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serial: Generalise the code to check the terminal size

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The EFI loader has some code to check the size (rows and columns) of an
attached terminal. Move this over to the serial uclass so that it can be
used elsewhere.

Create a new CONFIG_SERIAL_TERM_PRESENT to control whether it should be
used. Enable that for the EFI loader to preserve existing behaviour.

Adjust the implementation so that it returns a useful error code on
failure. Put the ESC and cESC values in the serial.h header.

Series-changes: 3
- Update comment for serial_query_size()

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass
2025-08-24 16:16:28 -06:00
parent 38af9c7f97
commit 8364e9af3e
4 changed files with 154 additions and 121 deletions
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124
lib/efi_loader/efi_console.c
View File

@@ -16,6 +16,7 @@
#include <efi_loader.h>
#include <env.h>
#include <log.h>
#include <serial.h>
#include <stdio_dev.h>
#include <video_console.h>
#include <linux/delay.h>
@@ -59,9 +60,6 @@ const efi_guid_t efi_guid_text_input_protocol =
const efi_guid_t efi_guid_text_output_protocol =
EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL_GUID;
#define cESC '\x1b'
#define ESC "\x1b"
/*
* efi_con_mode - mode information of the Simple Text Output Protocol
*
@@ -77,76 +75,6 @@ static struct simple_text_output_mode efi_con_mode = {
.cursor_visible = 1,
};
/**
* term_get_char() - read a character from the console
*
* Wait for up to 100 ms to read a character from the console.
*
* @c: pointer to the buffer to receive the character
* Return: 0 on success, 1 otherwise
*/
static int term_get_char(s32 *c)
{
u64 timeout;
/* Wait up to 100 ms for a character */
timeout = timer_get_us() + 100000;
while (!tstc())
if (timer_get_us() > timeout)
return 1;
*c = getchar();
return 0;
}
/**
* term_read_reply() - receive and parse a reply from the terminal
*
* @n: array of return values
* @num: number of return values expected
* @end_char: character indicating end of terminal message
* Return: non-zero indicates error
*/
static int term_read_reply(int *n, int num, char end_char)
{
s32 c;
int i = 0;
if (term_get_char(&c) || c != cESC)
return -1;
if (term_get_char(&c) || c != '[')
return -1;
n[0] = 0;
while (1) {
if (!term_get_char(&c)) {
if (c == ';') {
i++;
if (i >= num)
return -1;
n[i] = 0;
continue;
} else if (c == end_char) {
break;
} else if (c > '9' || c < '0') {
return -1;
}
/* Read one more decimal position */
n[i] *= 10;
n[i] += c - '0';
} else {
return -1;
}
}
if (i != num - 1)
return -1;
return 0;
}
/**
* efi_cout_output_string() - write Unicode string to console
*
@@ -272,52 +200,6 @@ static bool cout_mode_matches(struct cout_mode *mode, int rows, int cols)
return (mode->rows == rows) && (mode->columns == cols);
}
/**
* query_console_serial() - query serial console size
*
* When using a serial console or the net console we can only devise the
* terminal size by querying the terminal using ECMA-48 control sequences.
*
* @rows: pointer to return number of rows
* @cols: pointer to return number of columns
* Returns: 0 on success
*/
static int query_console_serial(int *rows, int *cols)
{
int ret = 0;
int n[2];
/* Empty input buffer */
while (tstc())
getchar();
/*
* Not all terminals understand CSI [18t for querying the console size.
* We should adhere to escape sequences documented in the console_codes
* man page and the ECMA-48 standard.
*
* So here we follow a different approach. We position the cursor to the
* bottom right and query its position. Before leaving the function we
* restore the original cursor position.
*/
printf(ESC "7" /* Save cursor position */
ESC "[r" /* Set scrolling region to full window */
ESC "[999;999H" /* Move to bottom right corner */
ESC "[6n"); /* Query cursor position */
/* Read {rows,cols} */
if (term_read_reply(n, 2, 'R')) {
ret = 1;
goto out;
}
*cols = n[1];
*rows = n[0];
out:
printf(ESC "8"); /* Restore cursor position */
return ret;
}
/**
* query_vidconsole() - query video console size
*
@@ -363,8 +245,8 @@ void efi_setup_console_size(void)
if (IS_ENABLED(CONFIG_VIDEO))
ret = query_vidconsole(&rows, &cols);
if (ret)
ret = query_console_serial(&rows, &cols);
if (ret && IS_ENABLED(CONFIG_DM_SERIAL))
ret = serial_query_size(&rows, &cols);
if (ret)
return;