/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2019 Ian Lepore.
 *
 * 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.
 */

/*
 * Driver for Texas Instruments ADS101x and ADS111x family i2c ADC chips.
 */

#include <sys/cdefs.h>
#include "opt_platform.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/endian.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/sx.h>
#include <sys/sysctl.h>

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

#include <dev/iicbus/iiconf.h>
#include <dev/iicbus/iicbus.h>

#include "iicbus_if.h"

/*
 * Chip registers, bit definitions, shifting and masking values.
 */
#define ADS111x_CONV                    0       /* Reg 0: Latest sample (ro) */

#define ADS111x_CONF                    1       /* Reg 1: Config (rw) */
#define   ADS111x_CONF_OS_SHIFT         15      /* Operational state */
#define   ADS111x_CONF_MUX_SHIFT        12      /* Input mux setting */
#define   ADS111x_CONF_GAIN_SHIFT        9      /* Programmable gain amp */
#define   ADS111x_CONF_MODE_SHIFT        8      /* Operational mode */
#define   ADS111x_CONF_RATE_SHIFT        5      /* Sample rate */
#define   ADS111x_CONF_COMP_DISABLE      3      /* Comparator disable */

#define ADS111x_LOTHRESH                2       /* Compare lo threshold (rw) */

#define ADS111x_HITHRESH                3       /* Compare hi threshold (rw) */

/*
 * On config write, the operational-state bit starts a measurement, on read it
 * indicates when the measurement process is complete/idle.
 */
#define   ADS111x_CONF_MEASURE          (1u << ADS111x_CONF_OS_SHIFT)
#define   ADS111x_CONF_IDLE             (1u << ADS111x_CONF_OS_SHIFT)

/*
 * The default values for config items that are not per-channel.  Mostly, this
 * turns off the comparator on chips that have that feature, because this driver
 * doesn't support it directly.  However, the user is allowed to enable the
 * comparator and we'll leave it alone if they do.  That allows them connect the
 * alert pin to something and use the feature without any help from this driver.
 */
#define ADS111x_CONF_DEFAULT    \
    ((1 << ADS111x_CONF_MODE_SHIFT) | ADS111x_CONF_COMP_DISABLE)
#define ADS111x_CONF_USERMASK   0x001f

/*
 * Per-channel defaults.  The chip only has one control register, and we load
 * per-channel values into it every time we make a measurement on that channel.
 * These are the default values for the control register from the datasheet, for
 * values we maintain on a per-channel basis.
 */
#define DEFAULT_GAINIDX         2
#define DEFAULT_RATEIDX         4

/*
 * Full-scale ranges for each available amplifier setting, in microvolts.  The
 * ADS1x13 chips are fixed-range, the other chips contain a programmable gain
 * amplifier, and the full scale range is based on the amplifier setting.
 */
static const u_int fixedranges[8] = {
        2048000, 2048000, 2048000, 2048000, 2048000, 2048000, 2048000, 2048000,
};
static const u_int gainranges[8] = {
        6144000, 4096000, 2048000, 1024000,  512000,  256000,  256000,  256000,
};

/* The highest value for the ADS101x chip is 0x7ff0, for ADS111x it's 0x7fff. */
#define ADS101x_RANGEDIV        ((1 << 15) - 15)
#define ADS111x_RANGEDIV        ((1 << 15) - 1)

/* Samples per second; varies based on chip type. */
static const u_int rates101x[8] = {128, 250, 490, 920, 1600, 2400, 3300, 3300};
static const u_int rates111x[8] = {  8,  16,  32,  64,  128,  250,  475,  860};

struct ads111x_channel {
        u_int gainidx;          /* Amplifier (full-scale range) config index */
        u_int rateidx;          /* Samples per second config index */
        bool  configured;       /* Channel has been configured */
};

