Clean up gpios interface

27 files changed, 88 insertions, 567 deletions

diff --git a/src/audio/audio_fsm.cpp b/src/audio/audio_fsm.cpp
index 1f4f1f44..36133626 100644
--- a/src/audio/audio_fsm.cpp
+++ b/src/audio/audio_fsm.cpp
@@ -22,9 +22,8 @@ namespace audio {
 
 static const char kTag[] = "audio_fsm";
 
-drivers::GpioExpander* AudioState::sGpioExpander;
+drivers::IGpios* AudioState::sIGpios;
 std::shared_ptr<drivers::I2SDac> AudioState::sDac;
-std::shared_ptr<drivers::DigitalPot> AudioState::sPots;
 std::weak_ptr<database::Database> AudioState::sDatabase;
 
 std::unique_ptr<FatfsAudioInput> AudioState::sFileSource;
@@ -33,20 +32,19 @@ std::vector<std::unique_ptr<IAudioElement>> AudioState::sPipeline;
 
 std::deque<AudioState::EnqueuedItem> AudioState::sTrackQueue;
 
-auto AudioState::Init(drivers::GpioExpander* gpio_expander,
+auto AudioState::Init(drivers::IGpios* gpio_expander,
                       std::weak_ptr<database::Database> database) -> bool {
-  sGpioExpander = gpio_expander;
+  sIGpios = gpio_expander;
 
   auto dac = drivers::I2SDac::create(gpio_expander);
   if (!dac) {
     return false;
   }
   sDac.reset(dac.value());
-  sPots.reset(new drivers::DigitalPot(gpio_expander));
   sDatabase = database;
 
   sFileSource.reset(new FatfsAudioInput());
-  sI2SOutput.reset(new I2SAudioOutput(sGpioExpander, sDac, sPots));
+  sI2SOutput.reset(new I2SAudioOutput(sIGpios, sDac));
 
   // Perform initial pipeline configuration.
   // TODO(jacqueline): Factor this out once we have any kind of dynamic
diff --git a/src/audio/i2s_audio_output.cpp b/src/audio/i2s_audio_output.cpp
index 77de7b43..5f705dd1 100644
--- a/src/audio/i2s_audio_output.cpp
+++ b/src/audio/i2s_audio_output.cpp
@@ -12,13 +12,12 @@
 #include <memory>
 #include <variant>
 
-#include "digital_pot.hpp"
 #include "esp_err.h"
 #include "freertos/portmacro.h"
 
 #include "audio_element.hpp"
 #include "freertos/projdefs.h"
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "i2s_dac.hpp"
 #include "result.hpp"
 #include "stream_info.hpp"
@@ -27,15 +26,13 @@ static const char* kTag = "I2SOUT";
 
 namespace audio {
 
-I2SAudioOutput::I2SAudioOutput(drivers::GpioExpander* expander,
-                               std::weak_ptr<drivers::I2SDac> dac,
-                               std::weak_ptr<drivers::DigitalPot> pots)
+I2SAudioOutput::I2SAudioOutput(drivers::IGpios* expander,
+                               std::weak_ptr<drivers::I2SDac> dac)
     : expander_(expander),
       dac_(dac.lock()),
-      pots_(pots.lock()),
       current_config_(),
       left_difference_(0),
-      attenuation_(pots_->GetMaxAttenuation()) {
+      attenuation_() {
   SetVolume(25);  // For testing
   dac_->SetSource(buffer());
 }
@@ -51,70 +48,33 @@ auto I2SAudioOutput::SetInUse(bool in_use) -> void {
   } else {
     dac_->Stop();
   }
-  pots_->SetZeroCrossDetect(in_use);
 }
 
 auto I2SAudioOutput::SetVolumeImbalance(int_fast8_t balance) -> void {
-  int_fast8_t new_difference = balance - left_difference_;
-  left_difference_ = balance;
-  if (attenuation_ + new_difference <= pots_->GetMinAttenuation()) {
-    // Volume is currently very high, so shift the left channel down.
-    pots_->SetRelative(drivers::DigitalPot::Channel::kLeft, -new_difference);
-  } else if (attenuation_ - new_difference >= pots_->GetMaxAttenuation()) {
-    // Volume is currently very low, so shift the left channel up.
-    pots_->SetRelative(drivers::DigitalPot::Channel::kLeft, new_difference);
-  } else {
-    ESP_LOGE(kTag, "volume imbalance higher than attenuation range");
-  }
+  // TODO.
 }
 
 auto I2SAudioOutput::SetVolume(uint_fast8_t percent) -> void {
-  percent = 100 - percent;
-  int_fast8_t target_attenuation =
-      static_cast<int_fast8_t>(static_cast<float>(GetAdjustedMaxAttenuation()) /
-                               100.0f * static_cast<float>(percent));
-  target_attenuation -= pots_->GetMinAttenuation();
-  int_fast8_t difference = target_attenuation - attenuation_;
-  pots_->SetRelative(difference);
-  attenuation_ = target_attenuation;
-  ESP_LOGI(kTag, "adjusting attenuation by %idB to %idB", difference,
-           attenuation_);
+  // TODO.
 }
 
 auto I2SAudioOutput::GetVolume() -> uint_fast8_t {
-  // Convert to percentage.
-  uint_fast8_t percent = static_cast<uint_fast8_t>(
-      static_cast<float>(attenuation_) /
-      static_cast<float>(GetAdjustedMaxAttenuation()) * 100.0f);
-  // Invert to get from attenuation to volume.
-  return 100 - percent;
+  // TODO.
+  return 100;
 }
 
 auto I2SAudioOutput::GetAdjustedMaxAttenuation() -> int_fast8_t {
-  // Clip to account for imbalance.
-  int_fast8_t adjusted_max =
-      pots_->GetMaxAttenuation() - std::abs(left_difference_);
-  // Shift to be zero minimum.
-  adjusted_max -= pots_->GetMinAttenuation();
-
-  return adjusted_max;
+  // TODO
+  return 0;
 }
 
