/*-
 * 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.
 */

/*
 * Silergy Corp. SY8106A buck regulator
 */

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

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

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

#include <dev/regulator/regulator.h>

#include "iicbus_if.h"
#include "regdev_if.h"

#define VOUT1_SEL               0x01
#define  SEL_GO                 (1 << 7)
#define  SEL_VOLTAGE_MASK       0x7f
#define  SEL_VOLTAGE_BASE       680000  /* uV */
#define  SEL_VOLTAGE_STEP       10000   /* uV */
#define VOUT_COM                0x02
#define  COM_DISABLE            (1 << 0)
#define SYS_STATUS              0x06

static struct ofw_compat_data compat_data[] = {
        { "silergy,sy8106a",                    1 },
        { NULL,                                 0 }
};

struct sy8106a_reg_sc {
        struct regnode          *regnode;
        device_t                base_dev;
        phandle_t               xref;
        struct regnode_std_param *param;
};

struct sy8106a_softc {
        uint16_t                addr;

        /* Regulator */
        struct sy8106a_reg_sc   *reg;
};

static int
sy8106a_read(device_t dev, uint8_t reg, uint8_t *data, uint8_t size)
{
        struct sy8106a_softc *sc;
        struct iic_msg msg[2];

        sc = device_get_softc(dev);

        msg[0].slave = sc->addr;
        msg[0].flags = IIC_M_WR;
        msg[0].len = 1;
        msg[0].buf = &reg;

        msg[1].slave = sc->addr;
        msg[1].flags = IIC_M_RD;
        msg[1].len = size;
        msg[1].buf = data;

        return (iicbus_transfer(dev, msg, 2));
}

static int
sy8106a_write(device_t dev, uint8_t reg, uint8_t val)
{
        struct sy8106a_softc *sc;
        struct iic_msg msg;
        uint8_t buffer[2];

        sc = device_get_softc(dev);

        buffer[0] = reg;
        buffer[1] = val;

        msg.slave = sc->addr;
        msg.flags = IIC_M_WR;
        msg.len = 2;
        msg.buf = buffer;

        return (iicbus_transfer(dev, &msg, 1));
}

static int
sy8106a_regnode_init(struct regnode *regnode)
{
        return (0);
}

static int
sy8106a_regnode_enable(struct regnode *regnode, bool enable, int *udelay)
{
        struct sy8106a_reg_sc *sc;
        uint8_t val;

        sc = regnode_get_softc(regnode);

        sy8106a_read(sc->base_dev, VOUT_COM, &val, 1);
        if (enable)
                val &= ~COM_DISABLE;
        else
                val |= COM_DISABLE;
        sy8106a_write(sc->base_dev, VOUT_COM, val);

        *udelay = sc->param->ramp_delay;

        return (0);
}

static int
sy8106a_regnode_set_voltage(struct regnode *regnode, int min_uvolt,
    int max_uvolt, int *udelay)
{
        struct sy8106a_reg_sc *sc;
        int cur_uvolt;
        uint8_t val, oval;

        sc = regnode_get_softc(regnode);

        /* Get current voltage */
        sy8106a_read(sc->base_dev, VOUT1_SEL, &oval, 1);
        cur_uvolt = (oval & SEL_VOLTAGE_MASK) * SEL_VOLTAGE_STEP +
            SEL_VOLTAGE_BASE;

        /* Set new voltage */
        val = SEL_GO | ((min_uvolt - SEL_VOLTAGE_BASE) / SEL_VOLTAGE_STEP);
        sy8106a_write(sc->base_dev, VOUT1_SEL, val);

        /* Time to delay is based on the number of voltage steps */
        *udelay = sc->param->ramp_delay *
            (abs(cur_uvolt - min_uvolt) / SEL_VOLTAGE_STEP);

        return (0);
}

static int
sy8106a_regnode_get_voltage(struct regnode *regnode, int *uvolt)
{
        struct sy8106a_reg_sc *sc;
        uint8_t val;

        sc = regnode_get_softc(regnode);

        sy8106a_read(sc->base_dev, VOUT1_SEL, &val, 1);
        *uvolt = (val & SEL_VOLTAGE_MASK) * SEL_VOLTAGE_STEP +
            SEL_VOLTAGE_BASE;

        return (0);
}

static regnode_method_t sy8106a_regnode_methods[] = {
        /* Regulator interface */
        REGNODEMETHOD(regnode_init,             sy8106a_regnode_init),
        REGNODEMETHOD(regnode_enable,           sy8106a_regnode_enable),
        REGNODEMETHOD(regnode_set_voltage,      sy8106a_regnode_set_voltage),
        REGNODEMETHOD(regnode_get_voltage,      sy8106a_regnode_get_voltage),
        REGNODEMETHOD_END
};
DEFINE_CLASS_1(sy8106a_regnode, sy8106a_regnode_class, sy8106a_regnode_methods,
    sizeof(struct sy8106a_reg_sc), regnode_class);

static struct sy8106a_reg_sc *
sy8106a_reg_attach(device_t dev, phandle_t node)
{
        struct sy8106a_reg_sc *reg_sc;
        struct regnode_init_def initdef;
        struct regnode *regnode;

        memset(&initdef, 0, sizeof(initdef));
        regulator_parse_ofw_stdparam(dev, node, &initdef);
        initdef.id = 0;
        initdef.ofw_node = node;
        regnode = regnode_create(dev, &sy8106a_regnode_class, &initdef);
        if (regnode == NULL) {
                device_printf(dev, "cannot create regulator\n");
                return (NULL);
        }

        reg_sc = regnode_get_softc(regnode);
        reg_sc->regnode = regnode;
        reg_sc->base_dev = dev;
        reg_sc->xref = OF_xref_from_node(node);
        reg_sc->param = regnode_get_stdparam(regnode);

        regnode_register(regnode);

        return (reg_sc);
}

static int
sy8106a_regdev_map(device_t dev, phandle_t xref, int ncells, pcell_t *cells,
    intptr_t *num)
{
        struct sy8106a_softc *sc;

        sc = device_get_softc(dev);

        if (sc->reg->xref != xref)
                return (ENXIO);

        *num = 0;

        return (0);
}

static int
sy8106a_probe(device_t dev)
{
        if (!ofw_bus_status_okay(dev))
                return (ENXIO);

        if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == 0)
                return (ENXIO);

        device_set_desc(dev, "Silergy SY8106A regulator");

        return (BUS_PROBE_DEFAULT);
}

static int
sy8106a_attach(device_t dev)
{
        struct sy8106a_softc *sc;
        phandle_t node;

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

        sc->addr = iicbus_get_addr(dev);

        sc->reg = sy8106a_reg_attach(dev, node);
        if (sc->reg == NULL) {
                device_printf(dev, "cannot attach regulator\n");
                return (ENXIO);
        }

        return (0);
}

static device_method_t sy8106a_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         sy8106a_probe),
        DEVMETHOD(device_attach,        sy8106a_attach),

        /* Regdev interface */
        DEVMETHOD(regdev_map,           sy8106a_regdev_map),

        DEVMETHOD_END
};

static driver_t sy8106a_driver = {
        "sy8106a",
        sy8106a_methods,
        sizeof(struct sy8106a_softc),
};

EARLY_DRIVER_MODULE(sy8106a, iicbus, sy8106a_driver, 0, 0, BUS_PASS_RESOURCE);
MODULE_VERSION(sy8106a, 1);
MODULE_DEPEND(sy8106a, iicbus, 1, 1, 1);
IICBUS_FDT_PNP_INFO(compat_data);