/*      $NetBSD: clock.c,v 1.34 2026/06/13 20:16:23 rkujawa Exp $       */
/*      $OpenBSD: clock.c,v 1.3 1997/10/13 13:42:53 pefo Exp $  */

/*
 * Copyright (C) 1995, 1996 Wolfgang Solfrank.
 * Copyright (C) 1995, 1996 TooLs GmbH.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by TooLs GmbH.
 * 4. The name of TooLs GmbH may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.34 2026/06/13 20:16:23 rkujawa Exp $");

#ifdef _KERNEL_OPT
#include "opt_ppcarch.h"
#include "opt_ppcparam.h"
#endif

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/timetc.h>
#include <sys/cpu.h>

#include <uvm/uvm_extern.h>

#include <prop/proplib.h>

#include <powerpc/spr.h>
#include <powerpc/ibm4xx/spr.h>
#include <powerpc/ibm4xx/cpu.h>

/*
 * Initially we assume a processor with a bus frequency of 12.5 MHz.
 */
static u_long ticks_per_sec;
static long ticks_per_intr;
static volatile u_long lasttb, lasttb2;
static u_long ticksmissed;
static volatile int tickspending;

static void init_ppc4xx_tc(void);
static u_int get_ppc4xx_timecount(struct timecounter *);

static struct timecounter ppc4xx_timecounter = {
        .tc_get_timecount = get_ppc4xx_timecount,
        .tc_counter_mask = ~0u,
        .tc_name = "ppc_timebase",
        .tc_quality = 100,
};

void decr_intr(struct clockframe *);    /* called from trap_subr.S */
void stat_intr(struct clockframe *);    /* called from trap_subr.S */

#ifdef FAST_STAT_CLOCK
/* Stat clock runs at ~ 1.5 kHz */
#define PERIOD_POWER    17
#define TCR_PERIOD      TCR_FP_2_17
#else
/* Stat clock runs at ~ 550Hz (440) / ~95Hz (405) */
#define PERIOD_POWER    21
#define TCR_PERIOD      TCR_FP_2_21
#endif

#ifdef PPC_IBM440
/*
 * tprof sampling shares the FIT
 */
void (*ibm4xx_tprof_samplefn)(struct clockframe *);
u_int ibm4xx_tprof_div;
#endif


void
stat_intr(struct clockframe *frame)
{
        struct cpu_info * const ci = curcpu();

        mtspr(SPR_TSR, TSR_FIS);        /* Clear TSR[FIS] */
        ci->ci_data.cpu_nintr++;
        ci->ci_ev_statclock.ev_count++;

#ifdef PPC_IBM440
        if (ibm4xx_tprof_div != 0) {
                static u_int statdiv;

                /* take a PC sample every (fast) FIT tick. */
                (*ibm4xx_tprof_samplefn)(frame);

                /* statclock only every ibm4xx_tprof_div ticks. */
                if (++statdiv < ibm4xx_tprof_div)
                        return;
                statdiv = 0;
        }
#endif

        /* Nobody can interrupt us, but see if we're allowed to run. */
        int s = splclock();

        /*
         * Reenable interrupts
         */
        __asm volatile ("wrteei 1");

        if (IPL_CLOCK > s) {
                ci->ci_idepth++;
                statclock(frame);
                ci->ci_idepth--;
        }
        splx(s);
}

void
decr_intr(struct clockframe *frame)
{
        struct cpu_info * const ci = curcpu();
        int pcpl;
        long tbtick, xticks;
        int nticks;

        /*
         * Check whether we are initialized.
         */
        if (!ticks_per_intr)
                return;

        tbtick = mftbl();
        mtspr(SPR_TSR, TSR_PIS);        /* Clear TSR[PIS] */

        xticks = tbtick - lasttb2;      /* Number of TLB cycles since last exception */
        for (nticks = 0; xticks > ticks_per_intr; nticks++)
                xticks -= ticks_per_intr;
        lasttb2 = tbtick - xticks;

        ci->ci_data.cpu_nintr++;
        ci->ci_ev_clock.ev_count++;
        pcpl = splclock();

