/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2022 Ruslan Bukin <br@bsdpad.com>
 *
 * This work was supported by Innovate UK project 105694, "Digital Security
 * by Design (DSbD) Technology Platform Prototype".
 *
 * 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/rman.h>
#include <sys/kernel.h>
#include <sys/module.h>

#include <machine/bus.h>

#include <dev/fdt/simplebus.h>
#include <dev/fdt/fdt_common.h>
#include <dev/ofw/ofw_bus_subr.h>

#include "arm_doorbell.h"

#define MHU_CHAN_RX_LP          0x000   /* Low priority channel */
#define MHU_CHAN_RX_HP          0x020   /* High priority channel */
#define MHU_CHAN_RX_SEC         0x200   /* Secure channel */
#define  MHU_INTR_STAT          0x00
#define  MHU_INTR_SET           0x08
#define  MHU_INTR_CLEAR         0x10

#define MHU_TX_REG_OFFSET       0x100

#define DOORBELL_N_CHANNELS     3
#define DOORBELL_N_DOORBELLS    (DOORBELL_N_CHANNELS * 32)

struct arm_doorbell dbells[DOORBELL_N_DOORBELLS];

static struct resource_spec arm_doorbell_spec[] = {
        { SYS_RES_MEMORY,       0,      RF_ACTIVE },
        { SYS_RES_IRQ,          0,      RF_ACTIVE },
        { SYS_RES_IRQ,          1,      RF_ACTIVE },
        { -1, 0 }
};

struct arm_doorbell_softc {
        struct resource         *res[3];
        void                    *lp_intr_cookie;
        void                    *hp_intr_cookie;
        device_t                dev;
};

static void
arm_doorbell_lp_intr(void *arg)
{
        struct arm_doorbell_softc *sc;
        struct arm_doorbell *db;
        uint32_t reg;
        int i;

        sc = arg;

        reg = bus_read_4(sc->res[0], MHU_CHAN_RX_LP + MHU_INTR_STAT);
        for (i = 0; i < 32; i++) {
                if (reg & (1 << i)) {
                        db = &dbells[i];
                        bus_write_4(sc->res[0], MHU_CHAN_RX_LP + MHU_INTR_CLEAR,
                            (1 << i));
                        if (db->func != NULL)
                                db->func(db->arg);
                }
        }
}

static void
arm_doorbell_hp_intr(void *arg)
{
        struct arm_doorbell_softc *sc;
        struct arm_doorbell *db;
        uint32_t reg;
        int i;

        sc = arg;

        reg = bus_read_4(sc->res[0], MHU_CHAN_RX_HP + MHU_INTR_STAT);
        for (i = 0; i < 32; i++) {
                if (reg & (1 << i)) {
                        db = &dbells[i];
                        bus_write_4(sc->res[0], MHU_CHAN_RX_HP + MHU_INTR_CLEAR,
                            (1 << i));
                        if (db->func != NULL)
                                db->func(db->arg);
                }
        }
}

static int
arm_doorbell_probe(device_t dev)
{

        if (!ofw_bus_is_compatible(dev, "arm,mhu-doorbell"))
                return (ENXIO);

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

        device_set_desc(dev, "ARM MHU Doorbell");

        return (BUS_PROBE_DEFAULT);
}

static int
arm_doorbell_attach(device_t dev)
{
        struct arm_doorbell_softc *sc;
        phandle_t node;
        int error;

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

        node = ofw_bus_get_node(dev);
        if (node == -1)
                return (ENXIO);

        if (bus_alloc_resources(dev, arm_doorbell_spec, sc->res) != 0) {
                device_printf(dev, "Can't allocate resources for device.\n");
                return (ENXIO);
        }

        /* Setup interrupt handlers. */
        error = bus_setup_intr(dev, sc->res[1], INTR_TYPE_MISC | INTR_MPSAFE,
            NULL, arm_doorbell_lp_intr, sc, &sc->lp_intr_cookie);
        if (error != 0) {
                device_printf(dev, "Can't setup LP interrupt handler.\n");
                bus_release_resources(dev, arm_doorbell_spec, sc->res);
                return (ENXIO);
        }

        error = bus_setup_intr(dev, sc->res[2], INTR_TYPE_MISC | INTR_MPSAFE,
            NULL, arm_doorbell_hp_intr, sc, &sc->hp_intr_cookie);
        if (error != 0) {
                device_printf(dev, "Can't setup HP interrupt handler.\n");
                bus_release_resources(dev, arm_doorbell_spec, sc->res);
                return (ENXIO);
        }