 auto I2SAudioOutput::AdjustVolumeUp() -> bool {
-  if (attenuation_ + left_difference_ <= pots_->GetMinAttenuation()) {
-    return false;
-  }
-  attenuation_--;
-  pots_->SetRelative(-1);
+  // TODO
   return true;
 }
 
 auto I2SAudioOutput::AdjustVolumeDown() -> bool {
-  if (attenuation_ - left_difference_ >= pots_->GetMaxAttenuation()) {
-    return false;
-  }
-  attenuation_++;
-  pots_->SetRelative(1);
+  // TODO
   return true;
 }
 
diff --git a/src/audio/include/audio_fsm.hpp b/src/audio/include/audio_fsm.hpp
index 7e84785f..1a52375b 100644
--- a/src/audio/include/audio_fsm.hpp
+++ b/src/audio/include/audio_fsm.hpp
@@ -14,7 +14,7 @@
 #include "database.hpp"
 #include "display.hpp"
 #include "fatfs_audio_input.hpp"
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "i2s_audio_output.hpp"
 #include "i2s_dac.hpp"
 #include "storage.hpp"
@@ -27,7 +27,7 @@ namespace audio {
 
 class AudioState : public tinyfsm::Fsm<AudioState> {
  public:
-  static auto Init(drivers::GpioExpander* gpio_expander,
+  static auto Init(drivers::IGpios* gpio_expander,
                    std::weak_ptr<database::Database>) -> bool;
 
   virtual ~AudioState() {}
@@ -54,9 +54,8 @@ class AudioState : public tinyfsm::Fsm<AudioState> {
   virtual void react(const AudioPipelineIdle&) {}
 
  protected:
-  static drivers::GpioExpander* sGpioExpander;
+  static drivers::IGpios* sIGpios;
   static std::shared_ptr<drivers::I2SDac> sDac;
-  static std::shared_ptr<drivers::DigitalPot> sPots;
   static std::weak_ptr<database::Database> sDatabase;
 
   static std::unique_ptr<FatfsAudioInput> sFileSource;
diff --git a/src/audio/include/i2s_audio_output.hpp b/src/audio/include/i2s_audio_output.hpp
index 5dd6cc27..583a5d6a 100644
--- a/src/audio/include/i2s_audio_output.hpp
+++ b/src/audio/include/i2s_audio_output.hpp
@@ -15,8 +15,7 @@
 #include "chunk.hpp"
 #include "result.hpp"
 
-#include "digital_pot.hpp"
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "i2s_dac.hpp"
 #include "stream_info.hpp"
 
@@ -24,9 +23,7 @@ namespace audio {
 
 class I2SAudioOutput : public IAudioSink {
  public:
-  I2SAudioOutput(drivers::GpioExpander* expander,
-                 std::weak_ptr<drivers::I2SDac> dac,
-                 std::weak_ptr<drivers::DigitalPot> pots);
+  I2SAudioOutput(drivers::IGpios* expander, std::weak_ptr<drivers::I2SDac> dac);
   ~I2SAudioOutput();
 
   auto SetInUse(bool) -> void override;
@@ -46,9 +43,8 @@ class I2SAudioOutput : public IAudioSink {
  private:
   auto GetAdjustedMaxAttenuation() -> int_fast8_t;
 
-  drivers::GpioExpander* expander_;
+  drivers::IGpios* expander_;
   std::shared_ptr<drivers::I2SDac> dac_;
-  std::shared_ptr<drivers::DigitalPot> pots_;
 
   std::optional<StreamInfo::Pcm> current_config_;
   int_fast8_t left_difference_;
diff --git a/src/drivers/CMakeLists.txt b/src/drivers/CMakeLists.txt
index fff61f5f..151a3afc 100644
--- a/src/drivers/CMakeLists.txt
+++ b/src/drivers/CMakeLists.txt
@@ -3,8 +3,8 @@
 # SPDX-License-Identifier: GPL-3.0-only
 
 idf_component_register(
-  SRCS "touchwheel.cpp" "i2s_dac.cpp" "gpio_expander.cpp" "battery.cpp" "storage.cpp" "i2c.cpp"
-  "spi.cpp" "display.cpp" "display_init.cpp" "samd.cpp" "relative_wheel.cpp" "digital_pot.cpp"
+  SRCS "touchwheel.cpp" "i2s_dac.cpp" "gpios.cpp" "battery.cpp" "storage.cpp" "i2c.cpp"
+  "spi.cpp" "display.cpp" "display_init.cpp" "samd.cpp" "relative_wheel.cpp"
   INCLUDE_DIRS "include"
   REQUIRES "esp_adc" "fatfs" "result" "lvgl" "span" "tasks")
 target_compile_options(${COMPONENT_LIB} PRIVATE ${EXTRA_WARNINGS})
diff --git a/src/drivers/digital_pot.cpp b/src/drivers/digital_pot.cpp
deleted file mode 100644
index b20d982d..00000000
--- a/src/drivers/digital_pot.cpp
+++ /dev/null
@@ -1,85 +0,0 @@
-/*
- * Copyright 2023 jacqueline <me@jacqueline.id.au>
- *
- * SPDX-License-Identifier: GPL-3.0-only
- */
-
-#include "digital_pot.hpp"
-
-#include <cstdint>
-
-namespace drivers {
-
-using GpioExpander::VOL_LEFT;
-using GpioExpander::VOL_RIGHT;
-using GpioExpander::VOL_UP_DOWN;
-using GpioExpander::VOL_Z_CROSS;
-
-DigitalPot::DigitalPot(GpioExpander* gpios) : gpios_(gpios) {
-  gpios_->set_pin(VOL_Z_CROSS, true);  // Active-low
-  gpios_->set_pin(VOL_UP_DOWN, true);
-  gpios_->set_pin(VOL_LEFT, false);
-  gpios_->set_pin(VOL_RIGHT, false);
-  gpios_->Write();
-
-  // Power-on reset sets attenuation to maximum anyway, but we want to be safe
-  // and not blow anyone's ears out.
-  for (int i = 0; i < 32; i++) {
-    gpios_->set_pin(VOL_LEFT, true);
-    gpios_->set_pin(VOL_RIGHT, true);
-    gpios_->Write();
-    gpios_->set_pin(VOL_LEFT, false);
-    gpios_->set_pin(VOL_RIGHT, false);
-    gpios_->Write();
-  }
-}
-
-auto DigitalPot::SetRelative(int_fast8_t change) -> void {
-  if (change == 0) {
-    return;
-  }
-
-  gpios_->set_pin(VOL_UP_DOWN, change > 0);
-  gpios_->Write();
-
-  for (int i = 0; i < std::abs(change); i++) {
-    gpios_->set_pin(VOL_LEFT, true);
-    gpios_->set_pin(VOL_RIGHT, true);
-    gpios_->Write();
-    gpios_->set_pin(VOL_LEFT, false);
-    gpios_->set_pin(VOL_RIGHT, false);
-    gpios_->Write();
-  }
-}
-
-auto DigitalPot::SetRelative(Channel ch, int_fast8_t change) -> void {
-  if (change == 0) {
-    return;
-  }
-
-  GpioExpander::Pin pin = (ch == Channel::kLeft) ? VOL_LEFT : VOL_RIGHT;
-  gpios_->set_pin(VOL_UP_DOWN, change > 0);
-  gpios_->Write();
-
-  for (int i = 0; i < std::abs(change); i++) {
-    gpios_->set_pin(pin, true);
-    gpios_->Write();
-    gpios_->set_pin(pin, false);
-    gpios_->Write();
-  }
-}
-
-auto DigitalPot::SetZeroCrossDetect(bool enabled) -> void {
-  gpios_->set_pin(VOL_Z_CROSS, !enabled);  // Active-low
-  gpios_->Write();
-}
-
-auto DigitalPot::GetMaxAttenuation() -> int_fast8_t {
-  return 31;
-}
-
-auto DigitalPot::GetMinAttenuation() -> int_fast8_t {
-  return 0;
-}
-
-}  // namespace drivers
diff --git a/src/drivers/display.cpp b/src/drivers/display.cpp
index 94f27bb6..d1ea367c 100644
--- a/src/drivers/display.cpp
+++ b/src/drivers/display.cpp
@@ -28,7 +28,7 @@
 #include "lvgl/lvgl.h"
 
