/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2013 Rui Paulo <rpaulo@FreeBSD.org>
 * Copyright (c) 2017 Manuel Stuehn
 * 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 ``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>
#include <sys/poll.h>
#include <sys/time.h>
#include <sys/uio.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.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/types.h>
#include <sys/sysctl.h>
#include <sys/event.h>
#include <sys/selinfo.h>
#include <machine/bus.h>
#include <machine/cpu.h>
#include <machine/frame.h>
#include <machine/intr.h>
#include <machine/atomic.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_pruss.h>
#include <arm/ti/ti_prm.h>

#ifdef DEBUG
#define DPRINTF(fmt, ...)       do {    \
        printf("%s: ", __func__);       \
        printf(fmt, __VA_ARGS__);       \
} while (0)
#else
#define DPRINTF(fmt, ...)
#endif

static d_open_t                 ti_pruss_irq_open;
static d_read_t                 ti_pruss_irq_read;
static d_poll_t                 ti_pruss_irq_poll;

static device_probe_t           ti_pruss_probe;
static device_attach_t          ti_pruss_attach;
static device_detach_t          ti_pruss_detach;
static void                     ti_pruss_intr(void *);
static d_open_t                 ti_pruss_open;
static d_mmap_t                 ti_pruss_mmap;
static void                     ti_pruss_irq_kqread_detach(struct knote *);
static int                      ti_pruss_irq_kqevent(struct knote *, long);
static d_kqfilter_t             ti_pruss_irq_kqfilter;
static void                     ti_pruss_privdtor(void *data);

#define TI_PRUSS_PRU_IRQS 2
#define TI_PRUSS_HOST_IRQS 8
#define TI_PRUSS_IRQS (TI_PRUSS_HOST_IRQS+TI_PRUSS_PRU_IRQS)
#define TI_PRUSS_EVENTS 64
#define NOT_SET_STR "NONE"
#define TI_TS_ARRAY 16

struct ctl
{
        size_t cnt;
        size_t idx;
};

struct ts_ring_buf
{
        struct ctl ctl;
        uint64_t ts[TI_TS_ARRAY];
};

struct ti_pruss_irqsc
{
        struct mtx              sc_mtx;
        struct cdev             *sc_pdev;
        struct selinfo          sc_selinfo;
        int8_t                  channel;
        int8_t                  last;
        int8_t                  event;
        bool                    enable;
        struct ts_ring_buf      tstamps;
};

static struct cdevsw ti_pruss_cdevirq = {
        .d_version =    D_VERSION,
        .d_name =       "ti_pruss_irq",
        .d_open =       ti_pruss_irq_open,
        .d_read =       ti_pruss_irq_read,
        .d_poll =       ti_pruss_irq_poll,
        .d_kqfilter =   ti_pruss_irq_kqfilter,
};

struct ti_pruss_softc {
        struct mtx              sc_mtx;
        struct resource         *sc_mem_res;
        struct resource         *sc_irq_res[TI_PRUSS_HOST_IRQS];
        void                    *sc_intr[TI_PRUSS_HOST_IRQS];
        struct ti_pruss_irqsc   sc_irq_devs[TI_PRUSS_IRQS];
        bus_space_tag_t         sc_bt;
        bus_space_handle_t      sc_bh;
        struct cdev             *sc_pdev;
        struct selinfo          sc_selinfo;
        bool                    sc_glob_irqen;
};

static struct cdevsw ti_pruss_cdevsw = {
        .d_version =    D_VERSION,
        .d_name =       "ti_pruss",
        .d_open =       ti_pruss_open,
        .d_mmap =       ti_pruss_mmap,
};

static device_method_t ti_pruss_methods[] = {
        DEVMETHOD(device_probe,         ti_pruss_probe),
        DEVMETHOD(device_attach,        ti_pruss_attach),
        DEVMETHOD(device_detach,        ti_pruss_detach),

        DEVMETHOD_END
};

static driver_t ti_pruss_driver = {
        "ti_pruss",
        ti_pruss_methods,
        sizeof(struct ti_pruss_softc)
};

