void cmd_reset(void)
{
    *(volatile u_int *)(base_addr + 0x15554) = 0xaa00aa;    // Read/Reset sequence
    *(volatile u_int *)(base_addr + 0x0aaa8) = 0x550055;    //
    *(volatile u_int *)(base_addr + 0x15554) = 0xf000f0;    //
}

u_int cmd_write_word(u_int data)
{
    *(volatile u_int *)(base_addr + 0x15554) = 0xaa00aa;    // Program sequence
    *(volatile u_int *)(base_addr + 0x0aaa8) = 0x550055;    //
    *(volatile u_int *)(base_addr + 0x15554) = 0xa000a0;    //
    *(volatile u_int *)(base_addr + offset) = data;
    return cmd_data_poll(data);
}

u_int cmd_erase_flash(void)
{
    cmd_erase_seq();
    *(volatile u_int *)(base_addr + 0x15554) = 0x100010;
    offset = 0x00;
    return cmd_data_poll(0xff00ff);
}

void cmd_identify(void)
{
    *(volatile u_int *)(base_addr + 0x15554) = 0xaa00aa;    // Autoselect sequence
    *(volatile u_int *)(base_addr + 0x0aaa8) = 0x550055;    //
    *(volatile u_int *)(base_addr + 0x15554) = 0x900090;    //
    manuf_code  = *(volatile u_int *)(base_addr);
    device_code = *(volatile u_int *)(base_addr + 0x04);
}

u_int cmd_erase_sector(void)
{
    cmd_erase_seq();
    *(volatile u_int *)(base_addr + offset) = 0x300030;
    return cmd_data_poll(0xff00ff);
}

void cmd_erase_seq(void)
{
    *(volatile u_int *)(base_addr + 0x15554) = 0xaa00aa;    // Erase sequence
    *(volatile u_int *)(base_addr + 0x0aaa8) = 0x550055;    //
    *(volatile u_int *)(base_addr + 0x15554) = 0x800080;    //
    *(volatile u_int *)(base_addr + 0x15554) = 0xaa00aa;    //
    *(volatile u_int *)(base_addr + 0x0aaa8) = 0x550055;    //
}    

u_int cmd_data_poll(u_int data)
{
    u_int a;

    do
    {
        a = *(volatile u_int*)(base_addr + offset);
    } while(((data & 0x800080) != (a & 0x800080)) && ((a & 0x200020) != 0x200020));
    if((data & 0x800080) != (*(volatile u_int*)(base_addr + offset) & 0x800080)) return 0x01;
    return 0x00;
}