Add mozc dial version.

Co-authored-by: Takashi Toyoshima <toyoshim@google.com>
Co-authored-by: Shun Ikejima <ikejima@google.com>

mozc-dial/firmware/sub/i2c_device.h

@@ -0,0 +1,37 @@
+// Copyright 2025 Google Inc.
+// Use of this source code is governed by an Apache License that can be found
+// in the LICENSE file.
+
+#ifndef I2C_DEVICE_H_
+#define I2C_DEVICE_H_
+
+#include <cstdint>
+#include <functional>
+
+#include "hardware/i2c.h"
+#include "pico/i2c_slave.h"
+
+class I2CDevice final {
+ public:
+  using ReadHandler = std::function<uint8_t(uint8_t /*address*/)>;
+  using WriteHandler = std::function<void(uint8_t /*address*/, uint8_t /*value*/)>;
+
+  I2CDevice(i2c_inst_t* i2c, uint8_t sda, uint8_t scl, uint8_t address);
+  I2CDevice(const I2CDevice&) = delete;
+  I2CDevice& operator=(const I2CDevice&) = delete;
+  ~I2CDevice() = default;
+
+  void SetReadHandler(ReadHandler handler);
+  void SetWriteHandler(WriteHandler handler);
+
+ private:
+  static void HandleEvent(i2c_inst_t* i2c, i2c_slave_event_t event);
+  void HandleEventInternal(i2c_inst_t* i2c, i2c_slave_event_t event);
+
+  ReadHandler reader_ = nullptr;
+  WriteHandler writer_ = nullptr;
+  bool address_ready_ = false;
+  uint8_t address_ = 0;
+};
+
+#endif  // I2C_DEVICE_H_