/*-
 * Copyright (c) 2016 Jared McNeill <jmcneill@invisible.ca>
 *
 * 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.
 */

/*
 * GPIO controlled regulators
 */

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

#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>

#include <dev/gpio/gpiobusvar.h>

#include <dev/regulator/regulator.h>

#include "regdev_if.h"

struct gpioregulator_state {
        int                     val;
        uint32_t                mask;
};

struct gpioregulator_init_def {
        struct regnode_init_def         reg_init_def;
        struct gpiobus_pin              *enable_pin;
        int                             enable_pin_valid;
        int                             startup_delay_us;
        int                             nstates;
        struct gpioregulator_state      *states;
        int                             npins;
        struct gpiobus_pin              **pins;
};

struct gpioregulator_reg_sc {
        struct regnode                  *regnode;
        device_t                        base_dev;
        struct regnode_std_param        *param;
        struct gpioregulator_init_def   *def;
};

struct gpioregulator_softc {
        device_t                        dev;
        struct gpioregulator_reg_sc     *reg_sc;
        struct gpioregulator_init_def   init_def;
};

static int
gpioregulator_regnode_init(struct regnode *regnode)
{
        struct gpioregulator_reg_sc *sc;
        int error, n;

        sc = regnode_get_softc(regnode);

        if (sc->def->enable_pin_valid == 1) {
                error = gpio_pin_setflags(sc->def->enable_pin, GPIO_PIN_OUTPUT);
                if (error != 0)
                        return (error);
        }

        for (n = 0; n < sc->def->npins; n++) {
                error = gpio_pin_setflags(sc->def->pins[n], GPIO_PIN_OUTPUT);
                if (error != 0)
                        return (error);
        }

        return (0);
}

static int
gpioregulator_regnode_enable(struct regnode *regnode, bool enable, int *udelay)
{
        struct gpioregulator_reg_sc *sc;
        bool active;
        int error;

        sc = regnode_get_softc(regnode);

        if (sc->def->enable_pin_valid == 1) {
                active = enable;
                if (!sc->param->enable_active_high)
                        active = !active;
                error = gpio_pin_set_active(sc->def->enable_pin, active);
                if (error != 0)
                        return (error);
        }

        *udelay = sc->def->startup_delay_us;

        return (0);
}

static int
gpioregulator_regnode_set_voltage(struct regnode *regnode, int min_uvolt,
    int max_uvolt, int *udelay)
{
        struct gpioregulator_reg_sc *sc;
        const struct gpioregulator_state *state;
        int error, n;

        sc = regnode_get_softc(regnode);
        state = NULL;

        for (n = 0; n < sc->def->nstates; n++) {
                if (sc->def->states[n].val >= min_uvolt &&
                    sc->def->states[n].val <= max_uvolt) {
                        state = &sc->def->states[n];
                        break;
                }
        }
        if (state == NULL)
                return (EINVAL);

        for (n = 0; n < sc->def->npins; n++) {
                error = gpio_pin_set_active(sc->def->pins[n],
                    (state->mask >> n) & 1);
                if (error != 0)
                        return (error);
        }

        *udelay = sc->def->startup_delay_us;

        return (0);
}

static int
gpioregulator_regnode_get_voltage(struct regnode *regnode, int *uvolt)
{
        struct gpioregulator_reg_sc *sc;
        uint32_t mask;
        int error, n;
        bool active;

        sc = regnode_get_softc(regnode);
        mask = 0;

        for (n = 0; n < sc->def->npins; n++) {
                error = gpio_pin_is_active(sc->def->pins[n], &active);
                if (error != 0)
                        return (error);
                mask |= (active << n);
        }

        for (n = 0; n < sc->def->nstates; n++) {
                if (sc->def->states[n].mask == mask) {
                        *uvolt = sc->def->states[n].val;
                        return (0);
                }
        }

        return (EIO);
}

static regnode_method_t gpioregulator_regnode_methods[] = {
        /* Regulator interface */
        REGNODEMETHOD(regnode_init,     gpioregulator_regnode_init),
        REGNODEMETHOD(regnode_enable,   gpioregulator_regnode_enable),
        REGNODEMETHOD(regnode_set_voltage, gpioregulator_regnode_set_voltage),
        REGNODEMETHOD(regnode_get_voltage, gpioregulator_regnode_get_voltage),
        REGNODEMETHOD_END
};
DEFINE_CLASS_1(gpioregulator_regnode, gpioregulator_regnode_class,
    gpioregulator_regnode_methods, sizeof(struct gpioregulator_reg_sc),
    regnode_class);

static int
gpioregulator_parse_fdt(struct gpioregulator_softc *sc)
{
        uint32_t *pstates, mask;
        phandle_t node;
        ssize_t len;
        int error, n;

        node = ofw_bus_get_node(sc->dev);
        pstates = NULL;
        mask = 0;

        error = regulator_parse_ofw_stdparam(sc->dev, node,
            &sc->init_def.reg_init_def);
        if (error != 0)
                return (error);

