struct map_desc {
unsigned long virtual; /* 映射后的虚拟地址 */
unsigned long pfn; /* 物理地址所在的页帧号 */
unsigned long length; /* 映射长度 */
unsigned int type; /* 映射的设备类型 */
};

/* minimal IO mapping */
static struct map_desc s3c_iodesc[] __initdata = {
	{
		.virtual	= (unsigned long)S3C_VA_SYS,
		.pfn		= __phys_to_pfn(S3C64XX_PA_SYSCON),
		.length		= SZ_4K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)S3C_VA_MEM,
		.pfn		= __phys_to_pfn(S3C64XX_PA_SROM),
		.length		= SZ_4K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)(S3C_VA_UART + UART_OFFS),
		.pfn		= __phys_to_pfn(S3C_PA_UART),
		.length		= SZ_4K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)VA_VIC0,
		.pfn		= __phys_to_pfn(S3C64XX_PA_VIC0),
		.length		= SZ_16K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)VA_VIC1,
		.pfn		= __phys_to_pfn(S3C64XX_PA_VIC1),
		.length		= SZ_16K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)S3C_VA_TIMER,
		.pfn		= __phys_to_pfn(S3C_PA_TIMER),
		.length		= SZ_16K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)S3C64XX_VA_GPIO,
		.pfn		= __phys_to_pfn(S3C64XX_PA_GPIO),
		.length		= SZ_4K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)S3C64XX_VA_MODEM,
		.pfn		= __phys_to_pfn(S3C64XX_PA_MODEM),
		.length		= SZ_4K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)S3C_VA_WATCHDOG,
		.pfn		= __phys_to_pfn(S3C64XX_PA_WATCHDOG),
		.length		= SZ_4K,
		.type		= MT_DEVICE,
	}, {
		.virtual	= (unsigned long)S3C_VA_USB_HSPHY,
		.pfn		= __phys_to_pfn(S3C64XX_PA_USB_HSPHY),
		.length		= SZ_1K,
		.type		= MT_DEVICE,
	},


};

/* read cpu identification code */

void __init s3c64xx_init_io(struct map_desc *mach_desc, int size)
{
	unsigned long idcode;

	/* initialise the io descriptors we need for initialisation */
	iotable_init(s3c_iodesc, ARRAY_SIZE(s3c_iodesc)); //建立映射
	iotable_init(mach_desc, size);

	idcode = __raw_readl(S3C_VA_SYS + 0x118);
	if (!idcode) {
		/* S3C6400 has the ID register in a different place,
		 * and needs a write before it can be read. */

		__raw_writel(0x0, S3C_VA_SYS + 0xA1C);
		idcode = __raw_readl(S3C_VA_SYS + 0xA1C);
	}

	s3c_init_cpu(idcode, cpu_ids, ARRAY_SIZE(cpu_ids));
}

/* read cpu identification code */

void __init s3c64xx_init_io(struct map_desc *mach_desc, int size)
{
	unsigned long idcode;

	/* initialise the io descriptors we need for initialisation */
	iotable_init(s3c_iodesc, ARRAY_SIZE(s3c_iodesc)); //建立映射
	iotable_init(mach_desc, size);

	idcode = __raw_readl(S3C_VA_SYS + 0x118);
	if (!idcode) {
		/* S3C6400 has the ID register in a different place,
		 * and needs a write before it can be read. */

		__raw_writel(0x0, S3C_VA_SYS + 0xA1C);
		idcode = __raw_readl(S3C_VA_SYS + 0xA1C);
	}

	s3c_init_cpu(idcode, cpu_ids, ARRAY_SIZE(cpu_ids));
}