4412驅動 led驅動 自動建立裝置節點

2021-07-31 11:25:40 字數 2311 閱讀 3039

驅動**

#include #include #include #include //file_operations


#include #include //request_mem_region


#include #include //class_create device_create


#define devname "ldm"


struct ldm_info ;


static struct ldm_info ldm;


#define gpm4con (*(volatile unsigned long*)(s5p_va_gpio2 + 0x02e0))


#define gpm4dat (*(volatile unsigned char*)(s5p_va_gpio2 + 0x02e4))


static void led_init(void)


//點燈，相應位為1，滅燈，0，亮燈


static void led_on(unsigned char led_stat)


static ssize_t ldm_write(struct file *filp, const char __user *buf, size_t size, loff_t *offset)


static int __init ldm_init(void)


//3 註冊裝置號，成功後可在/proc/devices看到註冊資訊


//從核心documentation/devices.txt中找乙個無人使用的裝置號


//核心中裝置號用dev_t表示，包含主裝置號和次裝置號，分別佔據不同的bit。mkdev,major,minor三個巨集用於合成和拆分裝置號


ldm.dev.dev = mkdev(40, 0);


ret = register_chrdev_region(ldm.dev.dev, 1, devname);


if (ret < 0) 


}	printk("dev number major=%d, minor=%d\n", major(ldm.dev.dev), minor(ldm.dev.dev));


//4 為fops填充操作方法


ldm.fops.write = ldm_write;


//5 註冊字元裝置


ret = cdev_add(&ldm.dev, ldm.dev.dev, 1);


if (ret < 0) 


//6 硬體初始化


led_init();


//7 自動建立裝置結點


//在/sys/class下建立相應資料夾和資訊，包含裝置號資訊。根檔案系統中的mdev服務會自動根據這些資訊，建立裝置結點


ldm.cls = class_create(this_module, devname);


if (is_err(ldm.cls)) 


struct device *dev = device_create(ldm.cls, null, ldm.dev.dev, null, devname);


if (is_err(dev)) 


return 0;


err_device_create:


class_destroy(ldm.cls);


err_class_create:


cdev_del(&ldm.dev);


err_cdev_add:


unregister_chrdev_region(ldm.dev.dev, 1);


err_alloc_chrdev_region:


release_mem_region(0x110002e0, 8);


err_request_mem_region:


return ret;


}static void __exit ldm_exit(void)


module_init(ldm_init);


module_exit(ldm_exit);


module_license("gpl");

應用** 

#include #include #include #include #define devname "/dev/ldm"


int main(int argc, char **argv)


int fd = open(devname, o_rdwr);


if (fd < 0) 


size_t led_status = atoi(argv[1]);


write(fd, &led_status, 1);


close(fd);


return 0;


}

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