/*      $NetBSD: clock.c,v 1.33 2022/10/05 08:18:00 rin 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 1.33 2022/10/05 08:18:00 rin 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 u_long ns_per_tick;
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 ~ 95Hz */
#define PERIOD_POWER    21
#define TCR_PERIOD      TCR_FP_2_21
#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++;

       /* 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();
       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);

       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);

       ns_per_tick = 1000000000 / ticks_per_sec;
}

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();
       /* use 1000ULL to force 64 bit math to avoid 32 bit overflows */
       tb += (n * 1000ULL + ns_per_tick - 1) / ns_per_tick;
       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);
}

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