        /* "states" property (required) */
        len = OF_getencprop_alloc_multi(node, "states", sizeof(*pstates),
            (void **)&pstates);
        if (len < 2) {
                device_printf(sc->dev, "invalid 'states' property\n");
                error = EINVAL;
                goto done;
        }
        sc->init_def.nstates = len / 2;
        sc->init_def.states = malloc(sc->init_def.nstates *
            sizeof(*sc->init_def.states), M_DEVBUF, M_WAITOK);
        for (n = 0; n < sc->init_def.nstates; n++) {
                sc->init_def.states[n].val = pstates[n * 2 + 0];
                sc->init_def.states[n].mask = pstates[n * 2 + 1];
                mask |= sc->init_def.states[n].mask;
        }

        /* "startup-delay-us" property (optional) */
        len = OF_getencprop(node, "startup-delay-us",
            &sc->init_def.startup_delay_us,
            sizeof(sc->init_def.startup_delay_us));
        if (len <= 0)
                sc->init_def.startup_delay_us = 0;

        /* "enable-gpio" property (optional) */
        error = gpio_pin_get_by_ofw_property(sc->dev, node, "enable-gpio",
            &sc->init_def.enable_pin);
        if (error == 0)
                sc->init_def.enable_pin_valid = 1;

        /* "gpios" property */
        sc->init_def.npins = 32 - __builtin_clz(mask);
        sc->init_def.pins = malloc(sc->init_def.npins *
            sizeof(sc->init_def.pins), M_DEVBUF, M_WAITOK | M_ZERO);
        for (n = 0; n < sc->init_def.npins; n++) {
                error = gpio_pin_get_by_ofw_idx(sc->dev, node, n,
                    &sc->init_def.pins[n]);
                if (error != 0) {
                        device_printf(sc->dev, "cannot get pin %d\n", n);
                        goto done;
                }
        }

done:
        if (error != 0) {
                for (n = 0; n < sc->init_def.npins; n++) {
                        if (sc->init_def.pins[n] != NULL)
                                gpio_pin_release(sc->init_def.pins[n]);
                }

                free(sc->init_def.states, M_DEVBUF);
                free(sc->init_def.pins, M_DEVBUF);

        }
        OF_prop_free(pstates);

        return (error);
}

static int
gpioregulator_probe(device_t dev)
{

        if (!ofw_bus_is_compatible(dev, "regulator-gpio"))
                return (ENXIO);

        device_set_desc(dev, "GPIO controlled regulator");
        return (BUS_PROBE_GENERIC);
}

static int
gpioregulator_attach(device_t dev)
{
        struct gpioregulator_softc *sc;
        struct regnode *regnode;
        phandle_t node;
        int error;

        sc = device_get_softc(dev);
        sc->dev = dev;
        node = ofw_bus_get_node(dev);

        error = gpioregulator_parse_fdt(sc);
        if (error != 0) {
                device_printf(dev, "cannot parse parameters\n");
                return (ENXIO);
        }
        sc->init_def.reg_init_def.id = 1;
        sc->init_def.reg_init_def.ofw_node = node;

        regnode = regnode_create(dev, &gpioregulator_regnode_class,
            &sc->init_def.reg_init_def);
        if (regnode == NULL) {
                device_printf(dev, "cannot create regulator\n");
                return (ENXIO);
        }

        sc->reg_sc = regnode_get_softc(regnode);
        sc->reg_sc->regnode = regnode;
        sc->reg_sc->base_dev = dev;
        sc->reg_sc->param = regnode_get_stdparam(regnode);
        sc->reg_sc->def = &sc->init_def;

        regnode_register(regnode);

        return (0);
}


static device_method_t gpioregulator_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         gpioregulator_probe),
        DEVMETHOD(device_attach,        gpioregulator_attach),

        /* Regdev interface */
        DEVMETHOD(regdev_map,           regdev_default_ofw_map),

        DEVMETHOD_END
};

static driver_t gpioregulator_driver = {
        "gpioregulator",
        gpioregulator_methods,
        sizeof(struct gpioregulator_softc),
};

EARLY_DRIVER_MODULE(gpioregulator, simplebus, gpioregulator_driver, 0, 0,
    BUS_PASS_INTERRUPT + BUS_PASS_ORDER_LAST);
MODULE_VERSION(gpioregulator, 1);