/* MN10300 Low level time management
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
* - Derived from arch/i386/kernel/time.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/profile.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/processor.h>
#include <asm/intctl-regs.h>
#include <asm/rtc.h>
#ifdef CONFIG_MN10300_RTC
unsigned long mn10300_ioclk; /* system I/O clock frequency */
unsigned long mn10300_iobclk; /* system I/O clock frequency */
unsigned long mn10300_tsc_per_HZ; /* number of ioclks per jiffy */
#endif /* CONFIG_MN10300_RTC */
static unsigned long mn10300_last_tsc; /* time-stamp counter at last time
* interrupt occurred */
static irqreturn_t timer_interrupt(int irq, void *dev_id);
static struct irqaction timer_irq = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED | IRQF_SHARED | IRQF_TIMER,
.mask = CPU_MASK_NONE,
.name = "timer",
};
/*
* scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
union {
unsigned long long l;
u32 w[2];
} quot;
quot.w[0] = mn10300_last_tsc - get_cycles();
quot.w[1] = 1000000000;
asm("mulu %2,%3,%0,%1"
: "=r"(quot.w[1]), "=r"(quot.w[0])
: "0"(quot.w[1]), "1"(quot.w[0])
: "cc");
do_div(quot.l, MN10300_TSCCLK);
return quot.l;
}
/*
* advance the kernel's time keeping clocks (xtime and jiffies)
* - we use Timer 0 & 1 cascaded as a clock to nudge us the next time
* there's a need to update
*/
static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
unsigned tsc, elapse;
write_seqlock(&xtime_lock);
while (tsc = get_cycles(),
elapse = mn10300_last_tsc - tsc, /* time elapsed since last
* tick */
elapse > MN10300_TSC_PER_HZ
) {
mn10300_last_tsc -= MN10300_TSC_PER_HZ;
/* advance the kernel's time tracking system */
profile_tick(CPU_PROFILING);
do_timer(1);
check_rtc_time();
}
write_sequnlock(&xtime_lock);
update_process_times(user_mode(get_irq_regs()));
return IRQ_HANDLED;
}
/*
* initialise the various timers used by the main part of the kernel
*/
void __init time_init(void)
{
/* we need the prescalar running to be able to use IOCLK/8
* - IOCLK runs at 1/4 (ST5 open) or 1/8 (ST5 closed) internal CPU clock
* - IOCLK runs at Fosc rate (crystal speed)
*/
TMPSCNT |= TMPSCNT_ENABLE;
startup_timestamp_counter();
printk(KERN_INFO
"timestamp counter I/O clock running at %lu.%02lu"
" (calibrated against RTC)\n",
MN10300_TSCCLK / 1000000, (MN10300_TSCCLK / 10000) % 100);
xtime.tv_sec = get_initial_rtc_time();
xtime.tv_nsec = 0;
mn10300_last_tsc = TMTSCBC;
/* use timer 0 & 1 cascaded to tick at as close to HZ as possible */
setup_irq(TMJCIRQ, &timer_irq);
set_intr_level(TMJCIRQ, TMJCICR_LEVEL);
startup_jiffies_counter();
#ifdef CONFIG_MN10300_WD_TIMER
/* start the watchdog timer */
watchdog_go();
#endif
}
