学步园

在调试的过程中我们通常需要去不停的修改寄存器的值来调试效果，在现在发现有两个手段，分别利用的proc和sys
proc--|
      |-----read_proc
      |-----write_proc
      
sys---|
      |-----show
      |-----store

proc的方法不依赖与kobject，sys中show和store则依赖于kobject。      
基本的使用如下：
----------------------------------------------------------------------
--------------------------  start proc   ----------------------------
----------------------------------------------------------------------

	struct proc_dir_entry *prEntry;


    prEntry = create_proc_entry("driver/proc_func", 0, NULL); 
    if (prEntry) {
        prEntry->read_proc = read_proc_func; 
        prEntry->write_proc = write_proc_func; 
    }
    else {
        printk("add /proc/driver/camsensor entry fail \n");  
    }

对于read_proc和write_proc的定义则参考proc_fs.h中的定义即可以实现

/*
 * This is not completely implemented yet. The idea is to
 * create an in-memory tree (like the actual /proc filesystem
 * tree) of these proc_dir_entries, so that we can dynamically
 * add new files to /proc.
 *
 * The "next" pointer creates a linked list of one /proc directory,
 * while parent/subdir create the directory structure (every
 * /proc file has a parent, but "subdir" is NULL for all
 * non-directory entries).
 */


typedef	int (read_proc_t)(char *page, char **start, off_t off,
			  int count, int *eof, void *data);
typedef	int (write_proc_t)(struct file *file, const char __user *buffer,
			   unsigned long count, void *data);

----------------------------------------------------------------------
--------------------------   end  proc   ---------------------------
----------------------------------------------------------------------

相对的利用sys中实现接口调试则如下实现，前提是有device设备哦，亲。
---------------------------------------------------------------------
--------------------------   start  sys   --------------------------
---------------------------------------------------------------------

static struct device_attribute test1_attr = {
	.attr = {
		.name = "test1",
		.mode = 0644,
		.owner = THIS_MODULE
	},
	.show = test1_show_func,
	.store = test1_store_func,
};


static struct device_attribute *test_attributes[] = {
	&test1_attr,
	&test2_attr,
	&test3_attr,
};


for (i = 0; i < ARRAY_SIZE(*test_attributes); i++) {
	ret = device_create_file(&dev,
					*test_attributes[i]);
	if (ret) {
		printk("failed: sysfs file %s\n",*test_attributes[i]->attr.name);
		goto failed_unregister_dev_file;
	}
}

关于show和store的函数的定义则如下

/* 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);
};

---------------------------------------------------------------------
--------------------------    end   sys   --------------------------
----------------------------------------------------------------------

通过这两种方式可以在调试LCM或者是Camera的时候不必要重新编译了，对调试效果帮助很大。