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