/*      $OpenBSD: imxrtc.c,v 1.3 2022/10/17 19:09:46 kettenis Exp $     */
/*
 * Copyright (c) 2018 Mark Kettenis <kettenis@openbsd.org>
 *
 * 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/device.h>

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

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

#include <dev/clock_subr.h>

/* Registers. */
#define LPCR                    0x38
#define  LPCR_SRTC_ENV          (1 << 0)
#define LPSR                    0x4c
#define LPSRTCMR                0x50
#define LPSRTCLR                0x54

#define HREAD4(sc, reg)                                                 \
        (regmap_read_4((sc)->sc_rm, (reg)))
#define HWRITE4(sc, reg, val)                                           \
        regmap_write_4((sc)->sc_rm, (reg), (val))

struct imxrtc_softc {
        struct device           sc_dev;
        struct regmap           *sc_rm;

        struct todr_chip_handle sc_todr;
};

int imxrtc_match(struct device *, void *, void *);
void imxrtc_attach(struct device *, struct device *, void *);

const struct cfattach   imxrtc_ca = {
        sizeof (struct imxrtc_softc), imxrtc_match, imxrtc_attach
};

struct cfdriver imxrtc_cd = {
        NULL, "imxrtc", DV_DULL
};

int     imxrtc_gettime(struct todr_chip_handle *, struct timeval *);
int     imxrtc_settime(struct todr_chip_handle *, struct timeval *);

int
imxrtc_match(struct device *parent, void *match, void *aux)
{
        struct fdt_attach_args *faa = aux;

        return OF_is_compatible(faa->fa_node, "fsl,sec-v4.0-mon-rtc-lp");
}

void
imxrtc_attach(struct device *parent, struct device *self, void *aux)
{
        struct imxrtc_softc *sc = (struct imxrtc_softc *)self;
        struct fdt_attach_args *faa = aux;
        uint32_t regmap;

        regmap = OF_getpropint(faa->fa_node, "regmap", 0);
        sc->sc_rm = regmap_byphandle(regmap);
        if (sc->sc_rm == NULL) {
                printf(": no registers\n");
                return;
        }

        printf("\n");

        sc->sc_todr.cookie = sc;
        sc->sc_todr.todr_gettime = imxrtc_gettime;
        sc->sc_todr.todr_settime = imxrtc_settime;
        sc->sc_todr.todr_quality = 0;
        todr_attach(&sc->sc_todr);
}

int
imxrtc_gettime(struct todr_chip_handle *handle, struct timeval *tv)
{
        struct imxrtc_softc *sc = handle->cookie;
        uint64_t mr, lr, srtc, srtc2;
        uint32_t cr;
        int retries;
        int s;

        cr = HREAD4(sc, LPCR);
        if ((cr & LPCR_SRTC_ENV) == 0)
                return EINVAL;

        /*
         * Read counters until we read back the same values twice.
         * This shouldn't take more than two attempts; throw in an
         * extra round just in case.
         */
        s = splhigh();
        mr = HREAD4(sc, LPSRTCMR);
        lr = HREAD4(sc, LPSRTCLR);
        srtc = (mr << 32) | lr;
        for (retries = 3; retries > 0; retries--) {
                mr = HREAD4(sc, LPSRTCMR);
                lr = HREAD4(sc, LPSRTCLR);
                srtc2 = (mr << 32) | lr;
                if (srtc == srtc2)
                        break;
                srtc = srtc2;
        }
        splx(s);
        if (retries == 0)
                return EIO;

        tv->tv_sec = srtc / 32768;
        tv->tv_usec = ((srtc % 32768) * 1000000U) / 32768U;
        return 0;
}

int
imxrtc_settime(struct todr_chip_handle *handle, struct timeval *tv)
{
        struct imxrtc_softc *sc = handle->cookie;
        uint64_t srtc;
        uint32_t cr;
        int timeout;

        /* Disable RTC. */
        cr = HREAD4(sc, LPCR);
        cr &= ~LPCR_SRTC_ENV;
        HWRITE4(sc, LPCR, cr);
        for (timeout = 1000000; timeout > 0; timeout--) {
                if ((HREAD4(sc, LPCR) & LPCR_SRTC_ENV) == 0)
                        break;
        }

        srtc = tv->tv_sec * 32768 + (tv->tv_usec * 32768U / 1000000U);
        HWRITE4(sc, LPSRTCMR, srtc >> 32);
        HWRITE4(sc, LPSRTCLR, srtc & 0xffffffff);

        /* Enable RTC. */
        cr |= LPCR_SRTC_ENV;
        HWRITE4(sc, LPCR, cr);
        for (timeout = 1000000; timeout > 0; timeout--) {
                if (HREAD4(sc, LPCR) & LPCR_SRTC_ENV)
                        break;
        }

        return 0;
}