diff options
Diffstat (limited to 'drivers/char/ftape/lowlevel/ftape-calibr.c')
| -rw-r--r-- | drivers/char/ftape/lowlevel/ftape-calibr.c | 275 |
1 files changed, 0 insertions, 275 deletions
diff --git a/drivers/char/ftape/lowlevel/ftape-calibr.c b/drivers/char/ftape/lowlevel/ftape-calibr.c deleted file mode 100644 index 8e50bfd35a5279..00000000000000 --- a/drivers/char/ftape/lowlevel/ftape-calibr.c +++ /dev/null @@ -1,275 +0,0 @@ -/* - * Copyright (C) 1993-1996 Bas Laarhoven. - - 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; see the file COPYING. If not, write to - the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. - - * - * $Source: /homes/cvs/ftape-stacked/ftape/lowlevel/ftape-calibr.c,v $ - * $Revision: 1.2 $ - * $Date: 1997/10/05 19:18:08 $ - * - * GP calibration routine for processor speed dependent - * functions. - */ - -#include <linux/errno.h> -#include <linux/jiffies.h> -#include <asm/system.h> -#include <asm/io.h> -#if defined(__alpha__) -# include <asm/hwrpb.h> -#elif defined(__x86_64__) -# include <asm/msr.h> -# include <asm/timex.h> -#elif defined(__i386__) -# include <linux/timex.h> -#endif -#include <linux/ftape.h> -#include "../lowlevel/ftape-tracing.h" -#include "../lowlevel/ftape-calibr.h" -#include "../lowlevel/fdc-io.h" - -#undef DEBUG - -#if !defined(__alpha__) && !defined(__i386__) && !defined(__x86_64__) -# error Ftape is not implemented for this architecture! -#endif - -#if defined(__alpha__) || defined(__x86_64__) -static unsigned long ps_per_cycle = 0; -#endif - -static spinlock_t calibr_lock; - -/* - * Note: On Intel PCs, the clock ticks at 100 Hz (HZ==100) which is - * too slow for certain timeouts (and that clock doesn't even tick - * when interrupts are disabled). For that reason, the 8254 timer is - * used directly to implement fine-grained timeouts. However, on - * Alpha PCs, the 8254 is *not* used to implement the clock tick - * (which is 1024 Hz, normally) and the 8254 timer runs at some - * "random" frequency (it seems to run at 18Hz, but it's not safe to - * rely on this value). Instead, we use the Alpha's "rpcc" - * instruction to read cycle counts. As this is a 32 bit counter, - * it will overflow only once per 30 seconds (on a 200MHz machine), - * which is plenty. - */ - -unsigned int ftape_timestamp(void) -{ -#if defined(__alpha__) - unsigned long r; - - asm volatile ("rpcc %0" : "=r" (r)); - return r; -#elif defined(__x86_64__) - unsigned long r; - rdtscl(r); - return r; -#elif defined(__i386__) - -/* - * Note that there is some time between counter underflowing and jiffies - * increasing, so the code below won't always give correct output. - * -Vojtech - */ - - unsigned long flags; - __u16 lo; - __u16 hi; - - spin_lock_irqsave(&calibr_lock, flags); - outb_p(0x00, 0x43); /* latch the count ASAP */ - lo = inb_p(0x40); /* read the latched count */ - lo |= inb(0x40) << 8; - hi = jiffies; - spin_unlock_irqrestore(&calibr_lock, flags); - return ((hi + 1) * (unsigned int) LATCH) - lo; /* downcounter ! */ -#endif -} - -static unsigned int short_ftape_timestamp(void) -{ -#if defined(__alpha__) || defined(__x86_64__) - return ftape_timestamp(); -#elif defined(__i386__) - unsigned int count; - unsigned long flags; - - spin_lock_irqsave(&calibr_lock, flags); - outb_p(0x00, 0x43); /* latch the count ASAP */ - count = inb_p(0x40); /* read the latched count */ - count |= inb(0x40) << 8; - spin_unlock_irqrestore(&calibr_lock, flags); - return (LATCH - count); /* normal: downcounter */ -#endif -} - -static unsigned int diff(unsigned int t0, unsigned int t1) -{ -#if defined(__alpha__) || defined(__x86_64__) - return (t1 - t0); -#elif defined(__i386__) - /* - * This is tricky: to work for both short and full ftape_timestamps - * we'll have to discriminate between these. - * If it _looks_ like short stamps with