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/* $Id: udelay.c,v 1.14 2003/10/12 04:46:19 reinelt Exp $ * * short delays * * Copyright 1999, 2000 Michael Reinelt <reinelt@eunet.at> * * This file is part of LCD4Linux. * * LCD4Linux 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. * * LCD4Linux 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 1.14 2003/10/12 04:46:19 reinelt * * * first try to integrate the Evaluator into a display driver (MatrixOrbital here) * small warning in processor.c fixed (thanks to Zachary Giles) * workaround for udelay() on alpha (no msr.h avaliable) (thanks to Zachary Giles) * * Revision 1.13 2003/10/05 17:58:50 reinelt * libtool junk; copyright messages cleaned up * * 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> #endif #endif #include "debug.h" #include "udelay.h" #ifdef USE_OLD_UDELAY unsigned 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; } } #else static 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) { #ifdef HAVE_ASM_MSR_H 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 #endif { ticks_per_usec=0; debug ("using gettimeofday() delay loop"); } } void ndelay (unsigned long nsec) { #ifdef HAVE_ASM_MSR_H 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 #endif { 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


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