Marek VasutandHeinrich Schuchardt
dc3765ede5
The "env" command is the recommended environment management command, its "set" subcommand is the equivalent replacement for legacy "setenv" command. Update the documentation to use the contemporary "env set" command instead of legacy "setenv" command. Note that the "setenv" command is unlikely to be removed from U-Boot in the near future due to it being integral part of the command line ABI. Implemented using: $ sed -i 's@\<setenv\>@env set@g' $(git grep -li '\<setenv\>' doc/) README Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
101 lines
3.1 KiB
Plaintext
101 lines
3.1 KiB
Plaintext
SPDX-License-Identifier: GPL-2.0+
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/*
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* (C) Copyright 2000
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* Paolo Scaffardi, AIRVENT SAM s.p.a - RIMINI(ITALY), arsenio@tin.it
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*/
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U-Boot console handling
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========================
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HOW THE CONSOLE WORKS?
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----------------------
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At system startup U-Boot initializes a serial console. When U-Boot
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relocates itself to RAM, all console drivers are initialized (they
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will register all detected console devices to the system for further
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use).
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If not defined in the environment, the first input device is assigned
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to the 'stdin' file, the first output one to 'stdout' and 'stderr'.
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You can use the command "coninfo" to see all registered console
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devices and their flags. You can assign a standard file (stdin,
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stdout or stderr) to any device you see in that list simply by
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assigning its name to the corresponding environment variable. For
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example:
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env set stdin serial <- To use the serial input
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env set stdout video <- To use the video console
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Do a simple "saveenv" to save the console settings in the environment
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and get them working on the next startup, too.
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HOW CAN I USE STANDARD FILE INTO THE SOURCES?
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---------------------------------------------
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You can use the following functions to access the console:
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* STDOUT:
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putc (to put a char to stdout)
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puts (to put a string to stdout)
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printf (to format and put a string to stdout)
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* STDIN:
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tstc (to test for the presence of a char in stdin)
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getc (to get a char from stdin)
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* STDERR:
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eputc (to put a char to stderr)
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eputs (to put a string to stderr)
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eprintf (to format and put a string to stderr)
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* FILE (can be 'stdin', 'stdout', 'stderr'):
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fputc (like putc but redirected to a file)
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fputs (like puts but redirected to a file)
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fprintf (like printf but redirected to a file)
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ftstc (like tstc but redirected to a file)
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fgetc (like getc but redirected to a file)
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Remember that all FILE-related functions CANNOT be used before
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U-Boot relocation (done in 'board_init_r' in arch/*/lib/board.c).
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HOW CAN I USE STANDARD FILE INTO APPLICATIONS?
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----------------------------------------------
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Use the 'bd_mon_fnc' field of the bd_info structure passed to the
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application to do everything you want with the console.
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But REMEMBER that that will work only if you have not overwritten any
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U-Boot code while loading (or uncompressing) the image of your
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application.
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For example, you won't get the console stuff running in the Linux
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kernel because the kernel overwrites U-Boot before running. Only
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some parameters like the framebuffer descriptors are passed to the
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kernel in the high memory area to let the applications (the kernel)
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use the framebuffers initialized by U-Boot.
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SUPPORTED DRIVERS
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-----------------
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Working drivers:
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serial (architecture dependent serial stuff)
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video (mpc8xx video controller)
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Work in progress:
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wl_kbd (Wireless 4PPM keyboard)
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Waiting for volounteers:
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lcd (mpc8xx lcd controller; to )
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TESTED CONFIGURATIONS
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---------------------
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The driver has been tested with the following configurations (see
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CREDITS for other contact informations):
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- MPC823FADS with AD7176 on a PAL TV (YCbYCr) - arsenio@tin.it
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