arch/cris/arch-v10/kernel/time.c

   1 /* $Id: time.c,v 1.5 2004/09/29 06:12:46 starvik Exp $
   2  *
   3  *  linux/arch/cris/arch-v10/kernel/time.c
   4  *
   5  *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
   6  *  Copyright (C) 1999-2002 Axis Communications AB
   7  *
   8  */
   9
  10 #include <linux/config.h>
  11 #include <linux/timex.h>
  12 #include <linux/time.h>
  13 #include <linux/jiffies.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/swap.h>
  16 #include <linux/sched.h>
  17 #include <linux/init.h>
  18 #include <asm/arch/svinto.h>
  19 #include <asm/types.h>
  20 #include <asm/signal.h>
  21 #include <asm/io.h>
  22 #include <asm/delay.h>
  23 #include <asm/rtc.h>
  24
  25 /* define this if you need to use print_timestamp */
  26 /* it will make jiffies at 96 hz instead of 100 hz though */
  27 #undef USE_CASCADE_TIMERS
  28
  29 extern void update_xtime_from_cmos(void);
  30 extern int set_rtc_mmss(unsigned long nowtime);
  31 extern int setup_irq(int, struct irqaction *);
  32 extern int have_rtc;
  33
  34 unsigned long get_ns_in_jiffie(void)
  35 {
  36         unsigned char timer_count, t1;
  37         unsigned short presc_count;
  38         unsigned long ns;
  39         unsigned long flags;
  40
  41         local_irq_save(flags);
  42         local_irq_disable();
  43         timer_count = *R_TIMER0_DATA;
  44         presc_count = *R_TIM_PRESC_STATUS;
  45         /* presc_count might be wrapped */
  46         t1 = *R_TIMER0_DATA;
  47
  48         if (timer_count != t1){
  49                 /* it wrapped, read prescaler again...  */
  50                 presc_count = *R_TIM_PRESC_STATUS;
  51                 timer_count = t1;
  52         }
  53         local_irq_restore(flags);
  54         if (presc_count >= PRESCALE_VALUE/2 ){
  55                 presc_count =  PRESCALE_VALUE - presc_count + PRESCALE_VALUE/2;
  56         } else {
  57                 presc_count =  PRESCALE_VALUE - presc_count - PRESCALE_VALUE/2;
  58         }
  59
  60         ns = ( (TIMER0_DIV - timer_count) * ((1000000000/HZ)/TIMER0_DIV )) +
  61              ( (presc_count) * (1000000000/PRESCALE_FREQ));
  62         return ns;
  63 }
  64
  65 unsigned long do_slow_gettimeoffset(void)
  66 {
  67         unsigned long count, t1;
  68         unsigned long usec_count = 0;
  69         unsigned short presc_count;
  70
  71         static unsigned long count_p = TIMER0_DIV;/* for the first call after boot */
  72         static unsigned long jiffies_p = 0;
  73
  74         /*
  75          * cache volatile jiffies temporarily; we have IRQs turned off.
  76          */
  77         unsigned long jiffies_t;
  78
  79         /* The timer interrupt comes from Etrax timer 0. In order to get
  80          * better precision, we check the current value. It might have
  81          * underflowed already though.
  82          */
  83
  84 #ifndef CONFIG_SVINTO_SIM
  85         /* Not available in the xsim simulator. */
  86         count = *R_TIMER0_DATA;
  87         presc_count = *R_TIM_PRESC_STATUS;
  88         /* presc_count might be wrapped */
  89         t1 = *R_TIMER0_DATA;
  90         if (count != t1){
  91                 /* it wrapped, read prescaler again...  */
  92                 presc_count = *R_TIM_PRESC_STATUS;
  93                 count = t1;
  94         }
  95 #else
  96         count = 0;
  97         presc_count = 0;
  98 #endif
  99
 100         jiffies_t = jiffies;
 101
 102         /*
 103          * avoiding timer inconsistencies (they are rare, but they happen)...
