| /* |
| * linux/include/asm-arm/arch-sa1100/time.h |
| * |
| * Copyright (C) 1998 Deborah Wallach. |
| * Twiddles (C) 1999 Hugo Fiennes <hugo@empeg.com> |
| * |
| * 2000/03/29 (C) Nicolas Pitre <nico@cam.org> |
| * Rewritten: big cleanup, much simpler, better HZ accuracy. |
| * |
| */ |
| |
| |
| #define RTC_DEF_DIVIDER (32768 - 1) |
| #define RTC_DEF_TRIM 0 |
| |
| static unsigned long __init sa1100_get_rtc_time(void) |
| { |
| /* |
| * According to the manual we should be able to let RTTR be zero |
| * and then a default diviser for a 32.768KHz clock is used. |
| * Apparently this doesn't work, at least for my SA1110 rev 5. |
| * If the clock divider is uninitialized then reset it to the |
| * default value to get the 1Hz clock. |
| */ |
| if (RTTR == 0) { |
| RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16); |
| printk(KERN_WARNING "Warning: uninitialized Real Time Clock\n"); |
| /* The current RTC value probably doesn't make sense either */ |
| RCNR = 0; |
| return 0; |
| } |
| return RCNR; |
| } |
| |
| static int sa1100_set_rtc(void) |
| { |
| unsigned long current_time = xtime.tv_sec; |
| |
| if (RTSR & RTSR_ALE) { |
| /* make sure not to forward the clock over an alarm */ |
| unsigned long alarm = RTAR; |
| if (current_time >= alarm && alarm >= RCNR) |
| return -ERESTARTSYS; |
| } |
| RCNR = current_time; |
| return 0; |
| } |
| |
| /* IRQs are disabled before entering here from do_gettimeofday() */ |
| static unsigned long sa1100_gettimeoffset (void) |
| { |
| unsigned long ticks_to_match, elapsed, usec; |
| |
| /* Get ticks before next timer match */ |
| ticks_to_match = OSMR0 - OSCR; |
| |
| /* We need elapsed ticks since last match */ |
| elapsed = LATCH - ticks_to_match; |
| |
| /* Now convert them to usec */ |
| usec = (unsigned long)(elapsed*tick)/LATCH; |
| |
| return usec; |
| } |
| |
| /* |
| * We will be entered with IRQs enabled. |
| * |
| * Loop until we get ahead of the free running timer. |
| * This ensures an exact clock tick count and time acuracy. |
| * IRQs are disabled inside the loop to ensure coherence between |
| * lost_ticks (updated in do_timer()) and the match reg value, so we |
| * can use do_gettimeofday() from interrupt handlers. |
| */ |
| static void sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) |
| { |
| unsigned int next_match; |
| unsigned long flags; |
| |
| do { |
| do_leds(); |
| local_irq_save(flags); |
| do_timer(regs); |
| OSSR = OSSR_M0; /* Clear match on timer 0 */ |
| next_match = (OSMR0 += LATCH); |
| local_irq_restore(flags); |
| do_set_rtc(); |
| } while ((signed long)(next_match - OSCR) <= 0); |
| |
| do_profile(regs); |
| } |
| |
| void __init time_init(void) |
| { |
| gettimeoffset = sa1100_gettimeoffset; |
| set_rtc = sa1100_set_rtc; |
| xtime.tv_sec = sa1100_get_rtc_time(); |
| timer_irq.handler = sa1100_timer_interrupt; |
| OSMR0 = 0; /* set initial match at 0 */ |
| OSSR = 0xf; /* clear status on all timers */ |
| setup_irq(IRQ_OST0, &timer_irq); |
| OIER |= OIER_E0; /* enable match on timer 0 to cause interrupts */ |
| OSCR = 0; /* initialize free-running timer, force first match */ |
| } |
| |