wrapping around we'll - * asume it are. This will generate a small error if it really - * was a (very large) delta from full ftape_timestamps. - */ - return (t1 <= t0 && t0 <= LATCH) ? t1 + LATCH - t0 : t1 - t0; -#endif -} - -static unsigned int usecs(unsigned int count) -{ -#if defined(__alpha__) || defined(__x86_64__) - return (ps_per_cycle * count) / 1000000UL; -#elif defined(__i386__) - return (10000 * count) / ((CLOCK_TICK_RATE + 50) / 100); -#endif -} - -unsigned int ftape_timediff(unsigned int t0, unsigned int t1) -{ - /* - * Calculate difference in usec for ftape_timestamp results t0 & t1. - * Note that on the i386 platform with short time-stamps, the - * maximum allowed timespan is 1/HZ or we'll lose ticks! - */ - return usecs(diff(t0, t1)); -} - -/* To get an indication of the I/O performance, - * measure the duration of the inb() function. - */ -static void time_inb(void) -{ - int i; - int t0, t1; - unsigned long flags; - int status; - TRACE_FUN(ft_t_any); - - spin_lock_irqsave(&calibr_lock, flags); - t0 = short_ftape_timestamp(); - for (i = 0; i < 1000; ++i) { - status = inb(fdc.msr); - } - t1 = short_ftape_timestamp(); - spin_unlock_irqrestore(&calibr_lock, flags); - TRACE(ft_t_info, "inb() duration: %d nsec", ftape_timediff(t0, t1)); - TRACE_EXIT; -} - -static void init_clock(void) -{ - TRACE_FUN(ft_t_any); - -#if defined(__x86_64__) - ps_per_cycle = 1000000000UL / cpu_khz; -#elif defined(__alpha__) - extern struct hwrpb_struct *hwrpb; - ps_per_cycle = (1000*1000*1000*1000UL) / hwrpb->cycle_freq; -#endif - TRACE_EXIT; -} - -/* - * Input: function taking int count as parameter. - * pointers to calculated calibration variables. - */ -void ftape_calibrate(char *name, - void (*fun) (unsigned int), - unsigned int *calibr_count, - unsigned int *calibr_time) -{ - static int first_time = 1; - int i; - unsigned int tc = 0; - unsigned int count; - unsigned int time; -#if defined(__i386__) - unsigned int old_tc = 0; - unsigned int old_count = 1; - unsigned int old_time = 1; -#endif - TRACE_FUN(ft_t_flow); - - if (first_time) { /* get idea of I/O performance */ - init_clock(); - time_inb(); - first_time = 0; - } - /* value of timeout must be set so that on very slow systems - * it will give a time less than one jiffy, and on - * very fast systems it'll give reasonable precision. - */ - - count = 40; - for (i = 0; i < 15; ++i) { - unsigned int t0; - unsigned int t1; - unsigned int once; - unsigned int multiple; - unsigned long flags; - - *calibr_count = - *calibr_time = count; /* set TC to 1 */ - spin_lock_irqsave(&calibr_lock, flags); - fun(0); /* dummy, get code into cache */ - t0 = short_ftape_timestamp(); - fun(0); /* overhead + one test */ - t1 = short_ftape_timestamp(); - once = diff(t0, t1); - t0 = short_ftape_timestamp(); - fun(count); /* overhead + count tests */ - t1 = short_ftape_timestamp(); - multiple = diff(t0, t1); - spin_unlock_irqrestore(&calibr_lock, flags); - time = ftape_timediff(0, multiple - once); - tc = (1000 * time) / (count - 1); - TRACE(ft_t_any, "once:%3d us,%6d times:%6d us, TC:%5d ns", - usecs(once), count - 1, usecs(multiple), tc); -#if defined(__alpha__) || defined(__x86_64__) - /* - * Increase the calibration count exponentially until the - * calibration time exceeds 100 ms. - */ - if (time >= 100*1000) { - break; - } -#elif defined(__i386__) - /* - * increase the count until the resulting time nears 2/HZ, - * then the tc will drop sharply because we lose LATCH counts. - */ - if (tc <= old_tc / 2) { - time = old_time; - count = old_count; - break; - } - old_tc = tc; - old_count = count; - old_time = time; -#endif - count *= 2; - } - *calibr_count = count - 1; - *calibr_time = time; - TRACE(ft_t_info, "TC for `%s()' = %d nsec (at %d counts)", - name, (1000 * *calibr_time) / *calibr_count, *calibr_count); - TRACE_EXIT; -} |