 104          * there are one problem that must be avoided here:
 105          *  1. the timer counter underflows
 106          */
 107         if( jiffies_t == jiffies_p ) {
 108                 if( count > count_p ) {
 109                         /* Timer wrapped, use new count and prescale
 110                          * increase the time corresponding to one jiffie
 111                          */
 112                         usec_count = 1000000/HZ;
 113                 }
 114         } else
 115                 jiffies_p = jiffies_t;
 116         count_p = count;
 117         if (presc_count >= PRESCALE_VALUE/2 ){
 118                 presc_count =  PRESCALE_VALUE - presc_count + PRESCALE_VALUE/2;
 119         } else {
 120                 presc_count =  PRESCALE_VALUE - presc_count - PRESCALE_VALUE/2;
 121         }
 122         /* Convert timer value to usec */
 123         usec_count += ( (TIMER0_DIV - count) * (1000000/HZ)/TIMER0_DIV ) +
 124                       (( (presc_count) * (1000000000/PRESCALE_FREQ))/1000);
 125
 126         return usec_count;
 127 }
 128
 129 /* Excerpt from the Etrax100 HSDD about the built-in watchdog:
 130  *
 131  * 3.10.4 Watchdog timer
 132
 133  * When the watchdog timer is started, it generates an NMI if the watchdog
 134  * isn't restarted or stopped within 0.1 s. If it still isn't restarted or
 135  * stopped after an additional 3.3 ms, the watchdog resets the chip.
 136  * The watchdog timer is stopped after reset. The watchdog timer is controlled
 137  * by the R_WATCHDOG register. The R_WATCHDOG register contains an enable bit
 138  * and a 3-bit key value. The effect of writing to the R_WATCHDOG register is
 139  * described in the table below:
 140  *
 141  *   Watchdog    Value written:
 142  *   state:      To enable:  To key:      Operation:
 143  *   --------    ----------  -------      ----------
 144  *   stopped         0         X          No effect.
 145  *   stopped         1       key_val      Start watchdog with key = key_val.
 146  *   started         0       ~key         Stop watchdog
 147  *   started         1       ~key         Restart watchdog with key = ~key.
 148  *   started         X       new_key_val  Change key to new_key_val.
 149  *
 150  * Note: '~' is the bitwise NOT operator.
 151  *
 152  */
 153
 154 /* right now, starting the watchdog is the same as resetting it */
 155 #define start_watchdog reset_watchdog
 156
 157 #if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
 158 static int watchdog_key = 0;  /* arbitrary number */
 159 #endif
 160
 161 /* number of pages to consider "out of memory". it is normal that the memory
 162  * is used though, so put this really low.
 163  */
 164
 165 #define WATCHDOG_MIN_FREE_PAGES 8
 166
 167 void
 168 reset_watchdog(void)
 169 {
 170 #if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
 171         /* only keep watchdog happy as long as we have memory left! */
 172         if(nr_free_pages() > WATCHDOG_MIN_FREE_PAGES) {
 173                 /* reset the watchdog with the inverse of the old key */
 174                 watchdog_key ^= 0x7; /* invert key, which is 3 bits */
 175                 *R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, watchdog_key) |
 176                         IO_STATE(R_WATCHDOG, enable, start);
 177         }
 178 #endif
 179 }
 180
 181 /* stop the watchdog - we still need the correct key */
 182
 183 void
 184 stop_watchdog(void)
 185 {
 186 #if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
 187         watchdog_key ^= 0x7; /* invert key, which is 3 bits */
 188         *R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, watchdog_key) |
 189                 IO_STATE(R_WATCHDOG, enable, stop);
 190 #endif
 191 }
 192
 193 /* last time the cmos clock got updated */
 194 static long last_rtc_update = 0;
 195
 196 /*
 197  * timer_interrupt() needs to keep up the real-time clock,
 198  * as well as call the "do_timer()" routine every clocktick
 199  */
 200
