/*      $NetBSD: mcp48x1.c,v 1.7 2025/09/13 14:10:44 thorpej Exp $ */

/*-
 * Copyright (c) 2014 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Radoslaw Kujawa.
 *
 * 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: mcp48x1.c,v 1.7 2025/09/13 14:10:44 thorpej Exp $");

/* 
 * Driver for Microchip MCP4801/MCP4811/MCP4821 DAC. 
 *
 * XXX: needs more testing.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/types.h>
#include <sys/sysctl.h>

#include <dev/sysmon/sysmonvar.h> 

#include <dev/spi/spivar.h>

#define MCP48X1DAC_DEBUG 0

#define MCP48X1DAC_WRITE        __BIT(15)       /* active low */
#define MCP48X1DAC_GAIN         __BIT(13)       /* active low */
#define MCP48X1DAC_SHDN         __BIT(12)       /* active low */
#define MCP48X1DAC_DATA         __BITS(11,0)    /* data */

struct mcp48x1dac_model {
        unsigned int name;
        uint8_t resolution;
        uint8_t shift;                  /* data left shift during write */
};

struct mcp48x1dac_softc {
        device_t sc_dev;
        spi_handle_t sc_sh;

        const struct mcp48x1dac_model *sc_dm;

        uint16_t sc_dac_data;
        bool sc_dac_gain;
        bool sc_dac_shutdown;
        
        struct sysmon_envsys *sc_sme;
        envsys_data_t sc_sm_vo;         /* envsys "sensor" (Vo) */
};

static int      mcp48x1dac_match(device_t, cfdata_t, void *);
static void     mcp48x1dac_attach(device_t, device_t, void *);

static bool     mcp48x1dac_envsys_attach(struct mcp48x1dac_softc *sc);
static void     mcp48x1dac_envsys_refresh(struct sysmon_envsys *,
                    envsys_data_t *);

static void     mcp48x1dac_write(struct mcp48x1dac_softc *);
static uint16_t mcp48x1dac_regval_to_mv(struct mcp48x1dac_softc *);

static void     mcp48x1dac_setup_sysctl(struct mcp48x1dac_softc *sc);
static int      sysctl_mcp48x1dac_data(SYSCTLFN_ARGS);
static int      sysctl_mcp48x1dac_gain(SYSCTLFN_ARGS);

CFATTACH_DECL_NEW(mcp48x1dac, sizeof(struct mcp48x1dac_softc),
    mcp48x1dac_match, mcp48x1dac_attach, NULL, NULL);

static const struct mcp48x1dac_model mcp4801 = {
        .name = 4801,
        .resolution = 8,
        .shift = 4
};

static const struct mcp48x1dac_model mcp4811 = {
        .name = 4811,
        .resolution = 10,
        .shift = 2
};

static const struct mcp48x1dac_model mcp4821 = {
        .name = 4821,
        .resolution = 12,
        .shift = 0
};

/*
 * N.B. The order of this table is important!  It matches the order
 * of the legacy mcp48x1_models[] array, which is used to manually
 * select the device type in the kernel configuration file when
 * direct configuration is not available.
 */
static const struct device_compatible_entry compat_data[] = {
        { .compat = "microchip,mcp4801",        .data = &mcp4801 },
        { .compat = "microchip,mcp4811",        .data = &mcp4811 },
        { .compat = "microchip,mcp4821",        .data = &mcp4821 },

        DEVICE_COMPAT_EOL
};
static const int mcp48x1_nmodels = __arraycount(compat_data) - 1;

static const struct mcp48x1dac_model *
mcp48x1dac_lookup(const struct spi_attach_args *sa, const cfdata_t cf)
{
        const struct mcp48x1dac_model *model = NULL;
        const struct device_compatible_entry *dce =
            spi_compatible_lookup(sa, compat_data);

        if (dce != NULL) {
                model = dce->data;
        } else if (cf->cf_flags >= 0 && cf->cf_flags < mcp48x1_nmodels) {
                model = compat_data[cf->cf_flags].data;
        }
        return model;
}

static int
mcp48x1dac_match(device_t parent, cfdata_t cf, void *aux)
{
        struct spi_attach_args *sa = aux;
        int match_result;

        if (spi_use_direct_match(sa, compat_data, &match_result)) {
                return match_result;
        }

