wrap driver instance ownership + di in a class

src/audio/audio_playback.cpp

@@ -5,6 +5,7 @@
 #include <memory>
 #include <string_view>
 
+#include "driver_cache.hpp"
 #include "freertos/portmacro.h"
 
 #include "audio_decoder.hpp"
@@ -21,19 +22,10 @@
 #include "stream_message.hpp"
 
 namespace audio {
-
+AudioPlayback::AudioPlayback(drivers::DriverCache* drivers)
-auto AudioPlayback::create(drivers::GpioExpander* expander)
-    -> cpp::result<std::unique_ptr<AudioPlayback>, Error> {
-  auto sink_res = I2SAudioOutput::create(expander);
-  if (sink_res.has_error()) {
-    return cpp::fail(ERR_INIT_ELEMENT);
-  }
-  return std::make_unique<AudioPlayback>(std::move(sink_res.value()));
-}
-
-AudioPlayback::AudioPlayback(std::unique_ptr<I2SAudioOutput> output)
     : file_source_(std::make_unique<FatfsAudioInput>()),
-      i2s_output_(std::move(output)) {
+      i2s_output_(std::make_unique<I2SAudioOutput>(drivers->AcquireGpios(),
+                                                   drivers->AcquireDac())) {
   AudioDecoder* codec = new AudioDecoder();
   elements_.emplace_back(codec);
 

src/audio/i2s_audio_output.cpp

@@ -2,6 +2,7 @@
 
 #include <algorithm>
 #include <cstddef>
+#include <memory>
 #include <variant>
 
 #include "esp_err.h"
@@ -18,27 +19,10 @@ static const char* kTag = "I2SOUT";
 
 namespace audio {
 
-auto I2SAudioOutput::create(drivers::GpioExpander* expander)
-    -> cpp::result<std::unique_ptr<I2SAudioOutput>, Error> {
-  // First, we need to perform initial configuration of the DAC chip.
-  auto dac_result = drivers::AudioDac::create(expander);
-  if (dac_result.has_error()) {
-    ESP_LOGE(kTag, "failed to init dac: %d", dac_result.error());
-    return cpp::fail(DAC_CONFIG);
-  }
-  std::unique_ptr<drivers::AudioDac> dac = std::move(dac_result.value());
-
-  // Soft mute immediately, in order to minimise any clicks and pops caused by
-  // the initial output element and pipeline configuration.
-  // dac->WriteVolume(255);
-  dac->WriteVolume(127);  // for testing
-
-  return std::make_unique<I2SAudioOutput>(expander, std::move(dac));
-}
-
 I2SAudioOutput::I2SAudioOutput(drivers::GpioExpander* expander,
-                               std::unique_ptr<drivers::AudioDac> dac)
+                               std::shared_ptr<drivers::AudioDac> dac)
     : expander_(expander), dac_(std::move(dac)), current_config_() {
+  dac->WriteVolume(127);  // for testing
   dac_->SetSource(buffer());
 }
 

src/audio/include/audio_playback.hpp

@@ -6,6 +6,7 @@
 #include <vector>
 
 #include "audio_task.hpp"
+#include "driver_cache.hpp"
 #include "esp_err.h"
 #include "fatfs_audio_input.hpp"
 #include "i2s_audio_output.hpp"
@@ -25,11 +26,7 @@ namespace audio {
  */
 class AudioPlayback {
  public:
-  enum Error { ERR_INIT_ELEMENT, ERR_MEM };
+  explicit AudioPlayback(drivers::DriverCache* drivers);
-  static auto create(drivers::GpioExpander* expander)
-      -> cpp::result<std::unique_ptr<AudioPlayback>, Error>;
-
-  explicit AudioPlayback(std::unique_ptr<I2SAudioOutput> output);
   ~AudioPlayback();
 
   /*

src/audio/include/i2s_audio_output.hpp

@@ -17,12 +17,8 @@ namespace audio {
 
 class I2SAudioOutput : public IAudioSink {
  public:
-  enum Error { DAC_CONFIG, I2S_CONFIG, STREAM_INIT };
-  static auto create(drivers::GpioExpander* expander)
-      -> cpp::result<std::unique_ptr<I2SAudioOutput>, Error>;
-
   I2SAudioOutput(drivers::GpioExpander* expander,
-                 std::unique_ptr<drivers::AudioDac> dac);
+                 std::shared_ptr<drivers::AudioDac> dac);
   ~I2SAudioOutput();
 
