diff --git a/pci_handler.hpp b/pci_handler.hpp
index df936e4..2594f09 100644
--- a/pci_handler.hpp
+++ b/pci_handler.hpp
@@ -8,13 +8,23 @@
 namespace blobs
 {
 
+/** P2A configuration response. */
+struct PciConfigResponse
+{
+    std::uint32_t address;
+} __attribute__((packed));
+
+/**
+ * Data handler for reading and writing data via the P2A bridge.
+ */
 class PciDataHandler : public DataInterface
 {
-
   public:
     PciDataHandler() = default;
 
     std::vector<std::uint8_t> copyFrom(std::uint32_t length) override;
+    bool write(const std::vector<std::uint8_t>& configuration) override;
+    std::vector<std::uint8_t> read() override;
 };
 
 } // namespace blobs