        /*
         * If we're doing indirect config, the user must
         * have specified a valid model.
         */
        if (mcp48x1dac_lookup(sa, cf) == NULL) {
                return 0;
        }

        return SPI_MATCH_DEFAULT;
}

static void
mcp48x1dac_attach(device_t parent, device_t self, void *aux)
{
        struct mcp48x1dac_softc *sc = device_private(self);
        struct spi_attach_args *sa = aux;
        const struct mcp48x1dac_model *model;
        int error;

        sc->sc_dev = self;
        sc->sc_sh = sa->sa_handle;

        model = mcp48x1dac_lookup(sa, device_cfdata(self));
        KASSERT(model != NULL);

        sc->sc_dm = model;

        aprint_naive(": Digital to Analog converter\n");        
        aprint_normal(": MCP%u DAC\n", model->name);

        /*
         * XXX Deal with other properties described in the device
         * tree bindings.
         *
         * https://www.kernel.org/doc/Documentation/devicetree/bindings/iio/dac/microchip%2Cmcp4821.yaml
         */

        error = spi_configure(self, sa->sa_handle, SPI_MODE_0,
            SPI_FREQ_MHz(20));
        if (error) {
                return;
        }

        if (!mcp48x1dac_envsys_attach(sc)) {
                aprint_error_dev(sc->sc_dev, "failed to attach envsys\n");
                return;
        };

        sc->sc_dac_data = 0;
        sc->sc_dac_gain = false;
        sc->sc_dac_shutdown = false;
        mcp48x1dac_write(sc);

        mcp48x1dac_setup_sysctl(sc);
}

static void
mcp48x1dac_write(struct mcp48x1dac_softc *sc) 
{
        int rv;
        uint16_t reg, regbe;

        reg = 0;

        if (!(sc->sc_dac_gain))
                reg |= MCP48X1DAC_GAIN;

        if (!(sc->sc_dac_shutdown))
                reg |= MCP48X1DAC_SHDN;

        reg |= sc->sc_dac_data << sc->sc_dm->shift;

        regbe = htobe16(reg);

#ifdef MCP48X1DAC_DEBUG
        aprint_normal_dev(sc->sc_dev, "sending %x over SPI\n", regbe);
#endif /* MCP48X1DAC_DEBUG */

        rv = spi_send(sc->sc_sh, 2, (uint8_t*) &regbe); /* XXX: ugly cast */
 
        if (rv != 0) 
                aprint_error_dev(sc->sc_dev, "error sending data over SPI\n");
}

static bool
mcp48x1dac_envsys_attach(struct mcp48x1dac_softc *sc)
{

        sc->sc_sme = sysmon_envsys_create();
        sc->sc_sm_vo.units = ENVSYS_SVOLTS_DC;
        sc->sc_sm_vo.state = ENVSYS_SINVALID;
        strlcpy(sc->sc_sm_vo.desc, device_xname(sc->sc_dev),
            sizeof(sc->sc_sm_vo.desc));
        if (sysmon_envsys_sensor_attach(sc->sc_sme, &sc->sc_sm_vo)) {
                sysmon_envsys_destroy(sc->sc_sme);
                return false;
        }

        sc->sc_sme->sme_name = device_xname(sc->sc_dev);
        sc->sc_sme->sme_refresh = mcp48x1dac_envsys_refresh;
        sc->sc_sme->sme_cookie = sc;

        if (sysmon_envsys_register(sc->sc_sme)) {
                aprint_error_dev(sc->sc_dev, "unable to register in sysmon\n");
                sysmon_envsys_destroy(sc->sc_sme);
        }

