/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2021 Jessica Clarke <jrtc27@FreeBSD.org>
 *
 * 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.
 */

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

#include <machine/intr.h>
#include <machine/sbi.h>
#include <machine/smp.h>

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

#include "pic_if.h"

struct sbi_ipi_softc {
        device_t                dev;
        struct resource         *irq_res;
        void                    *ih;
        struct intr_irqsrc      isrc;
        uint32_t                pending_ipis[MAXCPU];
};

static void
sbi_ipi_pic_ipi_send(device_t dev, struct intr_irqsrc *isrc, cpuset_t cpus,
    u_int ipi)
{
        struct sbi_ipi_softc *sc;
        struct pcpu *pc;
        u_long mask;
        u_int cpu;

        sc = device_get_softc(dev);

        KASSERT(isrc == &sc->isrc, ("%s: not the IPI isrc", __func__));
        KASSERT(ipi < INTR_IPI_COUNT,
            ("%s: not a valid IPI: %u", __func__, ipi));

        mask = 0;
        STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
                cpu = pc->pc_cpuid;
                if (CPU_ISSET(cpu, &cpus)) {
                        atomic_set_32(&sc->pending_ipis[cpu], 1u << ipi);
                        mask |= (1ul << pc->pc_hart);
                }
        }
        sbi_send_ipi(&mask);
}

static int
sbi_ipi_pic_ipi_setup(device_t dev, u_int ipi, struct intr_irqsrc **isrcp)
{
        struct sbi_ipi_softc *sc;

        sc = device_get_softc(dev);

        KASSERT(ipi < INTR_IPI_COUNT,
            ("%s: not a valid IPI: %u", __func__, ipi));

        *isrcp = &sc->isrc;

        return (0);

}

static int
sbi_ipi_intr(void *arg)
{
        struct sbi_ipi_softc *sc;
        uint32_t ipi_bitmap;
        u_int cpu, ipi;
        int bit;

        sc = arg;

        csr_clear(sip, SIP_SSIP);

        cpu = PCPU_GET(cpuid);

        mb();

        ipi_bitmap = atomic_readandclear_32(&sc->pending_ipis[cpu]);
        if (ipi_bitmap == 0)
                return (FILTER_HANDLED);

        mb();

        while ((bit = ffs(ipi_bitmap))) {
                ipi = (bit - 1);
                ipi_bitmap &= ~(1u << ipi);

                intr_ipi_dispatch(ipi);
        }

        return (FILTER_HANDLED);
}

static int
sbi_ipi_probe(device_t dev)
{
        device_set_desc(dev, "RISC-V SBI Inter-Processor Interrupts");

        return (BUS_PROBE_NOWILDCARD);
}

static int
sbi_ipi_attach(device_t dev)
{
        struct sbi_ipi_softc *sc;
        const char *name;
        int irq, rid, error;
        phandle_t iparent;
        pcell_t cell;
        device_t rootdev;

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

        memset(sc->pending_ipis, 0, sizeof(sc->pending_ipis));

        name = device_get_nameunit(dev);
        error = intr_isrc_register(&sc->isrc, sc->dev, INTR_ISRCF_IPI,
            "%s,ipi", name);
        if (error != 0) {
                device_printf(dev, "Can't register interrupt: %d\n", error);
                return (ENXIO);
        }

        rootdev = intr_irq_root_device(INTR_ROOT_IRQ);
        iparent = OF_xref_from_node(ofw_bus_get_node(rootdev));
        cell = IRQ_SOFTWARE_SUPERVISOR;
        irq = ofw_bus_map_intr(dev, iparent, 1, &cell);
        error = bus_set_resource(dev, SYS_RES_IRQ, 0, irq, 1);
        if (error != 0) {
                device_printf(dev, "Unable to register IRQ resource\n");
                return (ENXIO);
        }

        rid = 0;
        sc->irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ, &rid,
            RF_ACTIVE | RF_SHAREABLE);
        if (sc->irq_res == NULL) {
                device_printf(dev, "Unable to alloc IRQ resource\n");
                return (ENXIO);
        }

        error = bus_setup_intr(dev, sc->irq_res, INTR_TYPE_CLK,
            sbi_ipi_intr, NULL, sc, &sc->ih);
        if (error != 0) {
                device_printf(dev, "Unable to setup IRQ resource\n");
                return (ENXIO);
        }

        /* TODO: Define a set of priorities once other IPI sources exist */
        error = intr_ipi_pic_register(dev, 0);
        if (error != 0) {
                device_printf(dev, "Can't register as IPI source: %d\n", error);
                return (ENXIO);
        }

        return (0);
}

static device_method_t sbi_ipi_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         sbi_ipi_probe),
        DEVMETHOD(device_attach,        sbi_ipi_attach),

        /* Interrupt controller interface */
        DEVMETHOD(pic_ipi_send,         sbi_ipi_pic_ipi_send),
        DEVMETHOD(pic_ipi_setup,        sbi_ipi_pic_ipi_setup),

        DEVMETHOD_END
};

DEFINE_CLASS_0(sbi_ipi, sbi_ipi_driver, sbi_ipi_methods,
    sizeof(struct sbi_ipi_softc));
/* Local interrupt controller attaches during BUS_PASS_ORDER_FIRST */
EARLY_DRIVER_MODULE(sbi_ipi, sbi, sbi_ipi_driver, 0, 0,
    BUS_PASS_INTERRUPT + BUS_PASS_ORDER_EARLY);