[ion] Add getter method for PCB version in string form

ion/include/ion.h

@@ -34,6 +34,7 @@ const char * serialNumber();
 const char * softwareVersion();
 const char * patchLevel();
 const char * fccId();
+const char * pcbVersion();
 
 // CRC32 : non xor-ed, non reversed, direct, polynomial 4C11DB7
 uint32_t crc32Word(const uint32_t * data, size_t length); // Only accepts whole 32bit values

ion/src/device/shared/drivers/serial_number.cpp

@@ -1,4 +1,5 @@
 #include "serial_number.h"
+#include "board.h"
 #include <drivers/config/serial_number.h>
 #include "base64.h"
 
@@ -14,6 +15,24 @@ const char * serialNumber() {
   return serialNumber;
 }
 
+const char * pcbVersion() {
+  constexpr int pcbVersionLength = 5; // xx.yy
+  static char pcbVer[pcbVersionLength] = {'\0'};
+  if (pcbVer[0] == '\0') {
+    Device::Board::PCBVersion ver = Device::Board::pcbVersion();
+    assert(ver < 10000);
+    for (int i = pcbVersionLength - 1; i >= 0; i--) {
+      if (i == 2) {
+        pcbVer[i] = '.';
+      } else {
+        pcbVer[i] = '0' + ver % 10;
+        ver /= 10;
+      }
+    }
+  }
+  return pcbVer;
+}
+
 }
 
 namespace Ion {

ion/src/shared/dummy/serial_number.cpp

@@ -3,3 +3,7 @@
 const char * Ion::serialNumber() {
   return "000000000000";
 }
+
+const char * Ion::pcbVersion() {
+  return "0.0";
+}