/*
* Copyright 2001 MontaVista Software Inc.
* Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
* Copyright (c) 2003, 2004 Maciej W. Rozycki
*
* Common time service routines for MIPS machines. See
* Documentation/mips/time.README.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/bug.h>
#include <linux/clockchips.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/profile.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <asm/bootinfo.h>
#include <asm/cache.h>
#include <asm/compiler.h>
#include <asm/cpu.h>
#include <asm/cpu-features.h>
#include <asm/div64.h>
#include <asm/sections.h>
#include <asm/smtc_ipi.h>
#include <asm/time.h>
#include <irq.h>
/*
* forward reference
*/
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);
int __weak rtc_mips_set_time(unsigned long sec)
{
return 0;
}
EXPORT_SYMBOL(rtc_mips_set_time);
int __weak rtc_mips_set_mmss(unsigned long nowtime)
{
return rtc_mips_set_time(nowtime);
}
int update_persistent_clock(struct timespec now)
{
return rtc_mips_set_mmss(now.tv_sec);
}
/*
* Null high precision timer functions for systems lacking one.
*/
static cycle_t null_hpt_read(void)
{
return 0;
}
/*
* High precision timer functions for a R4k-compatible timer.
*/
static cycle_t c0_hpt_read(void)
{
return read_c0_count();
}
int (*mips_timer_state)(void);
int null_perf_irq(void)
{
return 0;
}
EXPORT_SYMBOL(null_perf_irq);
int (*perf_irq)(void) = null_perf_irq;
EXPORT_SYMBOL(perf_irq);
/*
* time_init() - it does the following things.
*
* 1) plat_time_init() -
* a) (optional) set up RTC routines,
* b) (optional) calibrate and set the mips_hpt_frequency
* (only needed if you intended to use cpu counter as timer interrupt
* source)
* 2) calculate a couple of cached variables for later usage
*/
unsigned int mips_hpt_frequency;
static unsigned int __init calibrate_hpt(void)
{
cycle_t frequency, hpt_start, hpt_end, hpt_count, hz;
const int loops = HZ / 10;
int log_2_loops = 0;
int i;
/*
* We want to calibrate for 0.1s, but to avoid a 64-bit
* division we round the number of loops up to the nearest
* power of 2.
*/
while (loops > 1 << log_2_loops)
log_2_loops++;
i = 1 << log_2_loops;
/*
* Wait for a rising edge of the timer interrupt.
*/
while (mips_timer_state());
while (!mips_timer_state());
/*
* Now see how many high precision timer ticks happen
* during the calculated number of periods between timer
* interrupts.
*/
hpt_start = clocksource_mips.read();
do {
while (mips_timer_state());
while (!mips_timer_state());
} while (--i);
hpt_end = clocksource_mips.read();
hpt_count = (hpt_end - hpt_start) & clocksource_mips.mask;
hz = HZ;
frequency = hpt_count * hz;
return frequency >> log_2_loops;
}
struct clocksource clocksource_mips = {
.name = "MIPS",
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
{
u64 temp;
u32 shift;
/* Find a shift value */
for (shift = 32; shift > 0; shift--) {
temp = (u64) NSEC_PER_SEC << shift;
do_div(temp, clock);
if ((temp >> 32) == 0)
break;
}
cs->shift = shift;
cs->mult = (u32) temp;
}
void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
unsigned int clock)
{
u64 temp;
u32 shift;
/* Find a shift value */
for (shift = 32; shift > 0; shift--) {
temp = (u64) clock << shift;
do_div(temp, NSEC_PER_SEC);
if ((temp >> 32) == 0)
break;
}
cd->shift = shift;
cd->mult = (u32) temp;
}
static void __init init_mips_clocksource(void)
{
if (!mips_hpt_frequency || clocksource_mips.read == null_hpt_read)
return;
/* Calclate a somewhat reasonable rating value */
clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
clocksource_set_clock(&clocksource_mips, mips_hpt_frequency);
clocksource_register(&clocksource_mips);
}
void __init __weak plat_time_init(void)
{
}
/*
* This function exists in order to cause an error due to a duplicate
* definition if platform code should have its own implementation. The hook
* to use instead is plat_time_init. plat_time_init does not receive the
* irqaction pointer argument anymore. This is because any function which
* initializes an interrupt timer now takes care of its own request_irq rsp.
* setup_irq calls and each clock_event_device should use its own
* struct irqrequest.
*/
void __init plat_timer_setup(struct irqaction *irq)
{
BUG();
}
void __init time_init(void)
{
plat_time_init();
/* Choose appropriate high precision timer routines. */
if (!cpu_has_counter && !clocksource_mips.read)
/* No high precision timer -- sorry. */
clocksource_mips.read = null_hpt_read;
else if (!mips_hpt_frequency && !mips_timer_state) {
/* A high precision timer of unknown frequency. */
if (!clocksource_mips.read)
/* No external high precision timer -- use R4k. */
clocksource_mips.read = c0_hpt_read;
} else {
/* We know counter frequency. Or we can get it. */
if (!clocksource_mips.read) {
/* No external high precision timer -- use R4k. */
clocksource_mips.read = c0_hpt_read;
}
if (!mips_hpt_frequency)
mips_hpt_frequency = calibrate_hpt();
/* Report the high precision timer rate for a reference. */
printk("Using %u.%03u MHz high precision timer.\n",
((mips_hpt_frequency + 500) / 1000) / 1000,
((mips_hpt_frequency + 500) / 1000) % 1000);
}
init_mips_clocksource();
mips_clockevent_init();
}