        OF_device_register_xref(OF_xref_from_node(node), dev);

        return (0);
}

static int
arm_doorbell_detach(device_t dev)
{

        return (EBUSY);
}

struct arm_doorbell *
arm_doorbell_ofw_get(device_t dev, const char *name)
{
        phandle_t node, parent;
        struct arm_doorbell *db;
        device_t db_dev;
        pcell_t *cells;
        int nmboxes;
        int ncells;
        int idx;
        int db_id;
        int error;
        int chan;

        node = ofw_bus_get_node(dev);

        error = ofw_bus_parse_xref_list_get_length(node, "mboxes",
            "#mbox-cells", &nmboxes);
        if (error) {
                device_printf(dev, "%s can't get mboxes list.\n", __func__);
                return (NULL);
        }

        if (nmboxes == 0) {
                device_printf(dev, "%s mbox list is empty.\n", __func__);
                return (NULL);
        }

        error = ofw_bus_find_string_index(node, "mbox-names", name, &idx);
        if (error != 0) {
                device_printf(dev, "%s can't find string index.\n",
                    __func__);
                return (NULL);
        }

        error = ofw_bus_parse_xref_list_alloc(node, "mboxes", "#mbox-cells",
            idx, &parent, &ncells, &cells);
        if (error != 0) {
                device_printf(dev, "%s can't get mbox device xref\n",
                    __func__);
                return (NULL);
        }

        if (ncells != 2) {
                device_printf(dev, "Unexpected data size.\n");
                OF_prop_free(cells);
                return (NULL);
        }

        db_dev = OF_device_from_xref(parent);
        if (db_dev == NULL) {
                device_printf(dev, "%s: Can't get arm_doorbell device\n",
                    __func__);
                OF_prop_free(cells);
                return (NULL);
        }

        chan = cells[0];
        if (chan >= DOORBELL_N_CHANNELS) {
                device_printf(dev, "Unexpected channel number.\n");
                OF_prop_free(cells);
                return (NULL);
        }

        db_id = cells[1];
        if (db_id >= 32) {
                device_printf(dev, "Unexpected channel bit.\n");
                OF_prop_free(cells);
                return (NULL);
        }

        db = &dbells[chan * db_id];
        db->dev = dev;
        db->db_dev = db_dev;
        db->chan = chan;
        db->db = db_id;

        OF_prop_free(cells);

        return (db);
}

void
arm_doorbell_set(struct arm_doorbell *db)
{
        struct arm_doorbell_softc *sc;
        uint32_t offset;

        sc = device_get_softc(db->db_dev);

        switch (db->chan) {
        case 0:
                offset = MHU_CHAN_RX_LP;
                break;
        case 1:
                offset = MHU_CHAN_RX_HP;
                break;
        case 2:
                offset = MHU_CHAN_RX_SEC;
                break;
        default:
                panic("not reached");
        };

        offset |= MHU_TX_REG_OFFSET;

        bus_write_4(sc->res[0], offset + MHU_INTR_SET, (1 << db->db));
}

int
arm_doorbell_get(struct arm_doorbell *db)
{
        struct arm_doorbell_softc *sc;
        uint32_t offset;
        uint32_t reg;

        sc = device_get_softc(db->db_dev);

        switch (db->chan) {
        case 0:
                offset = MHU_CHAN_RX_LP;
                break;
        case 1:
                offset = MHU_CHAN_RX_HP;
                break;
        case 2:
                offset = MHU_CHAN_RX_SEC;
                break;
        default:
                panic("not reached");
        };

        reg = bus_read_4(sc->res[0], offset + MHU_INTR_STAT);
        if (reg & (1 << db->db)) {
                bus_write_4(sc->res[0], offset + MHU_INTR_CLEAR,
                    (1 << db->db));
                return (1);
        }

        return (0);
}

void
arm_doorbell_set_handler(struct arm_doorbell *db, void (*func)(void *),
    void *arg)
{

        db->func = func;
        db->arg = arg;
}

static device_method_t arm_doorbell_methods[] = {
        DEVMETHOD(device_probe,         arm_doorbell_probe),
        DEVMETHOD(device_attach,        arm_doorbell_attach),
        DEVMETHOD(device_detach,        arm_doorbell_detach),
        DEVMETHOD_END
};

DEFINE_CLASS_1(arm_doorbell, arm_doorbell_driver, arm_doorbell_methods,
    sizeof(struct arm_doorbell_softc), simplebus_driver);

EARLY_DRIVER_MODULE(arm_doorbell, simplebus, arm_doorbell_driver, 0, 0,
    BUS_PASS_INTERRUPT + BUS_PASS_ORDER_MIDDLE);
MODULE_VERSION(arm_doorbell, 1);