LXR linux/arch/blackfin/kernel/time.c

   1/*
   2 * arch/blackfin/kernel/time.c
   3 *
   4 * This file contains the Blackfin-specific time handling details.
   5 * Most of the stuff is located in the machine specific files.
   6 *
   7 * Copyright 2004-2008 Analog Devices Inc.
   8 * Licensed under the GPL-2 or later.
   9 */
  10
  11#include <linux/module.h>
  12#include <linux/profile.h>
  13#include <linux/interrupt.h>
  14#include <linux/time.h>
  15#include <linux/irq.h>
  16#include <linux/delay.h>
  17#include <linux/sched.h>
  18
  19#include <asm/blackfin.h>
  20#include <asm/time.h>
  21#include <asm/gptimers.h>
  22
  23/* This is an NTP setting */
  24#define TICK_SIZE (tick_nsec / 1000)
  25
  26static struct irqaction bfin_timer_irq = {
  27        .name = "Blackfin Timer Tick",
  28        .flags = IRQF_DISABLED
  29};
  30
  31#if defined(CONFIG_IPIPE)
  32void __init setup_system_timer0(void)
  33{
  34        /* Power down the core timer, just to play safe. */
  35        bfin_write_TCNTL(0);
  36
  37        disable_gptimers(TIMER0bit);
  38        set_gptimer_status(0, TIMER_STATUS_TRUN0);
  39        while (get_gptimer_status(0) & TIMER_STATUS_TRUN0)
  40                udelay(10);
  41
  42        set_gptimer_config(0, 0x59); /* IRQ enable, periodic, PWM_OUT, SCLKed, OUT PAD disabled */
  43        set_gptimer_period(TIMER0_id, get_sclk() / HZ);
  44        set_gptimer_pwidth(TIMER0_id, 1);
  45        SSYNC();
  46        enable_gptimers(TIMER0bit);
  47}
  48#else
  49void __init setup_core_timer(void)
  50{
  51        u32 tcount;
  52
  53        /* power up the timer, but don't enable it just yet */
  54        bfin_write_TCNTL(1);
  55        CSYNC();
  56
  57        /* the TSCALE prescaler counter */
  58        bfin_write_TSCALE(TIME_SCALE - 1);
  59
  60        tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
  61        bfin_write_TPERIOD(tcount);
  62        bfin_write_TCOUNT(tcount);
  63
  64        /* now enable the timer */
  65        CSYNC();
  66
  67        bfin_write_TCNTL(7);
  68}
  69#endif
  70
  71static void __init
  72time_sched_init(irqreturn_t(*timer_routine) (int, void *))
  73{
  74#if defined(CONFIG_IPIPE)
  75        setup_system_timer0();
  76        bfin_timer_irq.handler = timer_routine;
  77        setup_irq(IRQ_TIMER0, &bfin_timer_irq);
  78#else
  79        setup_core_timer();
  80        bfin_timer_irq.handler = timer_routine;
  81        setup_irq(IRQ_CORETMR, &bfin_timer_irq);
  82#endif
  83}
  84
  85#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
  86/*
  87 * Should return useconds since last timer tick
  88 */
  89u32 arch_gettimeoffset(void)
  90{
  91        unsigned long offset;
  92        unsigned long clocks_per_jiffy;
  93
  94#if defined(CONFIG_IPIPE)
  95        clocks_per_jiffy = bfin_read_TIMER0_PERIOD();
  96        offset = bfin_read_TIMER0_COUNTER() / \
  97                (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
  98
  99        if ((get_gptimer_status(0) & TIMER_STATUS_TIMIL0) && offset < (100000 / HZ / 2))
 100                offset += (USEC_PER_SEC / HZ);
 101#else
 102        clocks_per_jiffy = bfin_read_TPERIOD();
 103        offset = (clocks_per_jiffy - bfin_read_TCOUNT()) / \
 104                (((clocks_per_jiffy + 1) * HZ) / USEC_PER_SEC);
 105
 106        /* Check if we just wrapped the counters and maybe missed a tick */
 107        if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
 108                && (offset < (100000 / HZ / 2)))
 109                offset += (USEC_PER_SEC / HZ);
 110#endif
 111        return offset;
 112}
 113#endif
 114
 115/*
 116 * timer_interrupt() needs to keep up the real-time clock,
 117 * as well as call the "do_timer()" routine every clocktick
 118 */
 119#ifdef CONFIG_CORE_TIMER_IRQ_L1
 120__attribute__((l1_text))
 121#endif
 122irqreturn_t timer_interrupt(int irq, void *dummy)
 123{
 124        write_seqlock(&xtime_lock);
 125        do_timer(1);
 126        write_sequnlock(&xtime_lock);
 127
 128#ifdef CONFIG_IPIPE
 129        update_root_process_times(get_irq_regs());
 130#else
 131        update_process_times(user_mode(get_irq_regs()));
 132#endif
 133        profile_tick(CPU_PROFILING);
 134
 135        return IRQ_HANDLED;
 136}
 137
 138void read_persistent_clock(struct timespec *ts)
 139{
 140        time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
 141        ts->tv_sec = secs_since_1970;
 142        ts->tv_nsec = 0;
 143}
 144
 145void __init time_init(void)
 146{
 147#ifdef CONFIG_RTC_DRV_BFIN
 148        /* [#2663] hack to filter junk RTC values that would cause
 149         * userspace to have to deal with time values greater than
 150         * 2^31 seconds (which uClibc cannot cope with yet)
 151         */
 152        if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
 153                printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
 154                bfin_write_RTC_STAT(0);
 155        }
 156#endif
 157
 158        time_sched_init(timer_interrupt);
 159}
 160