{var%20f='http://v.t.sina.com.cn/share/share.php?appkey=1515056452',u=z||d.location,p=['&url=',e(u),'&title=',e(t||d.title),'&source=',e(r),'&sourceUrl=',e(l),'&content=',c||'gb2312','&pic=',e(p||'')].join('');function%20a(){if(!window.open([f,p].join(''),'mb',['toolbar=0,status=0,resizable=1,width=440,height=430,left=',(s.width-440)/2,',top=',(s.height-430)/2].join('')))u.href=[f,p].join('');};if(/Firefox/.test(navigator.userAgent))setTimeout(a,0);else%20a();})(screen,document,encodeURIComponent,'','','https://www.xiaopingtou.cn//data/attach/topic/topicKPo7gB.jpg', '推荐 99terry 的文章《Linux内核中IO地址空间映射实例》','https://www.xiaopingtou.net/article-61375.html','页面编码gb2312|utf-8默认gb2312'));){kind=link}
关于IO地址映射，如中断外设的地址和映射后的地址访问
下面是P1020 手册中关于PIC中断控制器的描述
PIC Memory Map/Register Definition
The PIC programmable register map occupies 256 Kbytes of memory-mapped space. Reading undefined portions of the memory map returns all zeros; writing has no effect.
All PIC registers are 32 bits wide and, although located on 128-bit address boundaries,
should be accessed only as 32-bit quantities.
The PIC address offset map is divided into three areas:
• 0xnn4_0000-0xnn4_FFF0-Global registers
• 0xnn5_0000-0xnn5_FFF0-Interrupt source configuration registers
• 0xnn6_0000-0xnn7_FFF0-Per-CPU registers![]()
由图看到，假如我想访问PIC_EIVPR4，程序如下
注意PIC控制器的描述：
All PIC registers are 32 bits wide and, although located on 128-bit address boundaries,
should be accessed only as 32-bit quantities.
实际上PIC寄存器是32位宽，但占用了128bit（16个int）地址范围 但访问还是要按照32位的地址
The PIC programmable register map occupies 256 Kbytes of memory-mapped space. Reading undefined portions of the memory map returns all zeros; writing has no effect.
All PIC registers are 32 bits wide and, although located on 128-bit address boundaries,
should be accessed only as 32-bit quantities.
The PIC address offset map is divided into three areas:
• 0xnn4_0000-0xnn4_FFF0-Global registers
• 0xnn5_0000-0xnn5_FFF0-Interrupt source configuration registers
• 0xnn6_0000-0xnn7_FFF0-Per-CPU registers
由图看到，假如我想访问PIC_EIVPR4，程序如下
int16->pic_vaddr =(unsigned int *)ioremap(get_immrbase() + 0x50080, 128); 映射之后就可以访问了
如果我想访问PIC_EIDR4
out_be32((int16->pic_vaddr+4), regdata);为什么这个地方是+4呢，而不是+0x10 ???注意PIC控制器的描述：
All PIC registers are 32 bits wide and, although located on 128-bit address boundaries,
should be accessed only as 32-bit quantities.
实际上PIC寄存器是32位宽，但占用了128bit（16个int）地址范围 但访问还是要按照32位的地址