   auto Configure(const StreamInfo::Format& format) -> bool override;
@@ -36,7 +32,7 @@ class I2SAudioOutput : public IAudioSink {
   auto SetVolume(uint8_t volume) -> void;
 
   drivers::GpioExpander* expander_;
-  std::unique_ptr<drivers::AudioDac> dac_;
+  std::shared_ptr<drivers::AudioDac> dac_;
 
   std::optional<StreamInfo::Pcm> current_config_;
 };

src/drivers/CMakeLists.txt

@@ -1,6 +1,6 @@
 idf_component_register(
   SRCS "touchwheel.cpp" "dac.cpp" "gpio_expander.cpp" "battery.cpp" "storage.cpp" "i2c.cpp"
-  "spi.cpp" "display.cpp" "display_init.cpp"
+  "spi.cpp" "display.cpp" "display_init.cpp" "driver_cache.cpp"
   INCLUDE_DIRS "include"
   REQUIRES "esp_adc" "fatfs" "result" "lvgl" "span")
 target_compile_options(${COMPONENT_LIB} PRIVATE ${EXTRA_WARNINGS})

src/drivers/dac.cpp

@@ -27,8 +27,7 @@ static const char* kTag = "AUDIODAC";
 static const uint8_t kPcm5122Address = 0x4C;
 static const i2s_port_t kI2SPort = I2S_NUM_0;
 
-auto AudioDac::create(GpioExpander* expander)
+auto AudioDac::create(GpioExpander* expander) -> cpp::result<AudioDac*, Error> {
-    -> cpp::result<std::unique_ptr<AudioDac>, Error> {
   // TODO: tune.
   i2s_chan_handle_t i2s_handle;
   i2s_chan_config_t channel_config =
@@ -111,7 +110,7 @@ auto AudioDac::create(GpioExpander* expander)
     return state == RUN || state == STANDBY;
   });
 
-  return dac;
+  return dac.release();
 }
 
 AudioDac::AudioDac(GpioExpander* gpio, i2s_chan_handle_t i2s_handle)

src/drivers/display.cpp

@@ -63,7 +63,7 @@ extern "C" void FlushDataCallback(lv_disp_drv_t* disp_drv,
 
 auto Display::create(GpioExpander* expander,
                      const displays::InitialisationData& init_data)
-    -> std::unique_ptr<Display> {
+    -> Display* {
   ESP_LOGI(kTag, "Init I/O pins");
   gpio_config_t dr_config{
       .pin_bit_mask = 1ULL << kDisplayDr,
@@ -134,7 +134,7 @@ auto Display::create(GpioExpander* expander,
   ESP_LOGI(kTag, "Registering driver");
   display->display_ = lv_disp_drv_register(&display->driver_);
 
-  return display;
+  return display.release();
 }
 
 Display::Display(GpioExpander* gpio, spi_device_handle_t handle)

src/drivers/include/dac.hpp

@@ -117,8 +117,7 @@ class AudioDac {
     FAILED_TO_INSTALL_I2S,
   };
 
-  static auto create(GpioExpander* expander)
+  static auto create(GpioExpander* expander) -> cpp::result<AudioDac*, Error>;
-      -> cpp::result<std::unique_ptr<AudioDac>, Error>;
 
   AudioDac(GpioExpander* gpio, i2s_chan_handle_t i2s_handle);
   ~AudioDac();

src/drivers/include/display.hpp

@@ -23,8 +23,7 @@ class Display {
    * us back any kind of signal to tell us we're actually using them correctly.
    */
   static auto create(GpioExpander* expander,
-                     const displays::InitialisationData& init_data)
+                     const displays::InitialisationData& init_data) -> Display*;
-      -> std::unique_ptr<Display>;
 
   Display(GpioExpander* gpio, spi_device_handle_t handle);
   ~Display();

src/drivers/include/storage.hpp

@@ -25,14 +25,13 @@ class SdStorage {
     FAILED_TO_MOUNT,
   };
 
-  static auto create(GpioExpander* gpio)
+  static auto create(GpioExpander* gpio) -> cpp::result<SdStorage*, Error>;
-      -> cpp::result<std::shared_ptr<SdStorage>, Error>;
 
