/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2024 Arm Ltd
 *
 * 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/kernel.h>

#include <machine/cpu.h>
#include <machine/cpu_feat.h>

SYSCTL_NODE(_hw, OID_AUTO, feat, CTLFLAG_RD, 0, "CPU features/errata");

/* TODO: Make this a list if we ever grow a callback other than smccc_errata */
static cpu_feat_errata_check_fn cpu_feat_check_cb = NULL;

void
enable_cpu_feat(uint32_t stage)
{
        char tunable[32];
        struct cpu_feat **featp, *feat;
        uint32_t midr;
        u_int errata_count, *errata_list;
        cpu_feat_errata errata_status;
        cpu_feat_en check_status;
        bool val;

        MPASS((stage & ~CPU_FEAT_STAGE_MASK) == 0);

        midr = get_midr();
        SET_FOREACH(featp, cpu_feat_set) {
                feat = *featp;

                /* Read any tunable the user may have set */
                if (stage == CPU_FEAT_EARLY_BOOT && PCPU_GET(cpuid) == 0) {
                        snprintf(tunable, sizeof(tunable), "hw.feat.%s",
                            feat->feat_name);
                        if (TUNABLE_BOOL_FETCH(tunable, &val)) {
                                if (val) {
                                        feat->feat_flags |=
                                            CPU_FEAT_USER_ENABLED;
                                } else {
                                        feat->feat_flags |=
                                            CPU_FEAT_USER_DISABLED;
                                }
                        }
                }

                /* Run the enablement code at the correct stage of boot */
                if ((feat->feat_flags & CPU_FEAT_STAGE_MASK) != stage)
                        continue;

                /* If the feature is system wide run on a single CPU */
                if ((feat->feat_flags & CPU_FEAT_SCOPE_MASK)==CPU_FEAT_SYSTEM &&
                    PCPU_GET(cpuid) != 0)
                        continue;

                if (feat->feat_check != NULL) {
                        check_status = feat->feat_check(feat, midr);
                } else {
                        check_status = FEAT_DEFAULT_ENABLE;
                }
                /* Ignore features that are not present */
                if (check_status == FEAT_ALWAYS_DISABLE)
                        goto next;

                if (check_status != FEAT_ALWAYS_ENABLE) {
                        /* The user disabled the feature */
                        if ((feat->feat_flags & CPU_FEAT_USER_DISABLED) != 0)
                                goto next;

                        /*
                         * The feature was disabled by default and the user
                         * didn't enable it then skip.
                         */
                        if (check_status == FEAT_DEFAULT_DISABLE &&
                            (feat->feat_flags & CPU_FEAT_USER_ENABLED) == 0)
                                goto next;
                }

                /*
                 * Check if the feature has any errata that may need a
                 * workaround applied (or it is to install the workaround for
                 * known errata.
                 */
                errata_status = ERRATA_NONE;
                errata_list = NULL;
                errata_count = 0;
                if (feat->feat_has_errata != NULL) {
                        if (feat->feat_has_errata(feat, midr, &errata_list,
                            &errata_count)) {
                                /* Assume we are affected */
                                errata_status = ERRATA_AFFECTED;
                        }
                }

                if (errata_status == ERRATA_AFFECTED &&
                    cpu_feat_check_cb != NULL) {
                        for (int i = 0; i < errata_count; i++) {
                                cpu_feat_errata new_status;

                                /* Check if affected by this erratum */
                                new_status = cpu_feat_check_cb(feat,
                                    errata_list[i]);
                                if (new_status != ERRATA_UNKNOWN) {
                                        errata_status = new_status;
                                        errata_list = &errata_list[i];
                                        errata_count = 1;
                                        break;
                                }
                        }
                }

                /* Shouldn't be possible */
                MPASS(errata_status != ERRATA_UNKNOWN);

                if (feat->feat_enable(feat, errata_status, errata_list,
                    errata_count))
                        feat->feat_enabled = true;

next:
                if (!feat->feat_enabled && feat->feat_disabled != NULL)
                        feat->feat_disabled(feat);
        }
}

static void
enable_cpu_feat_after_dev(void *dummy __unused)
{
        MPASS(PCPU_GET(cpuid) == 0);
        enable_cpu_feat(CPU_FEAT_AFTER_DEV);
}
SYSINIT(enable_cpu_feat_after_dev, SI_SUB_CONFIGURE, SI_ORDER_MIDDLE,
    enable_cpu_feat_after_dev, NULL);

void
cpu_feat_register_errata_check(cpu_feat_errata_check_fn cb)
{
        MPASS(cpu_feat_check_cb == NULL);
        cpu_feat_check_cb = cb;
}