/* $Id: udelay.c,v 1.23 2006/08/13 06:46:51 reinelt Exp $ * * short delays * * Copyright (C) 1999, 2000 Michael Reinelt * Copyright (C) 2004 The LCD4Linux Team * * 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 1.23 2006/08/13 06:46:51 reinelt * T6963 soft-timing & enhancements; indent * * Revision 1.22 2006/08/10 19:06:52 reinelt * new 'fuzz' parameter for timings * * Revision 1.21 2005/12/12 09:08:08 reinelt * finally removed old udelay code path; read timing values from config * * Revision 1.20 2005/05/08 04:32:45 reinelt * CodingStyle added and applied * * Revision 1.19 2005/01/18 06:30:24 reinelt * added (C) to all copyright statements * * Revision 1.18 2004/09/18 09:48:29 reinelt * HD44780 cleanup and prepararation for I2C backend * LCM-162 submodel framework * * Revision 1.17 2004/06/20 10:09:56 reinelt * * 'const'ified the whole source * * Revision 1.16 2004/04/12 05:14:42 reinelt * another BIG FAT WARNING on the use of raw ports instead of ppdev * * Revision 1.15 2004/04/12 04:56:00 reinelt * emitted a BIG FAT WARNING if msr.h could not be found (and therefore * the gettimeofday() delay loop would be used) * * 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_init (void) * selects delay method (gettimeofday() ord rdtsc() according * to processor features * * unsigned long timing (const char *driver, const char *section, const char *name, const int defval, const char *unit); * returns a timing value from config or the default value * * 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 * */ #include "config.h" #include #include #include #include #include #include #include #include #ifdef HAVE_ASM_MSR_H #include #endif #include "debug.h" #include "cfg.h" #include "qprintf.h" #include "udelay.h" 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("udelay: open(/proc/cpuinfo) failed: %s", strerror(errno)); return; } if (read(fd, &buffer, sizeof(buffer) - 1) == -1) { error("udelay: read(/proc/cpuinfo) failed: %s", strerror(errno)); close(fd); return; } close(fd); p = strstr(buffer, "flags"); if (p == NULL) { info("udelay: /proc/cpuinfo has no 'flags' line"); } else { p = strstr(p, "tsc"); if (p == NULL) { info("udelay: CPU does not support Time Stamp Counter"); } else { info("udelay: CPU supports Time Stamp Counter"); *hasTSC = 1; } } p = strstr(buffer, "cpu MHz"); if (p == NULL) { info("udelay: /proc/cpuinfo has no 'cpu MHz' line"); } else { if (sscanf(p + 7, " : %lf", MHz) != 1) { error("udelay: parse(/proc/cpuinfo) failed: unknown 'cpu MHz' format"); *MHz = -1; } else { info("udelay: 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); info("udelay: using TSC delay loop, %u ticks per microsecond", ticks_per_usec); } else #else error("udelay: The file 'include/asm/msr.h' was missing at compile time."); error("udelay: Even if your CPU supports TSC, it will not be used!"); error("udelay: You *really* should install msr.h and recompile LCD4linux!"); #endif { ticks_per_usec = 0; info("udelay: using gettimeofday() delay loop"); } } unsigned long timing(const char *driver, const char *section, const char *name, const int defval, const char *unit) { char sec[256]; int fuzz, val; qprintf(sec, sizeof(sec), "%s.Timing", section); /* fuzz all timings by given factor */ cfg_number(sec, "fuzz", 100, 1, -1, &fuzz); cfg_number(sec, name, defval, 0, -1, &val); val = val * fuzz / 100; if (val != defval) { if (fuzz != 100) { info("%s: timing: %6s = %5d %s (default %d %s, fuzz %d)", driver, name, val, unit, defval, unit, fuzz); } else { info("%s: timing: %6s = %5d %s (default %d %s)", driver, name, val, unit, defval, unit); } } else { info("%s: timing: %6s = %5d %s (default)", driver, name, defval, unit); } return val; } void ndelay(const unsigned long nsec) { #ifdef HAVE_ASM_MSR_H if (ticks_per_usec) { unsigned int t1, t2; unsigned long tsc; tsc = (nsec * ticks_per_usec + 999) / 1000; rdtscl(t1); do { rep_nop(); rdtscl(t2); } while ((t2 - t1) < tsc); } 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); } }