DRIVER_MODULE(ti_pruss, simplebus, ti_pruss_driver, 0, 0);
MODULE_DEPEND(ti_pruss, ti_sysc, 1, 1, 1);
MODULE_DEPEND(ti_pruss, ti_prm, 1, 1, 1);

static struct resource_spec ti_pruss_irq_spec[] = {
        { SYS_RES_IRQ,      0,  RF_ACTIVE },
        { SYS_RES_IRQ,      1,  RF_ACTIVE },
        { SYS_RES_IRQ,      2,  RF_ACTIVE },
        { SYS_RES_IRQ,      3,  RF_ACTIVE },
        { SYS_RES_IRQ,      4,  RF_ACTIVE },
        { SYS_RES_IRQ,      5,  RF_ACTIVE },
        { SYS_RES_IRQ,      6,  RF_ACTIVE },
        { SYS_RES_IRQ,      7,  RF_ACTIVE },
        { -1,               0,  0 }
};
CTASSERT(TI_PRUSS_HOST_IRQS == nitems(ti_pruss_irq_spec) - 1);

static int
ti_pruss_irq_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
{
        struct ctl* irqs;
        struct ti_pruss_irqsc *sc;
        sc = dev->si_drv1;

        irqs = malloc(sizeof(struct ctl), M_DEVBUF, M_WAITOK);
        irqs->cnt = sc->tstamps.ctl.cnt;
        irqs->idx = sc->tstamps.ctl.idx;

        return devfs_set_cdevpriv(irqs, ti_pruss_privdtor);
}

static void
ti_pruss_privdtor(void *data)
{
    free(data, M_DEVBUF);
}

static int
ti_pruss_irq_poll(struct cdev *dev, int events, struct thread *td)
{
        struct ctl* irqs;
        struct ti_pruss_irqsc *sc;
        sc = dev->si_drv1;

        devfs_get_cdevpriv((void**)&irqs);

        if (events & (POLLIN | POLLRDNORM)) {
                if (sc->tstamps.ctl.cnt != irqs->cnt)
                        return events & (POLLIN | POLLRDNORM);
                else
                        selrecord(td, &sc->sc_selinfo);
        }
        return 0;
}

static int
ti_pruss_irq_read(struct cdev *cdev, struct uio *uio, int ioflag)
{
        const size_t ts_len = sizeof(uint64_t);
        struct ti_pruss_irqsc* irq;
        struct ctl* priv;
        int error = 0;
        size_t idx;
        ssize_t level;

        irq = cdev->si_drv1;

        if (uio->uio_resid < ts_len)
                return (EINVAL);

        error = devfs_get_cdevpriv((void**)&priv);
        if (error)
            return (error);

        mtx_lock(&irq->sc_mtx);

        if (irq->tstamps.ctl.cnt - priv->cnt > TI_TS_ARRAY)
        {
                priv->cnt = irq->tstamps.ctl.cnt;
                priv->idx = irq->tstamps.ctl.idx;
                mtx_unlock(&irq->sc_mtx);
                return (ENXIO);
        }

        do {
                idx = priv->idx;
                level = irq->tstamps.ctl.idx - idx;
                if (level < 0)
                        level += TI_TS_ARRAY;

                if (level == 0) {
                        if (ioflag & O_NONBLOCK) {
                                mtx_unlock(&irq->sc_mtx);
                                return (EWOULDBLOCK);
                        }

                        error = msleep(irq, &irq->sc_mtx, PCATCH | PDROP,
                                "pruirq", 0);
                        if (error)
                                return error;

                        mtx_lock(&irq->sc_mtx);
                }
        }while(level == 0);

        mtx_unlock(&irq->sc_mtx);

        error = uiomove(&irq->tstamps.ts[idx], ts_len, uio);

        if (++idx == TI_TS_ARRAY)
                idx = 0;
        priv->idx = idx;

        atomic_add_32(&priv->cnt, 1);

        return (error);
}

static struct ti_pruss_irq_arg {
        int                    irq;
        struct ti_pruss_softc *sc;
} ti_pruss_irq_args[TI_PRUSS_IRQS];

static __inline uint32_t
ti_pruss_reg_read(struct ti_pruss_softc *sc, uint32_t reg)
{
        return (bus_space_read_4(sc->sc_bt, sc->sc_bh, reg));
}

static __inline void
ti_pruss_reg_write(struct ti_pruss_softc *sc, uint32_t reg, uint32_t val)
{
        bus_space_write_4(sc->sc_bt, sc->sc_bh, reg, val);
}

static __inline void
ti_pruss_interrupts_clear(struct ti_pruss_softc *sc)
{
        /* disable global interrupt */
        ti_pruss_reg_write(sc, PRUSS_INTC_GER, 0 );