 #include "display_init.hpp"
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "soc/soc.h"
 #include "tasks.hpp"
 
@@ -84,7 +84,7 @@ extern "C" void FlushDataCallback(lv_disp_drv_t* disp_drv,
   instance->OnLvglFlush(disp_drv, area, color_map);
 }
 
-auto Display::Create(GpioExpander* expander,
+auto Display::Create(IGpios* expander,
                      const displays::InitialisationData& init_data)
     -> Display* {
   ESP_LOGI(kTag, "Init I/O pins");
@@ -181,7 +181,7 @@ auto Display::Create(GpioExpander* expander,
   return display.release();
 }
 
-Display::Display(GpioExpander* gpio, spi_device_handle_t handle)
+Display::Display(IGpios* gpio, spi_device_handle_t handle)
     : gpio_(gpio),
       handle_(handle),
       worker_task_(tasks::Worker::Start<tasks::Type::kUiFlush>()),
diff --git a/src/drivers/gpio_expander.cpp b/src/drivers/gpio_expander.cpp
deleted file mode 100644
index 5a9bb83e..00000000
--- a/src/drivers/gpio_expander.cpp
+++ /dev/null
@@ -1,140 +0,0 @@
-/*
- * Copyright 2023 jacqueline <me@jacqueline.id.au>
- *
- * SPDX-License-Identifier: GPL-3.0-only
- */
-
-#include "gpio_expander.hpp"
-#include <stdint.h>
-
-#include <cstdint>
-
-#include "driver/gpio.h"
-#include "hal/gpio_types.h"
-#include "i2c.hpp"
-
-namespace drivers {
-
-static const uint8_t kPca8575Address = 0x20;
-
-// Port A:
-// 0 - sd card mux switch
-// 1 - sd card mux enable (active low)
-// 2 - key up
-// 3 - key down
-// 4 - key lock
-// 5 - display reset (active low)
-// 6 - NC
-// 7 - sd card power (active low)
-// Default to SD card off, inputs high.
-static const uint8_t kPortADefault = 0b10111110;
-
-// Port B:
-// 0 - 3.5mm jack detect (active low)
-// 1 - headphone amp power enable
-// 2 - volume zero-cross detection
-// 3 - volume direction
-// 4 - volume left channel
-// 5 - volume right channel
-// 6 - NC
-// 7 - NC
-// Default input high, trs output low
-static const uint8_t kPortBDefault = 0b00000011;
-
-/*
- * Convenience mehod for packing the port a and b bytes into a single 16 bit
- * value.
- */
-constexpr uint16_t pack(uint8_t a, uint8_t b) {
-  return ((uint16_t)b) << 8 | a;
-}
-
-/*
- * Convenience mehod for unpacking the result of `pack` back into two single
- * byte port datas.
- */
-constexpr std::pair<uint8_t, uint8_t> unpack(uint16_t ba) {
-  return std::pair((uint8_t)ba, (uint8_t)(ba >> 8));
-}
-
-void interrupt_isr(void* arg) {
-  GpioExpander* instance = reinterpret_cast<GpioExpander*>(arg);
-  auto listener = instance->listener().lock();
-  if (listener) {
-    std::invoke(*listener);
-  }
-}
-
-auto GpioExpander::Create() -> GpioExpander* {
-  GpioExpander* instance = new GpioExpander();
-  // Read and write initial values on initialisation so that we do not have a
-  // strange partially-initialised state.
-  if (!instance->Write() || !instance->Read()) {
-    return nullptr;
-  }
-  return instance;
-}
-
-GpioExpander::GpioExpander()
-    : ports_(pack(kPortADefault, kPortBDefault)), inputs_(0), listener_() {
-  gpio_config_t config{
-      .pin_bit_mask = static_cast<uint64_t>(1) << GPIO_NUM_34,
-      .mode = GPIO_MODE_INPUT,
-      .pull_up_en = GPIO_PULLUP_ENABLE,
-      .pull_down_en = GPIO_PULLDOWN_DISABLE,
-      .intr_type = GPIO_INTR_NEGEDGE,
-  };
-  gpio_config(&config);
-  gpio_install_isr_service(ESP_INTR_FLAG_LOWMED | ESP_INTR_FLAG_SHARED |
-                           ESP_INTR_FLAG_IRAM);
-  gpio_isr_handler_add(GPIO_NUM_34, &interrupt_isr, this);
-}
-
-GpioExpander::~GpioExpander() {
-  gpio_isr_handler_remove(GPIO_NUM_34);
-  gpio_uninstall_isr_service();
-}
-
-bool GpioExpander::Write() {
-  std::pair<uint8_t, uint8_t> ports_ab = unpack(ports());
-
-  I2CTransaction transaction;
-  transaction.start()
-      .write_addr(kPca8575Address, I2C_MASTER_WRITE)
-      .write_ack(ports_ab.first, ports_ab.second)
-      .stop();
-
-  return transaction.Execute() == ESP_OK;
-}
-
-bool GpioExpander::Read() {
-  uint8_t input_a, input_b;
-
-  I2CTransaction transaction;
-  transaction.start()
-      .write_addr(kPca8575Address, I2C_MASTER_READ)
-      .read(&input_a, I2C_MASTER_ACK)
-      .read(&input_b, I2C_MASTER_LAST_NACK)
-      .stop();
-
-  esp_err_t ret = transaction.Execute();
-  if (ret != ESP_OK) {
-    return false;
-  }
-  inputs_ = pack(input_a, input_b);
-  return true;
-}
-
-void GpioExpander::set_pin(Pin pin, bool value) {
-  if (value) {
-    ports_ |= (1 << pin);
-  } else {
-    ports_ &= ~(1 << pin);
-  }
-}
-
-bool GpioExpander::get_input(Pin pin) const {
-  return (inputs_ & (1 << pin)) > 0;
-}
-
-}  // namespace drivers
diff --git a/src/drivers/i2s_dac.cpp b/src/drivers/i2s_dac.cpp
index dbbb58f1..78ffdea3 100644
--- a/src/drivers/i2s_dac.cpp
+++ b/src/drivers/i2s_dac.cpp
@@ -21,7 +21,7 @@
 #include "hal/gpio_types.h"
 #include "hal/i2c_types.h"
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "hal/i2s_types.h"
 #include "i2c.hpp"
 #include "soc/clk_tree_defs.h"
@@ -32,7 +32,7 @@ namespace drivers {
 static const char* kTag = "i2s_dac";
 static const i2s_port_t kI2SPort = I2S_NUM_0;
 
