/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2017 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.
 */

#include <sys/cdefs.h>
/*
 * Driver for ISL12xx family i2c realtime clocks:
 *  - ISL1209 = 2B sram, tamper/event timestamp
 *  - ISL1218 = 8B sram, DS13xx pin compatible (but not software compatible)
 *  - ISL1219 = 2B sram, tamper/event timestamp
 *  - ISL1220 = 8B sram, separate Fout
 *  - ISL1221 = 2B sram, separate Fout, tamper/event timestamp
 *
 * This driver supports only the basic RTC functionality in all these chips.
 */

#include "opt_platform.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/clock.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/sx.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 "clock_if.h"
#include "iicbus_if.h"

/*
 * All register and bit names as found in the datasheet.  When a bit name ends
 * in 'B' that stands for "bar" and it is an active-low signal; something named
 * "EVENB" implies 1=event-disable, 0=event-enable.
 */

#define ISL12XX_SC_REG          0x00            /* RTC Seconds */

#define ISL12XX_SR_REG          0x07            /* Status */
#define   ISL12XX_SR_ARST         (1u << 7)     /*   Auto-reset on status read */
#define   ISL12XX_SR_XTOSCB       (1u << 5)     /*   Osc disable (use ext osc) */
#define   ISL12XX_SR_WRTC         (1u << 4)     /*   Write RTC enable */
#define   ISL12XX_SR_EVT          (1u << 3)     /*   Event occurred (w0c) */
#define   ISL12XX_SR_ALM          (1u << 2)     /*   Alarm occurred (w0c) */
#define   ISL12XX_SR_BAT          (1u << 1)     /*   Running on battery (w0c) */
#define   ISL12XX_SR_RTCF         (1u << 0)     /*   RTC fail (power loss) */
#define   ISL12XX_SR_W0C_BITS (ISL12XX_SR_BAT | ISL12XX_SR_ALM | ISL12XX_SR_EVT)

#define ISL12XX_INT_REG         0x08            /* Interrupts */
#define   ISL12XX_INT_IM          (1u << 7)     /*   Alarm interrupt mode */
#define   ISL12XX_INT_ALME        (1u << 6)     /*   Alarm enable */
#define   ISL12XX_INT_LPMODE      (1u << 5)     /*   Low Power mode */
#define   ISL12XX_INT_FOBATB      (1u << 4)     /*   Fout/IRQ disabled on bat */
#define   ISL12XX_INT_FO_SHIFT    0             /*   Frequency output select */
#define   ISL12XX_INT_FO_MASK     0x0f          /*   shift and mask. */

#define ISL12XX_EV_REG          0x09            /* Event */
#define   ISL12XX_EV_EVIENB       (1u << 7)     /*   Disable internal pullup */
#define   ISL12XX_EV_EVBATB       (1u << 6)     /*   Disable ev detect on bat */
#define   ISL12XX_EV_RTCHLT       (1u << 5)     /*   Halt RTC on event */
#define   ISL12XX_EV_EVEN         (1u << 4)     /*   Event detect enable */
#define   ISL12XX_EV_EHYS_SHIFT   2             /*   Event input hysteresis */
#define   ISL12XX_EV_EHYS_MASK    0x03          /*   selection; see datasheet */
#define   ISL12XX_EV_ESMP_SHIFT   0             /*   Event input sample rate */
#define   ISL12XX_EV_ESMP_MASK    0x03          /*   selection; see datasheet */

#define ISL12XX_ATR_REG         0x0a            /* Analog trim (osc adjust) */

#define ISL12XX_DTR_REG         0x0b            /* Digital trim (osc adjust) */

#define ISL12XX_SCA_REG         0x0c            /* Alarm seconds */

#define ISL12XX_USR1_REG        0x12            /* User byte 1 */

#define ISL12XX_USR2_REG        0x13            /* User byte 2 */

#define ISL12XX_SCT_REG         0x14            /* Timestamp (event) seconds */

#define ISL12XX_24HR_FLAG       (1u << 7)       /* Hours register 24-hr mode */
#define ISL12XX_PM_FLAG         (1u << 5)       /* Hours register PM flag */
#define ISL12xx_12HR_MASK       0x1f            /* Hours mask in AM/PM mode */
#define ISL12xx_24HR_MASK       0x3f            /* Hours mask in 24-hr mode */

