From 8d33c6de364e3f231cdb2ae9b1bedb588381eb3c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Obrembski?= <michal@obrembski.dev>
Date: Sat, 3 May 2025 00:54:27 +0200
Subject: [PATCH] Added Banking support to tca9555, fixed input bug (#8003)

Co-authored-by: Jesse Hills <3060199+jesserockz@users.noreply.github.com>
---
 .../components/gpio_expander/cached_gpio.h    | 29 ++++++++++++++-----
 esphome/components/tca9555/tca9555.cpp        | 17 +++++++----
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/esphome/components/gpio_expander/cached_gpio.h b/esphome/components/gpio_expander/cached_gpio.h
index 784c5f0f4a..78c675cdb2 100644
--- a/esphome/components/gpio_expander/cached_gpio.h
+++ b/esphome/components/gpio_expander/cached_gpio.h
@@ -8,30 +8,45 @@ namespace esphome {
 namespace gpio_expander {
 
 /// @brief A class to cache the read state of a GPIO expander.
+///        This class caches reads between GPIO Pins which are on the same bank.
+///        This means that for reading whole Port (ex. 8 pins) component needs only one
+///        I2C/SPI read per main loop call. It assumes, that one bit in byte identifies one GPIO pin
+///        Template parameters:
+///           T - Type which represents internal register. Could be uint8_t or uint16_t. Adjust to
+///               match size of your internal GPIO bank register.
+///           N - Number of pins
 template<typename T, T N> class CachedGpioExpander {
  public:
   bool digital_read(T pin) {
-    if (!this->read_cache_invalidated_[pin]) {
-      this->read_cache_invalidated_[pin] = true;
-      return this->digital_read_cache(pin);
+    uint8_t bank = pin / (sizeof(T) * BITS_PER_BYTE);
+    if (this->read_cache_invalidated_[bank]) {
+      this->read_cache_invalidated_[bank] = false;
+      if (!this->digital_read_hw(pin))
+        return false;
     }
-    return this->digital_read_hw(pin);
+    return this->digital_read_cache(pin);
   }
 
   void digital_write(T pin, bool value) { this->digital_write_hw(pin, value); }
 
  protected:
+  /// @brief Call component low level function to read GPIO state from device
   virtual bool digital_read_hw(T pin) = 0;
+  /// @brief Call component read function from internal cache.
   virtual bool digital_read_cache(T pin) = 0;
+  /// @brief Call component low level function to write GPIO state to device
   virtual void digital_write_hw(T pin, bool value) = 0;
+  const uint8_t cache_byte_size_ = N / (sizeof(T) * BITS_PER_BYTE);
 
+  /// @brief Invalidate cache. This function should be called in component loop().
   void reset_pin_cache_() {
-    for (T i = 0; i < N; i++) {
-      this->read_cache_invalidated_[i] = false;
+    for (T i = 0; i < this->cache_byte_size_; i++) {
+      this->read_cache_invalidated_[i] = true;
     }
   }
 
-  std::array<bool, N> read_cache_invalidated_{};
+  static const uint8_t BITS_PER_BYTE = 8;
+  std::array<bool, N / (sizeof(T) * BITS_PER_BYTE)> read_cache_invalidated_{};
 };
 
 }  // namespace gpio_expander
diff --git a/esphome/components/tca9555/tca9555.cpp b/esphome/components/tca9555/tca9555.cpp
index cf0894427f..e065398c46 100644
--- a/esphome/components/tca9555/tca9555.cpp
+++ b/esphome/components/tca9555/tca9555.cpp
@@ -76,15 +76,20 @@ bool TCA9555Component::read_gpio_modes_() {
 bool TCA9555Component::digital_read_hw(uint8_t pin) {
   if (this->is_failed())
     return false;
-  bool success;
-  uint8_t data[2];
-  success = this->read_bytes(TCA9555_INPUT_PORT_REGISTER_0, data, 2);
-  this->input_mask_ = (uint16_t(data[1]) << 8) | (uint16_t(data[0]) << 0);
-
-  if (!success) {
+  uint8_t data;
+  uint8_t bank_number = pin < 8 ? 0 : 1;
+  uint8_t register_to_read = bank_number ? TCA9555_INPUT_PORT_REGISTER_1 : TCA9555_INPUT_PORT_REGISTER_0;
+  if (!this->read_bytes(register_to_read, &data, 1)) {
     this->status_set_warning("Failed to read input register");
     return false;
   }
+  uint8_t second_half = this->input_mask_ >> 8;
+  uint8_t first_half = this->input_mask_;
+  if (bank_number) {
+    this->input_mask_ = (data << 8) | (uint16_t(first_half) << 0);
+  } else {
+    this->input_mask_ = (uint16_t(second_half) << 8) | (data << 0);
+  }
 
   this->status_clear_warning();
   return true;