在开发模块功能时，需要用到一些调试或者传值给模块的方法，最简单的就是构造一个proc文件，然后配置传值或查看 。

如下提供了一个简单模板，需要时可以直接复制过去使用。

/* Init a test proc file 'btn_test'*/
#include <linux/proc_fs.h>


static char nvram_query_str[256]={0};
static ssize_t btn_test_read(struct file *file,
				char __user *buf,
				size_t len, loff_t *pos)
{
    int ret=0;

    ret = sprintf(buf, "%s", nvram_query_str);
    
    
    return simple_read_from_buffer(buf, len, pos, buf, strlen(buf));

}

static ssize_t btn_test_write(struct file *file, const char *buff, size_t len, loff_t *offset)
{
    memset(nvram_query_str, '\0', sizeof(nvram_query_str));

    if ((len > sizeof(nvram_query_str)-1) || (copy_from_user(nvram_query_str, buff, len) != 0))
        return -EFAULT;
    
    if('1' == nvram_query_str[0])
    {
        printk("[%s][%d] Do Restore action.\n", __FUNCTION__, __LINE__);
        btnHook_RestoreToDefault(0, NULL);
        
    }

    return len;
}

const struct file_operations btn_test_fops = {
	.owner = THIS_MODULE,
	.read = btn_test_read,
	.write = btn_test_write,

};

static int init_proc_btn_test(void)
{

    proc_create("btn_test", S_IRUGO, NULL, &btn_test_fops);

    printk("[%s][%d] Success.s\n", __FUNCTION__, __LINE__);
    
    return 0;
}

//file: fs/libfs.c
/**
 * simple_read_from_buffer - copy data from the buffer to user space
 * @to: the user space buffer to read to
 * @count: the maximum number of bytes to read
 * @ppos: the current position in the buffer
 * @from: the buffer to read from
 * @available: the size of the buffer
 *
 * The simple_read_from_buffer() function reads up to @count bytes from the
 * buffer @from at offset @ppos into the user space address starting at @to.
 *
 * On success, the number of bytes read is returned and the offset @ppos is
 * advanced by this number, or negative value is returned on error.
 **/
ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
				const void *from, size_t available)
{
	loff_t pos = *ppos;
	size_t ret;

	if (pos < 0)
		return -EINVAL;
	if (pos >= available || !count)
		return 0;
	if (count > available - pos)
		count = available - pos;
	ret = copy_to_user(to, from + pos, count);
	if (ret == count)
		return -EFAULT;
	count -= ret;
	*ppos = pos + count;
	return count;
}
EXPORT_SYMBOL(simple_read_from_buffer);
/**
 * simple_write_to_buffer - copy data from user space to the buffer
 * @to: the buffer to write to
 * @available: the size of the buffer
 * @ppos: the current position in the buffer
 * @from: the user space buffer to read from
 * @count: the maximum number of bytes to read
 *
 * The simple_write_to_buffer() function reads up to @count bytes from the user
 * space address starting at @from into the buffer @to at offset @ppos.
 *
 * On success, the number of bytes written is returned and the offset @ppos is
 * advanced by this number, or negative value is returned on error.
 **/
ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
		const void __user *from, size_t count)
{
	loff_t pos = *ppos;
	size_t res;

	if (pos < 0)
		return -EINVAL;
	if (pos >= available || !count)
		return 0;
	if (count > available - pos)
		count = available - pos;
	res = copy_from_user(to + pos, from, count);
	if (res == count)
		return -EFAULT;
	count -= res;
	*ppos = pos + count;
	return count;
}
EXPORT_SYMBOL(simple_write_to_buffer);