arch/blackfin/kernel/time.c

   1 /*
   2  * File:         arch/blackfin/kernel/time.c
   3  * Based on:     none - original work
   4  * Author:
   5  *
   6  * Created:
   7  * Description:  This file contains the bfin-specific time handling details.
   8  *               Most of the stuff is located in the machine specific files.
   9  *               FIXME: (This file is subject for removal)
  10  *
  11  * Modified:
  12  *               Copyright 2004-2008 Analog Devices Inc.
  13  *
  14  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  15  *
  16  * This program is free software; you can redistribute it and/or modify
  17  * it under the terms of the GNU General Public License as published by
  18  * the Free Software Foundation; either version 2 of the License, or
  19  * (at your option) any later version.
  20  *
  21  * This program is distributed in the hope that it will be useful,
  22  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24  * GNU General Public License for more details.
  25  *
  26  * You should have received a copy of the GNU General Public License
  27  * along with this program; if not, see the file COPYING, or write
  28  * to the Free Software Foundation, Inc.,
  29  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  30  */
  31
  32 #include <linux/module.h>
  33 #include <linux/profile.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/time.h>
  36 #include <linux/irq.h>
  37
  38 #include <asm/blackfin.h>
  39 #include <asm/time.h>
  40
  41 /* This is an NTP setting */
  42 #define TICK_SIZE (tick_nsec / 1000)
  43
  44 static void time_sched_init(irq_handler_t timer_routine);
  45 static unsigned long gettimeoffset(void);
  46
  47 static struct irqaction bfin_timer_irq = {
  48         .name = "BFIN Timer Tick",
  49         .flags = IRQF_DISABLED
  50 };
  51
  52 static void
  53 time_sched_init(irq_handler_t timer_routine)
  54 {
  55         u32 tcount;
  56
  57         /* power up the timer, but don't enable it just yet */
  58         bfin_write_TCNTL(1);
  59         CSYNC();
  60
  61         /*
  62          * the TSCALE prescaler counter.
  63          */
  64         bfin_write_TSCALE((TIME_SCALE - 1));
  65
  66         tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
  67         bfin_write_TPERIOD(tcount);
  68         bfin_write_TCOUNT(tcount);
  69
  70         /* now enable the timer */
  71         CSYNC();
  72
  73         bfin_write_TCNTL(7);
  74
  75         bfin_timer_irq.handler = (irq_handler_t)timer_routine;
  76         /* call setup_irq instead of request_irq because request_irq calls
  77          * kmalloc which has not been initialized yet
  78          */
  79         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
  80 }
  81
  82 /*
  83  * Should return useconds since last timer tick
  84  */
  85 static unsigned long gettimeoffset(void)
  86 {
  87         unsigned long offset;
  88         unsigned long clocks_per_jiffy;
  89
  90         clocks_per_jiffy = bfin_read_TPERIOD();
  91         offset =
  92             (clocks_per_jiffy -
  93              bfin_read_TCOUNT()) / (((clocks_per_jiffy + 1) * HZ) /
  94                                     USEC_PER_SEC);
  95
  96         /* Check if we just wrapped the counters and maybe missed a tick */
  97         if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
  98             && (offset < (100000 / HZ / 2)))
  99                 offset += (USEC_PER_SEC / HZ);
 100
 101         return offset;
 102 }
 103
 104 static inline int set_rtc_mmss(unsigned long nowtime)
 105 {
 106         return 0;
 107 }
 108
 109 /*
 110  * timer_interrupt() needs to keep up the real-time clock,
 111  * as well as call the "do_timer()" routine every clocktick
 112  */
 113 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 114 irqreturn_t timer_interrupt(int irq, void *dummy)__attribute__((l1_text));
 115 #endif
 116
 117 irqreturn_t timer_interrupt(int irq, void *dummy)
 118 {
 119         /* last time the cmos clock got updated */
 120         static long last_rtc_update;
 121
 122         write_seqlock(&xtime_lock);
 123
 124         do_timer(1);
 125
 126         profile_tick(CPU_PROFILING);
 127
 128         /*
 129          * If we have an externally synchronized Linux clock, then update
 130          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 131          * called as close as possible to 500 ms before the new second starts.
