From 053415a22e666a28e582c23fccebf89a033cfe88 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Thu, 4 Sep 2025 14:02:31 -0500
Subject: [PATCH] [mcp23016] Migrate to CachedGpioExpander to reduce I2C bus
 usage

---
 esphome/components/mcp23016/__init__.py  |  1 +
 esphome/components/mcp23016/mcp23016.cpp | 27 ++++++++++++++++++------
 esphome/components/mcp23016/mcp23016.h   | 14 ++++++++----
 3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/esphome/components/mcp23016/__init__.py b/esphome/components/mcp23016/__init__.py
index 3333e46c97..5a1f011617 100644
--- a/esphome/components/mcp23016/__init__.py
+++ b/esphome/components/mcp23016/__init__.py
@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_OUTPUT,
 )
 
+AUTO_LOAD = ["gpio_expander"]
 DEPENDENCIES = ["i2c"]
 MULTI_CONF = True
 
diff --git a/esphome/components/mcp23016/mcp23016.cpp b/esphome/components/mcp23016/mcp23016.cpp
index 9d8d6e4dae..56aa36b78b 100644
--- a/esphome/components/mcp23016/mcp23016.cpp
+++ b/esphome/components/mcp23016/mcp23016.cpp
@@ -22,14 +22,29 @@ void MCP23016::setup() {
   this->write_reg_(MCP23016_IODIR0, 0xFF);
   this->write_reg_(MCP23016_IODIR1, 0xFF);
 }
-bool MCP23016::digital_read(uint8_t pin) {
-  uint8_t bit = pin % 8;
+
+void MCP23016::loop() {
+  // Invalidate cache at the start of each loop
+  this->reset_pin_cache_();
+}
+bool MCP23016::digital_read_hw(uint8_t pin) {
   uint8_t reg_addr = pin < 8 ? MCP23016_GP0 : MCP23016_GP1;
   uint8_t value = 0;
-  this->read_reg_(reg_addr, &value);
-  return value & (1 << bit);
+  if (!this->read_reg_(reg_addr, &value)) {
+    return false;
+  }
+
+  // Update the appropriate part of input_mask_
+  if (pin < 8) {
+    this->input_mask_ = (this->input_mask_ & 0xFF00) | value;
+  } else {
+    this->input_mask_ = (this->input_mask_ & 0x00FF) | (uint16_t(value) << 8);
+  }
+  return true;
 }
-void MCP23016::digital_write(uint8_t pin, bool value) {
+
+bool MCP23016::digital_read_cache(uint8_t pin) { return this->input_mask_ & (1 << pin); }
+void MCP23016::digital_write_hw(uint8_t pin, bool value) {
   uint8_t reg_addr = pin < 8 ? MCP23016_OLAT0 : MCP23016_OLAT1;
   this->update_reg_(pin, value, reg_addr);
 }
@@ -41,7 +56,7 @@ void MCP23016::pin_mode(uint8_t pin, gpio::Flags flags) {
     this->update_reg_(pin, false, iodir);
   }
 }
-float MCP23016::get_setup_priority() const { return setup_priority::HARDWARE; }
+float MCP23016::get_setup_priority() const { return setup_priority::IO; }
 bool MCP23016::read_reg_(uint8_t reg, uint8_t *value) {
   if (this->is_failed())
     return false;
diff --git a/esphome/components/mcp23016/mcp23016.h b/esphome/components/mcp23016/mcp23016.h
index e4ed47a3b2..781c207de0 100644
--- a/esphome/components/mcp23016/mcp23016.h
+++ b/esphome/components/mcp23016/mcp23016.h
@@ -3,6 +3,7 @@
 #include "esphome/core/component.h"
 #include "esphome/core/hal.h"
 #include "esphome/components/i2c/i2c.h"
+#include "esphome/components/gpio_expander/cached_gpio.h"
 
 namespace esphome {
 namespace mcp23016 {
@@ -24,19 +25,22 @@ enum MCP23016GPIORegisters {
   MCP23016_IOCON1 = 0x0B,
 };
 
-class MCP23016 : public Component, public i2c::I2CDevice {
+class MCP23016 : public Component, public i2c::I2CDevice, public gpio_expander::CachedGpioExpander<uint8_t, 16> {
  public:
   MCP23016() = default;
 
   void setup() override;
-
-  bool digital_read(uint8_t pin);
-  void digital_write(uint8_t pin, bool value);
+  void loop() override;
   void pin_mode(uint8_t pin, gpio::Flags flags);
 
   float get_setup_priority() const override;
 
  protected:
+  // Virtual methods from CachedGpioExpander
+  bool digital_read_hw(uint8_t pin) override;
+  bool digital_read_cache(uint8_t pin) override;
+  void digital_write_hw(uint8_t pin, bool value) override;
+
   // read a given register
   bool read_reg_(uint8_t reg, uint8_t *value);
   // write a value to a given register
@@ -46,6 +50,8 @@ class MCP23016 : public Component, public i2c::I2CDevice {
 
   uint8_t olat_0_{0x00};
   uint8_t olat_1_{0x00};
+  // Cache for input values (16-bit combined for both banks)
+  uint16_t input_mask_{0x00};
 };
 
 class MCP23016GPIOPin : public GPIOPin {