        /* clear all events */
        ti_pruss_reg_write(sc, PRUSS_INTC_SECR0, 0xFFFFFFFF);
        ti_pruss_reg_write(sc, PRUSS_INTC_SECR1, 0xFFFFFFFF);

        /* disable all host interrupts */
        ti_pruss_reg_write(sc, PRUSS_INTC_HIER, 0);
}

static __inline int
ti_pruss_interrupts_enable(struct ti_pruss_softc *sc, int8_t irq, bool enable)
{
        if (enable && ((sc->sc_irq_devs[irq].channel == -1) ||
            (sc->sc_irq_devs[irq].event== -1)))
        {
                device_printf( sc->sc_pdev->si_drv1,
                        "Interrupt chain not fully configured, not possible to enable\n" );
                return (EINVAL);
        }

        sc->sc_irq_devs[irq].enable = enable;

        if (sc->sc_irq_devs[irq].sc_pdev) {
                destroy_dev(sc->sc_irq_devs[irq].sc_pdev);
                sc->sc_irq_devs[irq].sc_pdev = NULL;
        }

        if (enable) {
                sc->sc_irq_devs[irq].sc_pdev = make_dev(&ti_pruss_cdevirq, 0, UID_ROOT, GID_WHEEL,
                    0600, "pruss%d.irq%d", device_get_unit(sc->sc_pdev->si_drv1), irq);
                sc->sc_irq_devs[irq].sc_pdev->si_drv1 = &sc->sc_irq_devs[irq];

                sc->sc_irq_devs[irq].tstamps.ctl.idx = 0;
        }

        uint32_t reg = enable ? PRUSS_INTC_HIEISR : PRUSS_INTC_HIDISR;
        ti_pruss_reg_write(sc, reg, sc->sc_irq_devs[irq].channel);

        reg = enable ? PRUSS_INTC_EISR : PRUSS_INTC_EICR;
        ti_pruss_reg_write(sc, reg, sc->sc_irq_devs[irq].event );

        return (0);
}

static __inline void
ti_pruss_map_write(struct ti_pruss_softc *sc, uint32_t basereg, uint8_t index, uint8_t content)
{
        const size_t regadr = basereg + index & ~0x03;
        const size_t bitpos = (index & 0x03) * 8;
        uint32_t rmw = ti_pruss_reg_read(sc, regadr);
        rmw = (rmw & ~( 0xF << bitpos)) | ( (content & 0xF) << bitpos);
        ti_pruss_reg_write(sc, regadr, rmw);
}

static int
ti_pruss_event_map( SYSCTL_HANDLER_ARGS )
{
        struct ti_pruss_softc *sc;
        const int8_t irq = arg2;
        int err;
        char event[sizeof(NOT_SET_STR)];

        sc = arg1;

        if(sc->sc_irq_devs[irq].event == -1)
                bcopy(NOT_SET_STR, event, sizeof(event));
        else
                snprintf(event, sizeof(event), "%d", sc->sc_irq_devs[irq].event);

        err = sysctl_handle_string(oidp, event, sizeof(event), req);
        if(err != 0)
                return (err);

        if (req->newptr) {  // write event
                if (strcmp(NOT_SET_STR, event) == 0) {
                        ti_pruss_interrupts_enable(sc, irq, false);
                        sc->sc_irq_devs[irq].event = -1;
                } else {
                        if (sc->sc_irq_devs[irq].channel == -1) {
                                device_printf( sc->sc_pdev->si_drv1,
                                        "corresponding channel not configured\n");
                                return (ENXIO);
                        }

                        const int8_t channelnr = sc->sc_irq_devs[irq].channel;
                        const int8_t eventnr = strtol( event, NULL, 10 ); // TODO: check if strol is valid
                        if (eventnr > TI_PRUSS_EVENTS || eventnr < 0) {
                                device_printf( sc->sc_pdev->si_drv1,
                                        "Event number %d not valid (0 - %d)",
                                        channelnr, TI_PRUSS_EVENTS -1);
                                return (EINVAL);
                        }

                        sc->sc_irq_devs[irq].channel = channelnr;
                        sc->sc_irq_devs[irq].event = eventnr;

