// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020 Western Digital Corporation or its affiliates.
 */

#include <linux/efi.h>
#include <linux/libfdt.h>

#include <asm/efi.h>
#include <linux/unaligned.h>

#include "efistub.h"

typedef void __noreturn (*jump_kernel_func)(unsigned long, unsigned long);

static unsigned long hartid;

static int get_boot_hartid_from_fdt(void)
{
        const void *fdt;
        int chosen_node, len;
        const void *prop;

        fdt = get_efi_config_table(DEVICE_TREE_GUID);
        if (!fdt)
                return -EINVAL;

        chosen_node = fdt_path_offset(fdt, "/chosen");
        if (chosen_node < 0)
                return -EINVAL;

        prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", &len);
        if (!prop)
                return -EINVAL;

        if (len == sizeof(u32))
                hartid = (unsigned long) fdt32_to_cpu(*(fdt32_t *)prop);
        else if (len == sizeof(u64))
                hartid = (unsigned long) fdt64_to_cpu(__get_unaligned_t(fdt64_t, prop));
        else
                return -EINVAL;

        return 0;
}

static efi_status_t get_boot_hartid_from_efi(void)
{
        efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
        struct riscv_efi_boot_protocol *boot_protocol;
        efi_status_t status;

        status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
                             (void **)&boot_protocol);
        if (status != EFI_SUCCESS)
                return status;
        return efi_call_proto(boot_protocol, get_boot_hartid, &hartid);
}

efi_status_t check_platform_features(void)
{
        efi_status_t status;
        int ret;

        status = get_boot_hartid_from_efi();
        if (status != EFI_SUCCESS) {
                ret = get_boot_hartid_from_fdt();
                if (ret) {
                        efi_err("Failed to get boot hartid!\n");
                        return EFI_UNSUPPORTED;
                }
        }
        return EFI_SUCCESS;
}

unsigned long __weak stext_offset(void)
{
        /*
         * This fallback definition is used by the EFI zboot stub, which loads
         * the entire image so it can branch via the image header at offset #0.
         */
        return 0;
}

void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt,
                                 unsigned long fdt_size)
{
        unsigned long kernel_entry = entrypoint + stext_offset();
        jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry;

        /*
         * Jump to real kernel here with following constraints.
         * 1. MMU should be disabled.
         * 2. a0 should contain hartid
         * 3. a1 should DT address
         */
        csr_write(CSR_SATP, 0);
        jump_kernel(hartid, fdt);
}