/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2022 Ruslan Bukin <br@bsdpad.com>
 * Copyright (c) 2023 Arm Ltd
 *
 * 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/cpu.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>

#include <machine/atomic.h>

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

#include "mmio_sram_if.h"

#include "scmi_shmem.h"
#include "scmi.h"

#define INFLIGHT_NONE   0
#define INFLIGHT_REQ    1

struct shmem_softc {
        device_t                dev;
        device_t                parent;
        int                     reg;
        int                     inflight;
};

static void     scmi_shmem_read(device_t, bus_size_t, void *, bus_size_t);
static void     scmi_shmem_write(device_t, bus_size_t, const void *,
                                 bus_size_t);
static void     scmi_shmem_acquire_channel(struct shmem_softc *);
static void     scmi_shmem_release_channel(struct shmem_softc *);

static int      shmem_probe(device_t);
static int      shmem_attach(device_t);
static int      shmem_detach(device_t);

static int
shmem_probe(device_t dev)
{

        if (!ofw_bus_is_compatible(dev, "arm,scmi-shmem"))
                return (ENXIO);

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

        device_set_desc(dev, "ARM SCMI Shared Memory driver");

        return (BUS_PROBE_DEFAULT);
}

static int
shmem_attach(device_t dev)
{
        struct shmem_softc *sc;
        phandle_t node;
        int reg;

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

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

        OF_getencprop(node, "reg", &reg, sizeof(reg));

        sc->reg = reg;
        atomic_store_rel_int(&sc->inflight, INFLIGHT_NONE);

        OF_device_register_xref(OF_xref_from_node(node), dev);

        return (0);
}

static int
shmem_detach(device_t dev)
{

        return (0);
}

static void
scmi_shmem_read(device_t dev, bus_size_t offset, void *buf, bus_size_t len)
{
        struct shmem_softc *sc;
        uint8_t *addr;
        int i;

        sc = device_get_softc(dev);

        addr = (uint8_t *)buf;

        for (i = 0; i < len; i++)
                addr[i] = MMIO_SRAM_READ_1(sc->parent, sc->reg + offset + i);
}

static void
scmi_shmem_write(device_t dev, bus_size_t offset, const void *buf,
    bus_size_t len)
{
        struct shmem_softc *sc;
        const uint8_t *addr;
        int i;

        sc = device_get_softc(dev);

        addr = (const uint8_t *)buf;

        for (i = 0; i < len; i++)
                MMIO_SRAM_WRITE_1(sc->parent, sc->reg + offset + i, addr[i]);
}

device_t
scmi_shmem_get(device_t dev, phandle_t node, int index)
{
        phandle_t *shmems;
        device_t shmem_dev;
        size_t len;

        len = OF_getencprop_alloc_multi(node, "shmem", sizeof(*shmems),
            (void **)&shmems);
        if (len <= 0) {
                device_printf(dev, "%s: Can't get shmem node.\n", __func__);
                return (NULL);
        }

        if (index >= len) {
                OF_prop_free(shmems);
                return (NULL);
        }

        shmem_dev = OF_device_from_xref(shmems[index]);
        if (shmem_dev == NULL)
                device_printf(dev, "%s: Can't get shmem device.\n",
                    __func__);

        OF_prop_free(shmems);

        return (shmem_dev);
}

static void
scmi_shmem_acquire_channel(struct shmem_softc *sc)
{

         while ((atomic_cmpset_acq_int(&sc->inflight, INFLIGHT_NONE,
             INFLIGHT_REQ)) == 0)
                DELAY(1000);
}

static void
scmi_shmem_release_channel(struct shmem_softc *sc)
{

        atomic_store_rel_int(&sc->inflight, INFLIGHT_NONE);
}

int
scmi_shmem_prepare_msg(device_t dev, uint8_t *msg, uint32_t tx_len,
                bool polling)
{
        struct shmem_softc *sc;
        struct scmi_smt_header hdr = {};
        uint32_t channel_status;

        sc = device_get_softc(dev);

        /* Get exclusive write access to channel */
        scmi_shmem_acquire_channel(sc);