                        // event[nr] <= channel
                        ti_pruss_map_write(sc, PRUSS_INTC_CMR_BASE,
                            eventnr, channelnr);
                }
        }
        return (err);
}

static int
ti_pruss_channel_map(SYSCTL_HANDLER_ARGS)
{
        struct ti_pruss_softc *sc;
        int err;
        char channel[sizeof(NOT_SET_STR)];
        const int8_t irq = arg2;

        sc = arg1;

        if (sc->sc_irq_devs[irq].channel == -1)
                bcopy(NOT_SET_STR, channel, sizeof(channel));
        else
                snprintf(channel, sizeof(channel), "%d", sc->sc_irq_devs[irq].channel);

        err = sysctl_handle_string(oidp, channel, sizeof(channel), req);
        if (err != 0)
                return (err);

        if (req->newptr) { // write event
                if (strcmp(NOT_SET_STR, channel) == 0) {
                        ti_pruss_interrupts_enable(sc, irq, false);
                        ti_pruss_reg_write(sc, PRUSS_INTC_HIDISR,
                            sc->sc_irq_devs[irq].channel);
                        sc->sc_irq_devs[irq].channel = -1;
                } else {
                        const int8_t channelnr = strtol(channel, NULL, 10); // TODO: check if strol is valid
                        if (channelnr > TI_PRUSS_IRQS || channelnr < 0)
                        {
                                device_printf(sc->sc_pdev->si_drv1,
                                        "Channel number %d not valid (0 - %d)",
                                        channelnr, TI_PRUSS_IRQS-1);
                                return (EINVAL);
                        }

                        sc->sc_irq_devs[irq].channel = channelnr;
                        sc->sc_irq_devs[irq].last = -1;

                        // channel[nr] <= irqnr
                        ti_pruss_map_write(sc, PRUSS_INTC_HMR_BASE,
                                irq, channelnr);
                }
        }

        return (err);
}

static int
ti_pruss_interrupt_enable(SYSCTL_HANDLER_ARGS)
{
        struct ti_pruss_softc *sc;
        int err;
        bool irqenable;
        const int8_t irq = arg2;

        sc = arg1;
        irqenable = sc->sc_irq_devs[arg2].enable;

        err = sysctl_handle_bool(oidp, &irqenable, arg2, req);
        if (err != 0)
                return (err);

        if (req->newptr) // write enable
                return ti_pruss_interrupts_enable(sc, irq, irqenable);

        return (err);
}

static int
ti_pruss_global_interrupt_enable(SYSCTL_HANDLER_ARGS)
{
        struct ti_pruss_softc *sc;
        int err;
        bool glob_irqen;

        sc = arg1;
        glob_irqen = sc->sc_glob_irqen;

        err = sysctl_handle_bool(oidp, &glob_irqen, arg2, req);
        if (err != 0)
                return (err);

        if (req->newptr) {
                sc->sc_glob_irqen = glob_irqen;
                ti_pruss_reg_write(sc, PRUSS_INTC_GER, glob_irqen);
        }

        return (err);
}
static int
ti_pruss_probe(device_t dev)
{

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

        if (ofw_bus_is_compatible(dev, "ti,pruss-v1") ||
            ofw_bus_is_compatible(dev, "ti,pruss-v2")) {
                device_set_desc(dev, "TI Programmable Realtime Unit Subsystem");
                return (BUS_PROBE_DEFAULT);
        }

        return (ENXIO);
}

static int
ti_pruss_attach(device_t dev)
{
        struct ti_pruss_softc *sc;
        int rid, i, err, ncells;
        phandle_t node;
        clk_t l3_gclk, pruss_ocp_gclk;
        phandle_t ti_prm_ref, *cells;
        device_t ti_prm_dev;

        rid = 0;
        sc = device_get_softc(dev);
        node = ofw_bus_get_node(device_get_parent(dev));
        if (node <= 0) {
                device_printf(dev, "Cant get ofw node\n");
                return (ENXIO);
        }

        /*
         * Follow activate pattern from sys/arm/ti/am335x/am335x_prcm.c
         * by Damjan Marion
         */

