zero if there is no exception (interrupt)
+  // being processed.
+  uint32_t ipsr;
+  asm volatile("MRS %0, ipsr" : "=r"(ipsr));
+  return ipsr != 0;
+}
+#else
+#error "Please select an architecture specific backend."
+#endif
+
+}  // namespace pw::interrupt

pw_interrupt_cortex_m/public_overrides/pw_interrupt_backend/context_backend.h

@@ -0,0 +1,19 @@
+// Copyright 2020 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_m/context.h"