/* MN10300 Low level time management
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*
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* Copyright (C) 2007-2008 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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* - Derived from arch/i386/kernel/time.c
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/interrupt.h>
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#include <linux/time.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/profile.h>
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#include <linux/cnt32_to_63.h>
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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#include <asm/irq.h>
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#include <asm/div64.h>
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#include <asm/processor.h>
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#include <asm/intctl-regs.h>
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#include <asm/rtc.h>
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#include "internal.h"
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static unsigned long mn10300_last_tsc; /* time-stamp counter at last time
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* interrupt occurred */
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static unsigned long sched_clock_multiplier;
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/*
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* scheduler clock - returns current time in nanosec units.
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*/
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unsigned long long sched_clock(void)
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{
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union {
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unsigned long long ll;
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unsigned l[2];
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} tsc64, result;
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unsigned long tmp;
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unsigned product[3]; /* 96-bit intermediate value */
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/* cnt32_to_63() is not safe with preemption */
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preempt_disable();
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/* expand the tsc to 64-bits.
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* - sched_clock() must be called once a minute or better or the
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* following will go horribly wrong - see cnt32_to_63()
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*/
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tsc64.ll = cnt32_to_63(get_cycles()) & 0x7fffffffffffffffULL;
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preempt_enable();
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/* scale the 64-bit TSC value to a nanosecond value via a 96-bit
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* intermediate
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*/
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asm("mulu %2,%0,%3,%0 \n" /* LSW * mult -> 0:%3:%0 */
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"mulu %2,%1,%2,%1 \n" /* MSW * mult -> %2:%1:0 */
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"add %3,%1 \n"
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"addc 0,%2 \n" /* result in %2:%1:%0 */
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: "=r"(product[0]), "=r"(product[1]), "=r"(product[2]), "=r"(tmp)
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: "0"(tsc64.l[0]), "1"(tsc64.l[1]), "2"(sched_clock_multiplier)
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: "cc");
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result.l[0] = product[1] << 16 | product[0] >> 16;
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result.l[1] = product[2] << 16 | product[1] >> 16;
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return result.ll;
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}
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/*
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* initialise the scheduler clock
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*/
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static void __init mn10300_sched_clock_init(void)
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{
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sched_clock_multiplier =
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__muldiv64u(NSEC_PER_SEC, 1 << 16, MN10300_TSCCLK);
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}
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/**
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* local_timer_interrupt - Local timer interrupt handler
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*
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* Handle local timer interrupts for this CPU. They may have been propagated
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* to this CPU from the CPU that actually gets them by way of an IPI.
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*/
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irqreturn_t local_timer_interrupt(void)
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{
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profile_tick(CPU_PROFILING);
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update_process_times(user_mode(get_irq_regs()));
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return IRQ_HANDLED;
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}
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/*
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* initialise the various timers used by the main part of the kernel
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*/
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void __init time_init(void)
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{
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/* we need the prescalar running to be able to use IOCLK/8
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* - IOCLK runs at 1/4 (ST5 open) or 1/8 (ST5 closed) internal CPU clock
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* - IOCLK runs at Fosc rate (crystal speed)
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*/
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TMPSCNT |= TMPSCNT_ENABLE;
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init_clocksource();
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printk(KERN_INFO
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"timestamp counter I/O clock running at %lu.%02lu"
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" (calibrated against RTC)\n",
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MN10300_TSCCLK / 1000000, (MN10300_TSCCLK / 10000) % 100);
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mn10300_last_tsc = read_timestamp_counter();
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init_clockevents();
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#ifdef CONFIG_MN10300_WD_TIMER
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/* start the watchdog timer */
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watchdog_go();
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#endif
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mn10300_sched_clock_init();
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}
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