arch/blackfin/kernel/time.c

   1 /*
   2  * arch/blackfin/kernel/time.c
   3  *
   4  * This file contains the Blackfin-specific time handling details.
   5  * Most of the stuff is located in the machine specific files.
   6  *
   7  * Copyright 2004-2008 Analog Devices Inc.
   8  * Licensed under the GPL-2 or later.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/profile.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/time.h>
  15 #include <linux/irq.h>
  16 #include <linux/delay.h>
  17
  18 #include <asm/blackfin.h>
  19 #include <asm/time.h>
  20 #include <asm/gptimers.h>
  21
  22 /* This is an NTP setting */
  23 #define TICK_SIZE (tick_nsec / 1000)
  24
  25 static struct irqaction bfin_timer_irq = {
  26         .name = "Blackfin Timer Tick",
  27 #ifdef CONFIG_IRQ_PER_CPU
  28         .flags = IRQF_DISABLED | IRQF_PERCPU,
  29 #else
  30         .flags = IRQF_DISABLED
  31 #endif
  32 };
  33
  34 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
  35 void __init setup_system_timer0(void)
  36 {
  37         /* Power down the core timer, just to play safe. */
  38         bfin_write_TCNTL(0);
  39
  40         disable_gptimers(TIMER0bit);
  41         set_gptimer_status(0, TIMER_STATUS_TRUN0);
  42         while (get_gptimer_status(0) & TIMER_STATUS_TRUN0)
  43                 udelay(10);
  44
  45         set_gptimer_config(0, 0x59); /* IRQ enable, periodic, PWM_OUT, SCLKed, OUT PAD disabled */
  46         set_gptimer_period(TIMER0_id, get_sclk() / HZ);
  47         set_gptimer_pwidth(TIMER0_id, 1);
  48         SSYNC();
  49         enable_gptimers(TIMER0bit);
  50 }
  51 #else
  52 void __init setup_core_timer(void)
  53 {
  54         u32 tcount;
  55
  56         /* power up the timer, but don't enable it just yet */
  57         bfin_write_TCNTL(1);
  58         CSYNC();
  59
  60         /* the TSCALE prescaler counter */
  61         bfin_write_TSCALE(TIME_SCALE - 1);
  62
  63         tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
  64         bfin_write_TPERIOD(tcount);
  65         bfin_write_TCOUNT(tcount);
  66
  67         /* now enable the timer */
  68         CSYNC();
  69
  70         bfin_write_TCNTL(7);
  71 }
  72 #endif
  73
  74 static void __init
  75 time_sched_init(irqreturn_t(*timer_routine) (int, void *))
  76 {
  77 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
  78         setup_system_timer0();
  79         bfin_timer_irq.handler = timer_routine;
  80         setup_irq(IRQ_TIMER0, &bfin_timer_irq);
  81 #else
  82         setup_core_timer();
  83         bfin_timer_irq.handler = timer_routine;
  84         setup_irq(IRQ_CORETMR, &bfin_timer_irq);
  85 #endif
  86 }
  87
  88 /*
  89  * Should return useconds since last timer tick
  90  */
  91 #ifndef CONFIG_GENERIC_TIME
  92 static unsigned long gettimeoffset(void)
  93 {
  94         unsigned long offset;
  95         unsigned long clocks_per_jiffy;
  96
  97 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
  98         clocks_per_jiffy = bfin_read_TIMER0_PERIOD();
  99         offset = bfin_read_TIMER0_COUNTER() / \
 100                 (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
 101
 102         if ((get_gptimer_status(0) & TIMER_STATUS_TIMIL0) && offset < (100000 / HZ / 2))
 103                 offset += (USEC_PER_SEC / HZ);
 104 #else
 105         clocks_per_jiffy = bfin_read_TPERIOD();
 106         offset = (clocks_per_jiffy - bfin_read_TCOUNT()) / \
 107                 (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
 108
 109         /* Check if we just wrapped the counters and maybe missed a tick */
 110         if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
 111                 && (offset < (100000 / HZ / 2)))
 112                 offset += (USEC_PER_SEC / HZ);
 113 #endif
 114         return offset;
 115 }
 116 #endif
 117
 118 static inline int set_rtc_mmss(unsigned long nowtime)
 119 {
 120         return 0;
 121 }
 122
 123 /*
 124  * timer_interrupt() needs to keep up the real-time clock,
 125  * as well as call the "do_timer()" routine every clocktick
 126  */
 127 #ifdef CONFIG_CORE_TIMER_IRQ_L1
 128 __attribute__((l1_text))
 129 #endif
 130 irqreturn_t timer_interrupt(int irq, void *dummy)
 131 {
 132         /* last time the cmos clock got updated */
 133         static long last_rtc_update;
 134
 135         write_seqlock(&xtime_lock);
 136 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
 137         if (get_gptimer_status(0) & TIMER_STATUS_TIMIL0) {
 138 #endif
 139                 do_timer(1);
 140
 141                 /*
 142                  * If we have an externally synchronized Linux clock, then update
 143                  * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 144                  * called as close as possible to 500 ms before the new second starts.
