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