arch/unicore32/kernel/time.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/arch/unicore32/kernel/time.c
   4  *
   5  * Code specific to PKUnity SoC and UniCore ISA
   6  *
   7  *      Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
   8  *      Copyright (C) 2001-2010 Guan Xuetao
   9  */
  10 #include <linux/init.h>
  11 #include <linux/errno.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/irq.h>
  14 #include <linux/timex.h>
  15 #include <linux/clockchips.h>
  16
  17 #include <mach/hardware.h>
  18
  19 #define MIN_OSCR_DELTA 2
  20
  21 static irqreturn_t puv3_ost0_interrupt(int irq, void *dev_id)
  22 {
  23         struct clock_event_device *c = dev_id;
  24
  25         /* Disarm the compare/match, signal the event. */
  26         writel(readl(OST_OIER) & ~OST_OIER_E0, OST_OIER);
  27         writel(readl(OST_OSSR) & ~OST_OSSR_M0, OST_OSSR);
  28         c->event_handler(c);
  29
  30         return IRQ_HANDLED;
  31 }
  32
  33 static int
  34 puv3_osmr0_set_next_event(unsigned long delta, struct clock_event_device *c)
  35 {
  36         unsigned long next, oscr;
  37
  38         writel(readl(OST_OIER) | OST_OIER_E0, OST_OIER);
  39         next = readl(OST_OSCR) + delta;
  40         writel(next, OST_OSMR0);
  41         oscr = readl(OST_OSCR);
  42
  43         return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
  44 }
  45
  46 static int puv3_osmr0_shutdown(struct clock_event_device *evt)
  47 {
  48         writel(readl(OST_OIER) & ~OST_OIER_E0, OST_OIER);
  49         writel(readl(OST_OSSR) & ~OST_OSSR_M0, OST_OSSR);
  50         return 0;
  51 }
  52
  53 static struct clock_event_device ckevt_puv3_osmr0 = {
  54         .name                   = "osmr0",
  55         .features               = CLOCK_EVT_FEAT_ONESHOT,
  56         .rating                 = 200,
  57         .set_next_event         = puv3_osmr0_set_next_event,
  58         .set_state_shutdown     = puv3_osmr0_shutdown,
  59         .set_state_oneshot      = puv3_osmr0_shutdown,
  60 };
  61
  62 static u64 puv3_read_oscr(struct clocksource *cs)
  63 {
  64         return readl(OST_OSCR);
  65 }
  66
  67 static struct clocksource cksrc_puv3_oscr = {
  68         .name           = "oscr",
  69         .rating         = 200,
  70         .read           = puv3_read_oscr,
  71         .mask           = CLOCKSOURCE_MASK(32),
  72         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  73 };
  74
  75 static struct irqaction puv3_timer_irq = {
  76         .name           = "ost0",
  77         .flags          = IRQF_TIMER | IRQF_IRQPOLL,
  78         .handler        = puv3_ost0_interrupt,
  79         .dev_id         = &ckevt_puv3_osmr0,
  80 };
  81
  82 void __init time_init(void)
  83 {
  84         writel(0, OST_OIER);            /* disable any timer interrupts */
  85         writel(0, OST_OSSR);            /* clear status on all timers */
  86
  87         clockevents_calc_mult_shift(&ckevt_puv3_osmr0, CLOCK_TICK_RATE, 5);
  88
  89         ckevt_puv3_osmr0.max_delta_ns =
  90                 clockevent_delta2ns(0x7fffffff, &ckevt_puv3_osmr0);
  91         ckevt_puv3_osmr0.max_delta_ticks = 0x7fffffff;
  92         ckevt_puv3_osmr0.min_delta_ns =
  93                 clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_puv3_osmr0) + 1;
  94         ckevt_puv3_osmr0.min_delta_ticks = MIN_OSCR_DELTA * 2;
  95         ckevt_puv3_osmr0.cpumask = cpumask_of(0);
  96
  97         setup_irq(IRQ_TIMER0, &puv3_timer_irq);
  98
  99         clocksource_register_hz(&cksrc_puv3_oscr, CLOCK_TICK_RATE);
 100         clockevents_register_device(&ckevt_puv3_osmr0);
 101 }
 102
 103 #ifdef CONFIG_PM
 104 unsigned long osmr[4], oier;
 105
 106 void puv3_timer_suspend(void)
 107 {
 108         osmr[0] = readl(OST_OSMR0);
 109         osmr[1] = readl(OST_OSMR1);
 110         osmr[2] = readl(OST_OSMR2);
 111         osmr[3] = readl(OST_OSMR3);
 112         oier = readl(OST_OIER);
 113 }
 114
 115 void puv3_timer_resume(void)
 116 {
 117         writel(0, OST_OSSR);
 118         writel(osmr[0], OST_OSMR0);
 119         writel(osmr[1], OST_OSMR1);
 120         writel(osmr[2], OST_OSMR2);
 121         writel(osmr[3], OST_OSMR3);
 122         writel(oier, OST_OIER);
 123
 124         /*
 125          * OSMR0 is the system timer: make sure OSCR is sufficiently behind
 126          */
 127         writel(readl(OST_OSMR0) - LATCH, OST_OSCR);
 128 }
 129 #else
 130 void puv3_timer_suspend(void) { };
 131 void puv3_timer_resume(void) { };
 132 #endif
 133