/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2006 Sam Leffler.  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>
/*
 * Analog Devices AD7418 chip sitting on the I2C bus.
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/bus.h>
#include <sys/sysctl.h>
#include <sys/sx.h>

#include <dev/iicbus/iiconf.h>

#include "iicbus_if.h"

#define IIC_M_WR        0       /* write operation */

#define AD7418_ADDR     0x50    /* slave address */

#define AD7418_TEMP     0       /* Temperature Value (r/o) */
#define AD7418_CONF     1       /* Config Register (r/w) */
#define AD7418_CONF_SHUTDOWN    0x01
#define AD7418_CONF_CHAN        0xe0    /* channel select mask */
#define AD7418_CHAN_TEMP        0x00    /* temperature channel */
#define AD7418_CHAN_VOLT        0x80    /* voltage channel */
#define AD7418_THYST    2       /* Thyst Setpoint (r/o) */
#define AD7418_TOTI     3       /* Toti Setpoint */
#define AD7418_VOLT     4       /* ADC aka Voltage (r/o) */
#define AD7418_CONF2    5       /* Config2 Register (r/w) */

struct ad7418_softc {
        device_t        sc_dev;
        struct sx       sc_lock;
        int             sc_curchan;     /* current channel */
        int             sc_curtemp;
        int             sc_curvolt;
        int             sc_lastupdate;  /* in ticks */
};

static void ad7418_update(struct ad7418_softc *);
static int ad7418_read_1(device_t dev, int reg);
static int ad7418_write_1(device_t dev, int reg, int v);

static int
ad7418_probe(device_t dev)
{
        /* XXX really probe? */
        device_set_desc(dev, "Analog Devices AD7418 ADC");
        return (BUS_PROBE_NOWILDCARD);
}

static int
ad7418_sysctl_temp(SYSCTL_HANDLER_ARGS)
{
        struct ad7418_softc *sc = arg1;
        int temp;

        sx_xlock(&sc->sc_lock);
        ad7418_update(sc);
        temp = (sc->sc_curtemp / 64) * 25;
        sx_xunlock(&sc->sc_lock);
        return sysctl_handle_int(oidp, &temp, 0, req);
}

static int
ad7418_sysctl_voltage(SYSCTL_HANDLER_ARGS)
{
        struct ad7418_softc *sc = arg1;
        int volt;

        sx_xlock(&sc->sc_lock);
        ad7418_update(sc);
        volt = (sc->sc_curvolt >> 6) * 564 / 10;
        sx_xunlock(&sc->sc_lock);
        return sysctl_handle_int(oidp, &volt, 0, req);
}

static int
ad7418_attach(device_t dev)
{
        struct ad7418_softc *sc = device_get_softc(dev);
        struct sysctl_ctx_list *ctx = device_get_sysctl_ctx(dev);
        struct sysctl_oid *tree = device_get_sysctl_tree(dev);
        int conf;

        sc->sc_dev = dev;
        sc->sc_lastupdate = ticks - hz;

        sx_init(&sc->sc_lock, "ad7418");

        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "temp", CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_NEEDGIANT, sc, 0,
            ad7418_sysctl_temp, "I", "operating temperature");
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "volt", CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_NEEDGIANT, sc, 0,
            ad7418_sysctl_voltage, "I", "input voltage");

        /* enable chip if configured in shutdown mode */
        conf = ad7418_read_1(dev, AD7418_CONF);
        if (conf >= 0 && (conf & AD7418_CONF_SHUTDOWN))
                ad7418_write_1(dev, AD7418_CONF, conf &~ AD7418_CONF_SHUTDOWN);

        return (0);
}

static int
ad7418_read_1(device_t dev, int reg) 
{
        uint8_t addr = reg;
        uint8_t data[1];
        struct iic_msg msgs[2] = {
             { AD7418_ADDR, IIC_M_WR, 1, &addr },
             { AD7418_ADDR, IIC_M_RD, 1, data },
        };
        return iicbus_transfer(dev, msgs, 2) != 0 ? -1 : data[0];
}

static int
ad7418_write_1(device_t dev, int reg, int v) 
{
        /* NB: register pointer precedes actual data */
        uint8_t data[2];
        struct iic_msg msgs[1] = {
             { AD7418_ADDR, IIC_M_WR, 2, data },
        };
        data[0] = reg;
        data[1] = v & 0xff;
        return iicbus_transfer(dev, msgs, 1);
}

static void
ad7418_set_channel(struct ad7418_softc *sc, int chan)
{
        if (sc->sc_curchan == chan)
                return;
        ad7418_write_1(sc->sc_dev, AD7418_CONF, 
            (ad7418_read_1(sc->sc_dev, AD7418_CONF) &~ AD7418_CONF_CHAN)|chan);
        sc->sc_curchan = chan;
#if 0
        /*
         * NB: Linux driver delays here but chip data sheet
         *     says nothing and things appear to work fine w/o
         *     a delay on channel change.
         */
        /* let channel change settle, 1 tick should be 'nuf (need ~1ms) */
        tsleep(sc, 0, "ad7418", hz/1000);
#endif
}

static int
ad7418_read_2(device_t dev, int reg) 
{
        uint8_t addr = reg;
        uint8_t data[2];
        struct iic_msg msgs[2] = {
             { AD7418_ADDR, IIC_M_WR, 1, &addr },
             { AD7418_ADDR, IIC_M_RD, 2, data },
        };
        /* NB: D15..D8 precede D7..D0 per data sheet (Fig 12) */
        return iicbus_transfer(dev, msgs, 2) != 0 ?
                -1 : ((data[0] << 8) | data[1]);
}

static void
ad7418_update(struct ad7418_softc *sc)
{
        int v;

        sx_assert(&sc->sc_lock, SA_XLOCKED);
        /* NB: no point in updating any faster than the chip */
        if (ticks - sc->sc_lastupdate > hz) {
                ad7418_set_channel(sc, AD7418_CHAN_TEMP);
                v = ad7418_read_2(sc->sc_dev, AD7418_TEMP);
                if (v >= 0)
                        sc->sc_curtemp = v;
                ad7418_set_channel(sc, AD7418_CHAN_VOLT);
                v = ad7418_read_2(sc->sc_dev, AD7418_VOLT);
                if (v >= 0)
                        sc->sc_curvolt = v;
                sc->sc_lastupdate = ticks;
        }
}

static device_method_t ad7418_methods[] = {
        DEVMETHOD(device_probe,         ad7418_probe),
        DEVMETHOD(device_attach,        ad7418_attach),

        DEVMETHOD_END
};

static driver_t ad7418_driver = {
        "ad7418",
        ad7418_methods,
        sizeof(struct ad7418_softc),
};

DRIVER_MODULE(ad7418, iicbus, ad7418_driver, 0, 0);
MODULE_VERSION(ad7418, 1);
MODULE_DEPEND(ad7418, iicbus, 1, 1, 1);