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/*
* linux/arch/arm/mach-realview/localtimer.c
*
* Copyright (C) 2002 ARM Ltd.
* All Rights Reserved
*
* 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/init.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/smp.h>
#include <linux/jiffies.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>
#include <asm/mach/time.h>
#include <asm/hardware/arm_twd.h>
#include <asm/hardware/gic.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#define TWD_BASE(cpu) (__io_address(REALVIEW_TWD_BASE) + \
((cpu) * REALVIEW_TWD_SIZE))
static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
/*
* Used on SMP for either the local timer or IPI_TIMER
*/
void local_timer_interrupt(void)
{
struct clock_event_device *clk = &__get_cpu_var(local_clockevent);
clk->event_handler(clk);
}
#ifdef CONFIG_LOCAL_TIMERS
static unsigned long mpcore_timer_rate;
/*
* local_timer_ack: checks for a local timer interrupt.
*
* If a local timer interrupt has occurred, acknowledge and return 1.
* Otherwise, return 0.
*/
int local_timer_ack(void)
{
void __iomem *base = TWD_BASE(smp_processor_id());
if (__raw_readl(base + TWD_TIMER_INTSTAT)) {
__raw_writel(1, base + TWD_TIMER_INTSTAT);
return 1;
}
return 0;
}
void __cpuinit local_timer_setup(unsigned int cpu)
{
void __iomem *base = TWD_BASE(cpu);
unsigned int load, offset;
u64 waitjiffies;
unsigned int count;
/*
* If this is the first time round, we need to work out how fast
* the timer ticks
*/
if (mpcore_timer_rate == 0) {
printk("Calibrating local timer... ");
/* Wait for a tick to start */
waitjiffies = get_jiffies_64() + 1;
while (get_jiffies_64() < waitjiffies)
udelay(10);
/* OK, now the tick has started, let's get the timer going */
waitjiffies += 5;
/* enable, no interrupt or reload */
__raw_writel(0x1, base + TWD_TIMER_CONTROL);
/* maximum value */
__raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER);
while (get_jiffies_64() < waitjiffies)
udelay(10);
count = __raw_readl(base + TWD_TIMER_COUNTER);
mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000,
(mpcore_timer_rate / 100000) % 100);
}
load = mpcore_timer_rate / HZ;
__raw_writel(load, base + TWD_TIMER_LOAD);
__raw_writel(0x7, base + TWD_TIMER_CONTROL);
/*
* Now maneuver our local tick into the right part of the jiffy.
* Start by working out where within the tick our local timer
* interrupt should go.
*/
offset = ((mpcore_timer_rate / HZ) / (NR_CPUS + 1)) * (cpu + 1);
/*
* gettimeoffset() will return a number of us since the last tick.
* Convert this number of us to a local timer tick count.
* Be careful of integer overflow whilst keeping maximum precision.
*
* with HZ=100 and 1MHz (fpga) ~ 1GHz processor:
* load = 1 ~ 10,000
* mpcore_timer_rate/10000 = 100 ~ 100,000
*
* so the multiply value will be less than 10^9 always.
*/
load = (system_timer->offset() * (mpcore_timer_rate / 10000)) / 100;
/* Add on our offset to get the load value */
load = (load + offset) % (mpcore_timer_rate / HZ);
__raw_writel(load, base + TWD_TIMER_COUNTER);
/* Make sure our local interrupt controller has this enabled */
__raw_writel(1 << IRQ_LOCALTIMER,
__io_address(REALVIEW_GIC_DIST_BASE) + GIC_DIST_ENABLE_SET);
}
/*
* take a local timer down
*/
void __cpuexit local_timer_stop(unsigned int cpu)
{
__raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL);
}
#else /* CONFIG_LOCAL_TIMERS */
static void dummy_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *clk)
{
}
void __cpuinit local_timer_setup(unsigned int cpu)
{
struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
clk->name = "dummy_timer";
clk->features = CLOCK_EVT_FEAT_DUMMY;
clk->rating = 200;
clk->set_mode = dummy_timer_set_mode;
clk->broadcast = smp_timer_broadcast;
clk->cpumask = cpumask_of_cpu(cpu);
clockevents_register_device(clk);
}
#endif /* !CONFIG_LOCAL_TIMERS */
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