 145                  */
 146                 if (ntp_synced() &&
 147                     xtime.tv_sec > last_rtc_update + 660 &&
 148                     (xtime.tv_nsec / NSEC_PER_USEC) >=
 149                     500000 - ((unsigned)TICK_SIZE) / 2
 150                     && (xtime.tv_nsec / NSEC_PER_USEC) <=
 151                     500000 + ((unsigned)TICK_SIZE) / 2) {
 152                         if (set_rtc_mmss(xtime.tv_sec) == 0)
 153                                 last_rtc_update = xtime.tv_sec;
 154                         else
 155                                 /* Do it again in 60s. */
 156                                 last_rtc_update = xtime.tv_sec - 600;
 157                 }
 158 #ifdef CONFIG_TICK_SOURCE_SYSTMR0
 159                 set_gptimer_status(0, TIMER_STATUS_TIMIL0);
 160         }
 161 #endif
 162         write_sequnlock(&xtime_lock);
 163
 164         update_process_times(user_mode(get_irq_regs()));
 165         profile_tick(CPU_PROFILING);
 166
 167         return IRQ_HANDLED;
 168 }
 169
 170 void __init time_init(void)
 171 {
 172         time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 173
 174 #ifdef CONFIG_RTC_DRV_BFIN
 175         /* [#2663] hack to filter junk RTC values that would cause
 176          * userspace to have to deal with time values greater than
 177          * 2^31 seconds (which uClibc cannot cope with yet)
 178          */
 179         if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 180                 printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 181                 bfin_write_RTC_STAT(0);
 182         }
 183 #endif
 184
 185         /* Initialize xtime. From now on, xtime is updated with timer interrupts */
 186         xtime.tv_sec = secs_since_1970;
 187         xtime.tv_nsec = 0;
 188
 189         wall_to_monotonic.tv_sec = -xtime.tv_sec;
 190
 191         time_sched_init(timer_interrupt);
 192 }
 193
 194 #ifndef CONFIG_GENERIC_TIME
 195 void do_gettimeofday(struct timeval *tv)
 196 {
 197         unsigned long flags;
 198         unsigned long seq;
 199         unsigned long usec, sec;
 200
 201         do {
 202                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
 203                 usec = gettimeoffset();
 204                 sec = xtime.tv_sec;
 205                 usec += (xtime.tv_nsec / NSEC_PER_USEC);
 206         }
 207         while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
 208
 209         while (usec >= USEC_PER_SEC) {
 210                 usec -= USEC_PER_SEC;
 211                 sec++;
 212         }
 213
 214         tv->tv_sec = sec;
 215         tv->tv_usec = usec;
 216 }
 217 EXPORT_SYMBOL(do_gettimeofday);
 218
 219 int do_settimeofday(struct timespec *tv)
 220 {
 221         time_t wtm_sec, sec = tv->tv_sec;
 222         long wtm_nsec, nsec = tv->tv_nsec;
 223
 224         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
 225                 return -EINVAL;
 226
 227         write_seqlock_irq(&xtime_lock);
 228         /*
 229          * This is revolting. We need to set the xtime.tv_usec
 230          * correctly. However, the value in this location is
 231          * is value at the last tick.
 232          * Discover what correction gettimeofday
 233          * would have done, and then undo it!
 234          */
 235         nsec -= (gettimeoffset() * NSEC_PER_USEC);
 236
 237         wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
 238         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
 239
 240         set_normalized_timespec(&xtime, sec, nsec);
 241         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
 242
 243         ntp_clear();
 244
 245         write_sequnlock_irq(&xtime_lock);
 246         clock_was_set();
 247
 248         return 0;
 249 }
 250 EXPORT_SYMBOL(do_settimeofday);
 251 #endif /* !CONFIG_GENERIC_TIME */
 252
 253 /*
 254  * Scheduler clock - returns current time in nanosec units.
 255  */
 256 unsigned long long sched_clock(void)
 257 {
 258         return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);
 259 }