/* $NetBSD: imx23_rtc.c,v 1.8 2026/07/07 04:54:34 skrll Exp $ */

/*
* Copyright (c) 2014 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Petri Laakso.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 THE FOUNDATION OR CONTRIBUTORS
* 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/param.h>
#include <sys/types.h>
#include <sys/bus.h>
#include <sys/cdefs.h>
#include <sys/device.h>
#include <sys/errno.h>

#include <dev/fdt/fdtvar.h>

#include <arm/imx/imx23_rtcreg.h>
#include <arm/imx/imx23var.h>

struct imx23_rtc_softc {
        device_t sc_dev;
        bus_space_tag_t sc_iot;
        bus_space_handle_t sc_hdl;
};

static int      imx23_rtc_match(device_t, cfdata_t, void *);
static void     imx23_rtc_attach(device_t, device_t, void *);

static void     imx23_rtc_reset(struct imx23_rtc_softc *);

CFATTACH_DECL_NEW(imx23rtc, sizeof(struct imx23_rtc_softc), imx23_rtc_match,
                  imx23_rtc_attach, NULL, NULL);

static const struct device_compatible_entry compat_data[] = {
        { .compat = "fsl,imx23-rtc" },
        DEVICE_COMPAT_EOL
};

#define RTC_RD(sc, reg)                                                 \
        bus_space_read_4(sc->sc_iot, sc->sc_hdl, (reg))
#define RTC_WR(sc, reg, val)                                            \
        bus_space_write_4(sc->sc_iot, sc->sc_hdl, (reg), (val))

#define RTC_SOFT_RST_LOOP 455 /* At least 1 us ... */

static int
imx23_rtc_match(device_t parent, cfdata_t match, void *aux)
{
        struct fdt_attach_args * const faa = aux;

        return of_compatible_match(faa->faa_phandle, compat_data);
}

static void
imx23_rtc_attach(device_t parent, device_t self, void *aux)
{
        struct imx23_rtc_softc * const sc = device_private(self);
        struct fdt_attach_args * const faa = aux;
        const int phandle = faa->faa_phandle;

        sc->sc_dev = self;
        sc->sc_iot = faa->faa_bst;

        bus_addr_t addr;
        bus_size_t size;
        if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0) {
                aprint_error(": couldn't get register address\n");
                return;
        }
        if (bus_space_map(faa->faa_bst, addr, size, 0, &sc->sc_hdl)) {
                aprint_error(": couldn't map registers\n");
                return;
        }

        aprint_normal("\n");

        imx23_rtc_reset(sc);

        RTC_WR(sc, HW_RTC_PERSISTENT0_SET, (1<<19));
}

/*
 * Reset the RTC block.
 *
 * Inspired by i.MX23 RM "39.3.10 Correct Way to Soft Reset a Block"
 */
static void
imx23_rtc_reset(struct imx23_rtc_softc *sc)
{
        unsigned int loop;

        /*
         * Prepare for soft-reset by making sure that SFTRST is not currently
         * asserted. Also clear CLKGATE so we can wait for its assertion below.
         */
        RTC_WR(sc, HW_RTC_CTRL_CLR, HW_RTC_CTRL_SFTRST);

        /* Wait at least a microsecond for SFTRST to deassert. */
        loop = 0;
        while ((RTC_RD(sc, HW_RTC_CTRL) & HW_RTC_CTRL_SFTRST) ||
            (loop < RTC_SOFT_RST_LOOP))
                loop++;

        /* Clear CLKGATE so we can wait for its assertion below. */
        RTC_WR(sc, HW_RTC_CTRL_CLR, HW_RTC_CTRL_CLKGATE);

        /* Soft-reset the block. */
        RTC_WR(sc, HW_RTC_CTRL_SET, HW_RTC_CTRL_SFTRST);

        /* Wait until clock is in the gated state. */
        while (!(RTC_RD(sc, HW_RTC_CTRL) & HW_RTC_CTRL_CLKGATE))
                 continue;

        /* Bring block out of reset. */
        RTC_WR(sc, HW_RTC_CTRL_CLR, HW_RTC_CTRL_SFTRST);

        loop = 0;
        while ((RTC_RD(sc, HW_RTC_CTRL) & HW_RTC_CTRL_SFTRST) ||
            (loop < RTC_SOFT_RST_LOOP))
                loop++;

        RTC_WR(sc, HW_RTC_CTRL_CLR, HW_RTC_CTRL_CLKGATE);

        /* Wait until clock is in the NON-gated state. */
        while (RTC_RD(sc, HW_RTC_CTRL) & HW_RTC_CTRL_CLKGATE)
                continue;
}