kernel/arch/unicore32/kernel/time.c

   1 /*
   2  * linux/arch/unicore32/kernel/time.c
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   7  *      Copyright (C) 2001-2010 Guan Xuetao
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13 #include <linux/init.h>
  14 #include <linux/errno.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/irq.h>
  17 #include <linux/timex.h>
  18 #include <linux/clockchips.h>
  19
  20 #include <mach/hardware.h>
  21
  22 #define MIN_OSCR_DELTA 2
  23
  24 static irqreturn_t puv3_ost0_interrupt(int irq, void *dev_id)
  25 {
  26         struct clock_event_device *c = dev_id;
  27
  28         /* Disarm the compare/match, signal the event. */
  29         writel(readl(OST_OIER) & ~OST_OIER_E0, OST_OIER);
  30         writel(readl(OST_OSSR) & ~OST_OSSR_M0, OST_OSSR);
  31         c->event_handler(c);
  32
  33         return IRQ_HANDLED;
  34 }
  35
  36 static int
  37 puv3_osmr0_set_next_event(unsigned long delta, struct clock_event_device *c)
  38 {
  39         unsigned long next, oscr;
  40
  41         writel(readl(OST_OIER) | OST_OIER_E0, OST_OIER);
  42         next = readl(OST_OSCR) + delta;
  43         writel(next, OST_OSMR0);
  44         oscr = readl(OST_OSCR);
  45
  46         return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
  47 }
  48
  49 static int puv3_osmr0_shutdown(struct clock_event_device *evt)
  50 {
  51         writel(readl(OST_OIER) & ~OST_OIER_E0, OST_OIER);
  52         writel(readl(OST_OSSR) & ~OST_OSSR_M0, OST_OSSR);
  53         return 0;
  54 }
  55
  56 static struct clock_event_device ckevt_puv3_osmr0 = {
  57         .name                   = "osmr0",
  58         .features               = CLOCK_EVT_FEAT_ONESHOT,
  59         .rating                 = 200,
  60         .set_next_event         = puv3_osmr0_set_next_event,
  61         .set_state_shutdown     = puv3_osmr0_shutdown,
  62         .set_state_oneshot      = puv3_osmr0_shutdown,
  63 };
  64
  65 static cycle_t puv3_read_oscr(struct clocksource *cs)
  66 {
  67         return readl(OST_OSCR);
  68 }
  69
  70 static struct clocksource cksrc_puv3_oscr = {
  71         .name           = "oscr",
  72         .rating         = 200,
  73         .read           = puv3_read_oscr,
  74         .mask           = CLOCKSOURCE_MASK(32),
  75         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  76 };
  77
  78 static struct irqaction puv3_timer_irq = {
  79         .name           = "ost0",
  80         .flags          = IRQF_TIMER | IRQF_IRQPOLL,
  81         .handler        = puv3_ost0_interrupt,
  82         .dev_id         = &ckevt_puv3_osmr0,
  83 };
  84
  85 void __init time_init(void)
  86 {
  87         writel(0, OST_OIER);            /* disable any timer interrupts */
  88         writel(0, OST_OSSR);            /* clear status on all timers */
  89
  90         clockevents_calc_mult_shift(&ckevt_puv3_osmr0, CLOCK_TICK_RATE, 5);
  91
  92         ckevt_puv3_osmr0.max_delta_ns =
  93                 clockevent_delta2ns(0x7fffffff, &ckevt_puv3_osmr0);
  94         ckevt_puv3_osmr0.min_delta_ns =
  95                 clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_puv3_osmr0) + 1;
  96         ckevt_puv3_osmr0.cpumask = cpumask_of(0);
  97
  98         setup_irq(IRQ_TIMER0, &puv3_timer_irq);
  99
 100         clocksource_register_hz(&cksrc_puv3_oscr, CLOCK_TICK_RATE);
 101         clockevents_register_device(&ckevt_puv3_osmr0);
 102 }
 103
 104 #ifdef CONFIG_PM
 105 unsigned long osmr[4], oier;
 106
 107 void puv3_timer_suspend(void)
 108 {
 109         osmr[0] = readl(OST_OSMR0);
 110         osmr[1] = readl(OST_OSMR1);
 111         osmr[2] = readl(OST_OSMR2);
 112         osmr[3] = readl(OST_OSMR3);
 113         oier = readl(OST_OIER);
 114 }
 115
 116 void puv3_timer_resume(void)
 117 {
 118         writel(0, OST_OSSR);
 119         writel(osmr[0], OST_OSMR0);
 120         writel(osmr[1], OST_OSMR1);
 121         writel(osmr[2], OST_OSMR2);
 122         writel(osmr[3], OST_OSMR3);
 123         writel(oier, OST_OIER);
 124
 125         /*
 126          * OSMR0 is the system timer: make sure OSCR is sufficiently behind
 127          */
 128         writel(readl(OST_OSMR0) - LATCH, OST_OSCR);
 129 }
 130 #else
 131 void puv3_timer_suspend(void) { };
 132 void puv3_timer_resume(void) { };
 133 #endif
 134