/*-
 * Copyright (c) 2015 Ian lepore <ian@freebsd.org>
 * All rights reserved.
 *
 * 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 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 AUTHOR 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.
 */

/*
 * AM335x PPS driver using DMTimer capture.
 *
 * Note that this PPS driver does not use an interrupt.  Instead it uses the
 * hardware's ability to latch the timer's count register in response to a
 * signal on an IO pin.  Each of timers 4-7 have an associated pin, and this
 * code allows any one of those to be used.
 *
 * The timecounter routines in kern_tc.c call the pps poll routine periodically
 * to see if a new counter value has been latched.  When a new value has been
 * latched, the only processing done in the poll routine is to capture the
 * current set of timecounter timehands (done with pps_capture()) and the
 * latched value from the timer.  The remaining work (done by pps_event() while
 * holding a mutex) is scheduled to be done later in a non-interrupt context.
 */

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/rman.h>
#include <sys/timepps.h>
#include <sys/timetc.h>
#include <machine/bus.h>

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

#include <arm/ti/ti_sysc.h>
#include <arm/ti/ti_pinmux.h>
#include <arm/ti/am335x/am335x_scm_padconf.h>

#include "am335x_dmtreg.h"

#define PPS_CDEV_NAME   "dmtpps"

struct dmtpps_softc {
        device_t                dev;
        int                     mem_rid;
        struct resource *       mem_res;
        int                     tmr_num;        /* N from hwmod str "timerN" */
        char                    tmr_name[12];   /* "DMTimerN" */
        uint32_t                tclr;           /* Cached TCLR register. */
        struct timecounter      tc;
        int                     pps_curmode;    /* Edge mode now set in hw. */
        struct cdev *           pps_cdev;
        struct pps_state        pps_state;
        struct mtx              pps_mtx;
        clk_t                   clk_fck;
        uint64_t                sysclk_freq;
};

static int dmtpps_tmr_num;      /* Set by probe() */

/* List of compatible strings for FDT tree */
static struct ofw_compat_data compat_data[] = {
        {"ti,am335x-timer",     1},
        {"ti,am335x-timer-1ms", 1},
        {NULL,                  0},
};
SIMPLEBUS_PNP_INFO(compat_data);

/*
 * A table relating pad names to the hardware timer number they can be mux'd to.
 */
struct padinfo {
        char *  ballname;
        int     tmr_num;
};
static struct padinfo dmtpps_padinfo[] = {
        {"GPMC_ADVn_ALE",    4},
        {"I2C0_SDA",         4},
        {"MII1_TX_EN",       4},
        {"XDMA_EVENT_INTR0", 4},
        {"GPMC_BEn0_CLE",    5},
        {"MDC",              5},
        {"MMC0_DAT3",        5},
        {"UART1_RTSn",       5},
        {"GPMC_WEn",         6},
        {"MDIO",             6},
        {"MMC0_DAT2",        6},
        {"UART1_CTSn",       6},
        {"GPMC_OEn_REn",     7},
        {"I2C0_SCL",         7},
        {"UART0_CTSn",       7},
        {"XDMA_EVENT_INTR1", 7},
        {NULL, 0}
};

/*
 * This is either brilliantly user-friendly, or utterly lame...
 *
 * The am335x chip is used on the popular Beaglebone boards.  Those boards have
 * pins for all four capture-capable timers available on the P8 header. Allow
 * users to configure the input pin by giving the name of the header pin.
 */
struct nicknames {
        const char * nick;
        const char * name;
};
static struct nicknames dmtpps_pin_nicks[] = {
        {"P8-7",  "GPMC_ADVn_ALE"},
        {"P8-9",  "GPMC_BEn0_CLE"},
        {"P8-10", "GPMC_WEn"},
        {"P8-8",  "GPMC_OEn_REn",},
        {NULL, NULL}
};

#define DMTIMER_READ4(sc, reg)          bus_read_4((sc)->mem_res, (reg))
#define DMTIMER_WRITE4(sc, reg, val)    bus_write_4((sc)->mem_res, (reg), (val))

