/* $OpenBSD: agtimer.c,v 1.21 2023/09/17 14:50:51 cheloha Exp $ */
/*
 * Copyright (c) 2011 Dale Rahn <drahn@openbsd.org>
 * Copyright (c) 2013 Patrick Wildt <patrick@blueri.se>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/clockintr.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/stdint.h>
#include <sys/timetc.h>

#include <machine/intr.h>
#include <machine/bus.h>
#include <machine/fdt.h>

#include <arm/cpufunc.h>

#include <dev/ofw/fdt.h>
#include <dev/ofw/openfirm.h>

/* registers */
#define GTIMER_CNTP_CTL_ENABLE          (1 << 0)
#define GTIMER_CNTP_CTL_IMASK           (1 << 1)
#define GTIMER_CNTP_CTL_ISTATUS         (1 << 2)

#define TIMER_FREQUENCY         24 * 1000 * 1000 /* ARM core clock */
int32_t agtimer_frequency = TIMER_FREQUENCY;

u_int agtimer_get_timecount(struct timecounter *);

static struct timecounter agtimer_timecounter = {
        .tc_get_timecount = agtimer_get_timecount,
        .tc_counter_mask = 0xffffffff,
        .tc_frequency = 0,
        .tc_name = "agtimer",
        .tc_quality = 0,
        .tc_priv = NULL,
};

struct agtimer_softc {
        struct device           sc_dev;
        int                     sc_node;
        u_int32_t               sc_ticks_per_second;
        uint64_t                sc_nsec_cycle_ratio;
        uint64_t                sc_nsec_max;
};

int             agtimer_match(struct device *, void *, void *);
void            agtimer_attach(struct device *, struct device *, void *);
uint64_t        agtimer_readcnt64(void);
int             agtimer_intr(void *);
void            agtimer_cpu_initclocks(void);
void            agtimer_delay(u_int);
void            agtimer_setstatclockrate(int stathz);
void            agtimer_set_clockrate(int32_t new_frequency);
void            agtimer_startclock(void);

const struct cfattach agtimer_ca = {
        sizeof (struct agtimer_softc), agtimer_match, agtimer_attach
};

struct cfdriver agtimer_cd = {
        NULL, "agtimer", DV_DULL
};

void agtimer_rearm(void *, uint64_t);
void agtimer_trigger(void *);

struct intrclock agtimer_intrclock = {
        .ic_rearm = agtimer_rearm,
        .ic_trigger = agtimer_trigger
};

uint64_t
agtimer_readcnt64(void)
{
        uint64_t val;

        __asm volatile("mrrc p15, 0, %Q0, %R0, c14" : "=r" (val));

        return (val);
}

static inline int
agtimer_get_ctrl(void)
{
        uint32_t val;

        __asm volatile("mrc p15, 0, %0, c14, c2, 1" : "=r" (val));

        return (val);
}

static inline int
agtimer_set_ctrl(uint32_t val)
{
        __asm volatile("mcr p15, 0, %[val], c14, c2, 1" : :
            [val] "r" (val));

        cpu_drain_writebuf();
        //isb();

        return (0);
}

static inline int
agtimer_set_tval(uint32_t val)
{
        __asm volatile("mcr p15, 0, %[val], c14, c2, 0" : :
            [val] "r" (val));
        cpu_drain_writebuf();
        //isb();

        return (0);
}

int
agtimer_match(struct device *parent, void *cfdata, void *aux)
{
        struct fdt_attach_args *faa = (struct fdt_attach_args *)aux;

        return OF_is_compatible(faa->fa_node, "arm,armv7-timer");
}

void
agtimer_attach(struct device *parent, struct device *self, void *aux)
{
        struct agtimer_softc *sc = (struct agtimer_softc *)self;
        struct fdt_attach_args *faa = aux;

        sc->sc_node = faa->fa_node;

        agtimer_frequency =
            OF_getpropint(sc->sc_node, "clock-frequency", agtimer_frequency);
        sc->sc_ticks_per_second = agtimer_frequency;
        sc->sc_nsec_cycle_ratio =
            sc->sc_ticks_per_second * (1ULL << 32) / 1000000000;
        sc->sc_nsec_max = UINT64_MAX / sc->sc_nsec_cycle_ratio;
        printf(": %d kHz\n", sc->sc_ticks_per_second / 1000);

