/*
 * Copyright (c) 2015 Google, Inc
 *
 * SPDX-License-Identifier:     GPL-2.0+
 *
 * EFI information obtained here:
 * http://wiki.phoenix.com/wiki/index.php/EFI_BOOT_SERVICES
 *
 * Loads a payload (U-Boot) within the EFI environment. This is built as an
 * EFI application. It can be built either in 32-bit or 64-bit mode.
 */

#include <common.h>
#include <debug_uart.h>
#include <efi.h>
#include <efi_api.h>
#include <errno.h>
#include <ns16550.h>
#include <asm/cpu.h>
#include <asm/io.h>
#include <linux/err.h>
#include <linux/types.h>

DECLARE_GLOBAL_DATA_PTR;

#ifndef CONFIG_X86
/*
 * Problem areas:
 * - putc() uses the ns16550 address directly and assumed I/O access. Many
 *      platforms will use memory access
 * get_codeseg32() is only meaningful on x86
 */
#error "This file needs to be ported for use on architectures"
#endif

static struct efi_priv *global_priv;
static bool use_uart;

struct __packed desctab_info {
        uint16_t limit;
        uint64_t addr;
        uint16_t pad;
};

/*
 * EFI uses Unicode and we don't. The easiest way to get a sensible output
 * function is to use the U-Boot debug UART. We use EFI's console output
 * function where available, and assume the built-in UART after that. We rely
 * on EFI to set up the UART for us and just bring in the functions here.
 * This last bit is a bit icky, but it's only for debugging anyway. We could
 * build in ns16550.c with some effort, but this is a payload loader after
 * all.
 *
 * Note: We avoid using printf() so we don't need to bring in lib/vsprintf.c.
 * That would require some refactoring since we already build this for U-Boot.
 * Building an EFI shared library version would have to be a separate stem.
 * That might push us to using the SPL framework to build this stub. However
 * that would involve a round of EFI-specific changes in SPL. Worth
 * considering if we start needing more U-Boot functionality. Note that we
 * could then move get_codeseg32() to arch/x86/cpu/cpu.c.
 */
void _debug_uart_init(void)
{
}

void putc(const char ch)
{
        if (ch == '\n')
                putc('\r');

        if (use_uart) {
                NS16550_t com_port = (NS16550_t)0x3f8;

                while ((inb((ulong)&com_port->lsr) & UART_LSR_THRE) == 0)
                        ;
                outb(ch, (ulong)&com_port->thr);
        } else {
                efi_putc(global_priv, ch);
        }
}

void puts(const char *str)
{
        while (*str)
                putc(*str++);
}

static void _debug_uart_putc(int ch)
{
        putc(ch);
}

DEBUG_UART_FUNCS

void *memcpy(void *dest, const void *src, size_t size)
{
        unsigned char *dptr = dest;
        const unsigned char *ptr = src;
        const unsigned char *end = src + size;

        while (ptr < end)
                *dptr++ = *ptr++;

        return dest;
}

void *memset(void *inptr, int ch, size_t size)
{
        char *ptr = inptr;
        char *end = ptr + size;

        while (ptr < end)
                *ptr++ = ch;

        return ptr;
}

static void jump_to_uboot(ulong cs32, ulong addr, ulong info)
{
#ifdef CONFIG_EFI_STUB_32BIT
        /*
         * U-Boot requires these parameters in registers, not on the stack.
         * See _x86boot_start() for this code.
         */
        typedef void (*func_t)(int bist, int unused, ulong info)
                __attribute__((regparm(3)));

        ((func_t)addr)(0, 0, info);
#else
        cpu_call32(cs32, CONFIG_SYS_TEXT_BASE, info);
#endif
}

