arch/arm/mach-ns9xxx/time.c

   1 /*
   2  * arch/arm/mach-ns9xxx/time.c
   3  *
   4  * Copyright (C) 2006 by Digi International Inc.
   5  * All rights reserved.
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 as published by
   9  * the Free Software Foundation.
  10  */
  11 #include <linux/jiffies.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/irq.h>
  14 #include <linux/stringify.h>
  15 #include <linux/clocksource.h>
  16
  17 #include <asm/arch-ns9xxx/regs-sys.h>
  18 #include <asm/arch-ns9xxx/clock.h>
  19 #include <asm/arch-ns9xxx/irqs.h>
  20 #include <asm/arch/system.h>
  21 #include "generic.h"
  22
  23 #define TIMERCLOCKSELECT 64
  24 #define TIMER_CLOCKSOURCE 1
  25
  26 static irqreturn_t
  27 ns9xxx_timer_interrupt(int irq, void *dev_id)
  28 {
  29         int timerno = irq - IRQ_TIMER0;
  30         u32 tc;
  31
  32         write_seqlock(&xtime_lock);
  33         timer_tick();
  34         write_sequnlock(&xtime_lock);
  35
  36         /* clear irq */
  37         tc = SYS_TC(timerno);
  38         if (REGGET(tc, SYS_TCx, REN) == SYS_TCx_REN_DIS) {
  39                 REGSET(tc, SYS_TCx, TEN, DIS);
  40                 SYS_TC(timerno) = tc;
  41         }
  42         REGSET(tc, SYS_TCx, INTC, SET);
  43         SYS_TC(timerno) = tc;
  44         REGSET(tc, SYS_TCx, INTC, UNSET);
  45         SYS_TC(timerno) = tc;
  46
  47         return IRQ_HANDLED;
  48 }
  49
  50 static struct irqaction ns9xxx_timer_irq = {
  51         .name = "NS9xxx Timer Tick",
  52         .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
  53         .handler = ns9xxx_timer_interrupt,
  54 };
  55
  56 static cycle_t ns9xxx_clocksource_read(void)
  57 {
  58         return SYS_TR(TIMER_CLOCKSOURCE);
  59 }
  60
  61 static struct clocksource ns9xxx_clocksource = {
  62         .name   = "ns9xxx-timer" __stringify(TIMER_CLOCKSOURCE),
  63         .rating = 300,
  64         .read   = ns9xxx_clocksource_read,
  65         .mask   = CLOCKSOURCE_MASK(32),
  66         .shift  = 20,
  67         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
  68 };
  69
  70 static void __init ns9xxx_timer_init(void)
  71 {
  72         int tc;
  73
  74         /* disable timer */
  75         if ((tc = SYS_TC(0)) & SYS_TCx_TEN)
  76                 SYS_TC(0) = tc & ~SYS_TCx_TEN;
  77
  78         SYS_TRC(0) = SH_DIV(ns9xxx_cpuclock(), (TIMERCLOCKSELECT * HZ), 0);
  79
  80         REGSET(tc, SYS_TCx, TEN, EN);
  81         REGSET(tc, SYS_TCx, TLCS, DIV64); /* This must match TIMERCLOCKSELECT */
  82         REGSET(tc, SYS_TCx, INTS, EN);
  83         REGSET(tc, SYS_TCx, UDS, DOWN);
  84         REGSET(tc, SYS_TCx, TDBG, STOP);
  85         REGSET(tc, SYS_TCx, TSZ, 32);
  86         REGSET(tc, SYS_TCx, REN, EN);
  87         SYS_TC(0) = tc;
  88
  89         setup_irq(IRQ_TIMER0, &ns9xxx_timer_irq);
  90
  91         tc = SYS_TC(TIMER_CLOCKSOURCE);
  92         if (REGGET(tc, SYS_TCx, TEN)) {
  93                 REGSET(tc, SYS_TCx, TEN, DIS);
  94                 SYS_TC(TIMER_CLOCKSOURCE) = tc;
  95         }
  96
  97         SYS_TRC(TIMER_CLOCKSOURCE) = 0;
  98
  99         REGSET(tc, SYS_TCx, TEN, EN);
 100         REGSET(tc, SYS_TCx, TDBG, STOP);
 101         REGSET(tc, SYS_TCx, TLCS, CPU);
 102         REGSET(tc, SYS_TCx, TM, IEE);
 103         REGSET(tc, SYS_TCx, INTS, DIS);
 104         REGSET(tc, SYS_TCx, UDS, UP);
 105         REGSET(tc, SYS_TCx, TSZ, 32);
 106         REGSET(tc, SYS_TCx, REN, EN);
 107
 108         SYS_TC(TIMER_CLOCKSOURCE) = tc;
 109
 110         ns9xxx_clocksource.mult = clocksource_hz2mult(ns9xxx_cpuclock(),
 111                         ns9xxx_clocksource.shift);
 112
 113         clocksource_register(&ns9xxx_clocksource);
 114 }
 115
 116 struct sys_timer ns9xxx_timer = {
 117         .init = ns9xxx_timer_init,
 118 };