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/***************************************************************************/
/*
* pit.c -- Freescale ColdFire PIT timer. Currently this type of
* hardware timer only exists in the Freescale ColdFire
* 5270/5271, 5282 and 5208 CPUs. No doubt newer ColdFire
* family members will probably use it too.
*
* Copyright (C) 1999-2008, Greg Ungerer (gerg@snapgear.com)
* Copyright (C) 2001-2004, SnapGear Inc. (www.snapgear.com)
*/
/***************************************************************************/
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clockchips.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/coldfire.h>
#include <asm/mcfpit.h>
#include <asm/mcfsim.h>
/***************************************************************************/
/*
* By default use timer1 as the system clock timer.
*/
#define FREQ ((MCF_CLK / 2) / 64)
#define TA(a) (MCFPIT_BASE1 + (a))
#define PIT_CYCLES_PER_JIFFY (FREQ / HZ)
static u32 pit_cnt;
/*
* Initialize the PIT timer.
*
* This is also called after resume to bring the PIT into operation again.
*/
static void init_cf_pit_timer(enum clock_event_mode mode,
struct clock_event_device *evt)
{
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
__raw_writew(PIT_CYCLES_PER_JIFFY, TA(MCFPIT_PMR));
__raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | \
MCFPIT_PCSR_OVW | MCFPIT_PCSR_RLD | \
MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
break;
case CLOCK_EVT_MODE_ONESHOT:
__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
__raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE | \
MCFPIT_PCSR_OVW | MCFPIT_PCSR_CLK64, \
TA(MCFPIT_PCSR));
break;
case CLOCK_EVT_MODE_RESUME:
/* Nothing to do here */
break;
}
}
/*
* Program the next event in oneshot mode
*
* Delta is given in PIT ticks
*/
static int cf_pit_next_event(unsigned long delta,
struct clock_event_device *evt)
{
__raw_writew(delta, TA(MCFPIT_PMR));
return 0;
}
struct clock_event_device cf_pit_clockevent = {
.name = "pit",
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.set_mode = init_cf_pit_timer,
.set_next_event = cf_pit_next_event,
.shift = 32,
.irq = MCF_IRQ_PIT1,
};
/***************************************************************************/
static irqreturn_t pit_tick(int irq, void *dummy)
{
struct clock_event_device *evt = &cf_pit_clockevent;
u16 pcsr;
/* Reset the ColdFire timer */
pcsr = __raw_readw(TA(MCFPIT_PCSR));
__raw_writew(pcsr | MCFPIT_PCSR_PIF, TA(MCFPIT_PCSR));
pit_cnt += PIT_CYCLES_PER_JIFFY;
evt->event_handler(evt);
return IRQ_HANDLED;
}
/***************************************************************************/
static struct irqaction pit_irq = {
.name = "timer",
.flags = IRQF_TIMER,
.handler = pit_tick,
};
/***************************************************************************/
static cycle_t pit_read_clk(struct clocksource *cs)
{
unsigned long flags;
u32 cycles;
u16 pcntr;
local_irq_save(flags);
pcntr = __raw_readw(TA(MCFPIT_PCNTR));
cycles = pit_cnt;
local_irq_restore(flags);
return cycles + PIT_CYCLES_PER_JIFFY - pcntr;
}
/***************************************************************************/
static struct clocksource pit_clk = {
.name = "pit",
.rating = 100,
.read = pit_read_clk,
.mask = CLOCKSOURCE_MASK(32),
};
/***************************************************************************/
void hw_timer_init(irq_handler_t handler)
{
cf_pit_clockevent.cpumask = cpumask_of(smp_processor_id());
cf_pit_clockevent.mult = div_sc(FREQ, NSEC_PER_SEC, 32);
cf_pit_clockevent.max_delta_ns =
clockevent_delta2ns(0xFFFF, &cf_pit_clockevent);
cf_pit_clockevent.min_delta_ns =
clockevent_delta2ns(0x3f, &cf_pit_clockevent);
clockevents_register_device(&cf_pit_clockevent);
setup_irq(MCF_IRQ_PIT1, &pit_irq);
clocksource_register_hz(&pit_clk, FREQ);
}
/***************************************************************************/
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