chore: Initial multi-core compatibility (#2294)

src/CrossPointSettings.cpp

@@ -6,6 +6,7 @@
 #include <Serialization.h>
 
 #include <cstring>
+#include <mutex>
 #include <string>
 
 #include "I18nKeys.h"
@@ -96,6 +97,7 @@ uint8_t CrossPointSettings::sleepTimeoutEnumToMinutes(const uint8_t legacyValue)
 }
 
 bool CrossPointSettings::saveToFile() const {
+  std::lock_guard<std::mutex> lock(_mutex);
   Storage.mkdir("/.crosspoint");
   return JsonSettingsIO::saveSettings(*this, SETTINGS_FILE_JSON);
 }
@@ -106,7 +108,11 @@ bool CrossPointSettings::loadFromFile() {
     String json = Storage.readFile(SETTINGS_FILE_JSON);
     if (!json.isEmpty()) {
       bool resave = false;
-      bool result = JsonSettingsIO::loadSettings(*this, json.c_str(), &resave);
+      bool result;
+      {
+        std::lock_guard<std::mutex> lock(_mutex);
+        result = JsonSettingsIO::loadSettings(*this, json.c_str(), &resave);
+      }
       if (result && resave) {
         if (saveToFile()) {
           LOG_DBG("CPS", "Resaved settings to update format");
@@ -166,6 +172,7 @@ bool CrossPointSettings::loadFromBinaryFile() {
   if (!Storage.openFileForRead("CPS", SETTINGS_FILE_BIN, inputFile)) {
     return false;
   }
+  std::lock_guard<std::mutex> lock(_mutex);
 
   uint8_t version;
   serialization::readPod(inputFile, version);

src/CrossPointSettings.h

@@ -3,9 +3,12 @@
 
 #include <cstdint>
 #include <iosfwd>
+#include <mutex>
 
 class CrossPointSettings {
  private:
+  mutable std::mutex _mutex;
+
   // Private constructor for singleton
   CrossPointSettings() = default;
 
@@ -17,6 +20,10 @@ class CrossPointSettings {
   CrossPointSettings(const CrossPointSettings&) = delete;
   CrossPointSettings& operator=(const CrossPointSettings&) = delete;
 
+  // Access the settings mutex for protecting multi-field reads/writes from other cores.
+  // Callers must not re-enter SETTINGS methods that lock _mutex while holding it.
+  std::mutex& getMutex() const { return _mutex; }
+
   enum SLEEP_SCREEN_MODE {
     DARK = 0,
     LIGHT = 1,

src/CrossPointState.cpp

@@ -6,6 +6,7 @@
 #include <Serialization.h>
 
 #include <algorithm>
+#include <mutex>
 
 namespace {
 constexpr uint8_t STATE_FILE_VERSION = 4;
@@ -32,6 +33,7 @@ void CrossPointState::pushRecentSleep(uint16_t idx) {
 }
 
 bool CrossPointState::saveToFile() const {
+  std::lock_guard<std::mutex> lock(_mutex);
   Storage.mkdir("/.crosspoint");
   return JsonSettingsIO::saveState(*this, STATE_FILE_JSON);
 }
@@ -41,6 +43,7 @@ bool CrossPointState::loadFromFile() {
   if (Storage.exists(STATE_FILE_JSON)) {
     String json = Storage.readFile(STATE_FILE_JSON);
     if (!json.isEmpty()) {
+      std::lock_guard<std::mutex> lock(_mutex);
       return JsonSettingsIO::loadState(*this, json.c_str());
     }
   }
@@ -67,6 +70,7 @@ bool CrossPointState::loadFromBinaryFile() {
   if (!Storage.openFileForRead("CPS", STATE_FILE_BIN, inputFile)) {
     return false;
   }
+  std::lock_guard<std::mutex> lock(_mutex);
 
   uint8_t version;
   serialization::readPod(inputFile, version);

src/CrossPointState.h

@@ -1,12 +1,18 @@
 #pragma once
 #include <cstdint>
+#include <mutex>
 #include <string>
 
