SPDX-License-Identifier: GPL-2.0+

  /*
   * (C) Copyright 2000
   * Paolo Scaffardi, AIRVENT SAM s.p.a - RIMINI(ITALY), arsenio@tin.it

   */
  
  U-Boot console handling
  ========================
  
  HOW THE CONSOLE WORKS?
  ----------------------
  
  At system startup U-Boot initializes a serial console. When U-Boot
  relocates itself to RAM, all console drivers are initialized (they
  will register all detected console devices to the system for further
  use).
  
  If not defined in the environment, the first input device is assigned
  to the 'stdin' file, the first output one to 'stdout' and 'stderr'.
  
  You can use the command "coninfo" to see all registered console
  devices and their flags. You can assign a standard file (stdin,
  stdout or stderr) to any device you see in that list simply by
  assigning its name to the corresponding environment variable. For
  example:

      setenv stdin serial		<- To use the serial input

      setenv stdout video		<- To use the video console
  
  Do a simple "saveenv" to save the console settings in the environment
  and get them working on the next startup, too.
  
  HOW CAN I USE STANDARD FILE INTO THE SOURCES?
  ---------------------------------------------
  
  You can use the following functions to access the console:
  
  * STDOUT:
      putc	(to put a char to stdout)
      puts	(to put a string to stdout)
      printf	(to format and put a string to stdout)
  
  * STDIN:
      tstc	(to test for the presence of a char in stdin)
      getc	(to get a char from stdin)
  
  * STDERR:
      eputc	(to put a char to stderr)
      eputs	(to put a string to stderr)
      eprintf	(to format and put a string to stderr)
  
  * FILE (can be 'stdin', 'stdout', 'stderr'):
      fputc	(like putc but redirected to a file)
      fputs	(like puts but redirected to a file)
      fprintf	(like printf but redirected to a file)
      ftstc	(like tstc but redirected to a file)
      fgetc	(like getc but redirected to a file)
  
  Remember that all FILE-related functions CANNOT be used before

  U-Boot relocation (done in 'board_init_r' in arch/*/lib/board.c).

  
  HOW CAN I USE STANDARD FILE INTO APPLICATIONS?
  ----------------------------------------------
  
  Use the 'bd_mon_fnc' field of the bd_t structure passed to the
  application to do everything you want with the console.
  
  But REMEMBER that that will work only if you have not overwritten any
  U-Boot code while loading (or uncompressing) the image of your
  application.
  
  For example, you won't get the console stuff running in the Linux
  kernel because the kernel overwrites U-Boot before running. Only
  some parameters like the framebuffer descriptors are passed to the
  kernel in the high memory area to let the applications (the kernel)
  use the framebuffers initialized by U-Boot.
  
  SUPPORTED DRIVERS
  -----------------
  
  Working drivers:

      serial	(architecture dependent serial stuff)
      video	(mpc8xx video controller)

  
  Work in progress:
  
      wl_kbd	(Wireless 4PPM keyboard)
  
  Waiting for volounteers:
  
      lcd	(mpc8xx lcd controller; to )
  
  TESTED CONFIGURATIONS
  ---------------------
  
  The driver has been tested with the following configurations (see
  CREDITS for other contact informations):

  - MPC823FADS with AD7176 on a PAL TV (YCbYCr)	- arsenio@tin.it