学步园

        在调试芯片驱动的调试阶段，经常会碰到寄存器值不确定，需要不断更改寄存器的值来调试芯片驱动的效果到最佳状态，从而出现要不停的编译驱动代码，这样浪费了很多的时间，下面介绍一种调试的方法，通过创建节点，通过echo和cat来写和读设备寄存器的值，从而达到快速调试的效果。

        首先要创建节点，在驱动的探测函数中，创建节点：device_create_file(devices*, device_attribute*)；

        在驱动的卸载函数中，删除节点： device_remove_file(devices*, device_attribute*)；

        具体的实现如下代码

#define tw9912_TEST 1//Harvey add for tw9912 test
#if tw9912_TEST
#define tp_major 555
#endif

#if  tw9912_TEST
static u8 tw9912REG;
static u8 tw9912VAL;
static u8 cameramode;
static u8 camerafmt;
static ssize_t TEST_mode_show(struct device *dev,
			struct device_attribute *attr, char *_buf)//(struct class *cls, char *_buf)
{
    int count;
    
	count = sprintf(_buf,"tw9912Mode:%d\n",
                                        cameramode);
	printk(KERN_INFO "tw9912_data.CameraDispMode %d\n",cameramode);		
	return count;
}

static ssize_t TEST_mode_store(struct device *dev,
			struct device_attribute *attr, char *_buf,size_t _count)//(struct class *cls, const char *_buf, size_t _count)
{
     int tmp_get_android = 0;
    tmp_get_android = simple_strtol(_buf, NULL, 10); 
    printk(KERN_INFO "cameramode %d\n",tmp_get_android);
    cameramode=tmp_get_android;
    tw9912_init_Disp_mode(cameramode,camerafmt);
    return _count; 
}


static ssize_t TEST_FMT_show(struct device *dev,
			struct device_attribute *attr, char *_buf)//(struct class *cls, char *_buf)
{
    int count;
    
	count = sprintf(_buf,"tw9912FMT:%d\n",
                                        camerafmt);
	printk(KERN_INFO "tw9912_data.CameraDispFMT %d\n",camerafmt);		
	return count;
}

static ssize_t TEST_FMT_store(struct device *dev,
			struct device_attribute *attr, char *_buf,size_t _count)//(struct class *cls, const char *_buf, size_t _count)
{
     int tmp_get_android = 0;
    tmp_get_android = simple_strtol(_buf, NULL, 10); 
    printk(KERN_INFO "tw9912_data.CameraDispFMT %d\n",tmp_get_android);	
    camerafmt=tmp_get_android;
    tw9912_init_Disp_mode(cameramode,camerafmt);
    return _count; 
}


static ssize_t TEST_REG_show(struct device *dev,
			struct device_attribute *attr, char *_buf)//(struct class *cls, char *_buf)
{
    int count;
    
	count = sprintf(_buf,"tw9912REG:0x%x\n",
                                         tw9912REG);
	printk(KERN_INFO "tw9912REG 0x%x\n",tw9912REG);		
	return count;
}

static ssize_t TEST_REG_store(struct device *dev,
			struct device_attribute *attr, char *_buf,size_t _count)//(struct class *cls, const char *_buf, size_t _count)
{
   //  int tmp_get_android = 0;
    tw9912REG = simple_strtol(_buf, NULL, 16); 
    printk(KERN_INFO "tw9912REG %x\n",tw9912REG);	
    return _count; 
}

static ssize_t TEST_VAL_show(struct device *dev,
			struct device_attribute *attr, char *_buf)//(struct class *cls, char *_buf)
{
    int count;
	tw9912VAL=tw9912_read(tw9912REG);
//	   printk(KERN_INFO "tw9912Read ERROR\n");	   
	count = sprintf(_buf,"tw9912VAL:0x%x\n",
                                         tw9912VAL);
	printk(KERN_INFO "tw9912VAL 0x%x\n",tw9912VAL);		
	return count;
}

static ssize_t TEST_VAL_store(struct device *dev,
			struct device_attribute *attr, char *_buf,size_t _count)//(struct class *cls, const char *_buf, size_t _count)
{
   //  int tmp_get_android = 0;
    tw9912VAL = simple_strtol(_buf, NULL, 16); 
    printk(KERN_INFO "tw9912VAL %x\n",tw9912VAL);
    
   if(tw9912_write_reg(tw9912REG,tw9912VAL)<0)
   	 printk(KERN_INFO "tw9912Write ERROR\n");
    return _count; 
}

static struct class *tw9912_TEST_class = NULL;
static struct device *tw9912_TEST_dev=NULL;

static DEVICE_ATTR(TESTMODE, 0666, TEST_mode_show, TEST_mode_store);
static DEVICE_ATTR(TESTFMT, 0666, TEST_FMT_show, TEST_FMT_store);
static DEVICE_ATTR(TESTREG, 0666, TEST_REG_show, TEST_REG_store);
static DEVICE_ATTR(TESTVAL, 0666, TEST_VAL_show, TEST_VAL_store);
#endif

static int tw9912_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
        ……
     #if tw9912_TEST
    tw9912_TEST_class= class_create(THIS_MODULE, "tw9912Testclass");
     tw9912_TEST_dev= device_create(tw9912_TEST_class, NULL, MKDEV(tp_major, 0), NULL, "tw9912Testdev");
        device_create_file(tw9912_TEST_dev, &dev_attr_TESTMODE);
        device_create_file(tw9912_TEST_dev, &dev_attr_TESTFMT);
        device_create_file(tw9912_TEST_dev, &dev_attr_TESTREG);
        device_create_file(tw9912_TEST_dev, &dev_attr_TESTVAL);
#endif
        ……
}

static int tw9912_remove(struct i2c_client *client)
{
        ……
#if tw9912_TEST
    device_remove_file(tw9912_TEST_dev, &dev_attr_TESTMODE);
    device_remove_file(tw9912_TEST_dev, &dev_attr_TESTFMT);
    device_remove_file(tw9912_TEST_dev, &dev_attr_TESTREG);
    device_remove_file(tw9912_TEST_dev, &dev_attr_TESTVAL);
     device_destroy(tw9912_TEST_dev, MKDEV(tp_major, 0));    
     class_destroy(tw9912_TEST_class);
#endif
      ……
}