// SPDX-License-Identifier: GPL-2.0
/*
 * Extensible Firmware Interface
 *
 * Copyright (C) 2020 Western Digital Corporation or its affiliates.
 *
 * Based on Extensible Firmware Interface Specification version 2.4
 * Adapted from drivers/firmware/efi/arm-runtime.c
 *
 */

#include <linux/dmi.h>
#include <linux/efi.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/mm_types.h>
#include <linux/pgalloc.h>
#include <linux/pgtable.h>
#include <linux/preempt.h>
#include <linux/rbtree.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include <asm/cacheflush.h>
#include <asm/efi.h>
#include <asm/mmu.h>

static bool __init efi_virtmap_init(void)
{
        efi_memory_desc_t *md;

        efi_mm.pgd = pgd_alloc(&efi_mm);
        mm_init_cpumask(&efi_mm);
        init_new_context(NULL, &efi_mm);

        for_each_efi_memory_desc(md) {
                if (!(md->attribute & EFI_MEMORY_RUNTIME))
                        continue;
                if (md->virt_addr == U64_MAX)
                        return false;

                efi_create_mapping(&efi_mm, md);
        }

        if (efi_memattr_apply_permissions(&efi_mm, efi_set_mapping_permissions))
                return false;

        return true;
}

/*
 * Enable the UEFI Runtime Services if all prerequisites are in place, i.e.,
 * non-early mapping of the UEFI system table and virtual mappings for all
 * EFI_MEMORY_RUNTIME regions.
 */
static int __init riscv_enable_runtime_services(void)
{
        u64 mapsize;

        if (!efi_enabled(EFI_BOOT)) {
                pr_info("EFI services will not be available.\n");
                return 0;
        }

        efi_memmap_unmap();

        mapsize = efi.memmap.desc_size * efi.memmap.nr_map;

        if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
                pr_err("Failed to remap EFI memory map\n");
                return 0;
        }

        if (efi_soft_reserve_enabled()) {
                efi_memory_desc_t *md;

                for_each_efi_memory_desc(md) {
                        u64 md_size = md->num_pages << EFI_PAGE_SHIFT;
                        struct resource *res;

                        if (!(md->attribute & EFI_MEMORY_SP))
                                continue;

                        res = kzalloc_obj(*res);
                        if (WARN_ON(!res))
                                break;

                        res->start      = md->phys_addr;
                        res->end        = md->phys_addr + md_size - 1;
                        res->name       = "Soft Reserved";
                        res->flags      = IORESOURCE_MEM;
                        res->desc       = IORES_DESC_SOFT_RESERVED;

                        insert_resource(&iomem_resource, res);
                }
        }

        if (efi_runtime_disabled()) {
                pr_info("EFI runtime services will be disabled.\n");
                return 0;
        }

        if (efi_enabled(EFI_RUNTIME_SERVICES)) {
                pr_info("EFI runtime services access via paravirt.\n");
                return 0;
        }

        pr_info("Remapping and enabling EFI services.\n");

        if (!efi_virtmap_init()) {
                pr_err("UEFI virtual mapping missing or invalid -- runtime services will not be available\n");
                return -ENOMEM;
        }

        /* Set up runtime services function pointers */
        efi_native_runtime_setup();
        set_bit(EFI_RUNTIME_SERVICES, &efi.flags);

        return 0;
}
early_initcall(riscv_enable_runtime_services);

static void efi_virtmap_load(void)
{
        preempt_disable();
        switch_mm(current->active_mm, &efi_mm, NULL);
}

static void efi_virtmap_unload(void)
{
        switch_mm(&efi_mm, current->active_mm, NULL);
        preempt_enable();
}

void arch_efi_call_virt_setup(void)
{
        sync_kernel_mappings(efi_mm.pgd);
        efi_virtmap_load();
}

void arch_efi_call_virt_teardown(void)
{
        efi_virtmap_unload();
}

static int __init riscv_dmi_init(void)
{
        /*
         * On riscv, DMI depends on UEFI, and dmi_setup() needs to
         * be called early because dmi_id_init(), which is an arch_initcall
         * itself, depends on dmi_scan_machine() having been called already.
         */
        dmi_setup();

        return 0;
}
core_initcall(riscv_dmi_init);