/* $Id: udelay.c,v 1.12 2003/07/18 04:43:14 reinelt Exp $ * * short delays * * Copyright 1999, 2000 by Michael Reinelt (reinelt@eunet.at) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2, or (at your option) * any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * * $Log: udelay.c,v $ * Revision 1.12  2003/07/18 04:43:14  reinelt * udelay: unnecessary sanity check removed * * Revision 1.11  2003/04/04 06:02:04  reinelt * new parallel port abstraction scheme * * Revision 1.10  2003/02/27 07:43:11  reinelt * * asm/msr.h: included hard-coded definition of rdtscl() if msr.h cannot be found. * * autoconf/automake/autoanything: switched back to 1.4. Hope it works again. * * Revision 1.9  2002/08/21 06:09:53  reinelt * some T6963 fixes, ndelay wrap * * Revision 1.8  2002/08/17 14:14:21  reinelt * * USBLCD fixes * * Revision 1.7  2002/04/29 11:00:28  reinelt * * added Toshiba T6963 driver * added ndelay() with nanosecond resolution * * Revision 1.6  2001/08/08 05:40:24  reinelt * * renamed CLK_TCK to CLOCKS_PER_SEC * * Revision 1.5  2001/03/12 13:44:58  reinelt * * new udelay() using Time Stamp Counters * * Revision 1.4  2001/03/12 12:39:36  reinelt * * reworked autoconf a lot: drivers may be excluded, #define's went to config.h * * Revision 1.3  2001/03/01 22:33:50  reinelt * * renamed Raster_flush() to PPM_flush() * * Revision 1.2  2000/07/31 10:43:44  reinelt * * some changes to support kernel-2.4 (different layout of various files in /proc) * * Revision 1.1  2000/04/15 16:56:52  reinelt * * moved delay loops to udelay.c * renamed -d (debugging) switch to -v (verbose) * new switch -d to calibrate delay loop * 'Delay' entry for HD44780 back again * delay loops will not calibrate automatically, because this will fail with hich CPU load * *//*  * * exported fuctions: * * void udelay (unsigned long usec) *  delays program execution for usec microseconds *  uses global variable 'loops_per_usec', which has to be set before. *  This function does busy-waiting! so use only for delays smaller *  than 10 msec * * void udelay_calibrate (void) (if USE_OLD_UDELAY is defined) *   does a binary approximation for 'loops_per_usec' *   should be called several times on an otherwise idle machine *   the maximum value should be used * * void udelay_init (void) *   selects delay method (gettimeofday() ord rdtsc() according *   to processor features * */#include "config.h"#include <stdlib.h>#include <stdio.h>#ifdef USE_OLD_UDELAY#include <time.h>#else#include <math.h>#include <unistd.h>#include <fcntl.h>#include <errno.h>#include <string.h>#include <sys/time.h>#ifdef HAVE_ASM_MSR_H#include <asm/msr.h>#else#warning asm/msr.h not found.#warning using hard-coded definition.#define rdtscl(low) \     __asm__ __volatile__("rdtsc" : "=a" (low) : : "edx")#endif#endif#include "debug.h"#include "udelay.h"#ifdef USE_OLD_UDELAYunsigned long loops_per_usec;void ndelay (unsigned long nsec){  unsigned long loop=(nsec*loops_per_usec+999)/1000;    __asm__ (".align 16\n"	   "1:\tdecl %0\n"	   "\tjne 1b"	   : /* no result */ 	   :"a" (loop));}/* adopted from /usr/src/linux/init/main.c */void udelay_calibrate (void){  clock_t tick;  unsigned long bit;    loops_per_usec=1;  while (loops_per_usec<<=1) {    tick=clock();    while (clock()==tick);    tick=clock();    ndelay(1000000000/CLOCKS_PER_SEC);    if (clock()>tick)      break;  }    loops_per_usec>>=1;  bit=loops_per_usec;  while (bit>>=1) {    loops_per_usec|=bit;    tick=clock();    while (clock()==tick);    tick=clock();    ndelay(1000000000/CLOCKS_PER_SEC);    if (clock()>tick)      loops_per_usec&=~bit;  }}#elsestatic unsigned int ticks_per_usec=0;static void getCPUinfo (int *hasTSC, double *MHz){  int fd;  char buffer[4096], *p;    *hasTSC=0;  *MHz=-1;    fd=open("/proc/cpuinfo", O_RDONLY);  if (fd==-1) {    error ("open(/proc/cpuinfo) failed: %s", strerror(errno));    return;  }  if (read (fd, &buffer, sizeof(buffer)-1)==-1) {    error ("read(/proc/cpuinfo) failed: %s", strerror(errno));    close (fd);    return;  }  close (fd);  p=strstr(buffer, "flags");  if (p==NULL) {    debug ("/proc/cpuinfo has no 'flags' line");  } else {    p=strstr(p, "tsc");    if (p==NULL) {      debug ("CPU does not support Time Stamp Counter");    } else {      debug ("CPU supports Time Stamp Counter");      *hasTSC=1;    }  }    p=strstr(buffer, "cpu MHz");  if (p==NULL) {    debug ("/proc/cpuinfo has no 'cpu MHz' line");  } else {    if (sscanf(p+7, " : %lf", MHz)!=1) {      error ("parse(/proc/cpuinfo) failed: unknown 'cpu MHz' format");      *MHz=-1;    } else {      debug ("CPU runs at %f MHz", *MHz);    }  }}void udelay_init (void){  int tsc;  double mhz;    getCPUinfo (&tsc, &mhz);    if (tsc && mhz>0.0) {    ticks_per_usec=ceil(mhz);    debug ("using TSC delay loop, %u ticks per microsecond", ticks_per_usec);  } else {    ticks_per_usec=0;    debug ("using gettimeofday() delay loop");  }}void ndelay (unsigned long nsec){  if (ticks_per_usec) {    unsigned int t1, t2;        nsec=(nsec*ticks_per_usec+999)/1000;    rdtscl(t1);    do {      rep_nop();      rdtscl(t2);    } while ((t2-t1)<nsec);      } else {        struct timeval now, end;        gettimeofday (&end, NULL);    end.tv_usec+=(nsec+999)/1000;    while (end.tv_usec>1000000) {      end.tv_usec-=1000000;      end.tv_sec++;    }        do {      rep_nop();      gettimeofday(&now, NULL);    } while (now.tv_sec==end.tv_sec?now.tv_usec<end.tv_usec:now.tv_sec<end.tv_sec);  }}#endif