#include "bios.h"
#include "e820.h"
#include "pci.h"
#include "string.h"
#include "segment.h"
#include "fw_cfg.h"

#define PCI_VENDOR_ID_INTEL		0x8086
#define PCI_DEVICE_ID_INTEL_82441	0x1237
#define PCI_DEVICE_ID_INTEL_Q35_MCH     0x29c0

#define I440FX_PAM0                     0x59
#define Q35_HOST_BRIDGE_PAM0            0x90

static void make_bios_writable(void)
{
	const int bdf = 0;
	const uint8_t *bios_start = (uint8_t *)0xffff0000;
	uint8_t *low_start = (uint8_t *)0xf0000;
	int pambase;

        uint32_t id = pci_config_readl(bdf, 0);
        if (id == (PCI_VENDOR_ID_INTEL | (PCI_DEVICE_ID_INTEL_82441 << 16)))
		pambase = I440FX_PAM0;
        else if (id == (PCI_VENDOR_ID_INTEL | (PCI_DEVICE_ID_INTEL_Q35_MCH << 16)))
		pambase = Q35_HOST_BRIDGE_PAM0;
        else
		panic();

	// Make ram from 0xc0000-0xf0000 read-write
	int i;
	for (i=0; i<6; i++) {
		int pam = pambase + 1 + i;
		pci_config_writeb(bdf, pam, 0x33);
	}

	// Make ram from 0xf0000-0x100000 read-write and shadow BIOS
	// We're still running from 0xffff0000
	pci_config_writeb(bdf, pambase, 0x30);
	memcpy(low_start, bios_start, 0x10000);
}

static void set_realmode_int(int vec, void *p)
{
	uint16_t *realmode_idt = (uint16_t *) 0;
	realmode_idt[vec * 2] = flat_to_off16((uintptr_t) p);
	realmode_idt[vec * 2 + 1] = flat_to_seg16((uintptr_t) p);
}

static void setup_pic(void)
{
    /* Send ICW1 (select OCW1 + will send ICW4) */
    outb(0x20, 0x11);
    outb(0xa0, 0x11);
    /* Send ICW2 (base irqs: 0x08-0x0f for irq0-7, 0x70-0x77 for irq8-15) */
    outb(0x21, 8);
    outb(0xa1, 0x70);
    /* Send ICW3 (cascaded pic ids) */
    outb(0x21, 0x04);
    outb(0xa1, 0x02);
    /* Send ICW4 (enable 8086 mode) */
    outb(0x21, 0x01);
    outb(0xa1, 0x01);
    /* Mask all irqs (except cascaded PIC2 irq) */
    outb(0x21, ~(1 << 2));
    outb(0xa1, ~0);
}

static void setup_idt(void)
{
	int i;
	for (i = 0; i < 0x1f; i++)
		set_realmode_int(i, bios_intfake);
	for (i = 8; i < 16; i++)
		set_realmode_int(i, bios_irq);
	for (i = 0x70; i < 0x78; i++)
		set_realmode_int(i, bios_irq);
	set_realmode_int(0x10, bios_int10);
	set_realmode_int(0x15, bios_int15);
}

static void extract_e820(void)
{
	int id = fw_cfg_file_id("etc/e820");
	uint32_t size;

	if (id == -1)
		panic();

	size = fw_cfg_file_size(id);
	e820.nr_map = size / sizeof(e820.map[0]);
	fw_cfg_file_select(id);
	fw_cfg_read(&e820.map, size);
}

int main(void)
{
	make_bios_writable();
	setup_pic();
	setup_idt();
	fw_cfg_setup();
	// extract_acpi();
	extract_e820();
	// extract_smbios();
	// extract_kernel();
	// make_bios_readonly();
	boot_linux();
	panic();
}