/*
 * Translate a short friendly case-insensitive name to its canonical name.
 */
static const char *
dmtpps_translate_nickname(const char *nick)
{
        struct nicknames *nn;

        for (nn = dmtpps_pin_nicks; nn->nick != NULL; nn++)
                if (strcasecmp(nick, nn->nick) == 0)
                        return nn->name;
        return (nick);
}

/*
 * See if our tunable is set to the name of the input pin.  If not, that's NOT
 * an error, return 0.  If so, try to configure that pin as a timer capture
 * input pin, and if that works, then we have our timer unit number and if it
 * fails that IS an error, return -1.
 */
static int
dmtpps_find_tmr_num_by_tunable(void)
{
        struct padinfo *pi;
        char iname[20];
        char muxmode[12];
        const char * ballname;
        int err;

        if (!TUNABLE_STR_FETCH("hw.am335x_dmtpps.input", iname, sizeof(iname)))
                return (0);
        ballname = dmtpps_translate_nickname(iname);
        for (pi = dmtpps_padinfo; pi->ballname != NULL; pi++) {
                if (strcmp(ballname, pi->ballname) != 0)
                        continue;
                snprintf(muxmode, sizeof(muxmode), "timer%d", pi->tmr_num);
                err = ti_pinmux_padconf_set(pi->ballname, muxmode,
                    PADCONF_INPUT);
                if (err != 0) {
                        printf("am335x_dmtpps: unable to configure capture pin "
                            "for %s to input mode\n", muxmode);
                        return (-1);
                } else if (bootverbose) {
                        printf("am335x_dmtpps: configured pin %s as input "
                            "for %s\n", iname, muxmode);
                }
                return (pi->tmr_num);
        }

        /* Invalid name in the tunable, that's an error. */
        printf("am335x_dmtpps: unknown pin name '%s'\n", iname);
        return (-1);
}

/*
 * Ask the pinmux driver whether any pin has been configured as a TIMER4..TIMER7
 * input pin.  If so, return the timer number, if not return 0.
 */
static int
dmtpps_find_tmr_num_by_padconf(void)
{
        int err;
        unsigned int padstate;
        const char * padmux;
        struct padinfo *pi;
        char muxmode[12];

        for (pi = dmtpps_padinfo; pi->ballname != NULL; pi++) {
                err = ti_pinmux_padconf_get(pi->ballname, &padmux, &padstate);
                snprintf(muxmode, sizeof(muxmode), "timer%d", pi->tmr_num);
                if (err == 0 && (padstate & RXACTIVE) != 0 &&
                    strcmp(muxmode, padmux) == 0)
                        return (pi->tmr_num);
        }
        /* Nothing found, not an error. */
        return (0);
}

/*
 * Figure out which hardware timer number to use based on input pin
 * configuration.  This is done just once, the first time probe() runs.
 */
static int
dmtpps_find_tmr_num(void)
{
        int tmr_num;

        if ((tmr_num = dmtpps_find_tmr_num_by_tunable()) == 0)
                tmr_num = dmtpps_find_tmr_num_by_padconf();

        if (tmr_num <= 0) {
                printf("am335x_dmtpps: PPS driver not enabled: unable to find "
                    "or configure a capture input pin\n");
                tmr_num = -1; /* Must return non-zero to prevent re-probing. */
        }
        return (tmr_num);
}

static void
dmtpps_set_hw_capture(struct dmtpps_softc *sc, bool force_off)
{
        int newmode;

        if (force_off)
                newmode = 0;
        else
                newmode = sc->pps_state.ppsparam.mode & PPS_CAPTUREASSERT;

        if (newmode == sc->pps_curmode)
                return;
        sc->pps_curmode = newmode;

        if (newmode == PPS_CAPTUREASSERT)
                sc->tclr |= DMT_TCLR_CAPTRAN_LOHI;
        else
                sc->tclr &= ~DMT_TCLR_CAPTRAN_MASK;
        DMTIMER_WRITE4(sc, DMT_TCLR, sc->tclr);
}

static unsigned
dmtpps_get_timecount(struct timecounter *tc)
{
        struct dmtpps_softc *sc;

        sc = tc->tc_priv;

        return (DMTIMER_READ4(sc, DMT_TCRR));
}

static void
dmtpps_poll(struct timecounter *tc)
{
        struct dmtpps_softc *sc;

        sc = tc->tc_priv;