/*
 * A struct laid out in the same order as the time registers in the chip.
 */
struct time_regs {
        uint8_t sec, min, hour, day, month, year;
};

struct isl12xx_softc {
        device_t        dev;
        device_t        busdev;
        struct intr_config_hook 
                        init_hook;
        bool            use_ampm;
};

#ifdef FDT
static struct ofw_compat_data compat_data[] = {
        {"isil,isl1209", 1},
        {"isil,isl1218", 1},
        {"isil,isl1219", 1},
        {"isil,isl1220", 1},
        {"isil,isl1221", 1},
        {NULL,           0},
};
#endif

/*
 * When doing i2c IO, indicate that we need to wait for exclusive bus ownership,
 * but that we should not wait if we already own the bus.  This lets us put
 * iicbus_acquire_bus() calls with a non-recursive wait at the entry of our API
 * functions to ensure that only one client at a time accesses the hardware for
 * the entire series of operations it takes to read or write the clock.
 */
#define WAITFLAGS       (IIC_WAIT | IIC_RECURSIVE)

static inline int
isl12xx_read1(struct isl12xx_softc *sc, uint8_t reg, uint8_t *data) 
{

        return (iicdev_readfrom(sc->dev, reg, data, 1, WAITFLAGS));
}

static inline int
isl12xx_write1(struct isl12xx_softc *sc, uint8_t reg, uint8_t val) 
{

        return (iicdev_writeto(sc->dev, reg, &val, 1, WAITFLAGS));
}

static void
isl12xx_init(void *arg)
{
        struct isl12xx_softc *sc = arg;
        uint8_t sreg;

        config_intrhook_disestablish(&sc->init_hook);

        /*
         * Check the clock-stopped/power-fail bit, just so we can report it to
         * the user at boot time.
         */
        isl12xx_read1(sc, ISL12XX_SR_REG, &sreg);
        if (sreg & ISL12XX_SR_RTCF) {
                device_printf(sc->dev,
                    "RTC clock stopped; check battery\n");
        }

        /*
         * Register as a system realtime clock.
         */
        clock_register_flags(sc->dev, 1000000, CLOCKF_SETTIME_NO_ADJ);
        clock_schedule(sc->dev, 1);
}

static int
isl12xx_probe(device_t dev)
{

#ifdef FDT
        if (!ofw_bus_status_okay(dev))
                return (ENXIO);

        if (ofw_bus_search_compatible(dev, compat_data)->ocd_data != 0) {
                device_set_desc(dev, "Intersil ISL12xx RTC");
                return (BUS_PROBE_DEFAULT);
        }
#endif
        return (ENXIO);
}

static int
isl12xx_attach(device_t dev)
{
        struct isl12xx_softc *sc = device_get_softc(dev);

        sc->dev = dev;
        sc->busdev = device_get_parent(sc->dev);

        /*
         * Chip init must wait until interrupts are enabled.  Often i2c access
         * works only when the interrupts are available.
         */
        sc->init_hook.ich_func = isl12xx_init;
        sc->init_hook.ich_arg = sc;
        if (config_intrhook_establish(&sc->init_hook) != 0)
                return (ENOMEM);

        return (0);
}

static int
isl12xx_detach(device_t dev)
{

        clock_unregister(dev);
        return (0);
}

static int
isl12xx_gettime(device_t dev, struct timespec *ts)
{
        struct isl12xx_softc *sc = device_get_softc(dev);
        struct bcd_clocktime bct;
        struct time_regs tregs;
        int err;
        uint8_t hourmask, sreg;

        /*
         * Read the status and time registers.
         */
        if ((err = iicbus_request_bus(sc->busdev, sc->dev, IIC_WAIT)) == 0) {
                if ((err = isl12xx_read1(sc, ISL12XX_SR_REG, &sreg)) == 0) {
                        err = iicdev_readfrom(sc->dev, ISL12XX_SC_REG, &tregs,
                            sizeof(tregs), WAITFLAGS);
                }
                iicbus_release_bus(sc->busdev, sc->dev);
        }
        if (err != 0)
                return (err);

        /* If power failed, we can't provide valid time. */
        if (sreg & ISL12XX_SR_RTCF)
                return (EINVAL);

