我參考下面的三篇文章, 實做一個最基本功能的uio driver, 就為read 聽interrupt ,  mmap 去access 從kernel 映射到user space 的address , 後來發現聽interrupt 是可以, 但是 mmap 上來的位址,做讀取或寫入值的動作結果不如預期。我設定位置為chip select , 1mb (0x1A100000~0x1A1fffff), 讀取時會有一個固定的值, 但是怎麼read 都是錯的值,  char device 用ioremap(0x1A100000,0xf)作的話可以read正確的值,以下為程式碼, 最下面有三篇寫時所參考的文章:

kernel_part

#include <linux/module.h> 

#include <linux/platform_device.h> 

#include <linux/uio_driver.h>   

#include <linux/device.h> /* class_create */ 

#include <linux/kobject.h> /* kobject_uevent */ 

#include <linux/slab.h> /* kmalloc, kfree */ 

#define IRQ_INT 20

static struct resource abc[] = {

        [0] = {

                .start = 0x1A100000,

                .end =   0x1A100000+0xf,

                .flags = IORESOURCE_MEM,

        },

};

struct uio_info test_info = { 

        .name = "uio", 

        .version = "0.1", 

        .irq = IRQ_INT, 

}; 

static int drv_test_probe(struct device *dev); 

static int drv_test_remove(struct device *dev); 

static struct device_driver uio_test_driver = { 

        .name = "test", 

        .bus = &platform_bus_type, 

        .probe = drv_test_probe, 

        .remove = drv_test_remove, 

}; 

static irqreturn_t test_handler(int irq, struct uio_info *dev_info){

        printk("interrupt occur\n");

        return IRQ_HANDLED;

}

static int drv_test_probe(struct device *dev){ 

        test_info.mem[0].addr = abc[0].start;

        test_info.mem[0].size = abc[0].end - abc[0].start+1;

        test_info.mem[0].memtype = UIO_MEM_PHYS;

        test_info.mem[0].internal_addr= ioremap_nocache(test_info.mem[0].addr, test_info.mem[0].size+1);

    if(test_info.mem[0].addr == 0) 

            return -ENOMEM;

        test_info.irq = IRQ_INT;

    test_info.irq_flags = IRQF_SHARED;  

        test_info.handler=test_handler;

         if( uio_register_device(dev, &test_info)){ 

            kfree((void *)test_info.mem[0].addr); 

            return -ENODEV; 

    } 

    return 0; 

} 

static int drv_test_remove(struct device *dev) 

{ 

    uio_unregister_device(&test_info); 

    return 0; 

}

static struct platform_device * uio_test_device; 

static int __init uio_test_init(void){     

        uio_test_device = platform_device_register_simple("test", -1, NULL, 0); 

        return driver_register(&uio_test_driver); 

} 

static void __exit uio_test_exit(void){

        platform_device_unregister(uio_test_device); 

        driver_unregister(&uio_test_driver); 

} 

module_init(uio_test_init); 

module_exit(uio_test_exit); 

MODULE_LICENSE("Dual BSD/GPL");

MODULE_DESCRIPTION("UIO test driver");

User_space part

#include <errno.h>

#include <fcntl.h>

#include <stdio.h>

#include <sys/mman.h>

int main() {

        int uio_fd;

    void *access_address;

    int  interrupt=0;

        int i=0;

    uio_fd = open("/dev/uio0", O_RDWR | O_SYNC);

    if(uio_fd  < 0) {

        perror("uio open");

        return errno;

    }

    access_address = mmap(NULL, 0x10, PROT_READ | PROT_WRITE, MAP_SHARED, uio_fd, 0);

    if(access_address == MAP_FAILED) {

        perror("uio mmap");

        return errno;

    }

        printf("*access_address = %x\n", *((short *) access_address));

        unsigned int * addr = (unsigned int*) access_address;

        printf("*access_address = %x\n", *addr);

        read(uio_fd,&interrupt,sizeof(interrupt));

    return errno;

}

Reference:

        http://www.kernel.org/doc/htmldocs/uio-howto.html

http://blog.csdn.net/ganggexiongqi/article/details/6794215

http://daydreamer.idv.tw/rewrite.php/read-41.html