1 files changed, 83 insertions, 18 deletions

diff --git a/src/drivers/gpio_expander.cpp b/src/drivers/gpio_expander.cpp
index 87c5d038..5a9bb83e 100644
--- a/src/drivers/gpio_expander.cpp
+++ b/src/drivers/gpio_expander.cpp
@@ -5,35 +5,97 @@
  */
 
 #include "gpio_expander.hpp"
+#include <stdint.h>
 
 #include <cstdint>
 
+#include "driver/gpio.h"
+#include "hal/gpio_types.h"
 #include "i2c.hpp"
 
 namespace drivers {
 
-GpioExpander::GpioExpander() {
-  ports_ = pack(kPortADefault, kPortBDefault);
-  // Read and write initial values on initialisation so that we do not have a
-  // strange partially-initialised state.
-  // TODO: log or abort if these error; it's really bad!
-  Write();
-  Read();
+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;
 }
 
-GpioExpander::~GpioExpander() {}
+/*
+ * 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 GpioExpander::with(std::function<void(GpioExpander&)> f) {
-  f(*this);
-  Write();
+void interrupt_isr(void* arg) {
+  GpioExpander* instance = reinterpret_cast<GpioExpander*>(arg);
+  auto listener = instance->listener().lock();
+  if (listener) {
+    std::invoke(*listener);
+  }
 }
 
-esp_err_t GpioExpander::Write() {
-  i2c_cmd_handle_t handle = i2c_cmd_link_create();
-  if (handle == NULL) {
-    return ESP_ERR_NO_MEM;
+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;
@@ -42,10 +104,10 @@ esp_err_t GpioExpander::Write() {
       .write_ack(ports_ab.first, ports_ab.second)
       .stop();
 
-  return transaction.Execute();
+  return transaction.Execute() == ESP_OK;
 }
 
-esp_err_t GpioExpander::Read() {
+bool GpioExpander::Read() {
   uint8_t input_a, input_b;
 
   I2CTransaction transaction;
@@ -56,8 +118,11 @@ esp_err_t GpioExpander::Read() {
       .stop();
 
   esp_err_t ret = transaction.Execute();
+  if (ret != ESP_OK) {
+    return false;
+  }
   inputs_ = pack(input_a, input_b);
-  return ret;
+  return true;
 }
 
 void GpioExpander::set_pin(Pin pin, bool value) {