/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2019 Ian Lepore <ian@freebsd.org>
 *
 * 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 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 AUTHOR 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/cdefs.h>
#include "opt_platform.h"

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/systm.h>

#include <dev/iicbus/iicbus.h>
#include <dev/iicbus/iiconf.h>
#include "iicbus_if.h"
#include "iicmux_if.h"

static struct chip_info {
        const char      *partname;
        const char      *description;
        int             numchannels;
} chip_infos[] = {
        {"ltc4305", "LTC4305 I2C Mux", 2},
        {"ltc4306", "LTC4306 I2C Mux", 4},
};
#define CHIP_NONE       (-1)
#define CHIP_LTC4305    0
#define CHIP_LTC4306    1

#ifdef FDT
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#include <dev/ofw/openfirm.h>

static struct ofw_compat_data compat_data[] = {
        {"lltc,ltc4305",  CHIP_LTC4305},
        {"lltc,ltc4306",  CHIP_LTC4306},
        {NULL,            CHIP_NONE}
};
IICBUS_FDT_PNP_INFO(compat_data);
#endif

#include <dev/iicbus/mux/iicmux.h>

struct ltc430x_softc {
        struct iicmux_softc mux;
        bool idle_disconnect;
};

/*
 * The datasheet doesn't name the registers, it calls them control register 0-3.
 */
#define LTC430X_CTLREG_0        0
#define LTC430X_CTLREG_1        1
#define LTC430X_CTLREG_2        2
#define   LTC430X_CR2_ENABLE_MW   (1u << 3) /* Enable mass write address. */
#define LTC430X_CTLREG_3        3

static int
ltc430x_bus_select(device_t dev, int busidx, struct iic_reqbus_data *rd)
{
        struct ltc430x_softc *sc = device_get_softc(dev);
        uint8_t busbits;

        /*
         * The iicmux caller ensures busidx is between 0 and the number of buses
         * we passed to iicmux_init_softc(), no need for validation here.  If
         * the fdt data has the idle_disconnect property we idle the bus by
         * selecting no downstream buses, otherwise we just leave the current
         * bus active.  The upper bits of control register 3 activate the
         * downstream buses; bit 7 is the first bus, bit 6 the second, etc.
         */
        if (busidx == IICMUX_SELECT_IDLE) {
                if (sc->idle_disconnect)
                        busbits = 0;
                else
                        return (0);
        } else {
                busbits = 1u << (7 - busidx);
        }

        /*
         * We have to add the IIC_RECURSIVE flag because the iicmux core has
         * already reserved the bus for us, and iicdev_writeto() is going to try
         * to reserve it again, which is allowed with the recursive flag.
         */
        return (iicdev_writeto(dev, LTC430X_CTLREG_3, &busbits, sizeof(busbits),
            rd->flags | IIC_RECURSIVE));
}

static int
ltc430x_find_chiptype(device_t dev)
{
#ifdef FDT
        return (ofw_bus_search_compatible(dev, compat_data)->ocd_data);
#else
        const char *type;
        int i;

        if (resource_string_value(device_get_name(dev), device_get_unit(dev),
            "chip_type", &type) == 0) {
                for (i = 0; i < nitems(chip_infos); ++i) {
                        if (strcasecmp(type, chip_infos[i].partname) == 0) {
                                return (i);
                        }
                }
        }
        return (CHIP_NONE);
#endif
}

static int
ltc430x_probe(device_t dev)
{
        int type;

#ifdef FDT
        if (!ofw_bus_status_okay(dev))
                return (ENXIO);
#endif

        type = ltc430x_find_chiptype(dev);
        if (type == CHIP_NONE)
                return (ENXIO);

        device_set_desc(dev, chip_infos[type].description);

        return (BUS_PROBE_DEFAULT);
}

static int
ltc430x_attach(device_t dev)
{
        struct ltc430x_softc *sc __unused;
        int chip, err, numchan, val;
        uint8_t busbits, ctlreg2;

        sc = device_get_softc(dev);

        busbits = 0;
        ctlreg2 = LTC430X_CR2_ENABLE_MW;

        /*
         * Check for the idle-disconnect and ctlreg2 options, first in FDT data,
         * then allow them to be overridden by hints data.
         */
#ifdef FDT
        phandle_t node;

        node = ofw_bus_get_node(dev);
        sc->idle_disconnect = OF_hasprop(node, "i2c-mux-idle-disconnect");

        if (OF_getprop(node, "freebsd,ctlreg2", &val, sizeof(val)) > 0) {
                ctlreg2 = val;
        }
#endif

        if (resource_int_value(device_get_name(dev), device_get_unit(dev),
            "idle_disconnect", &val) == 0) {
                sc->idle_disconnect = val;
        }

        if (resource_int_value(device_get_name(dev), device_get_unit(dev),
            "ctlreg2", &val) == 0) {
                ctlreg2 = val;
        }

        /* We found the chip type when probing, so now it "can't fail". */
        if ((chip = ltc430x_find_chiptype(dev)) == CHIP_NONE) {
                device_printf(dev, "impossible: can't identify chip type\n");
                return (ENXIO);
        }
        numchan = chip_infos[chip].numchannels;

        /* Set control reg 2 with configured (or default) values. */
        iicdev_writeto(dev, LTC430X_CTLREG_2, &ctlreg2, sizeof(ctlreg2),
            IIC_WAIT);

        /* If configured for idle-disconnect, ensure we start disconnected. */
        if (sc->idle_disconnect) {
                iicdev_writeto(dev, LTC430X_CTLREG_3, &busbits, sizeof(busbits),
                    IIC_WAIT);
        }

        /*
         * Invoke the iicmux framework's attach code, and if it succeeds, invoke
         * the probe and attach code of any child iicbus instances it added.
         */
        if ((err = iicmux_attach(dev, device_get_parent(dev), numchan)) == 0)
                bus_attach_children(dev);

        return (err);
}

static int
ltc430x_detach(device_t dev)
{
        int err;

        if ((err = iicmux_detach(dev)) != 0)
                return (err);

        return (0);
}

static device_method_t ltc430x_methods[] = {
        /* device methods */
        DEVMETHOD(device_probe,                 ltc430x_probe),
        DEVMETHOD(device_attach,                ltc430x_attach),
        DEVMETHOD(device_detach,                ltc430x_detach),

        /* iicmux methods */
        DEVMETHOD(iicmux_bus_select,            ltc430x_bus_select),

        DEVMETHOD_END
};

DEFINE_CLASS_1(ltc430x, ltc430x_driver, ltc430x_methods,
    sizeof(struct ltc430x_softc), iicmux_driver);
DRIVER_MODULE(ltc430x, iicbus, ltc430x_driver, 0, 0);

#ifdef FDT
DRIVER_MODULE(ofw_iicbus, ltc430x, ofw_iicbus_driver, 0, 0);
#else
DRIVER_MODULE(iicbus, ltc430x, iicbus_driver, 0, 0);
#endif

MODULE_DEPEND(ltc430x, iicmux, 1, 1, 1);
MODULE_DEPEND(ltc430x, iicbus, 1, 1, 1);