SPDX-License-Identifier: GPL-2.0+

  /*
   * Copyright 2014 Broadcom Corporation.

   */
  
  Semihosting is ARM's way of having a real or virtual target communicate
  with a host or host debugger for basic operations such as file I/O,
  console I/O, etc. Please see
  http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0471c/Bgbjjgij.html for more information.
  
  For developing on armv8 virtual fastmodel platforms, semihosting is a
  valuable tool since it allows access to image/configuration files before
  eMMC or other NV media are available.
  
  There are two main ARM virtual Fixed Virtual Platform (FVP) models,
  Versatile Express (VE) FVP and BASE FVP (See
  http://www.arm.com/products/tools/models/fast-models/foundation-model.php)
  The initial vexpress64 u-boot board created here runs on the VE virtual
  platform using the license-free Foundation_v8 simulator. Fortunately,
  the Foundation_v8 simulator also supports the BASE_FVP model which
  companies can purchase licenses for and contain much more functionality.
  So we can, in u-boot, run either model by either using the VE FVP (default),
  or turning on CONFIG_BASE_FVP for the more full featured model.
  
  Rather than create a new armv8 board similar to armltd/vexpress64, add
  semihosting calls to the existing one, enabled with CONFIG_SEMIHOSTING
  and CONFIG_BASE_FVP both set. Also reuse the existing board config file
  vexpress_aemv8a.h but differentiate the two models by the presence or
  absence of CONFIG_BASE_FVP. This change is tested and works on both the
  Foundation and Base fastmodel simulators.

  The semihosting code adds a command:

    smhload <image> <address> [env var]

  That will load an image from the host filesystem into RAM at the specified
  address and optionally store the load end address in the specified
  environment variable.