-auto I2SDac::create(GpioExpander* expander) -> std::optional<I2SDac*> {
+auto I2SDac::create(IGpios* expander) -> std::optional<I2SDac*> {
   i2s_chan_handle_t i2s_handle;
   i2s_chan_config_t channel_config =
       I2S_CHANNEL_DEFAULT_CONFIG(kI2SPort, I2S_ROLE_MASTER);
@@ -78,7 +78,7 @@ auto I2SDac::create(GpioExpander* expander) -> std::optional<I2SDac*> {
   return dac.release();
 }
 
-I2SDac::I2SDac(GpioExpander* gpio, i2s_chan_handle_t i2s_handle)
+I2SDac::I2SDac(IGpios* gpio, i2s_chan_handle_t i2s_handle)
     : gpio_(gpio),
       i2s_handle_(i2s_handle),
       i2s_active_(false),
@@ -87,8 +87,7 @@ I2SDac::I2SDac(GpioExpander* gpio, i2s_chan_handle_t i2s_handle)
       slot_config_(I2S_STD_MSB_SLOT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT,
                                                    I2S_SLOT_MODE_STEREO)) {
   clock_config_.clk_src = I2S_CLK_SRC_PLL_160M;
-  gpio_->set_pin(GpioExpander::AMP_EN, false);
-  gpio_->Write();
+  gpio_->WriteSync(IGpios::Pin::kAmplifierEnable, false);
 }
 
 I2SDac::~I2SDac() {
@@ -97,8 +96,7 @@ I2SDac::~I2SDac() {
 }
 
 auto I2SDac::Start() -> void {
-  gpio_->set_pin(GpioExpander::AMP_EN, true);
-  gpio_->Write();
+  gpio_->WriteSync(IGpios::Pin::kAmplifierEnable, true);
 
   vTaskDelay(pdMS_TO_TICKS(1));
   i2s_channel_enable(i2s_handle_);
@@ -110,8 +108,7 @@ auto I2SDac::Stop() -> void {
   i2s_channel_disable(i2s_handle_);
   vTaskDelay(pdMS_TO_TICKS(1));
 
-  gpio_->set_pin(GpioExpander::AMP_EN, false);
-  gpio_->Write();
+  gpio_->WriteSync(IGpios::Pin::kAmplifierEnable, false);
 
   i2s_active_ = false;
 }
diff --git a/src/drivers/include/digital_pot.hpp b/src/drivers/include/digital_pot.hpp
deleted file mode 100644
index e2ca00b1..00000000
--- a/src/drivers/include/digital_pot.hpp
+++ /dev/null
@@ -1,49 +0,0 @@
-/*
- * Copyright 2023 jacqueline <me@jacqueline.id.au>
- *
- * SPDX-License-Identifier: GPL-3.0-only
- */
-
-#pragma once
-
-#include <stdint.h>
-#include <functional>
-
-#include "esp_err.h"
-#include "result.hpp"
-
-#include "gpio_expander.hpp"
-
-namespace drivers {
-
-/*
- * Driver for a two-channel digital potentiometer, with steps measured in
- * decibels.
- */
-class DigitalPot {
- public:
-  explicit DigitalPot(GpioExpander* gpios);
-  ~DigitalPot() {}
-
-  // Not copyable or movable.
-  DigitalPot(const DigitalPot&) = delete;
-  DigitalPot& operator=(const DigitalPot&) = delete;
-
-  enum class Channel {
-    kLeft,
-    kRight,
-  };
-
-  auto SetRelative(int_fast8_t change) -> void;
-  auto SetRelative(Channel ch, int_fast8_t change) -> void;
-
-  auto SetZeroCrossDetect(bool enabled) -> void;
-
-  auto GetMaxAttenuation() -> int_fast8_t;
-  auto GetMinAttenuation() -> int_fast8_t;
-
- private:
-  GpioExpander* gpios_;
-};
-
-}  // namespace drivers
diff --git a/src/drivers/include/display.hpp b/src/drivers/include/display.hpp
index 4b63e1c4..23bbbab9 100644
--- a/src/drivers/include/display.hpp
+++ b/src/drivers/include/display.hpp
@@ -16,7 +16,7 @@
 #include "tasks.hpp"
 
