a845243258
Tweak the documentation to look better when viewed. Use 'write' instead of 'put'. Series-to: concept Series-cc: heinrich Series-version: 2 Cover-letter: console: Refactor in preparation for the pager This series tidies up a few small things the serial and console areas: - Move detection of serial-console size to the serial module - Provide a Kconfig to disable serial detection - Fix some missing driver-model flags in stdio devices - Move console docs into the main documentation This series is marked v2 since some of the patches were sent in any earlier series. With various tweaks that series grew too large to be sent as a single series. END Signed-off-by: Simon Glass <sjg@chromium.org> Series-links: 2:17
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1.9 KiB
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63 lines
1.9 KiB
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.. SPDX-License-Identifier: GPL-2.0+
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.. sectionauthor:: Paolo Scaffardi, AIRVENT SAM s.p.a - RIMINI(ITALY), arsenio@tin.it
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.. (C) Copyright 2000
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=======================
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U-Boot console handling
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=======================
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Introduction
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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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# Use the serial input
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setenv stdin serial
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# Use the video console
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setenv stdout vidconsole
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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 to output text to the console
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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() - write a char to stdout
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- puts() - write a string to stdout
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- printf() - format and write a string to stdout
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stdin
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- tstc() - test for the presence of a char in stdin
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- getchar() - get a char from stdin
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stderr
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- eputc() - write a char to stderr
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- eputs() - write a string to stderr
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- eprintf() - format and write a string to stderr
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file ('stdin', 'stdout' or 'stderr')
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- fputc() - write a char to a file
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- fputs() - write a string to a file
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- fprintf() - format and write a string to a file
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- ftstc() - test for the presence of a char in file
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- fgetc() - get a char from a file
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Remember that FILE-related functions CANNOT be used before U-Boot relocation,
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which is done in `board_init_r()`.
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