#define ADS111x_MAX_CHANNELS    8

struct ads111x_chipinfo {
        const char      *name;
        const u_int     *rangetab;
        const u_int     *ratetab;
        u_int           numchan;
        int             rangediv;
};

static struct ads111x_chipinfo ads111x_chip_infos[] = {
        { "ADS1013", fixedranges, rates101x, 1, ADS101x_RANGEDIV },
        { "ADS1014", gainranges,  rates101x, 1, ADS101x_RANGEDIV },
        { "ADS1015", gainranges,  rates101x, 8, ADS101x_RANGEDIV },
        { "ADS1113", fixedranges, rates111x, 1, ADS111x_RANGEDIV },
        { "ADS1114", gainranges,  rates111x, 1, ADS111x_RANGEDIV },
        { "ADS1115", gainranges,  rates111x, 8, ADS111x_RANGEDIV },
};

#ifdef FDT
static struct ofw_compat_data compat_data[] = {
        {"ti,ads1013",   (uintptr_t)&ads111x_chip_infos[0]},
        {"ti,ads1014",   (uintptr_t)&ads111x_chip_infos[1]},
        {"ti,ads1015",   (uintptr_t)&ads111x_chip_infos[2]},
        {"ti,ads1113",   (uintptr_t)&ads111x_chip_infos[3]},
        {"ti,ads1114",   (uintptr_t)&ads111x_chip_infos[4]},
        {"ti,ads1115",   (uintptr_t)&ads111x_chip_infos[5]},
        {NULL,           (uintptr_t)NULL},
};
IICBUS_FDT_PNP_INFO(compat_data);
#endif

struct ads111x_softc {
        device_t        dev;
        struct sx       lock;
        int             addr;
        int             cfgword;
        const struct ads111x_chipinfo
                        *chipinfo;
        struct ads111x_channel
                        channels[ADS111x_MAX_CHANNELS];
};

static int
ads111x_write_2(struct ads111x_softc *sc, int reg, int val) 
{
        uint8_t data[3];
        struct iic_msg msgs[1];
        uint8_t slaveaddr;

        slaveaddr = iicbus_get_addr(sc->dev);

        data[0] = reg;
        be16enc(&data[1], val);

        msgs[0].slave = slaveaddr;
        msgs[0].flags = IIC_M_WR;
        msgs[0].len   = sizeof(data);
        msgs[0].buf   = data;

        return (iicbus_transfer_excl(sc->dev, msgs, nitems(msgs), IIC_WAIT));
}

static int
ads111x_read_2(struct ads111x_softc *sc, int reg, int *val) 
{
        int err;
        uint8_t data[2];

        err = iic2errno(iicdev_readfrom(sc->dev, reg, data, 2, IIC_WAIT));
        if (err == 0)
                *val = (int16_t)be16dec(data);

        return (err);
}

static int
ads111x_sample_voltage(struct ads111x_softc *sc, int channum, int *voltage) 
{
        struct ads111x_channel *chan;
        int err, cfgword, convword, rate, retries, waitns;
        int64_t fsrange;

        chan = &sc->channels[channum];

        /* Ask the chip to do a one-shot measurement of the given channel. */
        cfgword = sc->cfgword |
            (1 << ADS111x_CONF_OS_SHIFT) |
            (channum << ADS111x_CONF_MUX_SHIFT) |
            (chan->gainidx << ADS111x_CONF_GAIN_SHIFT) |
            (chan->rateidx << ADS111x_CONF_RATE_SHIFT);
        if ((err = ads111x_write_2(sc, ADS111x_CONF, cfgword)) != 0)
                return (err);

        /*
         * Calculate how long it will take to make the measurement at the
         * current sampling rate (round up).  The measurement averaging time
         * ranges from 300us to 125ms, so we yield the cpu while waiting.
         */
        rate = sc->chipinfo->ratetab[chan->rateidx];
        waitns = (1000000000 + rate - 1) / rate;
        err = pause_sbt("ads111x", nstosbt(waitns), 0, C_PREL(2));
        if (err != 0 && err != EWOULDBLOCK)
                return (err);