   SdStorage(GpioExpander* gpio,
             esp_err_t (*do_transaction)(sdspi_dev_handle_t, sdmmc_command_t*),
             sdspi_dev_handle_t handle_,
-            std::unique_ptr<sdmmc_host_t>& host_,
+            std::unique_ptr<sdmmc_host_t> host_,
-            std::unique_ptr<sdmmc_card_t>& card_,
+            std::unique_ptr<sdmmc_card_t> card_,
             FATFS* fs_);
   ~SdStorage();
 

src/drivers/storage.cpp

@@ -49,8 +49,9 @@ static esp_err_t do_transaction(sdspi_dev_handle_t handle,
 }
 }  // namespace callback
 
-auto SdStorage::create(GpioExpander* gpio)
+auto SdStorage::create(GpioExpander* gpio) -> cpp::result<SdStorage*, Error> {
-    -> cpp::result<std::shared_ptr<SdStorage>, Error> {
+  gpio->set_pin(GpioExpander::SD_CARD_POWER_ENABLE, 0);
+  gpio->set_pin(GpioExpander::SD_MUX_EN_ACTIVE_LOW, 0);
   gpio->set_pin(GpioExpander::SD_MUX_SWITCH, GpioExpander::SD_MUX_ESP);
   gpio->Write();
 
@@ -103,16 +104,16 @@ auto SdStorage::create(GpioExpander* gpio)
     return cpp::fail(Error::FAILED_TO_MOUNT);
   }
 
-  return std::make_unique<SdStorage>(gpio, do_transaction, handle, host, card,
+  return new SdStorage(gpio, do_transaction, handle, std::move(host),
-                                     fs);
+                       std::move(card), fs);
 }
 
 SdStorage::SdStorage(GpioExpander* gpio,
                      esp_err_t (*do_transaction)(sdspi_dev_handle_t,
                                                  sdmmc_command_t*),
                      sdspi_dev_handle_t handle,
-                     std::unique_ptr<sdmmc_host_t>& host,
+                     std::unique_ptr<sdmmc_host_t> host,
-                     std::unique_ptr<sdmmc_card_t>& card,
+                     std::unique_ptr<sdmmc_card_t> card,
                      FATFS* fs)
     : gpio_(gpio),
       do_transaction_(do_transaction),
@@ -136,6 +137,10 @@ SdStorage::~SdStorage() {
   // Uninstall the SPI driver
   sdspi_host_remove_device(this->handle_);
   sdspi_host_deinit();
+
+  gpio_->set_pin(GpioExpander::SD_CARD_POWER_ENABLE, 0);
+  gpio_->set_pin(GpioExpander::SD_MUX_EN_ACTIVE_LOW, 1);
+  gpio_->Write();
 }
 
 auto SdStorage::HandleTransaction(sdspi_dev_handle_t handle,

src/main/main.cpp

@@ -11,6 +11,7 @@
 #include "driver/sdspi_host.h"
 #include "driver/spi_common.h"
 #include "driver/spi_master.h"
+#include "driver_cache.hpp"
 #include "esp_freertos_hooks.h"
 #include "esp_intr_alloc.h"
 #include "esp_log.h"
@@ -39,50 +40,37 @@ extern "C" void app_main(void) {
 
   ESP_ERROR_CHECK(drivers::init_i2c());
   ESP_ERROR_CHECK(drivers::init_spi());
+  std::unique_ptr<drivers::DriverCache> drivers =
+      std::make_unique<drivers::DriverCache>();
 
   ESP_LOGI(TAG, "Init GPIOs");
-  drivers::GpioExpander* expander = new drivers::GpioExpander();
+  drivers::GpioExpander* expander = drivers->AcquireGpios();
 
   ESP_LOGI(TAG, "Enable power rails for development");
-  expander->with([&](auto& gpio) {
+  expander->with(
-    gpio.set_pin(drivers::GpioExpander::SD_MUX_EN_ACTIVE_LOW, 0);
+      [&](auto& gpio) { gpio.set_pin(drivers::GpioExpander::AMP_EN, 1); });
-    gpio.set_pin(drivers::GpioExpander::SD_MUX_SWITCH,
-                 drivers::GpioExpander::SD_MUX_ESP);
-    gpio.set_pin(drivers::GpioExpander::SD_CARD_POWER_ENABLE, 0);
-    gpio.set_pin(drivers::GpioExpander::AMP_EN, 1);
-  });
 
   ESP_LOGI(TAG, "Init battery measurement");
   drivers::Battery* battery = new drivers::Battery();
   ESP_LOGI(TAG, "it's reading %d mV!", (int)battery->Millivolts());
 