        /* Set MODULEMODE to ENABLE(2) */
        /* Wait for MODULEMODE to become ENABLE(2) */
        if (ti_sysc_clock_enable(device_get_parent(dev)) != 0) {
                device_printf(dev, "Could not enable PRUSS clock\n");
                return (ENXIO);
        }

        /* Set CLKTRCTRL to SW_WKUP(2) */
        /* Wait for the 200 MHz OCP clock to become active */
        /* Wait for the 200 MHz IEP clock to become active */
        /* Wait for the 192 MHz UART clock to become active */
        /*
         * At the moment there is no reference to CM_PER_PRU_ICSS_CLKSTCTRL@140
         * in the devicetree. The register reset state are SW_WKUP(2) as default
         * so at the moment ignore setting this register.
         */

        /* Select L3F as OCP clock */
        /* Get the clock and set the parent */
        err = clk_get_by_name(dev, "l3_gclk", &l3_gclk);
        if (err) {
                device_printf(dev, "Cant get l3_gclk err %d\n", err);
                return (ENXIO);
        }

        err = clk_get_by_name(dev, "pruss_ocp_gclk@530", &pruss_ocp_gclk);
        if (err) {
                device_printf(dev, "Cant get pruss_ocp_gclk@530 err %d\n", err);
                return (ENXIO);
        }

        err = clk_set_parent_by_clk(pruss_ocp_gclk, l3_gclk);
        if (err) {
                device_printf(dev,
                    "Cant set pruss_ocp_gclk parent to l3_gclk err %d\n", err);
                return (ENXIO);
        }

        /* Clear the RESET bit */
        /* Find the ti_prm */
        /* #reset-cells should not been used in this way but... */
        err = ofw_bus_parse_xref_list_alloc(node, "resets", "#reset-cells", 0,
            &ti_prm_ref, &ncells, &cells);
        OF_prop_free(cells);
        if (err) {
                device_printf(dev,
                    "Cant fetch \"resets\" reference %x\n", err);
                return (ENXIO);
        }

        ti_prm_dev = OF_device_from_xref(ti_prm_ref);
        if (ti_prm_dev == NULL) {
                device_printf(dev, "Cant get device from \"resets\"\n");
                return (ENXIO);
        }

        err = ti_prm_reset(ti_prm_dev);
        if (err) {
                device_printf(dev, "ti_prm_reset failed %d\n", err);
                return (ENXIO);
        }
        /* End of clock activation */

        mtx_init(&sc->sc_mtx, "TI PRUSS", NULL, MTX_DEF);
        sc->sc_mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
            RF_ACTIVE);
        if (sc->sc_mem_res == NULL) {
                device_printf(dev, "could not allocate memory resource\n");
                return (ENXIO);
        }

        struct sysctl_ctx_list *clist = device_get_sysctl_ctx(dev);
        if (!clist)
                return (EINVAL);

        struct sysctl_oid *poid;
        poid = device_get_sysctl_tree( dev );
        if (!poid)
                return (EINVAL);

        sc->sc_glob_irqen = false;
        struct sysctl_oid *irq_root = SYSCTL_ADD_NODE(clist, SYSCTL_CHILDREN(poid),
            OID_AUTO, "irq", CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
            "PRUSS Host Interrupts");
        SYSCTL_ADD_PROC(clist, SYSCTL_CHILDREN(poid), OID_AUTO,
            "global_interrupt_enable",
            CTLFLAG_RW | CTLTYPE_U8 | CTLFLAG_NEEDGIANT,
            sc, 0, ti_pruss_global_interrupt_enable,
            "CU", "Global interrupt enable");

        sc->sc_bt = rman_get_bustag(sc->sc_mem_res);
        sc->sc_bh = rman_get_bushandle(sc->sc_mem_res);
        if (bus_alloc_resources(dev, ti_pruss_irq_spec, sc->sc_irq_res) != 0) {
                device_printf(dev, "could not allocate interrupt resource\n");
                ti_pruss_detach(dev);
                return (ENXIO);
        }

        ti_pruss_interrupts_clear(sc);

        for (i = 0; i < TI_PRUSS_IRQS; i++) {
                char name[8];
                snprintf(name, sizeof(name), "%d", i);