        /*
         * If a new value has been latched we've got a PPS event.  Capture the
         * timecounter data, then override the capcount field (pps_capture()
         * populates it from the current DMT_TCRR register) with the latched
         * value from the TCAR1 register.
         *
         * Note that we don't have the TCAR interrupt enabled, but the hardware
         * still provides the status bits in the "RAW" status register even when
         * they're masked from generating an irq.  However, when clearing the
         * TCAR status to re-arm the capture for the next second, we have to
         * write to the IRQ status register, not the RAW register.  Quirky.
         *
         * We do not need to hold a lock while capturing the pps data, because
         * it is captured into an area of the pps_state struct which is read
         * only by pps_event().  We do need to hold a lock while calling
         * pps_event(), because it manipulates data which is also accessed from
         * the ioctl(2) context by userland processes.
         */
        if (DMTIMER_READ4(sc, DMT_IRQSTATUS_RAW) & DMT_IRQ_TCAR) {
                pps_capture(&sc->pps_state);
                sc->pps_state.capcount = DMTIMER_READ4(sc, DMT_TCAR1);
                DMTIMER_WRITE4(sc, DMT_IRQSTATUS, DMT_IRQ_TCAR);

                mtx_lock_spin(&sc->pps_mtx);
                pps_event(&sc->pps_state, PPS_CAPTUREASSERT);
                mtx_unlock_spin(&sc->pps_mtx);
        }
}

static int
dmtpps_open(struct cdev *dev, int flags, int fmt, 
    struct thread *td)
{
        struct dmtpps_softc *sc;

        sc = dev->si_drv1;

        /*
         * Begin polling for pps and enable capture in the hardware whenever the
         * device is open.  Doing this stuff again is harmless if this isn't the
         * first open.
         */
        sc->tc.tc_poll_pps = dmtpps_poll;
        dmtpps_set_hw_capture(sc, false);

        return 0;
}

static  int
dmtpps_close(struct cdev *dev, int flags, int fmt, 
    struct thread *td)
{
        struct dmtpps_softc *sc;

        sc = dev->si_drv1;

        /*
         * Stop polling and disable capture on last close.  Use the force-off
         * flag to override the configured mode and turn off the hardware.
         */
        sc->tc.tc_poll_pps = NULL;
        dmtpps_set_hw_capture(sc, true);

        return 0;
}

static int
dmtpps_ioctl(struct cdev *dev, u_long cmd, caddr_t data, 
    int flags, struct thread *td)
{
        struct dmtpps_softc *sc;
        int err;

        sc = dev->si_drv1;

        /* Let the kernel do the heavy lifting for ioctl. */
        mtx_lock_spin(&sc->pps_mtx);
        err = pps_ioctl(cmd, data, &sc->pps_state);
        mtx_unlock_spin(&sc->pps_mtx);
        if (err != 0)
                return (err);

        /*
         * The capture mode could have changed, set the hardware to whatever
         * mode is now current.  Effectively a no-op if nothing changed.
         */
        dmtpps_set_hw_capture(sc, false);

        return (err);
}

static struct cdevsw dmtpps_cdevsw = {
        .d_version =    D_VERSION,
        .d_open =       dmtpps_open,
        .d_close =      dmtpps_close,
        .d_ioctl =      dmtpps_ioctl,
        .d_name =       PPS_CDEV_NAME,
};

static int
dmtpps_probe(device_t dev)
{
        int tmr_num;
        uint64_t rev_address;

        if (!ofw_bus_status_okay(dev))
                return (ENXIO);