 #include "display_init.hpp"
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 
 namespace drivers {
 
@@ -30,10 +30,10 @@ class Display {
    * over SPI. This never fails, since unfortunately these display don't give
    * us back any kind of signal to tell us we're actually using them correctly.
    */
-  static auto Create(GpioExpander* expander,
+  static auto Create(IGpios* expander,
                      const displays::InitialisationData& init_data) -> Display*;
 
-  Display(GpioExpander* gpio, spi_device_handle_t handle);
+  Display(IGpios* gpio, spi_device_handle_t handle);
   ~Display();
 
   auto SetDisplayOn(bool) -> void;
@@ -48,7 +48,7 @@ class Display {
   Display& operator=(const Display&) = delete;
 
  private:
-  GpioExpander* gpio_;
+  IGpios* gpio_;
   spi_device_handle_t handle_;
 
   std::unique_ptr<tasks::Worker> worker_task_;
diff --git a/src/drivers/include/gpio_expander.hpp b/src/drivers/include/gpio_expander.hpp
deleted file mode 100644
index 8108d176..00000000
--- a/src/drivers/include/gpio_expander.hpp
+++ /dev/null
@@ -1,148 +0,0 @@
-/*
- * Copyright 2023 jacqueline <me@jacqueline.id.au>
- *
- * SPDX-License-Identifier: GPL-3.0-only
- */
-
-#pragma once
-
-#include <stdint.h>
-
-#include <atomic>
-#include <functional>
-#include <memory>
-#include <mutex>
-#include <optional>
-#include <tuple>
-#include <utility>
-
-#include "driver/i2c.h"
-#include "esp_check.h"
-#include "esp_err.h"
-#include "esp_log.h"
-#include "freertos/FreeRTOS.h"
-
-namespace drivers {
-
-/**
- * Wrapper for interfacing with the PCA8575 GPIO expander. Includes basic
- * low-level pin setting methods, as well as higher level convenience functions
- * for reading, writing, and atomically interacting with the SPI chip select
- * pins.
- *
- * Each method of this class can be called safely from any thread, and all
- * updates are guaranteed to be atomic. Any access to chip select related pins
- * should be done whilst holding `cs_lock` (preferably via the helper methods).
- */
-class GpioExpander {
- public:
-  static auto Create() -> GpioExpander*;
-  ~GpioExpander();
-
-  /*
-   * Convenience function for running some arbitrary pin writing code, then
-   * flushing a `Write()` to the expander. Example usage:
-   *
-   * ```
-   * gpio_.with([&](auto& gpio) {
-   *	gpio.set_pin(AUDIO_POWER_ENABLE, true);
-   * });
-   * ```
-   */
-  template <typename F>
-  auto with(F fn) -> void {
-    std::invoke(fn);
-    Write();
-  }
-
-  /**
-   * Sets the ports on the GPIO expander to the values currently represented
-   * in `ports`.
-   */
-  auto Write(void) -> bool;
-
-  /**
-   * Reads from the GPIO expander, populating `inputs` with the most recent
-   * values.
-   */
-  auto Read(void) -> bool;
-
-  /* Maps each pin of the expander to its number in a `pack`ed uint16. */
-  enum Pin {
-    // Port A
-    SD_MUX_SWITCH = 0,
-    SD_MUX_EN_ACTIVE_LOW = 1,
-    KEY_UP = 2,
-    KEY_DOWN = 3,
-    KEY_LOCK = 4,
-    DISPLAY_RESET_ACTIVE_LOW = 5,
-    // UNUSED = 6,
-    SD_CARD_POWER_ENABLE_ACTIVE_LOW = 7,
-
-    // Port B
-    PHONE_DETECT = 8,
-    AMP_EN = 9,
-    VOL_Z_CROSS = 10,
-    VOL_UP_DOWN = 11,
-    VOL_LEFT = 12,
-    VOL_RIGHT = 13,
-    // UNUSED = 14,
-    // UNUSED = 15,
-  };
-
-  /* Nicer value names for use with the SD_MUX_SWITCH pin. */
-  enum SdController {
-    SD_MUX_ESP = 0,
-    SD_MUX_SAMD = 1,
-  };
-
-  /**
-   * Returns the current driven status of each of the ports. The first byte is
-   * port a, and the second byte is port b.
-   */
-  std::atomic<uint16_t>& ports() { return ports_; }
-
-  /*
-   * Sets a single specific pin to the given value. `true` corresponds to
-   * HIGH, and `false` corresponds to LOW.
-   *
-   * Calls to this method will be buffered in memory until a call to `Write()`
-   * is made.
-   */
-  void set_pin(Pin pin, bool value);
-
-  /**
-   * Returns the input status of each of the ports. The first byte is port a,
-   * and the second byte is port b.
-   */
-  const std::atomic<uint16_t>& inputs() const { return inputs_; }
-
-  /* Returns the most recently cached value of the given pin. Only valid for
-   * pins used as inputs; to check what value we're driving a pin, use
-   * `ports()`.
-   */
-  bool get_input(Pin pin) const;
-
-  auto listener() -> std::weak_ptr<std::function<void(void)>>& {
-    return listener_;
-  }
-
-  auto set_listener(const std::weak_ptr<std::function<void(void)>>& l) -> void {
-    listener_ = l;
-  }
-
-  // Not copyable or movable. There should usually only ever be once instance
-  // of this class, and that instance will likely have a static lifetime.
-  GpioExpander(const GpioExpander&) = delete;
-  GpioExpander& operator=(const GpioExpander&) = delete;
-
- private:
-  GpioExpander();
-
-  std::atomic<uint16_t> ports_;
-  std::atomic<uint16_t> inputs_;
-
-  std::weak_ptr<std::function<void(void)>> listener_;
-};
-
-}  // namespace drivers
diff --git a/src/drivers/include/i2s_dac.hpp b/src/drivers/include/i2s_dac.hpp
index 388d09fa..39eb9c4c 100644
--- a/src/drivers/include/i2s_dac.hpp
+++ b/src/drivers/include/i2s_dac.hpp
@@ -22,7 +22,7 @@
 #include "result.hpp"
 #include "span.hpp"
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "sys/_stdint.h"
 