        /*
         * In theory the measurement should be available now; we waited long
         * enough.  However, the chip times its averaging intervals using an
         * internal 1 MHz oscillator which likely isn't running at the same rate
         * as the system clock, so we have to double-check that the measurement
         * is complete before reading the result.  If it's not ready yet, yield
         * the cpu again for 5% of the time we originally calculated.
         *
         * Unlike most i2c slaves, this device does not auto-increment the
         * register number on reads, so we can't read both status and
         * measurement in one operation.
         */
        for (retries = 5; ; --retries) {
                if (retries == 0)
                        return (EWOULDBLOCK);
                if ((err = ads111x_read_2(sc, ADS111x_CONF, &cfgword)) != 0)
                        return (err);
                if (cfgword & ADS111x_CONF_IDLE)
                        break;
                pause_sbt("ads111x", nstosbt(waitns / 20), 0, C_PREL(2));
        }

        /* Retrieve the sample and convert it to microvolts. */
        if ((err = ads111x_read_2(sc, ADS111x_CONV, &convword)) != 0)
                return (err);
        fsrange = sc->chipinfo->rangetab[chan->gainidx];
        *voltage = (int)((convword * fsrange ) / sc->chipinfo->rangediv);

        return (err);
}

static int
ads111x_sysctl_gainidx(SYSCTL_HANDLER_ARGS)
{
        struct ads111x_softc *sc;
        int chan, err, gainidx;

        sc = arg1;
        chan = arg2;

        gainidx = sc->channels[chan].gainidx;
        err = sysctl_handle_int(oidp, &gainidx, 0, req);
        if (err != 0 || req->newptr == NULL)
                return (err);
        if (gainidx < 0 || gainidx > 7)
                return (EINVAL);
        sx_xlock(&sc->lock);
        sc->channels[chan].gainidx = gainidx;
        sx_xunlock(&sc->lock);

        return (err);
}

static int
ads111x_sysctl_rateidx(SYSCTL_HANDLER_ARGS)
{
        struct ads111x_softc *sc;
        int chan, err, rateidx;

        sc = arg1;
        chan = arg2;

        rateidx = sc->channels[chan].rateidx;
        err = sysctl_handle_int(oidp, &rateidx, 0, req);
        if (err != 0 || req->newptr == NULL)
                return (err);
        if (rateidx < 0 || rateidx > 7)
                return (EINVAL);
        sx_xlock(&sc->lock);
        sc->channels[chan].rateidx = rateidx;
        sx_xunlock(&sc->lock);

        return (err);
}

static int
ads111x_sysctl_voltage(SYSCTL_HANDLER_ARGS)
{
        struct ads111x_softc *sc;
        int chan, err, voltage;

        sc = arg1;
        chan = arg2;

        if (req->oldptr != NULL) {
                sx_xlock(&sc->lock);
                err = ads111x_sample_voltage(sc, chan, &voltage);
                sx_xunlock(&sc->lock);
                if (err != 0) {
                        device_printf(sc->dev,
                            "conversion read failed, error %d\n", err);
                        return (err);
                }
        }
        err = sysctl_handle_int(oidp, &voltage, 0, req);
        return (err);
}

static int
ads111x_sysctl_config(SYSCTL_HANDLER_ARGS)
{
        struct ads111x_softc *sc;
        int config, err;

        sc = arg1;
        config = sc->cfgword & ADS111x_CONF_USERMASK;
        err = sysctl_handle_int(oidp, &config, 0, req);
        if (err != 0 || req->newptr == NULL)
                return (err);
        sx_xlock(&sc->lock);
        sc->cfgword = config & ADS111x_CONF_USERMASK;
        err = ads111x_write_2(sc, ADS111x_CONF, sc->cfgword);
        sx_xunlock(&sc->lock);

        return (err);
}
static int
ads111x_sysctl_lothresh(SYSCTL_HANDLER_ARGS)
{
        struct ads111x_softc *sc;
        int thresh, err;

        sc = arg1;
        if ((err = ads111x_read_2(sc, ADS111x_LOTHRESH, &thresh)) != 0)
                return (err);
        err = sysctl_handle_int(oidp, &thresh, 0, req);
        if (err != 0 || req->newptr == NULL)
                return (err);
        sx_xlock(&sc->lock);
        err = ads111x_write_2(sc, ADS111x_CONF, thresh);
        sx_xunlock(&sc->lock);

