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/*
* Copyright (C) 2004-2006 Atmel Corporation
*
* Based on MIPS implementation arch/mips/kernel/time.c
* Copyright 2001 MontaVista Software Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/time.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel_stat.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/sysdev.h>
#include <asm/div64.h>
#include <asm/sysreg.h>
#include <asm/io.h>
#include <asm/sections.h>
static cycle_t read_cycle_count(void)
{
return (cycle_t)sysreg_read(COUNT);
}
static struct clocksource clocksource_avr32 = {
.name = "avr32",
.rating = 350,
.read = read_cycle_count,
.mask = CLOCKSOURCE_MASK(32),
.shift = 16,
.is_continuous = 1,
};
/*
* By default we provide the null RTC ops
*/
static unsigned long null_rtc_get_time(void)
{
return mktime(2004, 1, 1, 0, 0, 0);
}
static int null_rtc_set_time(unsigned long sec)
{
return 0;
}
static unsigned long (*rtc_get_time)(void) = null_rtc_get_time;
static int (*rtc_set_time)(unsigned long) = null_rtc_set_time;
/* how many counter cycles in a jiffy? */
static unsigned long cycles_per_jiffy;
/* cycle counter value at the previous timer interrupt */
static unsigned int timerhi, timerlo;
/* the count value for the next timer interrupt */
static unsigned int expirelo;
static void avr32_timer_ack(void)
{
unsigned int count;
/* Ack this timer interrupt and set the next one */
expirelo += cycles_per_jiffy;
if (expirelo == 0) {
printk(KERN_DEBUG "expirelo == 0\n");
sysreg_write(COMPARE, expirelo + 1);
} else {
sysreg_write(COMPARE, expirelo);
}
/* Check to see if we have missed any timer interrupts */
count = sysreg_read(COUNT);
if ((count - expirelo) < 0x7fffffff) {
expirelo = count + cycles_per_jiffy;
sysreg_write(COMPARE, expirelo);
}
}
static unsigned int avr32_hpt_read(void)
{
return sysreg_read(COUNT);
}
/*
* Taken from MIPS c0_hpt_timer_init().
*
* Why is it so complicated, and what is "count"? My assumption is
* that `count' specifies the "reference cycle", i.e. the cycle since
* reset that should mean "zero". The reason COUNT is written twice is
* probably to make sure we don't get any timer interrupts while we
* are messing with the counter.
*/
static void avr32_hpt_init(unsigned int count)
{
count = sysreg_read(COUNT) - count;
expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
sysreg_write(COUNT, expirelo - cycles_per_jiffy);
sysreg_write(COMPARE, expirelo);
sysreg_write(COUNT, count);
}
/*
* Scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
/* There must be better ways...? */
return (unsigned long long)jiffies * (1000000000 / HZ);
}
/*
* local_timer_interrupt() does profiling and process accounting on a
* per-CPU basis.
*
* In UP mode, it is invoked from the (global) timer_interrupt.
*/
static void local_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
if (current->pid)
profile_tick(CPU_PROFILING, regs);
update_process_times(user_mode(regs));
}
static irqreturn_t
timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
unsigned int count;
/* ack timer interrupt and try to set next interrupt */
count = avr32_hpt_read();
avr32_timer_ack();
/* Update timerhi/timerlo for intra-jiffy calibration */
timerhi += count < timerlo; /* Wrap around */
timerlo = count;
/*
* Call the generic timer interrupt handler
*/
write_seqlock(&xtime_lock);
do_timer(regs);
write_sequnlock(&xtime_lock);
/*
* In UP mode, we call local_timer_interrupt() to do profiling
* and process accounting.
*
* SMP is not supported yet.
*/
local_timer_interrupt(irq, dev_id, regs);
return IRQ_HANDLED;
}
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED,
.name = "timer",
};
void __init time_init(void)
{
unsigned long mult, shift, count_hz;
int ret;
xtime.tv_sec = rtc_get_time();
xtime.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
printk("Before time_init: count=%08lx, compare=%08lx\n",
(unsigned long)sysreg_read(COUNT),
(unsigned long)sysreg_read(COMPARE));
count_hz = clk_get_rate(boot_cpu_data.clk);
shift = clocksource_avr32.shift;
mult = clocksource_hz2mult(count_hz, shift);
clocksource_avr32.mult = mult;
printk("Cycle counter: mult=%lu, shift=%lu\n", mult, shift);
{
u64 tmp;
tmp = TICK_NSEC;
tmp <<= shift;
tmp += mult / 2;
do_div(tmp, mult);
cycles_per_jiffy = tmp;
}
/* This sets up the high precision timer for the first interrupt. */
avr32_hpt_init(avr32_hpt_read());
printk("After time_init: count=%08lx, compare=%08lx\n",
(unsigned long)sysreg_read(COUNT),
(unsigned long)sysreg_read(COMPARE));
ret = clocksource_register(&clocksource_avr32);
if (ret)
printk(KERN_ERR
"timer: could not register clocksource: %d\n", ret);
ret = setup_irq(0, &timer_irqaction);
if (ret)
printk("timer: could not request IRQ 0: %d\n", ret);
}
static struct sysdev_class timer_class = {
set_kset_name("timer"),
};
static struct sys_device timer_device = {
.id = 0,
.cls = &timer_class,
};
static int __init init_timer_sysfs(void)
{
int err = sysdev_class_register(&timer_class);
if (!err)
err = sysdev_register(&timer_device);
return err;
}
device_initcall(init_timer_sysfs);
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