diff --git a/tools/i2c/i2c.cpp b/tools/i2c/i2c.cpp
index 04b9c27..bad5b89 100644
--- a/tools/i2c/i2c.cpp
+++ b/tools/i2c/i2c.cpp
@@ -17,16 +17,24 @@
 namespace i2c
 {
 
-void I2CDevice::checkReadFuncs(int type)
+unsigned long I2CDevice::getFuncs()
 {
-    unsigned long funcs;
-
-    /* Check adapter functionality */
-    if (ioctl(fd, I2C_FUNCS, &funcs) < 0)
+    // If functionality has not been cached
+    if (cachedFuncs == NO_FUNCS)
     {
-        throw I2CException("Failed to get funcs", busStr, devAddr, errno);
+        // Get functionality from adapter
+        if (ioctl(fd, I2C_FUNCS, &cachedFuncs) < 0)
+        {
+            throw I2CException("Failed to get funcs", busStr, devAddr, errno);
+        }
     }
 
+    return cachedFuncs;
+}
+
+void I2CDevice::checkReadFuncs(int type)
+{
+    unsigned long funcs = getFuncs();
     switch (type)
     {
         case I2C_SMBUS_BYTE:
@@ -73,14 +81,7 @@
 
 void I2CDevice::checkWriteFuncs(int type)
 {
-    unsigned long funcs;
-
-    /* Check adapter functionality */
-    if (ioctl(fd, I2C_FUNCS, &funcs) < 0)
-    {
-        throw I2CException("Failed to get funcs", busStr, devAddr, errno);
-    }
-
+    unsigned long funcs = getFuncs();
     switch (type)
     {
         case I2C_SMBUS_BYTE:
@@ -154,6 +155,7 @@
         throw I2CException("Failed to close", busStr, devAddr, errno);
     }
     fd = INVALID_FD;
+    cachedFuncs = NO_FUNCS;
 }
 
 void I2CDevice::read(uint8_t& data)
diff --git a/tools/i2c/i2c.hpp b/tools/i2c/i2c.hpp
index b5ddcb8..84e8386 100644
--- a/tools/i2c/i2c.hpp
+++ b/tools/i2c/i2c.hpp
@@ -23,7 +23,7 @@
     explicit I2CDevice(uint8_t busId, uint8_t devAddr,
                        InitialState initialState = InitialState::OPEN) :
         busId(busId),
-        devAddr(devAddr), fd(INVALID_FD)
+        devAddr(devAddr)
     {
         busStr = "/dev/i2c-" + std::to_string(busId);
         if (initialState == InitialState::OPEN)
@@ -35,6 +35,9 @@
     /** @brief Invalid file descriptor */
     static constexpr int INVALID_FD = -1;
 
+    /** @brief Empty adapter functionality value with no bit flags set */
+    static constexpr unsigned long NO_FUNCS = 0;
+
     /** @brief The I2C bus ID */
     uint8_t busId;
 
@@ -42,11 +45,14 @@
     uint8_t devAddr;
 
     /** @brief The file descriptor of the opened i2c device */
-    int fd;
+    int fd = INVALID_FD;
 
     /** @brief The i2c bus path in /dev */
     std::string busStr;
 
+    /** @brief Cached I2C adapter functionality value */
+    unsigned long cachedFuncs = NO_FUNCS;
+
     /** @brief Check that device interface is open
      *
      * @throw I2CException if device is not open
@@ -71,6 +77,16 @@
         }
     }
 
+    /** @brief Get I2C adapter functionality
+     *
+     * Caches the adapter functionality value since it shouldn't change after
+     * opening the device.
+     *
+     * @throw I2CException on error
+     * @return Adapter functionality value
+     */
+    unsigned long getFuncs();
+
     /** @brief Check i2c adapter read functionality
      *
      * Check if the i2c adapter has the functionality specified by the SMBus