        return (err);
}

static int
ads111x_sysctl_hithresh(SYSCTL_HANDLER_ARGS)
{
        struct ads111x_softc *sc;
        int thresh, err;

        sc = arg1;
        if ((err = ads111x_read_2(sc, ADS111x_HITHRESH, &thresh)) != 0)
                return (err);
        err = sysctl_handle_int(oidp, &thresh, 0, req);
        if (err != 0 || req->newptr == NULL)
                return (err);
        sx_xlock(&sc->lock);
        err = ads111x_write_2(sc, ADS111x_CONF, thresh);
        sx_xunlock(&sc->lock);

        return (err);
}

static void
ads111x_setup_channel(struct ads111x_softc *sc, int chan, int gainidx, int rateidx)
{
        struct ads111x_channel *c;
        struct sysctl_ctx_list *ctx;
        struct sysctl_oid *chantree, *devtree;
        char chanstr[4];

        c = &sc->channels[chan];
        c->gainidx = gainidx;
        c->rateidx = rateidx;

        /*
         *  If setting up the channel for the first time, create channel's
         *  sysctl entries.  We might have already configured the channel if
         *  config data for it exists in both FDT and hints.
         */

        if (c->configured)
                return;

        ctx = device_get_sysctl_ctx(sc->dev);
        devtree = device_get_sysctl_tree(sc->dev);
        snprintf(chanstr, sizeof(chanstr), "%d", chan);
        chantree = SYSCTL_ADD_NODE(ctx, SYSCTL_CHILDREN(devtree), OID_AUTO,
            chanstr, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, "channel data");
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(chantree), OID_AUTO,
            "gain_index", CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE,
            sc, chan, ads111x_sysctl_gainidx, "I",
            "programmable gain amp setting, 0-7");
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(chantree), OID_AUTO,
            "rate_index", CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE,
            sc, chan, ads111x_sysctl_rateidx, "I", "sample rate setting, 0-7");
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(chantree), OID_AUTO,
            "voltage",
            CTLTYPE_INT | CTLFLAG_RD | CTLFLAG_SKIP | CTLFLAG_MPSAFE, sc,
            chan, ads111x_sysctl_voltage, "I", "sampled voltage in microvolts");

        c->configured = true;
}

static void
ads111x_add_channels(struct ads111x_softc *sc)
{
        const char *name;
        uint32_t chan, gainidx, num_added, rateidx, unit;
        bool found;

#ifdef FDT
        phandle_t child, node;

        /* Configure any channels that have FDT data. */
        num_added = 0;
        node = ofw_bus_get_node(sc->dev);
        for (child = OF_child(node); child != 0; child = OF_peer(child)) {
                if (OF_getencprop(child, "reg", &chan, sizeof(chan)) == -1)
                        continue;
                if (chan >= ADS111x_MAX_CHANNELS)
                        continue;
                gainidx = DEFAULT_GAINIDX;
                rateidx = DEFAULT_RATEIDX;
                OF_getencprop(child, "ti,gain", &gainidx, sizeof(gainidx));
                OF_getencprop(child, "ti,datarate", &rateidx, sizeof(rateidx));
                ads111x_setup_channel(sc, chan, gainidx, rateidx);
                ++num_added;
        }
#else
        num_added = 0;
#endif

        /* Configure any channels that have hint data. */
        name = device_get_name(sc->dev);
        unit = device_get_unit(sc->dev);
        for (chan = 0; chan < sc->chipinfo->numchan; ++chan) {
                char resname[16];
                found = false;
                gainidx = DEFAULT_GAINIDX;
                rateidx = DEFAULT_RATEIDX;
                snprintf(resname, sizeof(resname), "%d.gain_index", chan);
                if (resource_int_value(name, unit, resname, &gainidx) == 0)
                        found = true;
                snprintf(resname, sizeof(resname), "%d.rate_index", chan);
                if (resource_int_value(name, unit, resname, &rateidx) == 0)
                        found = true;
                if (found) {
                        ads111x_setup_channel(sc, chan, gainidx, rateidx);
                        ++num_added;
                }
        }