 class CrossPointState {
+  mutable std::mutex _mutex;
+
   // Static instance
   static CrossPointState instance;
 
  public:
+  // Access the state mutex for protecting multi-field reads/writes from other cores.
+  std::mutex& getMutex() const { return _mutex; }
+
   static constexpr uint8_t SLEEP_RECENT_COUNT = 16;
 
   std::string openEpubPath;

src/activities/ActivityManager.cpp

@@ -19,12 +19,15 @@
 #include "settings/SettingsActivity.h"
 #include "util/FullScreenMessageActivity.h"
 
+static portMUX_TYPE activityManagerSpinlock = portMUX_INITIALIZER_UNLOCKED;
+
 void ActivityManager::begin() {
-  xTaskCreate(&renderTaskTrampoline, "ActivityManagerRender",
-              8192,              // Stack size
-              this,              // Parameters
-              1,                 // Priority
-              &renderTaskHandle  // Task handle
+  xTaskCreatePinnedToCore(&renderTaskTrampoline, "ActivityManagerRender",
+                          8192,               // Stack size
+                          this,               // Parameters
+                          1,                  // Priority
+                          &renderTaskHandle,  // Task handle
+                          0                   // Pin to core 0 (PRO_CPU)
   );
   assert(renderTaskHandle != nullptr && "Failed to create render task");
 }
@@ -46,10 +49,10 @@ void ActivityManager::renderTaskLoop() {
     }
     // Notify any task blocked in requestUpdateAndWait() that the render is done.
     TaskHandle_t waiter = nullptr;
-    taskENTER_CRITICAL(nullptr);
+    taskENTER_CRITICAL(&activityManagerSpinlock);
     waiter = waitingTaskHandle;
     waitingTaskHandle = nullptr;
-    taskEXIT_CRITICAL(nullptr);
+    taskEXIT_CRITICAL(&activityManagerSpinlock);
     if (waiter) {
       xTaskNotify(waiter, 1, eIncrement);
     }
@@ -137,8 +140,7 @@ void ActivityManager::loop() {
     }
   }
 
-  if (requestedUpdate) {
-    requestedUpdate = false;
+  if (requestedUpdate.exchange(false)) {
     // Using direct notification to signal the render task to update
     // Increment counter so multiple rapid calls won't be lost
     if (renderTaskHandle) {
@@ -280,7 +282,7 @@ void ActivityManager::requestUpdateAndWait() {
   }
 
   // Atomic section to perform checks
-  taskENTER_CRITICAL(nullptr);
+  taskENTER_CRITICAL(&activityManagerSpinlock);
   auto currTaskHandler = xTaskGetCurrentTaskHandle();
   auto mutexHolder = xSemaphoreGetMutexHolder(renderingMutex);
   bool isRenderTask = (currTaskHandler == renderTaskHandle);
@@ -289,7 +291,7 @@ void ActivityManager::requestUpdateAndWait() {
   if (!alreadyWaiting && !isRenderTask && !holdingRenderLock) {
     waitingTaskHandle = currTaskHandler;
   }
-  taskEXIT_CRITICAL(nullptr);
+  taskEXIT_CRITICAL(&activityManagerSpinlock);
 
   // Render task cannot call requestUpdateAndWait() or it will cause a deadlock
   assert(!isRenderTask && "Render task cannot call requestUpdateAndWait()");

src/activities/ActivityManager.h

@@ -4,6 +4,7 @@
 #include <freertos/semphr.h>
 #include <freertos/task.h>
 
+#include <atomic>
 #include <cassert>
 #include <memory>
 #include <string>
@@ -63,7 +64,7 @@ class ActivityManager {
 
   // Whether to trigger a render after the current loop()
   // This variable must only be set by the main loop, to avoid race conditions
-  bool requestedUpdate = false;
+  std::atomic<bool> requestedUpdate{false};
 
  public:
   explicit ActivityManager(GfxRenderer& renderer, MappedInputManager& mappedInput)