/* $NetBSD: rtcsram.c,v 1.2 2026/02/03 11:47:18 jmcneill Exp $ */

/*-
 * Copyright (c) 2024-2026 Jared McNeill <jmcneill@invisible.ca>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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: rtcsram.c,v 1.2 2026/02/03 11:47:18 jmcneill Exp $");

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/device.h>
#include <sys/systm.h>
#include <dev/clock_subr.h>

#include <lib/libkern/libkern.h>

#include <machine/wii.h>
#include <machine/wiiu.h>

#include "exi.h"

#define WII_RTCSRAM_FREQ        EXI_FREQ_8MHZ

#define RTC_BASE                0x20000000
#define SRAM_BASE               0x20000100
#define SRAM_BIAS               0x20000400

#define WRITE_OFFSET            0x80000000

struct rtcsram_sram {
        uint16_t        checksum[2];
        uint32_t        ead[2];
        int32_t         counter_bias;
        int8_t          display_offset_h;
        uint8_t         ntd;
        uint8_t         language;
        uint8_t         flags;
        uint16_t        flash_id[12];
        uint32_t        wireless_keyboard_id;
        uint32_t        wireless_pad_id[2];
        uint8_t         last_dvd_errorcode;
        uint8_t         padding1;
        uint16_t        flash_id_checksum[2];
        uint16_t        padding2;
} __aligned(32);
CTASSERT(sizeof(struct rtcsram_sram) == 64);

struct rtcsram_softc {
        device_t                sc_dev;
        struct todr_chip_handle sc_todr;

        uint8_t                 sc_chan;
        uint8_t                 sc_device;

        struct rtcsram_sram     sc_sram;
};

static int      rtcsram_match(device_t, cfdata_t, void *);
static void     rtcsram_attach(device_t, device_t, void *);

static uint32_t rtcsram_read_4(struct rtcsram_softc *, uint32_t);
static void     rtcsram_write_4(struct rtcsram_softc *, uint32_t, uint32_t);
static void     rtcsram_read_buf(struct rtcsram_softc *, uint32_t, void *,
                                 size_t);

static int      rtcsram_gettime_nobias(todr_chip_handle_t, struct timeval *);
static int      rtcsram_settime_nobias(todr_chip_handle_t, struct timeval *);
static int      rtcsram_gettime_bias(todr_chip_handle_t, struct timeval *);
static int      rtcsram_settime_bias(todr_chip_handle_t, struct timeval *);

CFATTACH_DECL_NEW(rtcsram, sizeof(struct rtcsram_softc),
        rtcsram_match, rtcsram_attach, NULL, NULL);

static int
rtcsram_match(device_t parent, cfdata_t cf, void *aux)
{
        struct exi_attach_args * const eaa = aux;

        /* RTC / SRAM is always on channel 0, device 1. */
        return eaa->eaa_chan == 0 && eaa->eaa_device == 1;
}

static void
rtcsram_attach(device_t parent, device_t self, void *aux)
{
        struct rtcsram_softc * const sc = device_private(self);
        struct exi_attach_args * const eaa = aux;

        aprint_naive("\n");
        aprint_normal(": RTC/SRAM\n");

        sc->sc_dev = self;
        sc->sc_chan = eaa->eaa_chan;
        sc->sc_device = eaa->eaa_device;

        rtcsram_read_buf(sc, SRAM_BASE, &sc->sc_sram, sizeof(sc->sc_sram));
        hexdump(aprint_debug, device_xname(self), &sc->sc_sram,
            sizeof(sc->sc_sram));

        sc->sc_todr.todr_dev = self;
        if (wiiu_plat) {
                sc->sc_todr.todr_gettime = rtcsram_gettime_bias;
                sc->sc_todr.todr_settime = rtcsram_settime_bias;
        } else {
                sc->sc_todr.todr_gettime = rtcsram_gettime_nobias;
                sc->sc_todr.todr_settime = rtcsram_settime_nobias;
        }
        todr_attach(&sc->sc_todr);
}

static uint32_t
rtcsram_read_4(struct rtcsram_softc *sc, uint32_t offset)
{
        uint32_t val;

        exi_select(sc->sc_chan, sc->sc_device, WII_RTCSRAM_FREQ);
        exi_send_imm(sc->sc_chan, sc->sc_device, &offset, sizeof(offset));
        exi_recv_imm(sc->sc_chan, sc->sc_device, &val, sizeof(val));
        exi_unselect(sc->sc_chan);

        return val;
}

static void
rtcsram_write_4(struct rtcsram_softc *sc, uint32_t offset, uint32_t val)
{
        offset |= WRITE_OFFSET;

        exi_select(sc->sc_chan, sc->sc_device, WII_RTCSRAM_FREQ);
        exi_send_imm(sc->sc_chan, sc->sc_device, &offset, sizeof(offset));
        exi_send_imm(sc->sc_chan, sc->sc_device, &val, sizeof(val));
        exi_unselect(sc->sc_chan);
}

static void
rtcsram_read_buf(struct rtcsram_softc *sc, uint32_t offset, void *data,
    size_t datalen)
{
        exi_select(sc->sc_chan, sc->sc_device, WII_RTCSRAM_FREQ);
        exi_send_imm(sc->sc_chan, sc->sc_device, &offset, sizeof(offset));
        exi_recv_dma(sc->sc_chan, sc->sc_device, data, datalen);
        exi_unselect(sc->sc_chan);
}

static int
rtcsram_gettime_nobias(todr_chip_handle_t ch, struct timeval *tv)
{
        struct rtcsram_softc * const sc = device_private(ch->todr_dev);
        uint32_t val;

        val = rtcsram_read_4(sc, RTC_BASE);
        tv->tv_sec = (uint64_t)val;
        tv->tv_usec = 0;

        return 0;
}

static int
rtcsram_settime_nobias(todr_chip_handle_t ch, struct timeval *tv)
{
        struct rtcsram_softc * const sc = device_private(ch->todr_dev);

        rtcsram_write_4(sc, RTC_BASE, tv->tv_sec);

        return 0;
}

static int
rtcsram_gettime_bias(todr_chip_handle_t ch, struct timeval *tv)
{
        struct rtcsram_softc * const sc = device_private(ch->todr_dev);
        uint32_t val;

        val = rtcsram_read_4(sc, RTC_BASE);
        tv->tv_sec = (uint64_t)val + sc->sc_sram.counter_bias;
        tv->tv_usec = 0;

        return 0;
}

static int
rtcsram_settime_bias(todr_chip_handle_t ch, struct timeval *tv)
{
        struct rtcsram_softc * const sc = device_private(ch->todr_dev);

        sc->sc_sram.counter_bias = tv->tv_sec - rtcsram_read_4(sc, RTC_BASE);
        rtcsram_write_4(sc, SRAM_BIAS, sc->sc_sram.counter_bias);

        return 0;
}