        /* If any channels were configured via FDT or hints, we're done. */
        if (num_added > 0)
                return;

        /*
         * No channel config; add all possible channels using default values,
         * and let the user configure the ones they want on the fly via sysctl.
         */
        for (chan = 0; chan < sc->chipinfo->numchan; ++chan) {
                gainidx = DEFAULT_GAINIDX;
                rateidx = DEFAULT_RATEIDX;
                ads111x_setup_channel(sc, chan, gainidx, rateidx);
        }
}

static const struct ads111x_chipinfo *
ads111x_find_chipinfo(device_t dev)
{
        const struct ads111x_chipinfo *info;
        const char *chiptype;
        int i;

#ifdef FDT
        if (ofw_bus_status_okay(dev)) {
                info = (struct ads111x_chipinfo*)
                    ofw_bus_search_compatible(dev, compat_data)->ocd_data;
                if (info != NULL)
                        return (info);
        }
#endif

        /* For hinted devices, we must be told the chip type. */
        chiptype = NULL;
        resource_string_value(device_get_name(dev), device_get_unit(dev),
            "type", &chiptype);
        if (chiptype != NULL) {
                for (i = 0; i < nitems(ads111x_chip_infos); ++i) {
                        info = &ads111x_chip_infos[i];
                        if (strcasecmp(chiptype, info->name) == 0)
                                return (info);
                }
        }
        return (NULL);
}

static int
ads111x_probe(device_t dev)
{
        const struct ads111x_chipinfo *info;

        info = ads111x_find_chipinfo(dev);
        if (info != NULL) {
                device_set_desc(dev, info->name);
#ifdef FDT
                return (BUS_PROBE_DEFAULT);
#else
                return (BUS_PROBE_NOWILDCARD);
#endif
        }

        return (ENXIO);
}

static int
ads111x_attach(device_t dev)
{
        struct ads111x_softc *sc;
        struct sysctl_ctx_list *ctx;
        struct sysctl_oid *tree;
        int err;

        sc = device_get_softc(dev);
        sc->dev = dev;
        sc->addr = iicbus_get_addr(dev);
        sc->cfgword = ADS111x_CONF_DEFAULT;

        sc->chipinfo = ads111x_find_chipinfo(sc->dev);
        if (sc->chipinfo == NULL) {
                device_printf(dev,
                    "cannot get chipinfo (but it worked during probe)");
                return (ENXIO);
        }

        /* Set the default chip config. */
        if ((err = ads111x_write_2(sc, ADS111x_CONF, sc->cfgword)) != 0) {
                device_printf(dev, "cannot write chip config register\n");
                return (err);
        }

        sx_init(&sc->lock, "ads111x");

        /* Add the sysctl handler to set the chip configuration register.  */
        ctx = device_get_sysctl_ctx(dev);
        tree = device_get_sysctl_tree(dev);
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "config", CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, sc, 0,
            ads111x_sysctl_config, "I", "configuration register word");
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "lo_thresh", CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, sc, 0,
            ads111x_sysctl_lothresh, "I", "comparator low threshold");
        SYSCTL_ADD_PROC(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
            "hi_thresh", CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, sc, 0,
            ads111x_sysctl_hithresh, "I", "comparator high threshold");

        /* Set up channels based on metadata or default config. */
        ads111x_add_channels(sc);

        return (0);
}

static int
ads111x_detach(device_t dev)
{
        struct ads111x_softc *sc;

        sc = device_get_softc(dev);

        sx_destroy(&sc->lock);
        return (0);
}

static device_method_t ads111x_methods[] = {
        DEVMETHOD(device_probe,         ads111x_probe),
        DEVMETHOD(device_attach,        ads111x_attach),
        DEVMETHOD(device_detach,        ads111x_detach),

        DEVMETHOD_END,
};

static driver_t ads111x_driver = {
        "ads111x",
        ads111x_methods,
        sizeof(struct ads111x_softc),
};

DRIVER_MODULE(ads111x, iicbus, ads111x_driver, NULL, NULL);
MODULE_VERSION(ads111x, 1);
MODULE_DEPEND(ads111x, iicbus, 1, 1, 1);