sead3-time.c

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/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2012 MIPS Technologies, Inc.  All rights reserved.
 */
#include <linux/init.h>

#include <asm/setup.h>
#include <asm/time.h>
#include <asm/irq.h>
#include <asm/mips-boards/generic.h>
#include <asm/mips-boards/prom.h>

unsigned long cpu_khz;

static int mips_cpu_timer_irq;
static int mips_cpu_perf_irq;

static void mips_timer_dispatch(void)
{
    do_IRQ(mips_cpu_timer_irq);
}

static void mips_perf_dispatch(void)
{
    do_IRQ(mips_cpu_perf_irq);
}

static void __iomem *status_reg = (void __iomem *)0xbf000410;

/*
 * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect.
 */
static unsigned int __init estimate_cpu_frequency(void)
{
    unsigned int prid = read_c0_prid() & 0xffff00;
    unsigned int tick = 0;
    unsigned int freq;
    unsigned int orig;
    unsigned long flags;

    local_irq_save(flags);

    orig = readl(status_reg) & 0x2;               /* get original sample */
    /* wait for transition */
    while ((readl(status_reg) & 0x2) == orig)
        ;
    orig = orig ^ 0x2;                            /* flip the bit */

    write_c0_count(0);

    /* wait 1 second (the sampling clock transitions every 10ms) */
    while (tick < 100) {
        /* wait for transition */
        while ((readl(status_reg) & 0x2) == orig)
            ;
        orig = orig ^ 0x2;                            /* flip the bit */
        tick++;
    }

    freq = read_c0_count();

    local_irq_restore(flags);

    mips_hpt_frequency = freq;

    /* Adjust for processor */
    if ((prid != (PRID_COMP_MIPS | PRID_IMP_20KC)) &&
        (prid != (PRID_COMP_MIPS | PRID_IMP_25KF)))
        freq *= 2;

    freq += 5000;        /* rounding */
    freq -= freq%10000;

    return freq ;
}

void read_persistent_clock(struct timespec *ts)
{
    ts->tv_sec = 0;
    ts->tv_nsec = 0;
}

static void __init plat_perf_setup(void)
{
    if (cp0_perfcount_irq >= 0) {
        if (cpu_has_vint)
            set_vi_handler(cp0_perfcount_irq, mips_perf_dispatch);
        mips_cpu_perf_irq = MIPS_CPU_IRQ_BASE + cp0_perfcount_irq;
    }
}

unsigned int __cpuinit get_c0_compare_int(void)
{
    if (cpu_has_vint)
        set_vi_handler(cp0_compare_irq, mips_timer_dispatch);
    mips_cpu_timer_irq = MIPS_CPU_IRQ_BASE + cp0_compare_irq;
    return mips_cpu_timer_irq;
}

void __init plat_time_init(void)
{
    unsigned int est_freq;

    est_freq = estimate_cpu_frequency();

    pr_debug("CPU frequency %d.%02d MHz\n", (est_freq / 1000000),
        (est_freq % 1000000) * 100 / 1000000);

    cpu_khz = est_freq / 1000;

    mips_scroll_message();

    plat_perf_setup();
}