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/*
* Copyright (C) 2004-2007 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 <linux/err.h>
#include <asm/div64.h>
#include <asm/sysreg.h>
#include <asm/io.h>
#include <asm/sections.h>
/* how many counter cycles in a jiffy? */
static u32 cycles_per_jiffy;
/* the count value for the next timer interrupt */
static u32 expirelo;
cycle_t __weak read_cycle_count(void)
{
return (cycle_t)sysreg_read(COUNT);
}
/*
* The architectural cycle count registers are a fine clocksource unless
* the system idle loop use sleep states like "idle": the CPU cycles
* measured by COUNT (and COMPARE) don't happen during sleep states.
* So we rate the clocksource using COUNT as very low quality.
*/
struct clocksource __weak clocksource_avr32 = {
.name = "avr32",
.rating = 50,
.read = read_cycle_count,
.mask = CLOCKSOURCE_MASK(32),
.shift = 16,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
irqreturn_t __weak timer_interrupt(int irq, void *dev_id);
struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED,
.name = "timer",
};
static void avr32_timer_ack(void)
{
u32 count;
/* Ack this timer interrupt and set the next one */
expirelo += cycles_per_jiffy;
/* setting COMPARE to 0 stops the COUNT-COMPARE */
if (expirelo == 0) {
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);
}
}
int __weak avr32_hpt_init(void)
{
int ret;
unsigned long mult, shift, count_hz;
count_hz = clk_get_rate(boot_cpu_data.clk);
shift = clocksource_avr32.shift;
mult = clocksource_hz2mult(count_hz, shift);
clocksource_avr32.mult = mult;
{
u64 tmp;
tmp = TICK_NSEC;
tmp <<= shift;
tmp += mult / 2;
do_div(tmp, mult);
cycles_per_jiffy = tmp;
}
ret = setup_irq(0, &timer_irqaction);
if (ret) {
pr_debug("timer: could not request IRQ 0: %d\n", ret);
return -ENODEV;
}
printk(KERN_INFO "timer: AT32AP COUNT-COMPARE at irq 0, "
"%lu.%03lu MHz\n",
((count_hz + 500) / 1000) / 1000,
((count_hz + 500) / 1000) % 1000);
return 0;
}
/*
* Taken from MIPS c0_hpt_timer_init().
*
* 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.
*/
int __weak avr32_hpt_start(void)
{
u32 count = sysreg_read(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);
return 0;
}
/*
* local_timer_interrupt() does profiling and process accounting on a
* per-CPU basis.
*
* In UP mode, it is invoked from the (global) timer_interrupt.
*/
void local_timer_interrupt(int irq, void *dev_id)
{
if (current->pid)
profile_tick(CPU_PROFILING);
update_process_times(user_mode(get_irq_regs()));
}
irqreturn_t __weak timer_interrupt(int irq, void *dev_id)
{
/* ack timer interrupt and try to set next interrupt */
avr32_timer_ack();
/*
* Call the generic timer interrupt handler
*/
write_seqlock(&xtime_lock);
do_timer(1);
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);
return IRQ_HANDLED;
}
void __init time_init(void)
{
int ret;
/*
* Make sure we don't get any COMPARE interrupts before we can
* handle them.
*/
sysreg_write(COMPARE, 0);
xtime.tv_sec = mktime(2007, 1, 1, 0, 0, 0);
xtime.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
ret = avr32_hpt_init();
if (ret) {
pr_debug("timer: failed setup: %d\n", ret);
return;
}
ret = clocksource_register(&clocksource_avr32);
if (ret)
pr_debug("timer: could not register clocksource: %d\n", ret);
ret = avr32_hpt_start();
if (ret) {
pr_debug("timer: failed starting: %d\n", ret);
return;
}
}
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