/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2024 Ruslan Bukin <br@bsdpad.com>
 *
 * This software was developed by the University of Cambridge Computer
 * Laboratory (Department of Computer Science and Technology) under 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/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#include <dev/fdt/fdt_common.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>

#define SIFIVE_CCACHE_CONFIG    0x000
#define  CCACHE_CONFIG_WAYS_S   8
#define  CCACHE_CONFIG_WAYS_M   (0xff << CCACHE_CONFIG_WAYS_S)
#define SIFIVE_CCACHE_WAYENABLE 0x008
#define SIFIVE_CCACHE_FLUSH64   0x200

#define SIFIVE_CCACHE_LINE_SIZE 64

#define RD8(sc, off)            (bus_read_8((sc)->res, (off)))
#define WR8(sc, off, val)       (bus_write_8((sc)->res, (off), (val)))
#define CC_WR8(offset, value)   \
    *(volatile uint64_t *)((uintptr_t)ccache_va + (offset)) = (value)

static struct ofw_compat_data compat_data[] = {
        { "sifive,eic7700",                     1 },
        { NULL,                                 0 }
};

struct ccache_softc {
        struct resource *res;
};

static void *ccache_va = NULL;

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

/*
 * Non-standard EIC7700 cache-flushing routine.
 */
static void
ccache_flush_range(vm_offset_t start, size_t len)
{
        vm_offset_t paddr;
        vm_offset_t sva;
        vm_offset_t step;
        uint64_t line;

        if (ccache_va == NULL || len == 0)
                return;

        mb();

        for (sva = start; len > 0;) {
                paddr = pmap_kextract(sva);
                step = min(PAGE_SIZE - (paddr & PAGE_MASK), len);
                for (line = rounddown2(paddr, SIFIVE_CCACHE_LINE_SIZE);
                    line < paddr + step;
                    line += SIFIVE_CCACHE_LINE_SIZE)
                        CC_WR8(SIFIVE_CCACHE_FLUSH64, line);
                sva += step;
                len -= step;
        }

        mb();
}

static void
ccache_install_hooks(void)
{
        struct riscv_cache_ops eswin_ops;

        eswin_ops.dcache_wbinv_range = ccache_flush_range;
        eswin_ops.dcache_inv_range = ccache_flush_range;
        eswin_ops.dcache_wb_range = ccache_flush_range;

        riscv_cache_install_hooks(&eswin_ops, SIFIVE_CCACHE_LINE_SIZE);
}

static int
ccache_probe(device_t dev)
{

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

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

        if (device_get_unit(dev) != 0)
                return (ENXIO);

        device_set_desc(dev, "SiFive Cache Controller");

        return (BUS_PROBE_DEFAULT);
}

static int
ccache_attach(device_t dev)
{
        struct ccache_softc *sc;
        size_t config, ways;

        sc = device_get_softc(dev);

        if (bus_alloc_resources(dev, ccache_spec, &sc->res) != 0) {
                device_printf(dev, "cannot allocate resources for device\n");
                return (ENXIO);
        }

        /* Non-standard EIC7700 cache unit configuration. */
        config = RD8(sc, SIFIVE_CCACHE_CONFIG);
        ways = (config & CCACHE_CONFIG_WAYS_M) >> CCACHE_CONFIG_WAYS_S;
        WR8(sc, SIFIVE_CCACHE_WAYENABLE, (ways - 1));

        ccache_va = rman_get_virtual(sc->res);
        ccache_install_hooks();

        return (0);
}

static device_method_t ccache_methods[] = {
        /* Device interface */
        DEVMETHOD(device_probe,         ccache_probe),
        DEVMETHOD(device_attach,        ccache_attach),
        DEVMETHOD_END
};

static driver_t ccache_driver = {
        "ccache",
        ccache_methods,
        sizeof(struct ccache_softc),
};

EARLY_DRIVER_MODULE(ccache, simplebus, ccache_driver, 0, 0,
    BUS_PASS_BUS + BUS_PASS_ORDER_FIRST);
MODULE_VERSION(ccache, 1);