diff options
Diffstat (limited to 'kernel/arch/x86/boot/tty.c')
-rw-r--r-- | kernel/arch/x86/boot/tty.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/kernel/arch/x86/boot/tty.c b/kernel/arch/x86/boot/tty.c new file mode 100644 index 000000000..def2451f4 --- /dev/null +++ b/kernel/arch/x86/boot/tty.c @@ -0,0 +1,139 @@ +/* -*- linux-c -*- ------------------------------------------------------- * + * + * Copyright (C) 1991, 1992 Linus Torvalds + * Copyright 2007 rPath, Inc. - All Rights Reserved + * Copyright 2009 Intel Corporation; author H. Peter Anvin + * + * This file is part of the Linux kernel, and is made available under + * the terms of the GNU General Public License version 2. + * + * ----------------------------------------------------------------------- */ + +/* + * 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 __attribute__((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 __attribute__((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 __attribute__((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 __attribute__((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! */ +} + |