 201 //static unsigned short myjiff; /* used by our debug routine print_timestamp */
 202
 203 extern void cris_do_profile(struct pt_regs *regs);
 204
 205 static inline irqreturn_t
 206 timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 207 {
 208         /* acknowledge the timer irq */
 209
 210 #ifdef USE_CASCADE_TIMERS
 211         *R_TIMER_CTRL =
 212                 IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
 213                 IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
 214                 IO_STATE( R_TIMER_CTRL, i1, clr) |
 215                 IO_STATE( R_TIMER_CTRL, tm1, run) |
 216                 IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
 217                 IO_STATE( R_TIMER_CTRL, i0, clr) |
 218                 IO_STATE( R_TIMER_CTRL, tm0, run) |
 219                 IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
 220 #else
 221         *R_TIMER_CTRL = r_timer_ctrl_shadow |
 222                 IO_STATE(R_TIMER_CTRL, i0, clr);
 223 #endif
 224
 225         /* reset watchdog otherwise it resets us! */
 226
 227         reset_watchdog();
 228
 229         /* call the real timer interrupt handler */
 230
 231         do_timer(regs);
 232
 233         cris_do_profile(regs); /* Save profiling information */
 234
 235         /*
 236          * If we have an externally synchronized Linux clock, then update
 237          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 238          * called as close as possible to 500 ms before the new second starts.
 239          *
 240          * The division here is not time critical since it will run once in
 241          * 11 minutes
 242          */
 243         if ((time_status & STA_UNSYNC) == 0 &&
 244             xtime.tv_sec > last_rtc_update + 660 &&
 245             (xtime.tv_nsec / 1000) >= 500000 - (tick_nsec / 1000) / 2 &&
 246             (xtime.tv_nsec / 1000) <= 500000 + (tick_nsec / 1000) / 2) {
 247                 if (set_rtc_mmss(xtime.tv_sec) == 0)
 248                         last_rtc_update = xtime.tv_sec;
 249                 else
 250                         last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
 251         }
 252         return IRQ_HANDLED;
 253 }
 254
 255 /* timer is SA_SHIRQ so drivers can add stuff to the timer irq chain
 256  * it needs to be SA_INTERRUPT to make the jiffies update work properly
 257  */
 258
 259 static struct irqaction irq2  = { timer_interrupt, SA_SHIRQ | SA_INTERRUPT,
 260                                   CPU_MASK_NONE, "timer", NULL, NULL};
 261
 262 void __init
 263 time_init(void)
 264 {
 265         /* probe for the RTC and read it if it exists
 266          * Before the RTC can be probed the loops_per_usec variable needs
 267          * to be initialized to make usleep work. A better value for
 268          * loops_per_usec is calculated by the kernel later once the
 269          * clock has started.
 270          */
 271         loops_per_usec = 50;
 272
 273         if(RTC_INIT() < 0) {
 274                 /* no RTC, start at 1980 */
 275                 xtime.tv_sec = 0;
 276                 xtime.tv_nsec = 0;
 277                 have_rtc = 0;
 278         } else {
 279                 /* get the current time */
 280                 have_rtc = 1;
 281                 update_xtime_from_cmos();
 282         }
 283
 284         /*
 285          * Initialize wall_to_monotonic such that adding it to xtime will yield zero, the
 286          * tv_nsec field must be normalized (i.e., 0 <= nsec < NSEC_PER_SEC).
 287          */
 288         set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
 289
 290         /* Setup the etrax timers
 291          * Base frequency is 25000 hz, divider 250 -> 100 HZ
 292          * In normal mode, we use timer0, so timer1 is free. In cascade
 293          * mode (which we sometimes use for debugging) both timers are used.
 294          * Remember that linux/timex.h contains #defines that rely on the
 295          * timer settings below (hz and divide factor) !!!
