feat: add support for corn staking enabled atokens

contracts/interfaces/ICornStakingSilo.sol

@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: AGPL-3.0
+pragma solidity ^0.8.0;
+
+
+interface ICornStakingSilo {
+    function sharesOf(address user, address token) external view returns (uint256);
+}

contracts/interfaces/IDefaultInterestRateStrategy.sol

@@ -42,6 +42,12 @@ interface IDefaultInterestRateStrategy is IReserveInterestRateStrategy {
    */
   function ADDRESSES_PROVIDER() external view returns (IPoolAddressesProvider);
 
+  /**
+   * @notice Returns the address of the Corn Staking Silo
+   * @return The address of the Corn Staking Silo contract
+   */
+  function CORN_STAKING() external view returns (ICornStakingSilo);
+
   /**
    * @notice Returns the variable rate slope below optimal usage ratio
    * @dev It's the variable rate when usage ratio > 0 and <= OPTIMAL_USAGE_RATIO

contracts/protocol/pool/DefaultReserveInterestRateStrategy.sol

@@ -9,6 +9,7 @@ import {Errors} from '../libraries/helpers/Errors.sol';
 import {IDefaultInterestRateStrategy} from '../../interfaces/IDefaultInterestRateStrategy.sol';
 import {IReserveInterestRateStrategy} from '../../interfaces/IReserveInterestRateStrategy.sol';
 import {IPoolAddressesProvider} from '../../interfaces/IPoolAddressesProvider.sol';
+import { ICornStakingSilo } from "../../interfaces/ICornStakingSilo.sol";
 
 /**
  * @title DefaultReserveInterestRateStrategy contract
@@ -58,6 +59,10 @@ contract DefaultReserveInterestRateStrategy is IDefaultInterestRateStrategy {
   // Additional premium applied to stable rate when stable debt surpass `OPTIMAL_STABLE_TO_TOTAL_DEBT_RATIO`
   uint256 internal immutable _stableRateExcessOffset;
 
+  // The corn staking contract
+  ICornStakingSilo public immutable CORN_STAKING;
+
+
   /**
    * @dev Constructor.
    * @param provider The address of the PoolAddressesProvider contract
@@ -81,7 +86,8 @@ contract DefaultReserveInterestRateStrategy is IDefaultInterestRateStrategy {
     uint256 stableRateSlope2,
     uint256 baseStableRateOffset,
     uint256 stableRateExcessOffset,
-    uint256 optimalStableToTotalDebtRatio
+    uint256 optimalStableToTotalDebtRatio,
+    address cornStaking
   ) {
     require(WadRayMath.RAY >= optimalUsageRatio, Errors.INVALID_OPTIMAL_USAGE_RATIO);
     require(
@@ -93,6 +99,7 @@ contract DefaultReserveInterestRateStrategy is IDefaultInterestRateStrategy {
     OPTIMAL_STABLE_TO_TOTAL_DEBT_RATIO = optimalStableToTotalDebtRatio;
     MAX_EXCESS_STABLE_TO_TOTAL_DEBT_RATIO = WadRayMath.RAY - optimalStableToTotalDebtRatio;
     ADDRESSES_PROVIDER = provider;
+    CORN_STAKING = ICornStakingSilo(cornStaking);
     _baseVariableBorrowRate = baseVariableBorrowRate;
     _variableRateSlope1 = variableRateSlope1;
     _variableRateSlope2 = variableRateSlope2;
@@ -170,6 +177,7 @@ contract DefaultReserveInterestRateStrategy is IDefaultInterestRateStrategy {
       vars.stableToTotalDebtRatio = params.totalStableDebt.rayDiv(vars.totalDebt);
       vars.availableLiquidity =
         IERC20(params.reserve).balanceOf(params.aToken) +
+        _getCornStakingBalance(params.reserve, params.aToken) +
         params.liquidityAdded -
         params.liquidityTaken;
 
@@ -253,4 +261,16 @@ contract DefaultReserveInterestRateStrategy is IDefaultInterestRateStrategy {
 
     return overallBorrowRate;
   }
+
+  /**
+   * @dev Returns the number of assets staked in the corn staking, if the asset is being staked into the corn staking
+   * else returns 0.
+   * @param asset The address of the asset
+   * @param aToken The address of the aToken
+   * @return The number of assets staked in the corn staking
+   */
+  function _getCornStakingBalance(address asset, address aToken) internal view returns (uint256) {
+    return CORN_STAKING.sharesOf(aToken, asset);
+  }
+
 }