        /*
         * Reenable interrupts
         */
        __asm volatile ("wrteei 1");

        if (pcpl >= IPL_CLOCK) {
                tickspending += nticks;
                ticksmissed += nticks;
        } else {
                nticks += tickspending;
                tickspending = 0;

                /*
                 * lasttb is used during microtime. Set it to the virtual
                 * start of this tick interval.
                 */
                lasttb = lasttb2;

                /*
                 * Do standard timer interrupt stuff.
                 */
                ci->ci_idepth++;
                while (nticks-- > 0)
                        hardclock(frame);
                ci->ci_idepth--;
        }
        splx(pcpl);
}

void
cpu_initclocks(void)
{
        struct cpu_info * const ci = curcpu();

        /* Initialized in powerpc/ibm4xx/cpu.c */
        evcnt_attach_static(&ci->ci_ev_clock);
        evcnt_attach_static(&ci->ci_ev_statclock);

        ticks_per_intr = ticks_per_sec / hz;
        stathz = profhz = ticks_per_sec / (1 << PERIOD_POWER);

        printf("Setting PIT to %ld/%d = %ld\n", ticks_per_sec, hz,
            ticks_per_intr);

        lasttb2 = lasttb = mftbl();
#ifdef PPC_IBM440
        /*
         * PIT is replaced by the decrementer!
         * TCR/TSR bit positions match.
         */
        mtspr(SPR_DECAR, ticks_per_intr);
        mtspr(SPR_DEC, ticks_per_intr);

        /* Enable DEC & FIT interrupts and auto-reload */
        mtspr(SPR_TCR, TCR_DIE | TCR_ARE | TCR_FIE | TCR_PERIOD);
#else
        mtspr(SPR_PIT, ticks_per_intr);

        /* Enable PIT & FIT(2^17c = 0.655ms) interrupts and auto-reload */
        mtspr(SPR_TCR, TCR_PIE | TCR_ARE | TCR_FIE | TCR_PERIOD);
#endif

        init_ppc4xx_tc();
}

void
calc_delayconst(void)
{
        prop_number_t freq;

        freq = prop_dictionary_get(board_properties, "processor-frequency");

#ifndef PPC_CPU_FREQ
        KASSERT(freq != NULL);
#else
        /* XXX hack for pckbc_cnattach() for Explora */
        if (freq == NULL)
                ticks_per_sec = (u_long) PPC_CPU_FREQ;
        else
#endif
                ticks_per_sec = (u_long) prop_number_integer_value(freq);
}

static u_int
get_ppc4xx_timecount(struct timecounter *tc)
{
        u_long tb;
        int msr;

        __asm volatile ("mfmsr %0; wrteei 0" : "=r" (msr));
        tb = mftbl();
        __asm volatile ("mtmsr %0" :: "r" (msr));

        return tb;
}

/*
 * Wait for about n microseconds (at least!).
 */
void
delay(unsigned int n)
{
        u_quad_t tb;
        u_long tbh, tbl, scratch;

        tb = mftb();
        /* Math must handle clock speed above 1GHz. */
        tb += ((u_quad_t)n * ticks_per_sec + 999999) / 1000000;
        tbh = tb >> 32;
        tbl = tb;
        __asm volatile (
        "1:"
#ifdef PPC_IBM403
                "mftbhi %0;"
#else
                "mftbu  %0;"
#endif
                "cmplw  %0,%1;"
                "blt    1b;"
                "bgt    2f;"
#ifdef PPC_IBM403
                "mftblo %0;"
#else
                "mftb   %0;"
#endif
                "cmplw  %0,%2;"
                "blt    1b;"
        "2:"
            : "=&r" (scratch)
            : "r" (tbh), "r" (tbl)
            : "cr0");
}

/*
 * Nothing to do.
 */
void
setstatclockrate(int arg)
{

        /* Do nothing */
}

static void
init_ppc4xx_tc(void)
{
        /* from machdep initialization */
        ppc4xx_timecounter.tc_frequency = ticks_per_sec;
        tc_init(&ppc4xx_timecounter);
}