 namespace drivers {
@@ -32,9 +32,9 @@ namespace drivers {
  */
 class I2SDac {
  public:
-  static auto create(GpioExpander* expander) -> std::optional<I2SDac*>;
+  static auto create(IGpios* expander) -> std::optional<I2SDac*>;
 
-  I2SDac(GpioExpander* gpio, i2s_chan_handle_t i2s_handle);
+  I2SDac(IGpios* gpio, i2s_chan_handle_t i2s_handle);
   ~I2SDac();
 
   auto Start() -> void;
@@ -70,7 +70,7 @@ class I2SDac {
   I2SDac& operator=(const I2SDac&) = delete;
 
  private:
-  GpioExpander* gpio_;
+  IGpios* gpio_;
   i2s_chan_handle_t i2s_handle_;
   bool i2s_active_;
   std::optional<uint8_t> active_page_;
diff --git a/src/drivers/include/relative_wheel.hpp b/src/drivers/include/relative_wheel.hpp
index 8d74d551..6edc006a 100644
--- a/src/drivers/include/relative_wheel.hpp
+++ b/src/drivers/include/relative_wheel.hpp
@@ -13,7 +13,7 @@
 #include "esp_err.h"
 #include "result.hpp"
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "touchwheel.hpp"
 
 namespace drivers {
diff --git a/src/drivers/include/storage.hpp b/src/drivers/include/storage.hpp
index daee13c4..a9269261 100644
--- a/src/drivers/include/storage.hpp
+++ b/src/drivers/include/storage.hpp
@@ -15,7 +15,7 @@
 #include "ff.h"
 #include "result.hpp"
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 
 namespace drivers {
 
@@ -31,9 +31,9 @@ class SdStorage {
     FAILED_TO_MOUNT,
   };
 
-  static auto Create(GpioExpander* gpio) -> cpp::result<SdStorage*, Error>;
+  static auto Create(IGpios* gpio) -> cpp::result<SdStorage*, Error>;
 
-  SdStorage(GpioExpander* gpio,
+  SdStorage(IGpios* 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_,
@@ -52,7 +52,7 @@ class SdStorage {
   SdStorage& operator=(const SdStorage&) = delete;
 
  private:
-  GpioExpander* gpio_;
+  IGpios* gpio_;
 
   esp_err_t (*do_transaction_)(sdspi_dev_handle_t, sdmmc_command_t*) = nullptr;
 
diff --git a/src/drivers/include/touchwheel.hpp b/src/drivers/include/touchwheel.hpp
index 5c3442d2..f42b575b 100644
--- a/src/drivers/include/touchwheel.hpp
+++ b/src/drivers/include/touchwheel.hpp
@@ -12,7 +12,7 @@
 #include "esp_err.h"
 #include "result.hpp"
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 
 namespace drivers {
 
diff --git a/src/drivers/storage.cpp b/src/drivers/storage.cpp
index 4f16f1d1..e3dd8f83 100644
--- a/src/drivers/storage.cpp
+++ b/src/drivers/storage.cpp
@@ -23,7 +23,7 @@
 #include "hal/spi_types.h"
 #include "sdmmc_cmd.h"
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 
 static const char* kTag = "SDSTORAGE";
 static const uint8_t kMaxOpenFiles = 8;
@@ -55,11 +55,10 @@ static esp_err_t do_transaction(sdspi_dev_handle_t handle,
 }
 }  // namespace callback
 
-auto SdStorage::Create(GpioExpander* gpio) -> cpp::result<SdStorage*, Error> {
-  gpio->set_pin(GpioExpander::SD_CARD_POWER_ENABLE_ACTIVE_LOW, 0);
-  gpio->set_pin(GpioExpander::SD_MUX_EN_ACTIVE_LOW, 0);
-  gpio->set_pin(GpioExpander::SD_MUX_SWITCH, GpioExpander::SD_MUX_ESP);
-  gpio->Write();
+auto SdStorage::Create(IGpios* gpio) -> cpp::result<SdStorage*, Error> {
+  gpio->WriteSync(IGpios::Pin::kSdPowerDisable, 0);
+  gpio->WriteSync(IGpios::Pin::kSdMuxSwitch, IGpios::SD_MUX_ESP);
+  gpio->WriteSync(IGpios::Pin::kSdMuxDisable, 0);
 
   sdspi_dev_handle_t handle;
   std::unique_ptr<sdmmc_host_t> host;
@@ -114,7 +113,7 @@ auto SdStorage::Create(GpioExpander* gpio) -> cpp::result<SdStorage*, Error> {
                        std::move(card), fs);
 }
 
-SdStorage::SdStorage(GpioExpander* gpio,
+SdStorage::SdStorage(IGpios* gpio,
                      esp_err_t (*do_transaction)(sdspi_dev_handle_t,
                                                  sdmmc_command_t*),
                      sdspi_dev_handle_t handle,
@@ -144,9 +143,8 @@ SdStorage::~SdStorage() {
   sdspi_host_remove_device(this->handle_);
   sdspi_host_deinit();
 
