[edk2-platforms][PATCH v2 2/5] Platform/RPi3/RpiFirmwareDxe: Improve serial number population

["Pete Batard" <pete@akeo.ie>]

Improve RpiFirmwareGetSerial() to derive a serial number from the
MAC address, in case the platform returns 0 for the serial number.

Also fix a typo where "%s" was used instead of "%a".

Signed-off-by: Pete Batard <pete@akeo.ie>
---
 Platform/RaspberryPi/RPi3/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Platform/RaspberryPi/RPi3/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c b/Platform/RaspberryPi/RPi3/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c
index 378c99bcba05..c2344252d2c0 100644
--- a/Platform/RaspberryPi/RPi3/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c
+++ b/Platform/RaspberryPi/RPi3/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.c
@@ -219,7 +219,7 @@ RpiFirmwareSetPowerState (
 
   if (!EFI_ERROR (Status) &&
       PowerState ^ (Cmd->TagBody.PowerState & RPI_MBOX_POWER_STATE_ENABLE)) {
-    DEBUG ((DEBUG_ERROR, "%a: failed to %sable power for device %d\n",
+    DEBUG ((DEBUG_ERROR, "%a: failed to %aable power for device %d\n",
       __FUNCTION__, PowerState ? "en" : "dis", DeviceId));
     Status = EFI_DEVICE_ERROR;
   }
@@ -393,7 +393,14 @@ RpiFirmwareGetSerial (
   }
 
   *Serial = Cmd->TagBody.Serial;
-  return EFI_SUCCESS;
+  // Some platforms return 0 for serial. For those, try to use the MAC address.
+  if (*Serial == 0) {
+    Status = RpiFirmwareGetMacAddress ((UINT8*) Serial);
+    // Convert to a more user-friendly value
+    *Serial = SwapBytes64 (*Serial << 16);
+  }
+
+  return Status;
 }
 
 #pragma pack()
-- 
2.21.0.windows.1