虚拟文件系统 的读和写

static DEVICE_ATTR(switch, 0666, xx_read, xx_write);

#define DEVICE_ATTR(_name, _mode, _show, _store) \

struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)

/* interface for exporting device attributes */

struct device_attribute {

struct attribute attr;

ssize_t (*show)(struct device *dev, struct device_attribute *attr,

char *buf);

ssize_t (*store)(struct device *dev, struct device_attribute *attr,

const char *buf, size_t count);

};

show是读取该文件的回调，store是写该文件的回调。

static ssize_t xxx_store(struct device *dev, struct device_attribute *attr,

const char *buf, size_t n)

{

printk("Hello world!!!!!!\n");

return n; 

}

这样在写该文件的时候，就会看到Hello world!!!的log.