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// SPDX-License-Identifier: GPL-2.0-only
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright 2007 rPath, Inc. - All Rights Reserved
* Copyright 2009 Intel Corporation; author H. Peter Anvin
*
* ----------------------------------------------------------------------- */
/*
* Very simple screen and serial I/O
*/
#include "boot.h"
int early_serial_base;
#define XMTRDY 0x20
#define TXR 0 /* Transmit register (WRITE) */
#define LSR 5 /* Line Status */
/*
* These functions are in .inittext so they can be used to signal
* error during initialization.
*/
static void __section(".inittext") serial_putchar(int ch)
{
unsigned timeout = 0xffff;
while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
cpu_relax();
outb(ch, early_serial_base + TXR);
}
static void __section(".inittext") bios_putchar(int ch)
{
struct biosregs ireg;
initregs(&ireg);
ireg.bx = 0x0007;
ireg.cx = 0x0001;
ireg.ah = 0x0e;
ireg.al = ch;
intcall(0x10, &ireg, NULL);
}
void __section(".inittext") putchar(int ch)
{
if (ch == '\n')
putchar('\r'); /* \n -> \r\n */
bios_putchar(ch);
if (early_serial_base != 0)
serial_putchar(ch);
}
void __section(".inittext") puts(const char *str)
{
while (*str)
putchar(*str++);
}
/*
* Read the CMOS clock through the BIOS, and return the
* seconds in BCD.
*/
static u8 gettime(void)
{
struct biosregs ireg, oreg;
initregs(&ireg);
ireg.ah = 0x02;
intcall(0x1a, &ireg, &oreg);
return oreg.dh;
}
/*
* Read from the keyboard
*/
int getchar(void)
{
struct biosregs ireg, oreg;
initregs(&ireg);
/* ireg.ah = 0x00; */
intcall(0x16, &ireg, &oreg);
return oreg.al;
}
static int kbd_pending(void)
{
struct biosregs ireg, oreg;
initregs(&ireg);
ireg.ah = 0x01;
intcall(0x16, &ireg, &oreg);
return !(oreg.eflags & X86_EFLAGS_ZF);
}
void kbd_flush(void)
{
for (;;) {
if (!kbd_pending())
break;
getchar();
}
}
int getchar_timeout(void)
{
int cnt = 30;
int t0, t1;
t0 = gettime();
while (cnt) {
if (kbd_pending())
return getchar();
t1 = gettime();
if (t0 != t1) {
cnt--;
t0 = t1;
}
}
return 0; /* Timeout! */
}
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