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/timex.h>
  16 #include <linux/clockchips.h>
  17
  18 #include <asm/mach/time.h>
  19 #include <asm/sched_clock.h>
  20 #include <mach/hardware.h>
  21
  22 static u32 notrace sa1100_read_sched_clock(void)
  23 {
  24         return OSCR;
  25 }
  26
  27 #define MIN_OSCR_DELTA 2
  28
  29 static irqreturn_t sa1100_ost0_interrupt(int irq, void *dev_id)
  30 {
  31         struct clock_event_device *c = dev_id;
  32
  33         /* Disarm the compare/match, signal the event. */
  34         OIER &= ~OIER_E0;
  35         OSSR = OSSR_M0;
  36         c->event_handler(c);
  37
  38         return IRQ_HANDLED;
  39 }
  40
  41 static int
  42 sa1100_osmr0_set_next_event(unsigned long delta, struct clock_event_device *c)
  43 {
  44         unsigned long next, oscr;
  45
  46         OIER |= OIER_E0;
  47         next = OSCR + delta;
  48         OSMR0 = next;
  49         oscr = OSCR;
  50
  51         return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
  52 }
  53
  54 static void
  55 sa1100_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *c)
  56 {
  57         switch (mode) {
  58         case CLOCK_EVT_MODE_ONESHOT:
  59         case CLOCK_EVT_MODE_UNUSED:
  60         case CLOCK_EVT_MODE_SHUTDOWN:
  61                 OIER &= ~OIER_E0;
  62                 OSSR = OSSR_M0;
  63                 break;
  64
  65         case CLOCK_EVT_MODE_RESUME:
  66         case CLOCK_EVT_MODE_PERIODIC:
  67                 break;
  68         }
  69 }
  70
  71 static struct clock_event_device ckevt_sa1100_osmr0 = {
  72         .name           = "osmr0",
  73         .features       = CLOCK_EVT_FEAT_ONESHOT,
  74         .rating         = 200,
  75         .set_next_event = sa1100_osmr0_set_next_event,
  76         .set_mode       = sa1100_osmr0_set_mode,
  77 };
  78
  79 static struct irqaction sa1100_timer_irq = {
  80         .name           = "ost0",
  81         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
  82         .handler        = sa1100_ost0_interrupt,
  83         .dev_id         = &ckevt_sa1100_osmr0,
  84 };
  85
  86 static void __init sa1100_timer_init(void)
  87 {
  88         OIER = 0;
  89         OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;
  90
  91         setup_sched_clock(sa1100_read_sched_clock, 32, 3686400);
  92
  93         clockevents_calc_mult_shift(&ckevt_sa1100_osmr0, 3686400, 4);
  94         ckevt_sa1100_osmr0.max_delta_ns =
  95                 clockevent_delta2ns(0x7fffffff, &ckevt_sa1100_osmr0);
  96         ckevt_sa1100_osmr0.min_delta_ns =
  97                 clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_sa1100_osmr0) + 1;
  98         ckevt_sa1100_osmr0.cpumask = cpumask_of(0);
  99
 100         setup_irq(IRQ_OST0, &sa1100_timer_irq);
 101
 102         clocksource_mmio_init(&OSCR, "oscr", CLOCK_TICK_RATE, 200, 32,
 103                 clocksource_mmio_readl_up);
 104         clockevents_register_device(&ckevt_sa1100_osmr0);
 105 }
 106
 107 #ifdef CONFIG_PM
 108 unsigned long osmr[4], oier;
 109
 110 static void sa1100_timer_suspend(void)
 111 {
 112         osmr[0] = OSMR0;
 113         osmr[1] = OSMR1;
 114         osmr[2] = OSMR2;
 115         osmr[3] = OSMR3;
 116         oier = OIER;
 117 }
 118
 119 static void sa1100_timer_resume(void)
 120 {
 121         OSSR = 0x0f;
 122         OSMR0 = osmr[0];
 123         OSMR1 = osmr[1];
 124         OSMR2 = osmr[2];
 125         OSMR3 = osmr[3];
 126         OIER = oier;
 127
 128         /*
 129          * OSMR0 is the system timer: make sure OSCR is sufficiently behind
 130          */
 131         OSCR = OSMR0 - LATCH;
 132 }
 133 #else
 134 #define sa1100_timer_suspend NULL
 135 #define sa1100_timer_resume NULL
 136 #endif
 137
 138 struct sys_timer sa1100_timer = {
 139         .init           = sa1100_timer_init,
 140         .suspend        = sa1100_timer_suspend,
 141         .resume         = sa1100_timer_resume,
 142 };