#ifdef CONFIG_EFI_STUB_64BIT
static void get_gdt(struct desctab_info *info)
{
        asm volatile ("sgdt %0" : : "m"(*info) : "memory");
}
#endif

static inline unsigned long read_cr3(void)
{
        unsigned long val;

        asm volatile("mov %%cr3,%0" : "=r" (val) : : "memory");
        return val;
}

/**
 * get_codeseg32() - Find the code segment to use for 32-bit code
 *
 * U-Boot only works in 32-bit mode at present, so when booting from 64-bit
 * EFI we must first change to 32-bit mode. To do this we need to find the
 * correct code segment to use (an entry in the Global Descriptor Table).
 *
 * @return code segment GDT offset, or 0 for 32-bit EFI, -ENOENT if not found
 */
static int get_codeseg32(void)
{
        int cs32 = 0;

#ifdef CONFIG_EFI_STUB_64BIT
        struct desctab_info gdt;
        uint64_t *ptr;
        int i;

        get_gdt(&gdt);
        for (ptr = (uint64_t *)(unsigned long)gdt.addr, i = 0; i < gdt.limit;
             i += 8, ptr++) {
                uint64_t desc = *ptr;
                uint64_t base, limit;

                /*
                 * Check that the target U-Boot jump address is within the
                 * selector and that the selector is of the right type.
                 */
                base = ((desc >> GDT_BASE_LOW_SHIFT) & GDT_BASE_LOW_MASK) |
                        ((desc >> GDT_BASE_HIGH_SHIFT) & GDT_BASE_HIGH_MASK)
                                << 16;
                limit = ((desc >> GDT_LIMIT_LOW_SHIFT) & GDT_LIMIT_LOW_MASK) |
                        ((desc >> GDT_LIMIT_HIGH_SHIFT) & GDT_LIMIT_HIGH_MASK)
                                << 16;
                base <<= 12;    /* 4KB granularity */
                limit <<= 12;
                if ((desc & GDT_PRESENT) && (desc && GDT_NOTSYS) &&
                    !(desc & GDT_LONG) && (desc & GDT_4KB) &&
                    (desc & GDT_32BIT) && (desc & GDT_CODE) &&
                    CONFIG_SYS_TEXT_BASE > base &&
                    CONFIG_SYS_TEXT_BASE + CONFIG_SYS_MONITOR_LEN < limit
                ) {
                        cs32 = i;
                        break;
                }
        }

#ifdef DEBUG
        puts("\ngdt: ");
        printhex8(gdt.limit);
        puts(", addr: ");
        printhex8(gdt.addr >> 32);
        printhex8(gdt.addr);
        for (i = 0; i < gdt.limit; i += 8) {
                uint32_t *ptr = (uint32_t *)((unsigned long)gdt.addr + i);

                puts("\n");
                printhex2(i);
                puts(": ");
                printhex8(ptr[1]);
                puts("  ");
                printhex8(ptr[0]);
        }
        puts("\n ");
        puts("32-bit code segment: ");
        printhex2(cs32);
        puts("\n ");

        puts("page_table: ");
        printhex8(read_cr3());
        puts("\n ");
#endif
        if (!cs32) {
                puts("Can't find 32-bit code segment\n");
                return -ENOENT;
        }
#endif

        return cs32;
}

static int setup_info_table(struct efi_priv *priv, int size)
{
        struct efi_info_hdr *info;
        efi_status_t ret;

        /* Get some memory for our info table */
        priv->info_size = size;
        info = efi_malloc(priv, priv->info_size, &ret);
        if (ret) {
                printhex2(ret);
                puts(" No memory for info table: ");
                return ret;
        }

        memset(info, '\0', sizeof(*info));
        info->version = EFI_TABLE_VERSION;
        info->hdr_size = sizeof(*info);
        priv->info = info;
        priv->next_hdr = (char *)info + info->hdr_size;

        return 0;
}

static void add_entry_addr(struct efi_priv *priv, enum efi_entry_t type,
                           void *ptr1, int size1, void *ptr2, int size2)
{
        struct efi_entry_hdr *hdr = priv->next_hdr;

        hdr->type = type;
        hdr->size = size1 + size2;
        hdr->addr = 0;
        hdr->link = ALIGN(sizeof(*hdr) + hdr->size, 16);
        priv->next_hdr += hdr->link;
        memcpy(hdr + 1, ptr1, size1);
        memcpy((void *)(hdr + 1) + size1, ptr2, size2);
        priv->info->total_size = (ulong)priv->next_hdr - (ulong)priv->info;
}

