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  *
  10  * Modified:
  11  *               Copyright 2004-2006 Analog Devices Inc.
  12  *
  13  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  14  *
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2 of the License, or
  18  * (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  23  * GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program; if not, see the file COPYING, or write
  27  * to the Free Software Foundation, Inc.,
  28  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  29  */
  30
  31 #include <linux/module.h>
  32 #include <linux/profile.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/time.h>
  35 #include <linux/irq.h>
  36
  37 #include <asm/blackfin.h>
  38
  39 /* This is an NTP setting */
  40 #define TICK_SIZE (tick_nsec / 1000)
  41
  42 static void time_sched_init(irqreturn_t(*timer_routine)
  43                         (int, void *));
  44 static unsigned long gettimeoffset(void);
  45 static inline void do_leds(void);
  46
  47 #if (defined(CONFIG_BFIN_ALIVE_LED) || defined(CONFIG_BFIN_IDLE_LED))
  48 void __init init_leds(void)
  49 {
  50         unsigned int tmp = 0;
  51
  52 #if defined(CONFIG_BFIN_ALIVE_LED)
  53         /* config pins as output. */
  54         tmp = bfin_read_CONFIG_BFIN_ALIVE_LED_DPORT();
  55         SSYNC();
  56         bfin_write_CONFIG_BFIN_ALIVE_LED_DPORT(tmp | CONFIG_BFIN_ALIVE_LED_PIN);
  57         SSYNC();
  58
  59         /*      First set led be off */
  60         tmp = bfin_read_CONFIG_BFIN_ALIVE_LED_PORT();
  61         SSYNC();
  62         bfin_write_CONFIG_BFIN_ALIVE_LED_PORT(tmp | CONFIG_BFIN_ALIVE_LED_PIN); /* light off */
  63         SSYNC();
  64 #endif
  65
  66 #if defined(CONFIG_BFIN_IDLE_LED)
  67         /* config pins as output. */
  68         tmp = bfin_read_CONFIG_BFIN_IDLE_LED_DPORT();
  69         SSYNC();
  70         bfin_write_CONFIG_BFIN_IDLE_LED_DPORT(tmp | CONFIG_BFIN_IDLE_LED_PIN);
  71         SSYNC();
  72
  73         /*      First set led be off */
  74         tmp = bfin_read_CONFIG_BFIN_IDLE_LED_PORT();
  75         SSYNC();
  76         bfin_write_CONFIG_BFIN_IDLE_LED_PORT(tmp | CONFIG_BFIN_IDLE_LED_PIN);   /* light off */
  77         SSYNC();
  78 #endif
  79 }
  80 #else
  81 void __init init_leds(void)
  82 {
  83 }
  84 #endif
  85
  86 #if defined(CONFIG_BFIN_ALIVE_LED)
  87 static inline void do_leds(void)
  88 {
  89         static unsigned int count = 50;
  90         static int flag;
  91         unsigned short tmp = 0;
  92
  93         if (--count == 0) {
  94                 count = 50;
  95                 flag = ~flag;
  96         }
  97         tmp = bfin_read_CONFIG_BFIN_ALIVE_LED_PORT();
  98         SSYNC();
  99
 100         if (flag)
 101                 tmp &= ~CONFIG_BFIN_ALIVE_LED_PIN;      /* light on */
 102         else
 103                 tmp |= CONFIG_BFIN_ALIVE_LED_PIN;       /* light off */
 104
 105         bfin_write_CONFIG_BFIN_ALIVE_LED_PORT(tmp);
 106         SSYNC();
 107
 108 }
 109 #else
 110 static inline void do_leds(void)
 111 {
 112 }
 113 #endif
 114
 115 static struct irqaction bfin_timer_irq = {
 116         .name = "BFIN Timer Tick",
 117         .flags = IRQF_DISABLED
 118 };
 119
 120 /*
 121  * The way that the Blackfin core timer works is:
 122  *  - CCLK is divided by a programmable 8-bit pre-scaler (TSCALE)
 123  *  - Every time TSCALE ticks, a 32bit is counted down (TCOUNT)
 124  *
 125  * If you take the fastest clock (1ns, or 1GHz to make the math work easier)
 126  *    10ms is 10,000,000 clock ticks, which fits easy into a 32-bit counter
 127  *    (32 bit counter is 4,294,967,296ns or 4.2 seconds) so, we don't need
 128  *    to use TSCALE, and program it to zero (which is pass CCLK through).
 129  *    If you feel like using it, try to keep HZ * TIMESCALE to some
 130  *    value that divides easy (like power of 2).
 131  */
 132
 133 #define TIME_SCALE 1
 134
 135 static void
 136 time_sched_init(irqreturn_t(*timer_routine) (int, void *))
 137 {
 138         u32 tcount;
 139
 140         /* power up the timer, but don't enable it just yet */
 141         bfin_write_TCNTL(1);
 142         CSYNC();
 143
 144         /*
 145          * the TSCALE prescaler counter.