                struct sysctl_oid *irq_nodes = SYSCTL_ADD_NODE(clist, SYSCTL_CHILDREN(irq_root),
                    OID_AUTO, name, CTLFLAG_RD | CTLFLAG_MPSAFE, 0,
                    "PRUSS Interrupts");
                SYSCTL_ADD_PROC(clist, SYSCTL_CHILDREN(irq_nodes), OID_AUTO,
                    "channel", CTLFLAG_RW | CTLTYPE_STRING | CTLFLAG_NEEDGIANT,
                    sc, i, ti_pruss_channel_map,
                    "A", "Channel attached to this irq");
                SYSCTL_ADD_PROC(clist, SYSCTL_CHILDREN(irq_nodes), OID_AUTO,
                    "event", CTLFLAG_RW | CTLTYPE_STRING | CTLFLAG_NEEDGIANT,
                    sc, i, ti_pruss_event_map,
                    "A", "Event attached to this irq");
                SYSCTL_ADD_PROC(clist, SYSCTL_CHILDREN(irq_nodes), OID_AUTO,
                    "enable", CTLFLAG_RW | CTLTYPE_U8 | CTLFLAG_NEEDGIANT,
                    sc, i, ti_pruss_interrupt_enable,
                    "CU", "Enable/Disable interrupt");

                sc->sc_irq_devs[i].event = -1;
                sc->sc_irq_devs[i].channel = -1;
                sc->sc_irq_devs[i].tstamps.ctl.idx = 0;

                if (i < TI_PRUSS_HOST_IRQS) {
                        ti_pruss_irq_args[i].irq = i;
                        ti_pruss_irq_args[i].sc = sc;
                        if (bus_setup_intr(dev, sc->sc_irq_res[i],
                            INTR_MPSAFE | INTR_TYPE_MISC,
                            NULL, ti_pruss_intr, &ti_pruss_irq_args[i],
                            &sc->sc_intr[i]) != 0) {
                                device_printf(dev,
                                    "unable to setup the interrupt handler\n");
                                ti_pruss_detach(dev);

                                return (ENXIO);
                        }
                        mtx_init(&sc->sc_irq_devs[i].sc_mtx, "TI PRUSS IRQ", NULL, MTX_DEF);
                        knlist_init_mtx(&sc->sc_irq_devs[i].sc_selinfo.si_note, &sc->sc_irq_devs[i].sc_mtx);
                }
        }

        if (ti_pruss_reg_read(sc, PRUSS_AM33XX_INTC) == PRUSS_AM33XX_REV)
                device_printf(dev, "AM33xx PRU-ICSS\n");

        sc->sc_pdev = make_dev(&ti_pruss_cdevsw, 0, UID_ROOT, GID_WHEEL,
            0600, "pruss%d", device_get_unit(dev));
        sc->sc_pdev->si_drv1 = dev;

        /*  Acc. to datasheet always write 1 to polarity registers */
        ti_pruss_reg_write(sc, PRUSS_INTC_SIPR0, 0xFFFFFFFF);
        ti_pruss_reg_write(sc, PRUSS_INTC_SIPR1, 0xFFFFFFFF);

        /* Acc. to datasheet always write 0 to event type registers */
        ti_pruss_reg_write(sc, PRUSS_INTC_SITR0, 0);
        ti_pruss_reg_write(sc, PRUSS_INTC_SITR1, 0);

        return (0);
}

static int
ti_pruss_detach(device_t dev)
{
        struct ti_pruss_softc *sc = device_get_softc(dev);

        ti_pruss_interrupts_clear(sc);

        for (int i = 0; i < TI_PRUSS_HOST_IRQS; i++) {
                ti_pruss_interrupts_enable( sc, i, false );

                if (sc->sc_intr[i])
                        bus_teardown_intr(dev, sc->sc_irq_res[i], sc->sc_intr[i]);
                if (sc->sc_irq_res[i])
                        bus_release_resource(dev, SYS_RES_IRQ,
                            rman_get_rid(sc->sc_irq_res[i]),
                            sc->sc_irq_res[i]);
                knlist_clear(&sc->sc_irq_devs[i].sc_selinfo.si_note, 0);
                mtx_lock(&sc->sc_irq_devs[i].sc_mtx);
                if (!knlist_empty(&sc->sc_irq_devs[i].sc_selinfo.si_note))
                        printf("IRQ %d KQueue not empty!\n", i );
                mtx_unlock(&sc->sc_irq_devs[i].sc_mtx);
                knlist_destroy(&sc->sc_irq_devs[i].sc_selinfo.si_note);
                mtx_destroy(&sc->sc_irq_devs[i].sc_mtx);
        }