 132          */
 133
 134         if (ntp_synced() &&
 135             xtime.tv_sec > last_rtc_update + 660 &&
 136             (xtime.tv_nsec / NSEC_PER_USEC) >=
 137             500000 - ((unsigned)TICK_SIZE) / 2
 138             && (xtime.tv_nsec / NSEC_PER_USEC) <=
 139             500000 + ((unsigned)TICK_SIZE) / 2) {
 140                 if (set_rtc_mmss(xtime.tv_sec) == 0)
 141                         last_rtc_update = xtime.tv_sec;
 142                 else
 143                         /* Do it again in 60s. */
 144                         last_rtc_update = xtime.tv_sec - 600;
 145         }
 146         write_sequnlock(&xtime_lock);
 147
 148 #ifndef CONFIG_SMP
 149         update_process_times(user_mode(get_irq_regs()));
 150 #endif
 151
 152         return IRQ_HANDLED;
 153 }
 154
 155 void __init time_init(void)
 156 {
 157         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 158
 159 #ifdef CONFIG_RTC_DRV_BFIN
 160         /* [#2663] hack to filter junk RTC values that would cause
 161          * userspace to have to deal with time values greater than
 162          * 2^31 seconds (which uClibc cannot cope with yet)
 163          */
 164         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 165                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 166                 bfin_write_RTC_STAT(0);
 167         }
 168 #endif
 169
 170         /* Initialize xtime. From now on, xtime is updated with timer interrupts */
 171         xtime.tv_sec = secs_since_1970;
 172         xtime.tv_nsec = 0;
 173
 174         wall_to_monotonic.tv_sec = -xtime.tv_sec;
 175
 176         time_sched_init(timer_interrupt);
 177 }
 178
 179 #ifndef CONFIG_GENERIC_TIME
 180 void do_gettimeofday(struct timeval *tv)
 181 {
 182         unsigned long flags;
 183         unsigned long seq;
 184         unsigned long usec, sec;
 185
 186         do {
 187                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 188                 usec = gettimeoffset();
 189                 sec = xtime.tv_sec;
 190                 usec += (xtime.tv_nsec / NSEC_PER_USEC);
 191         }
 192         while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 193
 194         while (usec >= USEC_PER_SEC) {
 195                 usec -= USEC_PER_SEC;
 196                 sec++;
 197         }
 198
 199         tv->tv_sec = sec;
 200         tv->tv_usec = usec;
 201 }
 202 EXPORT_SYMBOL(do_gettimeofday);
 203
 204 int do_settimeofday(struct timespec *tv)
 205 {
 206         time_t wtm_sec, sec = tv->tv_sec;
 207         long wtm_nsec, nsec = tv->tv_nsec;
 208
 209         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 210                 return -EINVAL;
 211
 212         write_seqlock_irq(&xtime_lock);
 213         /*
 214          * This is revolting. We need to set the xtime.tv_usec
 215          * correctly. However, the value in this location is
 216          * is value at the last tick.
 217          * Discover what correction gettimeofday
 218          * would have done, and then undo it!
 219          */
 220         nsec -= (gettimeoffset() * NSEC_PER_USEC);
 221
 222         wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 223         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 224
 225         set_normalized_timespec(&xtime, sec, nsec);
 226         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 227
 228         ntp_clear();
 229
 230         write_sequnlock_irq(&xtime_lock);
 231         clock_was_set();
 232
 233         return 0;
 234 }
 235 EXPORT_SYMBOL(do_settimeofday);
 236 #endif /* !CONFIG_GENERIC_TIME */
 237
 238 /*
 239  * Scheduler clock - returns current time in nanosec units.
 240  */
 241 unsigned long long sched_clock(void)
 242 {
 243         return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);
 244 }