diff --git a/selfdrive/boardd/panda.cc b/selfdrive/boardd/panda.cc
index d4d53aa230..b12b26fb62 100644
--- a/selfdrive/boardd/panda.cc
+++ b/selfdrive/boardd/panda.cc
@@ -3,7 +3,9 @@
 #include <unistd.h>
 
 #include <cassert>
+#include <iomanip>
 #include <stdexcept>
+#include <sstream>
 
 #include "cereal/messaging/messaging.h"
 #include "common/swaglog.h"
@@ -40,7 +42,26 @@ bool Panda::comms_healthy() {
 }
 
 std::vector<std::string> Panda::list() {
-  return PandaUsbHandle::list();
+  std::vector<std::string> serials = PandaUsbHandle::list();
+
+  // check SPI
+  const int uid_len = 12;
+  uint8_t uid[uid_len] = {0};
+  PandaSpiHandle spi_handle("/dev/spidev0.0");
+  int ret = spi_handle.control_read(0xc3, 0, 0, uid, uid_len);
+  if (ret == uid_len) {
+    std::stringstream stream;
+    for (int i = 0; i < uid_len; i++) {
+      stream << std::hex << std::setw(2) << std::setfill('0') << int(uid[i]);
+    }
+
+    // might be on USB too
+    if (std::find(serials.begin(), serials.end(), stream.str()) == serials.end()) {
+      serials.push_back(stream.str());
+    }
+  }
+
+  return serials;
 }
 
 void Panda::set_safety_model(cereal::CarParams::SafetyModel safety_model, uint16_t safety_param) {
diff --git a/selfdrive/boardd/panda_comms.h b/selfdrive/boardd/panda_comms.h
index bd262dfa0e..9d1f69e671 100644
--- a/selfdrive/boardd/panda_comms.h
+++ b/selfdrive/boardd/panda_comms.h
@@ -30,9 +30,6 @@ public:
   virtual int control_read(uint8_t request, uint16_t param1, uint16_t param2, unsigned char *data, uint16_t length, unsigned int timeout=TIMEOUT) = 0;
   virtual int bulk_write(unsigned char endpoint, unsigned char* data, int length, unsigned int timeout=TIMEOUT) = 0;
   virtual int bulk_read(unsigned char endpoint, unsigned char* data, int length, unsigned int timeout=TIMEOUT) = 0;
-
-protected:
-  std::recursive_mutex hw_lock;
 };
 
 class PandaUsbHandle : public PandaCommsHandle {
@@ -50,6 +47,7 @@ public:
 private:
   libusb_context *ctx = NULL;
   libusb_device_handle *dev_handle = NULL;
+  std::recursive_mutex hw_lock;
   void handle_usb_issue(int err, const char func[]);
 };
 
@@ -69,6 +67,7 @@ private:
   int spi_fd = -1;
   uint8_t tx_buf[SPI_BUF_SIZE];
   uint8_t rx_buf[SPI_BUF_SIZE];
+  inline static std::recursive_mutex hw_lock;
 
   int wait_for_ack(spi_ioc_transfer &transfer, uint8_t ack);
   int bulk_transfer(uint8_t endpoint, uint8_t *tx_data, uint16_t tx_len, uint8_t *rx_data, uint16_t rx_len);