        mtx_destroy(&sc->sc_mtx);
        if (sc->sc_mem_res)
                bus_release_resource(dev, SYS_RES_MEMORY, rman_get_rid(sc->sc_mem_res),
                    sc->sc_mem_res);
        if (sc->sc_pdev)
                destroy_dev(sc->sc_pdev);

        return (0);
}

static void
ti_pruss_intr(void *arg)
{
        int val;
        struct ti_pruss_irq_arg *iap = arg;
        struct ti_pruss_softc *sc = iap->sc;
        /*
         * Interrupts pr1_host_intr[0:7] are mapped to
         * Host-2 to Host-9 of PRU-ICSS IRQ-controller.
         */
        const int pru_int = iap->irq + TI_PRUSS_PRU_IRQS;
        const int pru_int_mask = (1 << pru_int);
        const int pru_channel = sc->sc_irq_devs[pru_int].channel;
        const int pru_event = sc->sc_irq_devs[pru_channel].event;

        val = ti_pruss_reg_read(sc, PRUSS_INTC_HIER);
        if (!(val & pru_int_mask))
                return;

        ti_pruss_reg_write(sc, PRUSS_INTC_HIDISR, pru_int);
        ti_pruss_reg_write(sc, PRUSS_INTC_SICR, pru_event);
        ti_pruss_reg_write(sc, PRUSS_INTC_HIEISR, pru_int);

        struct ti_pruss_irqsc* irq = &sc->sc_irq_devs[pru_channel];
        size_t wr = irq->tstamps.ctl.idx;

        struct timespec ts;
        nanouptime(&ts);
        irq->tstamps.ts[wr] = ts.tv_sec * 1000000000 + ts.tv_nsec;

        if (++wr == TI_TS_ARRAY)
                wr = 0;
        atomic_add_32(&irq->tstamps.ctl.cnt, 1);

        irq->tstamps.ctl.idx = wr;

        KNOTE_UNLOCKED(&irq->sc_selinfo.si_note, pru_int);
        wakeup(irq);
        selwakeup(&irq->sc_selinfo);
}

static int
ti_pruss_open(struct cdev *cdev __unused, int oflags __unused,
    int devtype __unused, struct thread *td __unused)
{
        return (0);
}

static int
ti_pruss_mmap(struct cdev *cdev, vm_ooffset_t offset, vm_paddr_t *paddr,
    int nprot, vm_memattr_t *memattr)
{
        device_t dev = cdev->si_drv1;
        struct ti_pruss_softc *sc = device_get_softc(dev);

        if (offset >= rman_get_size(sc->sc_mem_res))
                return (ENOSPC);
        *paddr = rman_get_start(sc->sc_mem_res) + offset;
        *memattr = VM_MEMATTR_UNCACHEABLE;

        return (0);
}

static const struct filterops ti_pruss_kq_read = {
        .f_isfd = 1,
        .f_detach = ti_pruss_irq_kqread_detach,
        .f_event = ti_pruss_irq_kqevent,
        .f_copy = knote_triv_copy,
};

static void
ti_pruss_irq_kqread_detach(struct knote *kn)
{
        struct ti_pruss_irqsc *sc = kn->kn_hook;

        knlist_remove(&sc->sc_selinfo.si_note, kn, 0);
}

static int
ti_pruss_irq_kqevent(struct knote *kn, long hint)
{
    struct ti_pruss_irqsc* irq_sc;
    int notify;

    irq_sc = kn->kn_hook;

    if (hint > 0)
        kn->kn_data = hint - 2;

    if (hint > 0 || irq_sc->last > 0)
        notify = 1;
    else
        notify = 0;

    irq_sc->last = hint;

    return (notify);
}

static int
ti_pruss_irq_kqfilter(struct cdev *cdev, struct knote *kn)
{
        struct ti_pruss_irqsc *sc = cdev->si_drv1;

        switch (kn->kn_filter) {
        case EVFILT_READ:
                kn->kn_hook = sc;
                kn->kn_fop = &ti_pruss_kq_read;
                knlist_add(&sc->sc_selinfo.si_note, kn, 0);
                break;
        default:
                return (EINVAL);
        }

        return (0);
}