-  gpio_->set_pin(GpioExpander::SD_CARD_POWER_ENABLE_ACTIVE_LOW, 1);
-  gpio_->set_pin(GpioExpander::SD_MUX_EN_ACTIVE_LOW, 1);
-  gpio_->Write();
+  gpio_->WriteSync(IGpios::Pin::kSdPowerDisable, 1);
+  gpio_->WriteSync(IGpios::Pin::kSdMuxDisable, 1);
 }
 
 auto SdStorage::HandleTransaction(sdspi_dev_handle_t handle,
diff --git a/src/drivers/test/test_dac.cpp b/src/drivers/test/test_dac.cpp
index edf9e1e9..e8d8dd94 100644
--- a/src/drivers/test/test_dac.cpp
+++ b/src/drivers/test/test_dac.cpp
@@ -10,7 +10,7 @@
 
 #include "catch2/catch.hpp"
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "i2c.hpp"
 #include "i2c_fixture.hpp"
 
@@ -18,7 +18,7 @@ namespace drivers {
 
 TEST_CASE("dac configuration", "[integration]") {
   I2CFixture i2c;
-  GpioExpander expander;
+  IGpios expander;
   cpp::result<AudioDac*, AudioDac::Error> dac_res = AudioDac::create(&expander);
   REQUIRE(dac_res.has_value());
   std::unique_ptr<AudioDac> dac(dac_res.value());
diff --git a/src/drivers/test/test_gpio_expander.cpp b/src/drivers/test/test_gpio_expander.cpp
index 2a31d9c7..972bcf09 100644
--- a/src/drivers/test/test_gpio_expander.cpp
+++ b/src/drivers/test/test_gpio_expander.cpp
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: GPL-3.0-only
  */
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 
 #include "catch2/catch.hpp"
 
@@ -15,17 +15,16 @@ namespace drivers {
 
 TEST_CASE("gpio expander", "[integration]") {
   I2CFixture i2c;
-  GpioExpander expander;
+  IGpios expander;
   SECTION("with() writes when ") {
     // Initial value.
     expander.Read();
-    REQUIRE(expander.get_input(GpioExpander::KEY_DOWN) == true);
+    REQUIRE(expander.get_input(IGpios::KEY_DOWN) == true);
 
-    expander.with(
-        [&](auto& gpio) { gpio.set_pin(GpioExpander::KEY_DOWN, false); });
+    expander.with([&](auto& gpio) { gpio.set_pin(IGpios::KEY_DOWN, false); });
 
     expander.Read();
-    REQUIRE(expander.get_input(GpioExpander::KEY_DOWN) == false);
+    REQUIRE(expander.get_input(IGpios::KEY_DOWN) == false);
   }
 }
 
diff --git a/src/drivers/test/test_storage.cpp b/src/drivers/test/test_storage.cpp
index 90f2843a..c785fa01 100644
--- a/src/drivers/test/test_storage.cpp
+++ b/src/drivers/test/test_storage.cpp
@@ -14,7 +14,7 @@
 
 #include "catch2/catch.hpp"
 
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "i2c.hpp"
 #include "i2c_fixture.hpp"
 #include "spi.hpp"
@@ -29,7 +29,7 @@ static const std::string kTestFilePath =
 TEST_CASE("sd card storage", "[integration]") {
   I2CFixture i2c;
   SpiFixture spi;
-  GpioExpander expander;
+  IGpios expander;
 
   {
     std::unique_ptr<SdStorage> result(SdStorage::create(&expander).value());
diff --git a/src/system_fsm/booting.cpp b/src/system_fsm/booting.cpp
index e7505f11..41adb906 100644
--- a/src/system_fsm/booting.cpp
+++ b/src/system_fsm/booting.cpp
@@ -11,7 +11,7 @@
 #include "esp_err.h"
 #include "esp_log.h"
 #include "event_queue.hpp"
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "lvgl/lvgl.h"
 #include "relative_wheel.hpp"
 #include "spi.hpp"
@@ -42,12 +42,12 @@ auto Booting::entry() -> void {
 
   // These drivers are the bare minimum to even show an error. If these fail,
   // then the system is completely hosed.
-  sGpioExpander.reset(drivers::GpioExpander::Create());
-  assert(sGpioExpander != nullptr);
+  sGpios.reset(drivers::Gpios::Create());
+  assert(sGpios != nullptr);
 
   // Start bringing up LVGL now, since we have all of its prerequisites.
   ESP_LOGI(kTag, "starting ui");
-  if (!ui::UiState::Init(sGpioExpander.get())) {
+  if (!ui::UiState::Init(sGpios.get())) {
     events::Dispatch<FatalError, SystemState, ui::UiState, audio::AudioState>(
         FatalError());
     return;
@@ -68,7 +68,7 @@ auto Booting::entry() -> void {
   // state machines and inform them that the system is ready.
 
   ESP_LOGI(kTag, "starting audio");
-  if (!audio::AudioState::Init(sGpioExpander.get(), sDatabase)) {
+  if (!audio::AudioState::Init(sGpios.get(), sDatabase)) {
     events::Dispatch<FatalError, SystemState, ui::UiState, audio::AudioState>(
         FatalError());
     return;
diff --git a/src/system_fsm/include/system_fsm.hpp b/src/system_fsm/include/system_fsm.hpp
index 725f2f50..f6a52019 100644
--- a/src/system_fsm/include/system_fsm.hpp
+++ b/src/system_fsm/include/system_fsm.hpp
@@ -12,7 +12,7 @@
 #include "battery.hpp"
 #include "database.hpp"
 #include "display.hpp"
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 #include "relative_wheel.hpp"
 #include "samd.hpp"
 #include "storage.hpp"
@@ -48,7 +48,7 @@ class SystemState : public tinyfsm::Fsm<SystemState> {
   virtual void react(const StorageError&) {}
 
  protected:
-  static std::shared_ptr<drivers::GpioExpander> sGpioExpander;
+  static std::shared_ptr<drivers::Gpios> sGpios;
   static std::shared_ptr<drivers::Samd> sSamd;
 
