timers.c

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/***************************************************************************/

/*
 *  timers.c -- generic ColdFire hardware timer support.
 *
 *  Copyright (C) 1999-2008, Greg Ungerer <[email protected]>
 */

/***************************************************************************/

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/profile.h>
#include <linux/clocksource.h>
#include <asm/io.h>
#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/coldfire.h>
#include <asm/mcftimer.h>
#include <asm/mcfsim.h>

/***************************************************************************/

/*
 *  By default use timer1 as the system clock timer.
 */
#define FREQ    (MCF_BUSCLK / 16)
#define TA(a)   (MCFTIMER_BASE1 + (a))

/*
 *  These provide the underlying interrupt vector support.
 *  Unfortunately it is a little different on each ColdFire.
 */
void coldfire_profile_init(void);

#if defined(CONFIG_M532x) || defined(CONFIG_M5441x)
#define __raw_readtrr   __raw_readl
#define __raw_writetrr  __raw_writel
#else
#define __raw_readtrr   __raw_readw
#define __raw_writetrr  __raw_writew
#endif

static u32 mcftmr_cycles_per_jiffy;
static u32 mcftmr_cnt;

static irq_handler_t timer_interrupt;

/***************************************************************************/

static void init_timer_irq(void)
{
#ifdef MCFSIM_ICR_AUTOVEC
    /* Timer1 is always used as system timer */
    writeb(MCFSIM_ICR_AUTOVEC | MCFSIM_ICR_LEVEL6 | MCFSIM_ICR_PRI3,
        MCFSIM_TIMER1ICR);
    mcf_mapirq2imr(MCF_IRQ_TIMER, MCFINTC_TIMER1);

#ifdef CONFIG_HIGHPROFILE
    /* Timer2 is to be used as a high speed profile timer  */
    writeb(MCFSIM_ICR_AUTOVEC | MCFSIM_ICR_LEVEL7 | MCFSIM_ICR_PRI3,
        MCFSIM_TIMER2ICR);
    mcf_mapirq2imr(MCF_IRQ_PROFILER, MCFINTC_TIMER2);
#endif
#endif /* MCFSIM_ICR_AUTOVEC */
}

/***************************************************************************/

static irqreturn_t mcftmr_tick(int irq, void *dummy)
{
    /* Reset the ColdFire timer */
    __raw_writeb(MCFTIMER_TER_CAP | MCFTIMER_TER_REF, TA(MCFTIMER_TER));

    mcftmr_cnt += mcftmr_cycles_per_jiffy;
    return timer_interrupt(irq, dummy);
}

/***************************************************************************/

static struct irqaction mcftmr_timer_irq = {
    .name    = "timer",
    .flags   = IRQF_DISABLED | IRQF_TIMER,
    .handler = mcftmr_tick,
};

/***************************************************************************/

static cycle_t mcftmr_read_clk(struct clocksource *cs)
{
    unsigned long flags;
    u32 cycles;
    u16 tcn;

    local_irq_save(flags);
    tcn = __raw_readw(TA(MCFTIMER_TCN));
    cycles = mcftmr_cnt;
    local_irq_restore(flags);

    return cycles + tcn;
}

/***************************************************************************/

static struct clocksource mcftmr_clk = {
    .name   = "tmr",
    .rating = 250,
    .read   = mcftmr_read_clk,
    .mask   = CLOCKSOURCE_MASK(32),
    .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
};

/***************************************************************************/

void hw_timer_init(irq_handler_t handler)
{
    __raw_writew(MCFTIMER_TMR_DISABLE, TA(MCFTIMER_TMR));
    mcftmr_cycles_per_jiffy = FREQ / HZ;
    /*
     *  The coldfire timer runs from 0 to TRR included, then 0
     *  again and so on.  It counts thus actually TRR + 1 steps
     *  for 1 tick, not TRR.  So if you want n cycles,
     *  initialize TRR with n - 1.
     */
    __raw_writetrr(mcftmr_cycles_per_jiffy - 1, TA(MCFTIMER_TRR));
    __raw_writew(MCFTIMER_TMR_ENORI | MCFTIMER_TMR_CLK16 |
        MCFTIMER_TMR_RESTART | MCFTIMER_TMR_ENABLE, TA(MCFTIMER_TMR));

    clocksource_register_hz(&mcftmr_clk, FREQ);

    timer_interrupt = handler;
    init_timer_irq();
    setup_irq(MCF_IRQ_TIMER, &mcftmr_timer_irq);

#ifdef CONFIG_HIGHPROFILE
    coldfire_profile_init();
#endif
}

/***************************************************************************/
#ifdef CONFIG_HIGHPROFILE
/***************************************************************************/

/*
 *  By default use timer2 as the profiler clock timer.
 */
#define PA(a)   (MCFTIMER_BASE2 + (a))

/*
 *  Choose a reasonably fast profile timer. Make it an odd value to
 *  try and get good coverage of kernel operations.
 */
#define PROFILEHZ   1013

/*
 *  Use the other timer to provide high accuracy profiling info.
 */
irqreturn_t coldfire_profile_tick(int irq, void *dummy)
{
    /* Reset ColdFire timer2 */
    __raw_writeb(MCFTIMER_TER_CAP | MCFTIMER_TER_REF, PA(MCFTIMER_TER));
    if (current->pid)
        profile_tick(CPU_PROFILING);
    return IRQ_HANDLED;
}

/***************************************************************************/

static struct irqaction coldfire_profile_irq = {
    .name    = "profile timer",
    .flags   = IRQF_DISABLED | IRQF_TIMER,
    .handler = coldfire_profile_tick,
};

void coldfire_profile_init(void)
{
    printk(KERN_INFO "PROFILE: lodging TIMER2 @ %dHz as profile timer\n",
           PROFILEHZ);

    /* Set up TIMER 2 as high speed profile clock */
    __raw_writew(MCFTIMER_TMR_DISABLE, PA(MCFTIMER_TMR));

    __raw_writetrr(((MCF_BUSCLK / 16) / PROFILEHZ), PA(MCFTIMER_TRR));
    __raw_writew(MCFTIMER_TMR_ENORI | MCFTIMER_TMR_CLK16 |
        MCFTIMER_TMR_RESTART | MCFTIMER_TMR_ENABLE, PA(MCFTIMER_TMR));

    setup_irq(MCF_IRQ_PROFILER, &coldfire_profile_irq);
}

/***************************************************************************/
#endif  /* CONFIG_HIGHPROFILE */
/***************************************************************************/