tangara-fw/src/drivers/gpios.cpp

/*
 * Copyright 2023 jacqueline <me@jacqueline.id.au>
 *
 * SPDX-License-Identifier: GPL-3.0-only
 */

#include "gpios.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) {
  Gpios* instance = reinterpret_cast<Gpios*>(arg);
  auto listener = instance->listener();
  if (listener != nullptr) {
    std::invoke(*listener);
  }
}

auto Gpios::Create() -> Gpios* {
  Gpios* instance = new Gpios();
  // Read and write initial values on initialisation so that we do not have a
  // strange partially-initialised state.
  if (!instance->Flush() || !instance->Read()) {
    return nullptr;
  }
  return instance;
}

Gpios::Gpios()
    : ports_(pack(kPortADefault, kPortBDefault)),
      inputs_(0),
      listener_(nullptr) {
  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);
}

Gpios::~Gpios() {
  gpio_isr_handler_remove(GPIO_NUM_34);
  gpio_uninstall_isr_service();
}

auto Gpios::WriteBuffered(Pin pin, bool value) -> void {
  if (value) {
    ports_ |= (1 << static_cast<int>(pin));
  } else {
    ports_ &= ~(1 << static_cast<int>(pin));
  }
}

auto Gpios::WriteSync(Pin pin, bool value) -> bool {
  WriteBuffered(pin, value);
  return Flush();
}

auto Gpios::Flush() -> bool {
  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;
}

auto Gpios::Get(Pin pin) const -> bool {
  return (inputs_ & (1 << static_cast<int>(pin))) > 0;
}

auto Gpios::Read() -> bool {
  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;
}

}  // namespace drivers