time.c

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/*
 * Copyright 2001, 2002, 2003 MontaVista Software Inc.
 * Author: Jun Sun, [email protected] or [email protected]
 * Copyright (C) 2007 Ralf Baechle ([email protected])
 *
 * Common time service routines for MIPS machines. See
 * Documents/MIPS/README.txt.
 *
 * This program is free software; you can redistribute  it and/or modify it
 * under  the terms of  the GNU General  Public License as published by the
 * Free Software Foundation;  either version 2 of the  License, or (at your
 * option) any later version.
 */
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/time.h>
#include <linux/timer.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>

#include <asm/bootinfo.h>
#include <asm/cpu.h>
#include <asm/time.h>
#include <asm/hardirq.h>
#include <asm/div64.h>
#include <asm/debug.h>

#include <int.h>
#include <cm.h>

static unsigned long cpj;

static cycle_t hpt_read(struct clocksource *cs)
{
    return read_c0_count2();
}

static struct clocksource pnx_clocksource = {
    .name       = "pnx8xxx",
    .rating     = 200,
    .read       = hpt_read,
    .flags      = CLOCK_SOURCE_IS_CONTINUOUS,
};

static irqreturn_t pnx8xxx_timer_interrupt(int irq, void *dev_id)
{
    struct clock_event_device *c = dev_id;

    /* clear MATCH, signal the event */
    c->event_handler(c);

    return IRQ_HANDLED;
}

static struct irqaction pnx8xxx_timer_irq = {
    .handler    = pnx8xxx_timer_interrupt,
    .flags      = IRQF_PERCPU | IRQF_TIMER,
    .name       = "pnx8xxx_timer",
};

static irqreturn_t monotonic_interrupt(int irq, void *dev_id)
{
    /* Timer 2 clear interrupt */
    write_c0_compare2(-1);
    return IRQ_HANDLED;
}

static struct irqaction monotonic_irqaction = {
    .handler = monotonic_interrupt,
    .flags = IRQF_TIMER,
    .name = "Monotonic timer",
};

static int pnx8xxx_set_next_event(unsigned long delta,
                struct clock_event_device *evt)
{
    write_c0_compare(delta);
    return 0;
}

static struct clock_event_device pnx8xxx_clockevent = {
    .name       = "pnx8xxx_clockevent",
    .features   = CLOCK_EVT_FEAT_ONESHOT,
    .set_next_event = pnx8xxx_set_next_event,
};

static inline void timer_ack(void)
{
    write_c0_compare(cpj);
}

__init void plat_time_init(void)
{
    unsigned int configPR;
    unsigned int n;
    unsigned int m;
    unsigned int p;
    unsigned int pow2p;

    pnx8xxx_clockevent.cpumask = cpu_none_mask;
    clockevents_register_device(&pnx8xxx_clockevent);
    clocksource_register(&pnx_clocksource);

    /* Timer 1 start */
    configPR = read_c0_config7();
    configPR &= ~0x00000008;
    write_c0_config7(configPR);

    /* Timer 2 start */
    configPR = read_c0_config7();
    configPR &= ~0x00000010;
    write_c0_config7(configPR);

    /* Timer 3 stop */
    configPR = read_c0_config7();
    configPR |= 0x00000020;
    write_c0_config7(configPR);


        /* PLL0 sets MIPS clock (PLL1 <=> TM1, PLL6 <=> TM2, PLL5 <=> mem) */
        /* (but only if CLK_MIPS_CTL select value [bits 3:1] is 1:  FIXME) */

        n = (PNX8550_CM_PLL0_CTL & PNX8550_CM_PLL_N_MASK) >> 16;
        m = (PNX8550_CM_PLL0_CTL & PNX8550_CM_PLL_M_MASK) >> 8;
        p = (PNX8550_CM_PLL0_CTL & PNX8550_CM_PLL_P_MASK) >> 2;
    pow2p = (1 << p);

    db_assert(m != 0 && pow2p != 0);

        /*
     * Compute the frequency as in the PNX8550 User Manual 1.0, p.186
     * (a.k.a. 8-10).  Divide by HZ for a timer offset that results in
     * HZ timer interrupts per second.
     */
    mips_hpt_frequency = 27UL * ((1000000UL * n)/(m * pow2p));
    cpj = DIV_ROUND_CLOSEST(mips_hpt_frequency, HZ);
    write_c0_count(0);
    timer_ack();

    /* Setup Timer 2 */
    write_c0_count2(0);
    write_c0_compare2(0xffffffff);

    setup_irq(PNX8550_INT_TIMER1, &pnx8xxx_timer_irq);
    setup_irq(PNX8550_INT_TIMER2, &monotonic_irqaction);
}