 146          */
 147         bfin_write_TSCALE((TIME_SCALE - 1));
 148
 149         tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
 150         bfin_write_TPERIOD(tcount);
 151         bfin_write_TCOUNT(tcount);
 152
 153         /* now enable the timer */
 154         CSYNC();
 155
 156         bfin_write_TCNTL(7);
 157
 158         bfin_timer_irq.handler = (irq_handler_t)timer_routine;
 159         /* call setup_irq instead of request_irq because request_irq calls
 160          * kmalloc which has not been initialized yet
 161          */
 162         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
 163 }
 164
 165 /*
 166  * Should return useconds since last timer tick
 167  */
 168 static unsigned long gettimeoffset(void)
 169 {
 170         unsigned long offset;
 171         unsigned long clocks_per_jiffy;
 172
 173         clocks_per_jiffy = bfin_read_TPERIOD();
 174         offset =
 175             (clocks_per_jiffy -
 176              bfin_read_TCOUNT()) / (((clocks_per_jiffy + 1) * HZ) /
 177                                     USEC_PER_SEC);
 178
 179         /* Check if we just wrapped the counters and maybe missed a tick */
 180         if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
 181             && (offset < (100000 / HZ / 2)))
 182                 offset += (USEC_PER_SEC / HZ);
 183
 184         return offset;
 185 }
 186
 187 static inline int set_rtc_mmss(unsigned long nowtime)
 188 {
 189         return 0;
 190 }
 191
 192 /*
 193  * timer_interrupt() needs to keep up the real-time clock,
 194  * as well as call the "do_timer()" routine every clocktick
 195  */
 196 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 197 irqreturn_t timer_interrupt(int irq, void *dummy)__attribute__((l1_text));
 198 #endif
 199
 200 irqreturn_t timer_interrupt(int irq, void *dummy)
 201 {
 202         /* last time the cmos clock got updated */
 203         static long last_rtc_update;
 204
 205         write_seqlock(&xtime_lock);
 206
 207         do_timer(1);
 208         do_leds();
 209
 210 #ifndef CONFIG_SMP
 211         update_process_times(user_mode(get_irq_regs()));
 212 #endif
 213         profile_tick(CPU_PROFILING);
 214
 215         /*
 216          * If we have an externally synchronized Linux clock, then update
 217          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 218          * called as close as possible to 500 ms before the new second starts.
 219          */
 220
 221         if (ntp_synced() &&
 222             xtime.tv_sec > last_rtc_update + 660 &&
 223             (xtime.tv_nsec / NSEC_PER_USEC) >=
 224             500000 - ((unsigned)TICK_SIZE) / 2
 225             && (xtime.tv_nsec / NSEC_PER_USEC) <=
 226             500000 + ((unsigned)TICK_SIZE) / 2) {
 227                 if (set_rtc_mmss(xtime.tv_sec) == 0)
 228                         last_rtc_update = xtime.tv_sec;
 229                 else
 230                         /* Do it again in 60s. */
 231                         last_rtc_update = xtime.tv_sec - 600;
 232         }
 233         write_sequnlock(&xtime_lock);
 234         return IRQ_HANDLED;
 235 }
 236
 237 void __init time_init(void)
 238 {
 239         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 240
 241 #ifdef CONFIG_RTC_DRV_BFIN
 242         /* [#2663] hack to filter junk RTC values that would cause
 243          * userspace to have to deal with time values greater than
 244          * 2^31 seconds (which uClibc cannot cope with yet)
 245          */
 246         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 247                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 248                 bfin_write_RTC_STAT(0);
 249         }
 250 #endif
 251
 252         /* Initialize xtime. From now on, xtime is updated with timer interrupts */
 253         xtime.tv_sec = secs_since_1970;
 254         xtime.tv_nsec = 0;
 255
 256         wall_to_monotonic.tv_sec = -xtime.tv_sec;
 257
 258         time_sched_init(timer_interrupt);
 259 }
 260
 261 #ifndef CONFIG_GENERIC_TIME
 262 void do_gettimeofday(struct timeval *tv)
 263 {
 264         unsigned long flags;
 265         unsigned long seq;
 266         unsigned long usec, sec;
 267
 268         do {
 269                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 270                 usec = gettimeoffset();
 271                 sec = xtime.tv_sec;
 272                 usec += (xtime.tv_nsec / NSEC_PER_USEC);
 273         }
 274         while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 275
 276         while (usec >= USEC_PER_SEC) {
 277                 usec -= USEC_PER_SEC;
 278                 sec++;
 279         }
 280
 281         tv->tv_sec = sec;
 282         tv->tv_usec = usec;
 283 }
 284 EXPORT_SYMBOL(do_gettimeofday);
 285
 286 int do_settimeofday(struct timespec *tv)
 287 {
 288         time_t wtm_sec, sec = tv->tv_sec;
 289         long wtm_nsec, nsec = tv->tv_nsec;
 290
 291         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 292                 return -EINVAL;
 293
 294         write_seqlock_irq(&xtime_lock);
 295         /*
 296          * This is revolting. We need to set the xtime.tv_usec
 297          * correctly. However, the value in this location is
 298          * is value at the last tick.
 299          * Discover what correction gettimeofday
 300          * would have done, and then undo it!
 301          */
 302         nsec -= (gettimeoffset() * NSEC_PER_USEC);
 303
 304         wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 305         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 306
 307         set_normalized_timespec(&xtime, sec, nsec);
 308         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 309
 310         ntp_clear();
 311
 312         write_sequnlock_irq(&xtime_lock);
 313         clock_was_set();
 314
 315         return 0;
 316 }
 317 EXPORT_SYMBOL(do_settimeofday);
 318 #endif /* !CONFIG_GENERIC_TIME */
 319
 320 /*
 321  * Scheduler clock - returns current time in nanosec units.
 322  */
 323 unsigned long long sched_clock(void)
 324 {
 325         return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);
 326 }