1 files changed, 87 insertions, 0 deletions
diff --git a/src/drivers/gpio-expander.cpp b/src/drivers/gpio-expander.cpp
new file mode 100644
index 00000000..6b472d1c
--- /dev/null
+++ b/src/drivers/gpio-expander.cpp
@@ -0,0 +1,87 @@
+#include "gpio-expander.hpp"
+
+#include "i2c.hpp"
+
+#include <cstdint>
+
+namespace gay_ipod {
+
+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();
+}
+
+GpioExpander::~GpioExpander() {}
+
+void GpioExpander::with(std::function<void(GpioExpander&)> f) {
+  f(*this);
+  Write();
+}
+
+esp_err_t GpioExpander::Write() {
+  i2c_cmd_handle_t handle = i2c_cmd_link_create();
+  if (handle == NULL) {
+    return ESP_ERR_NO_MEM;
+  }
+
+  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_err_t 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();
+  inputs_ = pack(input_a, input_b);
+  return ret;
+}
+
+void GpioExpander::set_pin(ChipSelect cs, bool value) {
+  set_pin((Pin)cs, value);
+}
+
+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;
+}
+
+GpioExpander::SpiLock GpioExpander::AcquireSpiBus(ChipSelect cs) {
+  // TODO: also spi_device_acquire_bus?
+  return SpiLock(*this, cs);
+}
+
+GpioExpander::SpiLock::SpiLock(GpioExpander& gpio, ChipSelect cs)
+    : lock_(gpio.cs_mutex_), gpio_(gpio), cs_(cs) {
+  gpio_.with([&](auto& gpio) { gpio.set_pin(cs_, 0); });
+}
+
+GpioExpander::SpiLock::~SpiLock() {
+  gpio_.with([&](auto& gpio) { gpio.set_pin(cs_, 1); });
+}
+
+}  // namespace gay_ipod