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

        /*
         * If we haven't chosen which hardware timer to use yet, go do that now.
         * We need to know that to decide whether to return success for this
         * hardware timer instance or not.
         */
        if (dmtpps_tmr_num == 0)
                dmtpps_tmr_num = dmtpps_find_tmr_num();

        /*
         * Figure out which hardware timer is being probed and see if it matches
         * the configured timer number determined earlier.
         */
        rev_address = ti_sysc_get_rev_address(device_get_parent(dev));
        switch (rev_address) {
                case DMTIMER1_1MS_REV:
                        tmr_num = 1;
                        break;
                case DMTIMER2_REV:
                        tmr_num = 2;
                        break;
                case DMTIMER3_REV:
                        tmr_num = 3;
                        break;
                case DMTIMER4_REV:
                        tmr_num = 4;
                        break;
                case DMTIMER5_REV:
                        tmr_num = 5;
                        break;
                case DMTIMER6_REV:
                        tmr_num = 6;
                        break;
                case DMTIMER7_REV:
                        tmr_num = 7;
                        break;
                default:
                        return (ENXIO);
        }

        if (dmtpps_tmr_num != tmr_num)
                return (ENXIO);

        device_set_descf(dev, "AM335x PPS-Capture DMTimer%d", tmr_num);

        return(BUS_PROBE_DEFAULT);
}

static int
dmtpps_attach(device_t dev)
{
        struct dmtpps_softc *sc;
        struct make_dev_args mda;
        int err;
        clk_t sys_clkin;
        uint64_t rev_address;

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

        /* Figure out which hardware timer this is and set the name string. */
        rev_address = ti_sysc_get_rev_address(device_get_parent(dev));
        switch (rev_address) {
                case DMTIMER1_1MS_REV:
                        sc->tmr_num = 1;
                        break;
                case DMTIMER2_REV:
                        sc->tmr_num = 2;
                        break;
                case DMTIMER3_REV:
                        sc->tmr_num = 3;
                        break;
                case DMTIMER4_REV:
                        sc->tmr_num = 4;
                        break;
                case DMTIMER5_REV:
                        sc->tmr_num = 5;
                        break;
                case DMTIMER6_REV:
                        sc->tmr_num = 6;
                        break;
                case DMTIMER7_REV:
                        sc->tmr_num = 7;
                        break;
        }
        snprintf(sc->tmr_name, sizeof(sc->tmr_name), "DMTimer%d", sc->tmr_num);

        /* expect one clock */
        err = clk_get_by_ofw_index(dev, 0, 0, &sc->clk_fck);
        if (err != 0) {
                device_printf(dev, "Cant find clock index 0. err: %d\n", err);
                return (ENXIO);
        }

        err = clk_get_by_name(dev, "sys_clkin_ck@40", &sys_clkin);
        if (err != 0) {
                device_printf(dev, "Cant find sys_clkin_ck@40 err: %d\n", err);
                return (ENXIO);
        }

        /* Select M_OSC as DPLL parent */
        err = clk_set_parent_by_clk(sc->clk_fck, sys_clkin);
        if (err != 0) {
                device_printf(dev, "Cant set mux to CLK_M_OSC\n");
                return (ENXIO);
        }

        /* Enable clocks and power on the device. */
        err = ti_sysc_clock_enable(device_get_parent(dev));
        if (err != 0) {
                device_printf(dev, "Cant enable sysc clkctrl, err %d\n", err);
                return (ENXIO);
        }

        /* Get the base clock frequency. */
        err = clk_get_freq(sc->clk_fck, &sc->sysclk_freq);
        if (err != 0) {
                device_printf(dev, "Cant get sysclk frequency, err %d\n", err);
                return (ENXIO);
        }
        /* Request the memory resources. */
        sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY,
            &sc->mem_rid, RF_ACTIVE);
        if (sc->mem_res == NULL) {
                return (ENXIO);
        }

