ArmPlatformPkg/ArmVExpressFastBootDxe: clean up code and comments

This module contains an implementation of the Android Fastboot Platform
protocol. So follow common Tianocore practice, and duplicate the per-method
comment blocks from the interface definition into the implementation.

In addition, let's make all methods and the procotol struct STATIC, given
that they are never referenced via external linkage.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Laszlo Ersek <lersek@redhat.com>

ArmPlatformPkg/ArmVExpressPkg/ArmVExpressFastBootDxe/ArmVExpressFastBoot.c

@@ -1,6 +1,7 @@
 /** @file
 
   Copyright (c) 2014, ARM Ltd. All rights reserved.<BR>
+  Copyright (c) 2016, Linaro Ltd. All rights reserved.<BR>
 
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
@@ -135,11 +136,13 @@ ReadPartitionEntries (
 
 
 /*
-  Initialise: Open the Android NVM device and find the partitions on it. Save them in
-  a list along with the "PartitionName" fields for their GPT entries.
-  We will use these partition names as the key in
-  ArmFastbootPlatformFlashPartition.
+  Do any initialisation that needs to be done in order to be able to respond to
+  commands.
+
+  @retval EFI_SUCCESS   Initialised successfully.
+  @retval !EFI_SUCCESS  Error in initialisation.
 */
+STATIC
 EFI_STATUS
 ArmFastbootPlatformInit (
   VOID
@@ -164,6 +167,7 @@ ArmFastbootPlatformInit (
   //
   // Get EFI_HANDLES for all the partitions on the block devices pointed to by
   // PcdFastbootFlashDevicePath, also saving their GPT partition labels.
+  // We will use these labels as the key in ArmFastbootPlatformFlashPartition.
   // There's no way to find all of a device's children, so we get every handle
   // in the system supporting EFI_BLOCK_IO_PROTOCOL and then filter out ones
   // that don't represent partitions on the flash device.
@@ -296,6 +300,11 @@ Exit:
 
 }
 
+/*
+  To be called when Fastboot is finished and we aren't rebooting or booting an
+  image. Undo initialisation, free resrouces.
+*/
+STATIC
 VOID
 ArmFastbootPlatformUnInit (
   VOID
@@ -304,6 +313,18 @@ ArmFastbootPlatformUnInit (
   FreePartitionList ();
 }
 
+/*
+  Flash the partition named (according to a platform-specific scheme)
+  PartitionName, with the image pointed to by Buffer, whose size is BufferSize.
+
+  @param[in] PartitionName  Null-terminated name of partition to write.
+  @param[in] BufferSize     Size of Buffer in byets.
+  @param[in] Buffer         Data to write to partition.
+
+  @retval EFI_NOT_FOUND     No such partition.
+  @retval EFI_DEVICE_ERROR  Flashing failed.
+*/
+STATIC
 EFI_STATUS
 ArmFastbootPlatformFlashPartition (
   IN CHAR8  *PartitionName,
@@ -381,6 +402,15 @@ ArmFastbootPlatformFlashPartition (
   return Status;
 }
 
+/*
+  Erase the partition named PartitionName.
+
+  @param[in] PartitionName  Null-terminated name of partition to erase.
+
+  @retval EFI_NOT_FOUND     No such partition.
+  @retval EFI_DEVICE_ERROR  Erasing failed.
+*/
+STATIC
 EFI_STATUS
 ArmFastbootPlatformErasePartition (
   IN CHAR8 *Partition
@@ -389,6 +419,25 @@ ArmFastbootPlatformErasePartition (
   return EFI_SUCCESS;
 }
 
+/*
+  If the variable referred to by Name exists, copy it (as a null-terminated
+  string) into Value. If it doesn't exist, put the Empty string in Value.
+
+  Variable names and values may not be larger than 60 bytes, excluding the
+  terminal null character. This is a limitation of the Fastboot protocol.
+
+  The Fastboot application will handle platform-nonspecific variables
+  (Currently "version" is the only one of these.)
+
+  @param[in]  Name   Null-terminated name of Fastboot variable to retrieve.
+  @param[out] Value  Caller-allocated buffer for null-terminated value of
+                     variable.
+
+  @retval EFI_SUCCESS       The variable was retrieved, or it doesn't exist.
+  @retval EFI_DEVICE_ERROR  There was an error looking up the variable. This
+                            does _not_ include the variable not existing.
+*/
+STATIC
 EFI_STATUS
 ArmFastbootPlatformGetVar (
   IN  CHAR8   *Name,
@@ -403,6 +452,26 @@ ArmFastbootPlatformGetVar (
   return EFI_SUCCESS;
 }
 
+/*
+  React to an OEM-specific command.
+
+  Future versions of this function might want to allow the platform to do some
+  extra communication with the host. A way to do this would be to add a function
+  to the FASTBOOT_TRANSPORT_PROTOCOL that allows the implementation of
+  DoOemCommand to replace the ReceiveEvent with its own, and to restore the old
+  one when it's finished.
+
+  However at the moment although the specification allows it, the AOSP fastboot
+  host application doesn't handle receiving any data from the client, and it
+  doesn't support a data phase for OEM commands.
+
+  @param[in] Command    Null-terminated command string.
+
+  @retval EFI_SUCCESS       The command executed successfully.
+  @retval EFI_NOT_FOUND     The command wasn't recognised.
+  @retval EFI_DEVICE_ERROR  There was an error executing the command.
+*/
+STATIC
 EFI_STATUS
 ArmFastbootPlatformOemCommand (
   IN  CHAR8   *Command
@@ -424,7 +493,7 @@ ArmFastbootPlatformOemCommand (
   }
 }
 
-FASTBOOT_PLATFORM_PROTOCOL mPlatformProtocol = {
+STATIC FASTBOOT_PLATFORM_PROTOCOL mPlatformProtocol = {
   ArmFastbootPlatformInit,
   ArmFastbootPlatformUnInit,
   ArmFastbootPlatformFlashPartition,