/***************************************************************************/
/*
* 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/clocksource.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) (MCF_IPSBAR + MCFPIT_BASE1 + (a))
#define INTC0 (MCF_IPSBAR + MCFICM_INTC0)
static u32 pit_cycles_per_jiffy;
static u32 pit_cnt;
/***************************************************************************/
static irqreturn_t pit_tick(int irq, void *dummy)
{
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;
return arch_timer_interrupt(irq, dummy);
}
/***************************************************************************/
static struct irqaction pit_irq = {
.name = "timer",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = pit_tick,
};
/***************************************************************************/
static cycle_t pit_read_clk(void)
{
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 = 250,
.read = pit_read_clk,
.shift = 20,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/***************************************************************************/
void hw_timer_init(void)
{
u32 imr;
setup_irq(MCFINT_VECBASE + MCFINT_PIT1, &pit_irq);
__raw_writeb(ICR_INTRCONF, INTC0 + MCFINTC_ICR0 + MCFINT_PIT1);
imr = __raw_readl(INTC0 + MCFPIT_IMR);
imr &= ~MCFPIT_IMR_IBIT;
__raw_writel(imr, INTC0 + MCFPIT_IMR);
/* Set up PIT timer 1 as poll clock */
pit_cycles_per_jiffy = FREQ / HZ;
__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));
pit_clk.mult = clocksource_hz2mult(FREQ, pit_clk.shift);
clocksource_register(&pit_clk);
}
/***************************************************************************/
