1ca987d46SWarner Losh /*- 2ca987d46SWarner Losh * Copyright (c) 1998 Michael Smith <msmith@freebsd.org> 3ca987d46SWarner Losh * All rights reserved. 4ca987d46SWarner Losh * 5ca987d46SWarner Losh * Redistribution and use in source and binary forms, with or without 6ca987d46SWarner Losh * modification, are permitted provided that the following conditions 7ca987d46SWarner Losh * are met: 8ca987d46SWarner Losh * 1. Redistributions of source code must retain the above copyright 9ca987d46SWarner Losh * notice, this list of conditions and the following disclaimer. 10ca987d46SWarner Losh * 2. Redistributions in binary form must reproduce the above copyright 11ca987d46SWarner Losh * notice, this list of conditions and the following disclaimer in the 12ca987d46SWarner Losh * documentation and/or other materials provided with the distribution. 13ca987d46SWarner Losh * 14ca987d46SWarner Losh * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15ca987d46SWarner Losh * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16ca987d46SWarner Losh * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17ca987d46SWarner Losh * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18ca987d46SWarner Losh * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19ca987d46SWarner Losh * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20ca987d46SWarner Losh * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21ca987d46SWarner Losh * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22ca987d46SWarner Losh * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23ca987d46SWarner Losh * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24ca987d46SWarner Losh * SUCH DAMAGE. 25ca987d46SWarner Losh */ 26ca987d46SWarner Losh 27ca987d46SWarner Losh #include <sys/cdefs.h> 28ca987d46SWarner Losh __FBSDID("$FreeBSD$"); 29ca987d46SWarner Losh 30ca987d46SWarner Losh #include <stand.h> 31ca987d46SWarner Losh #include <btxv86.h> 32ca987d46SWarner Losh #include "bootstrap.h" 33ca987d46SWarner Losh #include "libi386.h" 34ca987d46SWarner Losh 35ca987d46SWarner Losh time_t getsecs(void); 36ca987d46SWarner Losh static int bios_seconds(void); 37ca987d46SWarner Losh 38ca987d46SWarner Losh /* 39ca987d46SWarner Losh * Return the BIOS time-of-day value. 40ca987d46SWarner Losh * 41ca987d46SWarner Losh * XXX uses undocumented BCD support from libstand. 42ca987d46SWarner Losh */ 43ca987d46SWarner Losh static int 44ca987d46SWarner Losh bios_seconds(void) 45ca987d46SWarner Losh { 46ca987d46SWarner Losh int hr, minute, sec; 47ca987d46SWarner Losh 48ca987d46SWarner Losh v86.ctl = 0; 49ca987d46SWarner Losh v86.addr = 0x1a; /* int 0x1a, function 2 */ 50ca987d46SWarner Losh v86.eax = 0x0200; 51ca987d46SWarner Losh v86int(); 52ca987d46SWarner Losh 53ca987d46SWarner Losh hr = bcd2bin((v86.ecx & 0xff00) >> 8); /* hour in %ch */ 54ca987d46SWarner Losh minute = bcd2bin(v86.ecx & 0xff); /* minute in %cl */ 55ca987d46SWarner Losh sec = bcd2bin((v86.edx & 0xff00) >> 8); /* second in %dh */ 56ca987d46SWarner Losh 57ca987d46SWarner Losh return (hr * 3600 + minute * 60 + sec); 58ca987d46SWarner Losh } 59ca987d46SWarner Losh 60ca987d46SWarner Losh /* 61ca987d46SWarner Losh * Return the time in seconds since the beginning of the day. 62ca987d46SWarner Losh * 63ca987d46SWarner Losh * Some BIOSes (notably qemu) don't correctly read the RTC 64ca987d46SWarner Losh * registers in an atomic way, sometimes returning bogus values. 65ca987d46SWarner Losh * Therefore we "debounce" the reading by accepting it only when 66ca987d46SWarner Losh * we got 8 identical values in succession. 67ca987d46SWarner Losh * 68ca987d46SWarner Losh * If we pass midnight, don't wrap back to 0. 69ca987d46SWarner Losh */ 70ca987d46SWarner Losh time_t 71ca987d46SWarner Losh time(time_t *t) 72ca987d46SWarner Losh { 73ca987d46SWarner Losh static time_t lasttime; 74ca987d46SWarner Losh time_t now, check; 75ca987d46SWarner Losh int same, try; 76ca987d46SWarner Losh 77ca987d46SWarner Losh same = try = 0; 78ca987d46SWarner Losh check = bios_seconds(); 79ca987d46SWarner Losh do { 80ca987d46SWarner Losh now = check; 81ca987d46SWarner Losh check = bios_seconds(); 82ca987d46SWarner Losh if (check != now) 83ca987d46SWarner Losh same = 0; 84ca987d46SWarner Losh } while (++same < 8 && ++try < 1000); 85ca987d46SWarner Losh 86ca987d46SWarner Losh if (now < lasttime) 87ca987d46SWarner Losh now += 24 * 3600; 88ca987d46SWarner Losh lasttime = now; 89ca987d46SWarner Losh 90ca987d46SWarner Losh if (t != NULL) 91ca987d46SWarner Losh *t = now; 92ca987d46SWarner Losh return(now); 93ca987d46SWarner Losh } 94ca987d46SWarner Losh 95ca987d46SWarner Losh time_t 96ca987d46SWarner Losh getsecs(void) 97ca987d46SWarner Losh { 98ca987d46SWarner Losh time_t n = 0; 99ca987d46SWarner Losh time(&n); 100ca987d46SWarner Losh return n; 101ca987d46SWarner Losh } 102ca987d46SWarner Losh 103ca987d46SWarner Losh /* 104ca987d46SWarner Losh * Use the BIOS Wait function to pause for (period) microseconds. 105ca987d46SWarner Losh * 106ca987d46SWarner Losh * Resolution of this function is variable, but typically around 107ca987d46SWarner Losh * 1ms. 108ca987d46SWarner Losh */ 109ca987d46SWarner Losh void 110ca987d46SWarner Losh delay(int period) 111ca987d46SWarner Losh { 112ca987d46SWarner Losh v86.ctl = 0; 113ca987d46SWarner Losh v86.addr = 0x15; /* int 0x15, function 0x86 */ 114ca987d46SWarner Losh v86.eax = 0x8600; 115ca987d46SWarner Losh v86.ecx = period >> 16; 116ca987d46SWarner Losh v86.edx = period & 0xffff; 117ca987d46SWarner Losh v86int(); 118ca987d46SWarner Losh } 119