 296          */
 297
 298 #ifdef USE_CASCADE_TIMERS
 299         *R_TIMER_CTRL =
 300                 IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
 301                 IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
 302                 IO_STATE( R_TIMER_CTRL, i1, nop) |
 303                 IO_STATE( R_TIMER_CTRL, tm1, stop_ld) |
 304                 IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
 305                 IO_STATE( R_TIMER_CTRL, i0, nop) |
 306                 IO_STATE( R_TIMER_CTRL, tm0, stop_ld) |
 307                 IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
 308
 309         *R_TIMER_CTRL = r_timer_ctrl_shadow =
 310                 IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
 311                 IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
 312                 IO_STATE( R_TIMER_CTRL, i1, nop) |
 313                 IO_STATE( R_TIMER_CTRL, tm1, run) |
 314                 IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
 315                 IO_STATE( R_TIMER_CTRL, i0, nop) |
 316                 IO_STATE( R_TIMER_CTRL, tm0, run) |
 317                 IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
 318 #else
 319         *R_TIMER_CTRL =
 320                 IO_FIELD(R_TIMER_CTRL, timerdiv1, 192)      |
 321                 IO_FIELD(R_TIMER_CTRL, timerdiv0, TIMER0_DIV)      |
 322                 IO_STATE(R_TIMER_CTRL, i1,        nop)      |
 323                 IO_STATE(R_TIMER_CTRL, tm1,       stop_ld)  |
 324                 IO_STATE(R_TIMER_CTRL, clksel1,   c19k2Hz)  |
 325                 IO_STATE(R_TIMER_CTRL, i0,        nop)      |
 326                 IO_STATE(R_TIMER_CTRL, tm0,       stop_ld)  |
 327                 IO_STATE(R_TIMER_CTRL, clksel0,   flexible);
 328
 329         *R_TIMER_CTRL = r_timer_ctrl_shadow =
 330                 IO_FIELD(R_TIMER_CTRL, timerdiv1, 192)      |
 331                 IO_FIELD(R_TIMER_CTRL, timerdiv0, TIMER0_DIV)      |
 332                 IO_STATE(R_TIMER_CTRL, i1,        nop)      |
 333                 IO_STATE(R_TIMER_CTRL, tm1,       run)      |
 334                 IO_STATE(R_TIMER_CTRL, clksel1,   c19k2Hz)  |
 335                 IO_STATE(R_TIMER_CTRL, i0,        nop)      |
 336                 IO_STATE(R_TIMER_CTRL, tm0,       run)      |
 337                 IO_STATE(R_TIMER_CTRL, clksel0,   flexible);
 338
 339         *R_TIMER_PRESCALE = PRESCALE_VALUE;
 340 #endif
 341
 342         *R_IRQ_MASK0_SET =
 343                 IO_STATE(R_IRQ_MASK0_SET, timer0, set); /* unmask the timer irq */
 344
 345         /* now actually register the timer irq handler that calls timer_interrupt() */
 346
 347         setup_irq(2, &irq2); /* irq 2 is the timer0 irq in etrax */
 348
 349         /* enable watchdog if we should use one */
 350
 351 #if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
 352         printk("Enabling watchdog...\n");
 353         start_watchdog();
 354
 355         /* If we use the hardware watchdog, we want to trap it as an NMI
 356            and dump registers before it resets us.  For this to happen, we
 357            must set the "m" NMI enable flag (which once set, is unset only
 358            when an NMI is taken).
 359
 360            The same goes for the external NMI, but that doesn't have any
 361            driver or infrastructure support yet.  */
 362         asm ("setf m");
 363
 364         *R_IRQ_MASK0_SET =
 365                 IO_STATE(R_IRQ_MASK0_SET, watchdog_nmi, set);
 366         *R_VECT_MASK_SET =
 367                 IO_STATE(R_VECT_MASK_SET, nmi, set);
 368 #endif
 369 }