        return true;
}

static uint16_t 
mcp48x1dac_regval_to_mv(struct mcp48x1dac_softc *sc)
{
        uint16_t mv;

        mv = (2048 * sc->sc_dac_data / (1 << sc->sc_dm->resolution));

        if (sc->sc_dac_gain)
                mv *= 2;

        return mv;
}

static void
mcp48x1dac_envsys_refresh(struct sysmon_envsys *sme, envsys_data_t *edata)
{
        struct mcp48x1dac_softc *sc;

        sc = sme->sme_cookie;

        edata->value_cur = mcp48x1dac_regval_to_mv(sc); 
        edata->state = ENVSYS_SVALID;
}

static void
mcp48x1dac_setup_sysctl(struct mcp48x1dac_softc *sc)
{
        const struct sysctlnode *me = NULL, *node = NULL;
 
        sysctl_createv(NULL, 0, NULL, &me,
            CTLFLAG_READWRITE,
            CTLTYPE_NODE, device_xname(sc->sc_dev), NULL,
            NULL, 0, NULL, 0,
            CTL_MACHDEP, CTL_CREATE, CTL_EOL);

        sysctl_createv(NULL, 0, NULL, &node,
            CTLFLAG_READWRITE | CTLFLAG_OWNDESC,
            CTLTYPE_INT, "data", "Digital value to convert to analog",
            sysctl_mcp48x1dac_data, 1, (void *)sc, 0,
            CTL_MACHDEP, me->sysctl_num, CTL_CREATE, CTL_EOL);
        
        sysctl_createv(NULL, 0, NULL, &node,
            CTLFLAG_READWRITE | CTLFLAG_OWNDESC,
            CTLTYPE_INT, "gain", "Gain 2x enable",
            sysctl_mcp48x1dac_gain, 1, (void *)sc, 0,
            CTL_MACHDEP, me->sysctl_num, CTL_CREATE, CTL_EOL);

}


SYSCTL_SETUP(sysctl_mcp48x1dac_setup, "sysctl mcp48x1dac subtree setup")
{
        sysctl_createv(NULL, 0, NULL, NULL, CTLFLAG_PERMANENT,
            CTLTYPE_NODE, "machdep", NULL, NULL, 0, NULL, 0,
            CTL_MACHDEP, CTL_EOL);
}


static int
sysctl_mcp48x1dac_data(SYSCTLFN_ARGS)
{
        struct sysctlnode node = *rnode;
        struct mcp48x1dac_softc *sc = node.sysctl_data;
        int newdata, err;

        node.sysctl_data = &sc->sc_dac_data;
        if ((err = (sysctl_lookup(SYSCTLFN_CALL(&node)))) != 0) 
                return err;

        if (newp) {
                newdata = *(int *)node.sysctl_data;
                if (newdata > (1 << sc->sc_dm->resolution))
                        return EINVAL;
                sc->sc_dac_data = (uint16_t) newdata;
                mcp48x1dac_write(sc);
                return 0;
        } else {
                /* nothing to do, since we can't read from DAC */
                node.sysctl_size = 4;
        }

        return err;
}

static int
sysctl_mcp48x1dac_gain(SYSCTLFN_ARGS)
{
        struct sysctlnode node = *rnode;
        struct mcp48x1dac_softc *sc = node.sysctl_data;
        int newgain, err;

        node.sysctl_data = &sc->sc_dac_gain;
        if ((err = (sysctl_lookup(SYSCTLFN_CALL(&node)))) != 0) 
                return err;

        if (newp) {
                newgain = *(int *)node.sysctl_data;
                sc->sc_dac_gain = (bool) newgain;
                mcp48x1dac_write(sc);
                return 0;
        } else {
                /* nothing to do, since we can't read from DAC */
                node.sysctl_size = 4;
        }

        return err;
}