/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2011 Nathan Whitehorn
 * 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 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/cdefs.h>
#include <sys/endian.h>
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/stdarg.h>

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

#include <machine/bus.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/rtas.h>

#include <dev/ofw/openfirm.h>

static MALLOC_DEFINE(M_RTAS, "rtas", "Run Time Abstraction Service");

static vm_offset_t      rtas_bounce_phys;
static caddr_t          rtas_bounce_virt;
static off_t            rtas_bounce_offset;
static size_t           rtas_bounce_size;
static uintptr_t        rtas_private_data;
static struct mtx       rtas_mtx;
static phandle_t        rtas;

/* From ofwcall.S */
int rtascall(vm_offset_t callbuffer, uintptr_t rtas_privdat);
extern uintptr_t        rtas_entry;
extern register_t       rtasmsr;

/*
 * After the VM is up, allocate RTAS memory and instantiate it
 */

static void rtas_setup(void *);

SYSINIT(rtas_setup, SI_SUB_KMEM, SI_ORDER_ANY, rtas_setup, NULL);

static void
rtas_setup(void *junk)
{
        ihandle_t rtasi;
        cell_t rtas_size = 0, rtas_ptr;
        char path[31];
        int result;

        rtas = OF_finddevice("/rtas");
        if (rtas == -1) {
                rtas = 0;
                return;
        }
        OF_package_to_path(rtas, path, sizeof(path));

        mtx_init(&rtas_mtx, "RTAS", NULL, MTX_SPIN);

        /* RTAS must be called with everything turned off in MSR */
        rtasmsr = mfmsr();
        rtasmsr &= ~(PSL_IR | PSL_DR | PSL_EE | PSL_SE | PSL_LE);
        #ifdef __powerpc64__
        rtasmsr &= ~PSL_SF;
        #endif

        /*
         * Allocate rtas_size + one page of contiguous, wired physical memory
         * that can fit into a 32-bit address space and accessed from real mode.
         * This is used both to bounce arguments and for RTAS private data.
         *
         * It must be 4KB-aligned and not cross a 256 MB boundary.
         */

        OF_getencprop(rtas, "rtas-size", &rtas_size, sizeof(rtas_size));
        rtas_size = round_page(rtas_size);
        rtas_bounce_virt = contigmalloc(rtas_size + PAGE_SIZE, M_RTAS, 0, 0,
            ulmin(platform_real_maxaddr(), BUS_SPACE_MAXADDR_32BIT),
            4096, 256*1024*1024);

        rtas_private_data = vtophys(rtas_bounce_virt);
        rtas_bounce_virt += rtas_size;  /* Actual bounce area */
        rtas_bounce_phys = vtophys(rtas_bounce_virt);
        rtas_bounce_size = PAGE_SIZE;

        /*
         * Instantiate RTAS. We always use the 32-bit version.
         */

        if (OF_hasprop(rtas, "linux,rtas-entry") &&
            OF_hasprop(rtas, "linux,rtas-base")) {
                OF_getencprop(rtas, "linux,rtas-base", &rtas_ptr,
                    sizeof(rtas_ptr));
                rtas_private_data = rtas_ptr;
                OF_getencprop(rtas, "linux,rtas-entry", &rtas_ptr,
                    sizeof(rtas_ptr));
        } else {
                rtasi = OF_open(path);
                if (rtasi == 0) {
                        rtas = 0;
                        printf("Error initializing RTAS: could not open "
                            "node\n");
                        return;
                }

                result = OF_call_method("instantiate-rtas", rtasi, 1, 1,
                    (cell_t)rtas_private_data, &rtas_ptr);
                OF_close(rtasi);

                if (result != 0) {
                        rtas = 0;
                        rtas_ptr = 0;
                        printf("Error initializing RTAS (%d)\n", result);
                        return;
                }
        }

        rtas_entry = (uintptr_t)(rtas_ptr);
}

static cell_t
rtas_real_map(const void *buf, size_t len)
{
        cell_t phys;

        mtx_assert(&rtas_mtx, MA_OWNED);

        /*
         * Make sure the bounce page offset satisfies any reasonable
         * alignment constraint.
         */
        rtas_bounce_offset += sizeof(register_t) -
            (rtas_bounce_offset % sizeof(register_t));

        if (rtas_bounce_offset + len > rtas_bounce_size) {
                panic("Oversize RTAS call!");
                return 0;
        }

        if (buf != NULL)
                memcpy(rtas_bounce_virt + rtas_bounce_offset, buf, len);
        else
                return (0);

        phys = rtas_bounce_phys + rtas_bounce_offset;
        rtas_bounce_offset += len;

        return (phys);
}

static void
rtas_real_unmap(cell_t physaddr, void *buf, size_t len)
{
        mtx_assert(&rtas_mtx, MA_OWNED);

        if (physaddr == 0)
                return;

        memcpy(buf, rtas_bounce_virt + (physaddr - rtas_bounce_phys), len);
}

/* Check if we have RTAS */
int
rtas_exists(void)
{
        return (rtas != 0);
}

/* Call an RTAS method by token */
int
rtas_call_method(cell_t token, int nargs, int nreturns, ...)
{
        vm_offset_t argsptr;
        jmp_buf env, *oldfaultbuf;
        va_list ap;
        struct {
                cell_t token;
                cell_t nargs;
                cell_t nreturns;
                cell_t args_n_results[12];
        } args;
        int n, result;

        if (!rtas_exists() || nargs + nreturns > 12)
                return (-1);

        args.token = htobe32(token);
        va_start(ap, nreturns);

        mtx_lock_spin(&rtas_mtx);
        rtas_bounce_offset = 0;

        args.nargs = htobe32(nargs);
        args.nreturns = htobe32(nreturns);

        for (n = 0; n < nargs; n++)
                args.args_n_results[n] = htobe32(va_arg(ap, cell_t));

        argsptr = rtas_real_map(&args, sizeof(args));

        /* Get rid of any stale machine checks that have been waiting.  */
        __asm __volatile ("sync; isync");
        oldfaultbuf = curthread->td_pcb->pcb_onfault;
        curthread->td_pcb->pcb_onfault = &env;
        if (!setjmp(env)) {
                __asm __volatile ("sync");
                result = rtascall(argsptr, rtas_private_data);
                __asm __volatile ("sync; isync");
        } else {
                result = RTAS_HW_ERROR;
        }
        curthread->td_pcb->pcb_onfault = oldfaultbuf;
        __asm __volatile ("sync");

        rtas_real_unmap(argsptr, &args, sizeof(args));
        mtx_unlock_spin(&rtas_mtx);

        if (result < 0)
                return (result);

        for (n = nargs; n < nargs + nreturns; n++)
                *va_arg(ap, cell_t *) = be32toh(args.args_n_results[n]);
        return (result);
}

/* Look up an RTAS token */
cell_t
rtas_token_lookup(const char *method)
{
        cell_t token;

        if (!rtas_exists())
                return (-1);

        if (OF_getencprop(rtas, method, &token, sizeof(token)) == -1)
                return (-1);

        return (token);
}