LINUX下读写寄存器

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1、arm裸机下读写寄存器很容易,各个寄存器和内存的地址是单一地址空间,他们是用相同的指令进行读写操作的.而在linux下就要复杂很多,因为linux支持多个体系架构的CPU。比如arm和x86就不一样，具体的差别我暂时也说不上来，这个涉及到CPU体系的设计。目前我只关心：linux为了支持多个硬件体系，在IO访问上做了自己的接口。可以通过IO内存和IO端口这两种方式进行IO访问。在LED的例子上给出这两种方式的具体实现：1.利用IOPort的方式：[cpp]viewplaincopy#include

2、ux/module.h>#include#include#include/*printk()*/#include/*kmalloc()*/#include/*everything...*/#include/*errorcodes*/#include/*size_t*/#include

3、/proc_fs.h>#include/*O_ACCMODE*/#include#include#include#include#include/*cli(),*_flags*/#include/*copy_*_user*/#include#defineLED_NUM4

4、structled_dev{structcdevdev;unsignedport;unsignedlongoffset;};structled_devled[4];dev_tdev=0;staticstructresource*led_resource;intled_open(structinode*inode,structfile*filp){structled_dev*led;/*deviceinformation*/led=container_of(inode->i_cdev,structled_d

5、ev,dev);filp->private_data=led;/*forothermethods*/return0;/*success*/}intled_release(structinode*inode,structfile*filp){return0;}ssize_tled_read(structfile*filp,char__user*buf,size_tcount,loff_t*f_pos){return0;}ssize_tled_write(structfile*filp,constchar__

6、user*buf,size_tcount,loff_t*f_pos){chardata;structled_dev*led;u32value;printk(KERN_INFO"debugbybaikal:leddevwrite");led=(structled_dev*)filp->private_data;copy_from_user(&data,buf,count);if(data=='0'){printk(KERN_INFO"debugbybaikal:ledoff");value=inl(

7、(unsigned)(S3C2410_GPBDAT));outl(value

8、1<offset,(unsigned)(S3C2410_GPBDAT));//value=ioread32(led->base);//iowrite32(value

9、1<offset,led->base);}else{printk(KERN_INFO"debugbybaikal:ledon");value=inl((unsigned)(S3C2410_GPBDAT));outl(value&~(1<<

10、led->offset),(unsigned)(S3C2410_GPBDAT));//value=ioread32(led->base);//iowrite32(value&~(1<offset),led->base);}}structfile_operationsled_fops={.owner=THIS_MODULE,.read=led_read,.write=led_write,//.ioctl=led_io