        /* Read channel status */
        scmi_shmem_read(dev, SMT_OFFSET_CHAN_STATUS, &channel_status,
            SMT_SIZE_CHAN_STATUS);
        if ((channel_status & SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE) == 0) {
                scmi_shmem_release_channel(sc);
                device_printf(dev, "Shmem channel busy. Abort !.\n");
                return (1);
        }

        /* Update header */
        hdr.channel_status &= ~SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE;
        hdr.msg_header = htole32(*((uint32_t *)msg));
        hdr.length = htole32(tx_len);
        if (!polling)
                hdr.flags |= SCMI_SHMEM_FLAG_INTR_ENABLED;
        else
                hdr.flags &= ~SCMI_SHMEM_FLAG_INTR_ENABLED;

        /* Write header */
        scmi_shmem_write(dev, 0, &hdr, SMT_SIZE_HEADER);

        /* Write request payload if any */
        if (tx_len > SCMI_MSG_HDR_SIZE)
                scmi_shmem_write(dev, SMT_SIZE_HEADER,
                    &msg[SCMI_MSG_HDR_SIZE], tx_len - SCMI_MSG_HDR_SIZE);

        return (0);
}

void
scmi_shmem_clear_channel(device_t dev)
{
        uint32_t channel_status = 0;

        if (dev == NULL)
                return;

        channel_status |= SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE;
        scmi_shmem_write(dev, SMT_OFFSET_CHAN_STATUS, &channel_status,
            SMT_SIZE_CHAN_STATUS);
}

int
scmi_shmem_read_msg_header(device_t dev, uint32_t *msg_header, unsigned int *rx_len)
{
        uint32_t length, header;

        /* Read and check length. */
        scmi_shmem_read(dev, SMT_OFFSET_LENGTH, &length, SMT_SIZE_LENGTH);
        if (le32toh(length) < sizeof(header))
                return (EINVAL);

        *rx_len = le32toh(length);
        /* Read header. */
        scmi_shmem_read(dev, SMT_OFFSET_MSG_HEADER, &header,
            SMT_SIZE_MSG_HEADER);

        *msg_header = le32toh(header);

        return (0);
}

int
scmi_shmem_read_msg_payload(device_t dev, uint8_t *buf, uint32_t buf_len, uint32_t rx_len)
{
        uint32_t payld_len;

        payld_len = rx_len - SCMI_MSG_HDR_SIZE;
        if (payld_len > buf_len) {
                device_printf(dev,
                    "RX payload %dbytes exceeds buflen %dbytes. Truncate.\n",
                    payld_len, buf_len);
                payld_len = buf_len;
        }

        /* Read response payload */
        scmi_shmem_read(dev, SMT_SIZE_HEADER, buf, payld_len);

        return (0);
}

void
scmi_shmem_tx_complete(device_t dev)
{
        struct shmem_softc *sc;

        sc = device_get_softc(dev);
        scmi_shmem_release_channel(sc);
}

bool scmi_shmem_poll_msg(device_t dev, uint32_t *msg_header, uint32_t *rx_len)
{
        uint32_t status;
        bool ret;

        scmi_shmem_read(dev, SMT_OFFSET_CHAN_STATUS, &status,
            SMT_SIZE_CHAN_STATUS);

        ret = (status & (SCMI_SHMEM_CHAN_STAT_CHANNEL_ERROR |
            SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE));
        if (ret)
                scmi_shmem_read_msg_header(dev, msg_header, rx_len);

        return (ret);
}

static device_method_t shmem_methods[] = {
        DEVMETHOD(device_probe,         shmem_probe),
        DEVMETHOD(device_attach,        shmem_attach),
        DEVMETHOD(device_detach,        shmem_detach),
        DEVMETHOD_END
};

DEFINE_CLASS_1(shmem, shmem_driver, shmem_methods, sizeof(struct shmem_softc),
    simplebus_driver);

EARLY_DRIVER_MODULE(shmem, mmio_sram, shmem_driver, 0, 0,
    BUS_PASS_INTERRUPT + BUS_PASS_ORDER_MIDDLE);
MODULE_VERSION(scmi_shmem, 1);