arch/arm/mach-sa1100/time.c

   1 /*
   2  * linux/arch/arm/mach-sa1100/time.c
   3  *
   4  * Copyright (C) 1998 Deborah Wallach.
   5  * Twiddles  (C) 1999 Hugo Fiennes <hugo@empeg.com>
   6  *
   7  * 2000/03/29 (C) Nicolas Pitre <nico@fluxnic.net>
   8  *      Rewritten: big cleanup, much simpler, better HZ accuracy.
   9  *
  10  */
  11 #include <linux/init.h>
  12 #include <linux/errno.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/irq.h>
  15 #include <linux/sched.h>        /* just for sched_clock() - funny that */
  16 #include <linux/timex.h>
  17 #include <linux/clockchips.h>
  18
  19 #include <asm/mach/time.h>
  20 #include <asm/sched_clock.h>
  21 #include <mach/hardware.h>
  22
  23 /*
  24  * This is the SA11x0 sched_clock implementation.
  25  */
  26 static DEFINE_CLOCK_DATA(cd);
  27
  28 /*
  29  * Constants generated by clocks_calc_mult_shift(m, s, 3.6864MHz,
  30  * NSEC_PER_SEC, 60).
  31  * This gives a resolution of about 271ns and a wrap period of about 19min.
  32  */
  33 #define SC_MULT         2275555556u
  34 #define SC_SHIFT        23
  35
  36 unsigned long long notrace sched_clock(void)
  37 {
  38         u32 cyc = OSCR;
  39         return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT);
  40 }
  41
  42 static void notrace sa1100_update_sched_clock(void)
  43 {
  44         u32 cyc = OSCR;
  45         update_sched_clock(&cd, cyc, (u32)~0);
  46 }
  47
  48 #define MIN_OSCR_DELTA 2
  49
  50 static irqreturn_t sa1100_ost0_interrupt(int irq, void *dev_id)
  51 {
  52         struct clock_event_device *c = dev_id;
  53
  54         /* Disarm the compare/match, signal the event. */
  55         OIER &= ~OIER_E0;
  56         OSSR = OSSR_M0;
  57         c->event_handler(c);
  58
  59         return IRQ_HANDLED;
  60 }
  61
  62 static int
  63 sa1100_osmr0_set_next_event(unsigned long delta, struct clock_event_device *c)
  64 {
  65         unsigned long next, oscr;
  66
  67         OIER |= OIER_E0;
  68         next = OSCR + delta;
  69         OSMR0 = next;
  70         oscr = OSCR;
  71
  72         return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
  73 }
  74
  75 static void
  76 sa1100_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *c)
  77 {
  78         switch (mode) {
  79         case CLOCK_EVT_MODE_ONESHOT:
  80         case CLOCK_EVT_MODE_UNUSED:
  81         case CLOCK_EVT_MODE_SHUTDOWN:
  82                 OIER &= ~OIER_E0;
  83                 OSSR = OSSR_M0;
  84                 break;
  85
  86         case CLOCK_EVT_MODE_RESUME:
  87         case CLOCK_EVT_MODE_PERIODIC:
  88                 break;
  89         }
  90 }
  91
  92 static struct clock_event_device ckevt_sa1100_osmr0 = {
  93         .name           = "osmr0",
  94         .features       = CLOCK_EVT_FEAT_ONESHOT,
  95         .rating         = 200,
  96         .set_next_event = sa1100_osmr0_set_next_event,
  97         .set_mode       = sa1100_osmr0_set_mode,
  98 };
  99
 100 static struct irqaction sa1100_timer_irq = {
 101         .name           = "ost0",
 102         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 103         .handler        = sa1100_ost0_interrupt,
 104         .dev_id         = &ckevt_sa1100_osmr0,
 105 };
 106
 107 static void __init sa1100_timer_init(void)
 108 {
 109         OIER = 0;
 110         OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;
 111
 112         init_fixed_sched_clock(&cd, sa1100_update_sched_clock, 32,
 113                                3686400, SC_MULT, SC_SHIFT);
 114
 115         clockevents_calc_mult_shift(&ckevt_sa1100_osmr0, 3686400, 4);
 116         ckevt_sa1100_osmr0.max_delta_ns =
 117                 clockevent_delta2ns(0x7fffffff, &ckevt_sa1100_osmr0);
 118         ckevt_sa1100_osmr0.min_delta_ns =
 119                 clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_sa1100_osmr0) + 1;
 120         ckevt_sa1100_osmr0.cpumask = cpumask_of(0);
 121
 122         setup_irq(IRQ_OST0, &sa1100_timer_irq);
 123
 124         clocksource_mmio_init(&OSCR, "oscr", CLOCK_TICK_RATE, 200, 32,
 125                 clocksource_mmio_readl_up);
 126         clockevents_register_device(&ckevt_sa1100_osmr0);
 127 }
 128
 129 #ifdef CONFIG_PM
 130 unsigned long osmr[4], oier;
 131
 132 static void sa1100_timer_suspend(void)
 133 {
 134         osmr[0] = OSMR0;
 135         osmr[1] = OSMR1;
 136         osmr[2] = OSMR2;
 137         osmr[3] = OSMR3;
 138         oier = OIER;
 139 }
 140
 141 static void sa1100_timer_resume(void)
 142 {
 143         OSSR = 0x0f;
 144         OSMR0 = osmr[0];
 145         OSMR1 = osmr[1];
 146         OSMR2 = osmr[2];
 147         OSMR3 = osmr[3];
 148         OIER = oier;
 149
 150         /*
 151          * OSMR0 is the system timer: make sure OSCR is sufficiently behind
 152          */
 153         OSCR = OSMR0 - LATCH;
 154 }
 155 #else
 156 #define sa1100_timer_suspend NULL
 157 #define sa1100_timer_resume NULL
 158 #endif
 159
 160 struct sys_timer sa1100_timer = {
 161         .init           = sa1100_timer_init,
 162         .suspend        = sa1100_timer_suspend,
 163         .resume         = sa1100_timer_resume,
 164 };