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【转】s3c2440的IO静态映射的分析

来源: ChinaUnix博客 　日期： 2008.12.23 11:02　(共有0条评论) 我要评论
 

s3c2440的IO静态映射的分析
s3c2440的IO静态映射的分析
作者：creator
     
sz111@126.com
    昨天移植uda1341声卡到2440，出现io错误，最后发现IIS没有做内存映射，但是当时奇怪为何GPIO也没有做内存映射怎么就可以了呢？今天上午仔细分析了内核，发现内存的静态映射分几个部分在做，GPIO部分已经做了。下面就是内存映射的部分的分析。
    内存映射分3个层次，1.开发板的层次（如：声卡，网卡和开发板相关的部分）。2.其他系统的层次（不影响开机的部分，如：usb，lcd，adc），3.最小系统的层次（系统必需的几个，如GPIO,IRQ,MEMCTRL,UART).
    1.开发板的mapio的初始化。
    smdk2440_map_io函数中会调用：
    s3c24xx_init_io(smdk2440_iodesc, ARRAY_SIZE(smdk2440_iodesc));
    而开发板相关的内存映射在smdk2440_iodesc，有ISA，声卡，网卡等。
    定义如下：
    static struct map_desc smdk2440_iodesc[] __initdata = {
    /* ISA IO Space map (memory space selected by A24) */
    { (u32)S3C24XX_VA_ISA_WORD, S3C2410_CS2, SZ_16M, MT_DEVICE },
    { (u32)S3C24XX_VA_ISA_BYTE, S3C2410_CS2, SZ_16M, MT_DEVICE },
};
   2.s3c24xx_init_io函数会调用：iotable_init(s3c_iodesc, ARRAY_SIZE(s3c_iodesc));
     而s3c_iodesc定义如下：
     /* minimal IO mapping */
static struct map_desc s3c_iodesc[] __initdata = {
    IODESC_ENT(GPIO),
    IODESC_ENT(IRQ),
    IODESC_ENT(MEMCTRL),
    IODESC_ENT(UART)
};
     这个部分是系统启动必须的映射。
    后续会调用(cpu->map_io)(mach_desc, size);来完成其他映射。
    这个函数会调用iotable_init(s3c2440_iodesc, ARRAY_SIZE(s3c2440_iodesc));
    定义如下：
    static struct map_desc s3c2440_iodesc[] __initdata = {
    IODESC_ENT(USBHOST),
    IODESC_ENT(USBDEV),
    IODESC_ENT(CLKPWR),
    IODESC_ENT(LCD),
    IODESC_ENT(TIMER),
    IODESC_ENT(ADC),
    IODESC_ENT(WATCHDOG),
};
    综合上述发现，如果一个新加驱动，首先要看是否完成了IO映射，如果没有的话，就在开发板部分加入。
     


本文来自ChinaUnix博客，如果查看原文请点：http://blog.chinaunix.net/u2/78225/showart_1736164.html

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