kernel-fxtec-pro1x/arch/mn10300/kernel/time.c
Akira Takeuchi 368dd5acd1 MN10300: And Panasonic AM34 subarch and implement SMP
Implement the Panasonic MN10300 AM34 CPU subarch and implement SMP support for
MN10300.  Also implement support for the MN2WS0060 processor and the ASB2364
evaluation board which are AM34 based.

Signed-off-by: Akira Takeuchi <takeuchi.akr@jp.panasonic.com>
Signed-off-by: Kiyoshi Owada <owada.kiyoshi@jp.panasonic.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2010-10-27 17:28:55 +01:00

171 lines
4.4 KiB
C

/* MN10300 Low level time management
*
* Copyright (C) 2007-2008 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 <linux/cnt32_to_63.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/processor.h>
#include <asm/intctl-regs.h>
#include <asm/rtc.h>
#include "internal.h"
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,
.name = "timer",
};
static unsigned long sched_clock_multiplier;
/*
* scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
union {
unsigned long long ll;
unsigned l[2];
} tsc64, result;
unsigned long tsc, tmp;
unsigned product[3]; /* 96-bit intermediate value */
/* cnt32_to_63() is not safe with preemption */
preempt_disable();
/* read the TSC value
*/
tsc = 0 - get_cycles(); /* get_cycles() counts down */
/* expand to 64-bits.
* - sched_clock() must be called once a minute or better or the
* following will go horribly wrong - see cnt32_to_63()
*/
tsc64.ll = cnt32_to_63(tsc) & 0x7fffffffffffffffULL;
preempt_enable();
/* scale the 64-bit TSC value to a nanosecond value via a 96-bit
* intermediate
*/
asm("mulu %2,%0,%3,%0 \n" /* LSW * mult -> 0:%3:%0 */
"mulu %2,%1,%2,%1 \n" /* MSW * mult -> %2:%1:0 */
"add %3,%1 \n"
"addc 0,%2 \n" /* result in %2:%1:%0 */
: "=r"(product[0]), "=r"(product[1]), "=r"(product[2]), "=r"(tmp)
: "0"(tsc64.l[0]), "1"(tsc64.l[1]), "2"(sched_clock_multiplier)
: "cc");
result.l[0] = product[1] << 16 | product[0] >> 16;
result.l[1] = product[2] << 16 | product[1] >> 16;
return result.ll;
}
/*
* initialise the scheduler clock
*/
static void __init mn10300_sched_clock_init(void)
{
sched_clock_multiplier =
__muldiv64u(NSEC_PER_SEC, 1 << 16, MN10300_TSCCLK);
}
/**
* local_timer_interrupt - Local timer interrupt handler
*
* Handle local timer interrupts for this CPU. They may have been propagated
* to this CPU from the CPU that actually gets them by way of an IPI.
*/
irqreturn_t local_timer_interrupt(void)
{
profile_tick(CPU_PROFILING);
update_process_times(user_mode(get_irq_regs()));
return IRQ_HANDLED;
}
/*
* 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;
irqreturn_t ret;
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 */
do_timer(1);
}
write_sequnlock(&xtime_lock);
ret = local_timer_interrupt();
#ifdef CONFIG_SMP
send_IPI_allbutself(LOCAL_TIMER_IPI);
#endif
return ret;
}
/*
* 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);
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, NUM2GxICR_LEVEL(CONFIG_TIMER_IRQ_LEVEL));
startup_jiffies_counter();
#ifdef CONFIG_MN10300_WD_TIMER
/* start the watchdog timer */
watchdog_go();
#endif
mn10300_sched_clock_init();
}