   ESP_LOGI(TAG, "Init SD card");
-  auto storage_res = drivers::SdStorage::create(expander);
+  auto storage = drivers->AcquireStorage();
-  std::shared_ptr<drivers::SdStorage> storage;
+  if (!storage) {
-  if (storage_res.has_error()) {
     ESP_LOGE(TAG, "Failed! Do you have an SD card?");
-  } else {
-    storage = std::move(storage_res.value());
   }
 
   ESP_LOGI(TAG, "Init touch wheel");
-  std::unique_ptr<drivers::TouchWheel> touchwheel =
+  std::shared_ptr<drivers::TouchWheel> touchwheel =
-      std::make_unique<drivers::TouchWheel>();
+      drivers->AcquireTouchWheel();
 
   std::atomic<bool> lvgl_quit;
   TaskHandle_t lvgl_task_handle;
-  ui::StartLvgl(expander, &lvgl_quit, &lvgl_task_handle);
+  ui::StartLvgl(drivers.get(), &lvgl_quit, &lvgl_task_handle);
-
+
-  std::unique_ptr<audio::AudioPlayback> playback;
+  ESP_LOGI(TAG, "Init audio pipeline");
-  if (storage) {
+  std::unique_ptr<audio::AudioPlayback> playback =
-    ESP_LOGI(TAG, "Init audio pipeline");
+      std::make_unique<audio::AudioPlayback>(drivers.get());
-    auto playback_res = audio::AudioPlayback::create(expander);
-    if (playback_res.has_error()) {
-      ESP_LOGE(TAG, "Failed! Playback will not work.");
-    } else {
-      playback = std::move(playback_res.value());
-    }
-  }
 
   ESP_LOGI(TAG, "Waiting for background tasks before launching console...");
   vTaskDelay(pdMS_TO_TICKS(1000));

src/ui/include/lvgl_task.hpp

@@ -5,11 +5,12 @@
 
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
-#include "gpio_expander.hpp"
+
+#include "driver_cache.hpp"
 
 namespace ui {
 
-auto StartLvgl(drivers::GpioExpander* gpios,
+auto StartLvgl(drivers::DriverCache* drivers,
                std::atomic<bool>* quit,
                TaskHandle_t* handle) -> bool;
 

src/ui/lvgl_task.cpp

@@ -26,7 +26,7 @@
 #include "widgets/lv_label.h"
 
 #include "display.hpp"
-#include "display_init.hpp"
+#include "driver_cache.hpp"
 #include "gpio_expander.hpp"
 
 namespace ui {
@@ -38,16 +38,14 @@ auto tick_hook(TimerHandle_t xTimer) -> void {
 }
 
 struct LvglArgs {
-  drivers::GpioExpander* gpio_expander;
+  drivers::DriverCache* drivers;
   std::atomic<bool>* quit;
 };
 
 void LvglMain(void* voidArgs) {
-  LvglArgs* args = (LvglArgs*)voidArgs;
+  LvglArgs* args = reinterpret_cast<LvglArgs*>(voidArgs);
-  drivers::GpioExpander* gpio_expander = args->gpio_expander;
+  drivers::DriverCache* drivers = args->drivers;
   std::atomic<bool>* quit = args->quit;
-
-  // Dispose of the args now that we've gotten everything out of them.
   delete args;
 
   {
@@ -59,8 +57,7 @@ void LvglMain(void* voidArgs) {
         xTimerCreate("lv_tick", pdMS_TO_TICKS(1), pdTRUE, NULL, &tick_hook);
 
     ESP_LOGI(kTag, "init display");
-    std::unique_ptr<drivers::Display> display =
+    std::shared_ptr<drivers::Display> display = drivers->AcquireDisplay();
-        drivers::Display::create(gpio_expander, drivers::displays::kST7735R);
 
     lv_style_t style;
     lv_style_init(&style);
@@ -96,11 +93,11 @@ static const size_t kLvglStackSize = 8 * 1024;
 static StaticTask_t sLvglTaskBuffer = {};
 static StackType_t sLvglStack[kLvglStackSize] = {0};
 
-auto StartLvgl(drivers::GpioExpander* gpios,
+auto StartLvgl(drivers::DriverCache* drivers,
                std::atomic<bool>* quit,
                TaskHandle_t* handle) -> bool {
   LvglArgs* args = new LvglArgs();
-  args->gpio_expander = gpios;
+  args->drivers = drivers;
   args->quit = quit;
 
   return xTaskCreateStaticPinnedToCore(&LvglMain, "LVGL", kLvglStackSize,