   static std::shared_ptr<drivers::TouchWheel> sTouch;
diff --git a/src/system_fsm/running.cpp b/src/system_fsm/running.cpp
index 87c25440..1822a071 100644
--- a/src/system_fsm/running.cpp
+++ b/src/system_fsm/running.cpp
@@ -27,7 +27,7 @@ static const char kTag[] = "RUN";
 void Running::entry() {
   ESP_LOGI(kTag, "mounting sd card");
   vTaskDelay(pdMS_TO_TICKS(250));
-  auto storage_res = drivers::SdStorage::Create(sGpioExpander.get());
+  auto storage_res = drivers::SdStorage::Create(sGpios.get());
   if (storage_res.has_error()) {
     ESP_LOGW(kTag, "failed to mount!");
     events::Dispatch<StorageError, SystemState, audio::AudioState, ui::UiState>(
diff --git a/src/system_fsm/system_fsm.cpp b/src/system_fsm/system_fsm.cpp
index dd5161ed..9483088e 100644
--- a/src/system_fsm/system_fsm.cpp
+++ b/src/system_fsm/system_fsm.cpp
@@ -12,7 +12,7 @@
 
 namespace system_fsm {
 
-std::shared_ptr<drivers::GpioExpander> SystemState::sGpioExpander;
+std::shared_ptr<drivers::Gpios> SystemState::sGpios;
 std::shared_ptr<drivers::Samd> SystemState::sSamd;
 
 std::shared_ptr<drivers::TouchWheel> SystemState::sTouch;
@@ -32,21 +32,17 @@ void SystemState::react(const FatalError& err) {
 
 void SystemState::react(const internal::GpioInterrupt& ev) {
   ESP_LOGI("sys", "gpios changed");
-  bool prev_key_up = sGpioExpander->get_input(drivers::GpioExpander::KEY_UP);
-  bool prev_key_down =
-      sGpioExpander->get_input(drivers::GpioExpander::KEY_DOWN);
-  bool prev_key_lock =
-      sGpioExpander->get_input(drivers::GpioExpander::KEY_LOCK);
-  bool prev_has_headphones =
-      sGpioExpander->get_input(drivers::GpioExpander::PHONE_DETECT);
+  bool prev_key_up = sGpios->Get(drivers::Gpios::Pin::kKeyUp);
+  bool prev_key_down = sGpios->Get(drivers::Gpios::Pin::kKeyDown);
+  bool prev_key_lock = sGpios->Get(drivers::Gpios::Pin::kKeyLock);
+  bool prev_has_headphones = sGpios->Get(drivers::Gpios::Pin::kPhoneDetect);
 
-  sGpioExpander->Read();
+  sGpios->Read();
 
-  bool key_up = sGpioExpander->get_input(drivers::GpioExpander::KEY_UP);
-  bool key_down = sGpioExpander->get_input(drivers::GpioExpander::KEY_DOWN);
-  bool key_lock = sGpioExpander->get_input(drivers::GpioExpander::KEY_LOCK);
-  bool has_headphones =
-      sGpioExpander->get_input(drivers::GpioExpander::PHONE_DETECT);
+  bool key_up = sGpios->Get(drivers::Gpios::Pin::kKeyUp);
+  bool key_down = sGpios->Get(drivers::Gpios::Pin::kKeyDown);
+  bool key_lock = sGpios->Get(drivers::Gpios::Pin::kKeyLock);
+  bool has_headphones = sGpios->Get(drivers::Gpios::Pin::kPhoneDetect);
 
   if (key_up != prev_key_up) {
     events::Dispatch<KeyUpChanged, audio::AudioState, ui::UiState>(
diff --git a/src/ui/include/ui_fsm.hpp b/src/ui/include/ui_fsm.hpp
index d0bb7b2f..4de9344c 100644
--- a/src/ui/include/ui_fsm.hpp
+++ b/src/ui/include/ui_fsm.hpp
@@ -21,7 +21,7 @@ namespace ui {
 
 class UiState : public tinyfsm::Fsm<UiState> {
  public:
-  static auto Init(drivers::GpioExpander* gpio_expander) -> bool;
+  static auto Init(drivers::IGpios* gpio_expander) -> bool;
 
   virtual ~UiState() {}
 
@@ -41,7 +41,7 @@ class UiState : public tinyfsm::Fsm<UiState> {
   virtual void react(const system_fsm::BootComplete&) {}
 
  protected:
-  static drivers::GpioExpander* sGpioExpander;
+  static drivers::IGpios* sIGpios;
   static std::shared_ptr<drivers::TouchWheel> sTouchWheel;
   static std::shared_ptr<drivers::RelativeWheel> sRelativeWheel;
   static std::shared_ptr<drivers::Display> sDisplay;
diff --git a/src/ui/lvgl_task.cpp b/src/ui/lvgl_task.cpp
index d70782b2..37cde858 100644
--- a/src/ui/lvgl_task.cpp
+++ b/src/ui/lvgl_task.cpp
@@ -42,7 +42,7 @@
 #include "widgets/lv_label.h"
 
 #include "display.hpp"
-#include "gpio_expander.hpp"
+#include "gpios.hpp"
 
 namespace ui {
 
diff --git a/src/ui/ui_fsm.cpp b/src/ui/ui_fsm.cpp
index c2ac6d8b..709778c7 100644
--- a/src/ui/ui_fsm.cpp
+++ b/src/ui/ui_fsm.cpp
@@ -18,15 +18,15 @@
 
 namespace ui {
 
-drivers::GpioExpander* UiState::sGpioExpander;
+drivers::IGpios* UiState::sIGpios;
 std::shared_ptr<drivers::TouchWheel> UiState::sTouchWheel;
 std::shared_ptr<drivers::RelativeWheel> UiState::sRelativeWheel;
 std::shared_ptr<drivers::Display> UiState::sDisplay;
 
 std::shared_ptr<Screen> UiState::sCurrentScreen;
 
-auto UiState::Init(drivers::GpioExpander* gpio_expander) -> bool {
-  sGpioExpander = gpio_expander;
+auto UiState::Init(drivers::IGpios* gpio_expander) -> bool {
+  sIGpios = gpio_expander;
 
   lv_init();
   sDisplay.reset(