        /* XXX: disable user access */

        /*
         * private timer and interrupts not enabled until
         * timer configures
         */

        arm_clock_register(agtimer_cpu_initclocks, agtimer_delay,
            agtimer_setstatclockrate, agtimer_startclock);

        agtimer_timecounter.tc_frequency = sc->sc_ticks_per_second;
        agtimer_timecounter.tc_priv = sc;
        tc_init(&agtimer_timecounter);

        agtimer_intrclock.ic_cookie = sc;
}

u_int
agtimer_get_timecount(struct timecounter *tc)
{
        return agtimer_readcnt64();
}

void
agtimer_rearm(void *cookie, uint64_t nsecs)
{
        struct agtimer_softc *sc = cookie;
        uint32_t cycles;

        if (nsecs > sc->sc_nsec_max)
                nsecs = sc->sc_nsec_max;
        cycles = (nsecs * sc->sc_nsec_cycle_ratio) >> 32;
        if (cycles > INT32_MAX)
                cycles = INT32_MAX;
        agtimer_set_tval(cycles);
}

void
agtimer_trigger(void *unused)
{
        agtimer_set_tval(0);
}

int
agtimer_intr(void *frame)
{
        return clockintr_dispatch(frame);
}

void
agtimer_set_clockrate(int32_t new_frequency)
{
        struct agtimer_softc    *sc = agtimer_cd.cd_devs[0];

        agtimer_frequency = new_frequency;

        if (sc == NULL)
                return;

        sc->sc_ticks_per_second = agtimer_frequency;
        sc->sc_nsec_cycle_ratio =
            sc->sc_ticks_per_second * (1ULL << 32) / 1000000000;
        sc->sc_nsec_max = UINT64_MAX / sc->sc_nsec_cycle_ratio;

        agtimer_timecounter.tc_frequency = sc->sc_ticks_per_second;

        printf("agtimer0: adjusting clock: new rate %d kHz\n",
            sc->sc_ticks_per_second / 1000);
}

void
agtimer_cpu_initclocks(void)
{
        struct agtimer_softc    *sc = agtimer_cd.cd_devs[0];

        stathz = hz;
        profhz = stathz * 10;
        statclock_is_randomized = 1;

        if (sc->sc_ticks_per_second != agtimer_frequency) {
                agtimer_set_clockrate(agtimer_frequency);
        }

        /* Setup secure and non-secure timer IRQs. */
        arm_intr_establish_fdt_idx(sc->sc_node, 0, IPL_CLOCK,
            agtimer_intr, NULL, "tick");
        arm_intr_establish_fdt_idx(sc->sc_node, 1, IPL_CLOCK,
            agtimer_intr, NULL, "tick");
}

void
agtimer_delay(u_int usecs)
{
        u_int32_t               clock, oclock, delta, delaycnt;
        volatile int            j;
        int                     csec, usec;

        if (usecs > (0x80000000 / agtimer_frequency)) {
                csec = usecs / 10000;
                usec = usecs % 10000;

                delaycnt = (agtimer_frequency / 100) * csec +
                    (agtimer_frequency / 100) * usec / 10000;
        } else {
                delaycnt = agtimer_frequency * usecs / 1000000;
        }
        if (delaycnt <= 1)
                for (j = 100; j > 0; j--)
                        ;

        oclock = agtimer_readcnt64();
        while (1) {
                for (j = 100; j > 0; j--)
                        ;
                clock = agtimer_readcnt64();
                delta = clock - oclock;
                if (delta > delaycnt)
                        break;
        }
}

void
agtimer_setstatclockrate(int newhz)
{
}

void
agtimer_startclock(void)
{
        uint32_t reg;

        clockintr_cpu_init(&agtimer_intrclock);

        reg = agtimer_get_ctrl();
        reg &= ~GTIMER_CNTP_CTL_IMASK;
        reg |= GTIMER_CNTP_CTL_ENABLE;
        agtimer_set_tval(INT32_MAX);
        agtimer_set_ctrl(reg);

        clockintr_trigger();
}

void
agtimer_init(void)
{
        uint32_t id_pfr1, cntfrq = 0;

        /* Check for Generic Timer support. */
        __asm volatile("mrc p15, 0, %0, c0, c1, 1" : "=r"(id_pfr1));
        if ((id_pfr1 & 0x000f0000) == 0x00010000)
                __asm volatile("mrc p15, 0, %0, c14, c0, 0" : "=r" (cntfrq));

        if (cntfrq != 0) {
                agtimer_frequency = cntfrq;
                arm_clock_register(NULL, agtimer_delay, NULL, NULL);
        }
}