        /*
         * Configure the timer pulse/capture pin to input/capture mode.  This is
         * required in addition to configuring the pin as input with the pinmux
         * controller (which was done via fdt data or tunable at probe time).
         */
        sc->tclr = DMT_TCLR_GPO_CFG;
        DMTIMER_WRITE4(sc, DMT_TCLR, sc->tclr);

        /* Set up timecounter hardware, start it. */
        DMTIMER_WRITE4(sc, DMT_TSICR, DMT_TSICR_RESET);
        while (DMTIMER_READ4(sc, DMT_TIOCP_CFG) & DMT_TIOCP_RESET)
                continue;

        sc->tclr |= DMT_TCLR_START | DMT_TCLR_AUTOLOAD;
        DMTIMER_WRITE4(sc, DMT_TLDR, 0);
        DMTIMER_WRITE4(sc, DMT_TCRR, 0);
        DMTIMER_WRITE4(sc, DMT_TCLR, sc->tclr);

        /* Register the timecounter. */
        sc->tc.tc_name           = sc->tmr_name;
        sc->tc.tc_get_timecount  = dmtpps_get_timecount;
        sc->tc.tc_counter_mask   = ~0u;
        sc->tc.tc_frequency      = sc->sysclk_freq;
        sc->tc.tc_quality        = 1000;
        sc->tc.tc_priv           = sc;

        tc_init(&sc->tc);

        /*
         * Indicate our PPS capabilities.  Have the kernel init its part of the
         * pps_state struct and add its capabilities.
         *
         * While the hardware has a mode to capture each edge, it's not clear we
         * can use it that way, because there's only a single interrupt/status
         * bit to say something was captured, but not which edge it was.  For
         * now, just say we can only capture assert events (the positive-going
         * edge of the pulse).
         */
        mtx_init(&sc->pps_mtx, "dmtpps", NULL, MTX_SPIN);
        sc->pps_state.flags = PPSFLAG_MTX_SPIN;
        sc->pps_state.ppscap = PPS_CAPTUREASSERT;
        sc->pps_state.driver_abi = PPS_ABI_VERSION;
        sc->pps_state.driver_mtx = &sc->pps_mtx;
        pps_init_abi(&sc->pps_state);

        /* Create the PPS cdev. */
        make_dev_args_init(&mda);
        mda.mda_flags = MAKEDEV_WAITOK;
        mda.mda_devsw = &dmtpps_cdevsw;
        mda.mda_cr = NULL;
        mda.mda_uid = UID_ROOT;
        mda.mda_gid = GID_WHEEL;
        mda.mda_mode = 0600;
        mda.mda_unit = device_get_unit(dev);
        mda.mda_si_drv1 = sc;
        if ((err = make_dev_s(&mda, &sc->pps_cdev, PPS_CDEV_NAME)) != 0) {
                device_printf(dev, "Failed to create cdev %s\n", PPS_CDEV_NAME);
                return (err);
        }

        if (bootverbose)
                device_printf(sc->dev, "Using %s for PPS device /dev/%s\n",
                    sc->tmr_name, PPS_CDEV_NAME);

        return (0);
}

static int
dmtpps_detach(device_t dev)
{

        /*
         * There is no way to remove a timecounter once it has been registered,
         * even if it's not in use, so we can never detach.  If we were
         * dynamically loaded as a module this will prevent unloading.
         */
        return (EBUSY);
}

static device_method_t dmtpps_methods[] = {
        DEVMETHOD(device_probe,         dmtpps_probe),
        DEVMETHOD(device_attach,        dmtpps_attach),
        DEVMETHOD(device_detach,        dmtpps_detach),
        { 0, 0 }
};

static driver_t dmtpps_driver = {
        "am335x_dmtpps",
        dmtpps_methods,
        sizeof(struct dmtpps_softc),
};

DRIVER_MODULE(am335x_dmtpps, simplebus, dmtpps_driver, 0, 0);
MODULE_DEPEND(am335x_dmtpps, ti_sysc, 1, 1, 1);