        /* If chip is in AM/PM mode remember that for when we set time. */
        if (tregs.hour & ISL12XX_24HR_FLAG) {
                hourmask = ISL12xx_24HR_MASK;
        } else {
                sc->use_ampm = true;
                hourmask = ISL12xx_12HR_MASK;
        }

        bct.nsec = 0;
        bct.sec  = tregs.sec;
        bct.min  = tregs.min;
        bct.hour = tregs.hour & hourmask;
        bct.day  = tregs.day;
        bct.mon  = tregs.month;
        bct.year = tregs.year;
        bct.ispm = tregs.hour & ISL12XX_PM_FLAG;

        clock_dbgprint_bcd(sc->dev, CLOCK_DBG_READ, &bct); 
        return (clock_bcd_to_ts(&bct, ts, sc->use_ampm));
}

static int
isl12xx_settime(device_t dev, struct timespec *ts)
{
        struct isl12xx_softc *sc = device_get_softc(dev);
        struct bcd_clocktime bct;
        struct time_regs tregs;
        int err;
        uint8_t ampmflags, sreg;

        /*
         * We request a timespec with no resolution-adjustment.  That also
         * disables utc adjustment, so apply that ourselves.
         */
        ts->tv_sec -= utc_offset();
        ts->tv_nsec = 0;
        clock_ts_to_bcd(ts, &bct, sc->use_ampm);
        clock_dbgprint_bcd(sc->dev, CLOCK_DBG_WRITE, &bct); 

        /* If the chip is in AM/PM mode, set flags as needed. */
        if (!sc->use_ampm)
                ampmflags = ISL12XX_24HR_FLAG;
        else
                ampmflags = bct.ispm ? ISL12XX_PM_FLAG : 0;

        tregs.sec   = bct.sec;
        tregs.min   = bct.min;
        tregs.hour  = bct.hour | ampmflags;
        tregs.day   = bct.day;
        tregs.month = bct.mon;
        tregs.year  = bct.year % 100;

        /*
         * To set the time we have to set the WRTC enable bit in the control
         * register, then write the time regs, then clear the WRTC bit.  While
         * doing so we have to be careful to not write a 0 to any sreg bit which
         * is "write 0 to clear". One of those bits could get set between
         * reading and writing the register.  All those bits ignore attempts to
         * write a 1, so just always OR-in all the W0C bits to be sure we never
         * accidentally clear one.  We hold ownership of the i2c bus for the
         * whole read-modify-write sequence.
         */
        if ((err = iicbus_request_bus(sc->busdev, sc->dev, IIC_WAIT)) != 0)
                return (err);
        if ((err = isl12xx_read1(sc, ISL12XX_SR_REG, &sreg)) == 0) {
                sreg |= ISL12XX_SR_WRTC | ISL12XX_SR_W0C_BITS;
                if ((err = isl12xx_write1(sc, ISL12XX_SR_REG, sreg)) == 0) {
                        err = iicdev_writeto(sc->dev, ISL12XX_SC_REG, &tregs,
                            sizeof(tregs), WAITFLAGS);
                        sreg &= ~ISL12XX_SR_WRTC;
                        isl12xx_write1(sc, ISL12XX_SR_REG, sreg);
                }
        }
        iicbus_release_bus(sc->busdev, sc->dev);

        return (err);
}

static device_method_t isl12xx_methods[] = {
        /* device_if methods */
        DEVMETHOD(device_probe,         isl12xx_probe),
        DEVMETHOD(device_attach,        isl12xx_attach),
        DEVMETHOD(device_detach,        isl12xx_detach),

        /* clock_if methods */
        DEVMETHOD(clock_gettime,        isl12xx_gettime),
        DEVMETHOD(clock_settime,        isl12xx_settime),

        DEVMETHOD_END,
};

static driver_t isl12xx_driver = {
        "isl12xx",
        isl12xx_methods,
        sizeof(struct isl12xx_softc),
};

DRIVER_MODULE(isl12xx, iicbus, isl12xx_driver, NULL, NULL);
MODULE_VERSION(isl12xx, 1);
MODULE_DEPEND(isl12xx, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
IICBUS_FDT_PNP_INFO(compat_data);