/**
 * efi_main() - Start an EFI image
 *
 * This function is called by our EFI start-up code. It handles running
 * U-Boot. If it returns, EFI will continue.
 */
efi_status_t efi_main(efi_handle_t image, struct efi_system_table *sys_table)
{
        struct efi_priv local_priv, *priv = &local_priv;
        struct efi_boot_services *boot = sys_table->boottime;
        struct efi_mem_desc *desc;
        struct efi_entry_memmap map;
        efi_uintn_t key, desc_size, size;
        efi_status_t ret;
        u32 version;
        int cs32;

        ret = efi_init(priv, "Payload", image, sys_table);
        if (ret) {
                printhex2(ret); puts(" efi_init() failed\n");
                return ret;
        }
        global_priv = priv;

        cs32 = get_codeseg32();
        if (cs32 < 0)
                return EFI_UNSUPPORTED;

        /* Get the memory map so we can switch off EFI */
        size = 0;
        ret = boot->get_memory_map(&size, NULL, &key, &desc_size, &version);
        if (ret != EFI_BUFFER_TOO_SMALL) {
                printhex2(BITS_PER_LONG);
                printhex2(ret);
                puts(" No memory map\n");
                return ret;
        }
        size += 1024;   /* Since doing a malloc() may change the memory map! */
        desc = efi_malloc(priv, size, &ret);
        if (!desc) {
                printhex2(ret);
                puts(" No memory for memory descriptor: ");
                return ret;
        }
        ret = setup_info_table(priv, size + 128);
        if (ret)
                return ret;

        ret = boot->get_memory_map(&size, desc, &key, &desc_size, &version);
        if (ret) {
                printhex2(ret);
                puts(" Can't get memory map\n");
                return ret;
        }

        ret = boot->exit_boot_services(image, key);
        if (ret) {
                /*
                 * Unfortunately it happens that we cannot exit boot services
                 * the first time. But the second time it work. I don't know
                 * why but this seems to be a repeatable problem. To get
                 * around it, just try again.
                 */
                printhex2(ret);
                puts(" Can't exit boot services\n");
                size = sizeof(desc);
                ret = boot->get_memory_map(&size, desc, &key, &desc_size,
                                           &version);
                if (ret) {
                        printhex2(ret);
                        puts(" Can't get memory map\n");
                        return ret;
                }
                ret = boot->exit_boot_services(image, key);
                if (ret) {
                        printhex2(ret);
                        puts(" Can't exit boot services 2\n");
                        return ret;
                }
        }

        map.version = version;
        map.desc_size = desc_size;
        add_entry_addr(priv, EFIET_MEMORY_MAP, &map, sizeof(map), desc, size);
        add_entry_addr(priv, EFIET_END, NULL, 0, 0, 0);

        /* The EFI UART won't work now, switch to a debug one */
        use_uart = true;

        memcpy((void *)CONFIG_SYS_TEXT_BASE, _binary_u_boot_bin_start,
               (ulong)_binary_u_boot_bin_end -
               (ulong)_binary_u_boot_bin_start);

#ifdef DEBUG
        puts("EFI table at ");
        printhex8((ulong)priv->info);
        puts(" size ");
        printhex8(priv->info->total_size);
#endif
        putc('\n');
        jump_to_uboot(cs32, CONFIG_SYS_TEXT_BASE, (ulong)priv->info);

        return EFI_LOAD_ERROR;
}