Android底层驱动移植--gslx680电容触摸屏驱动

###前言
gslx680电容触摸屏是一种目前Android嵌入式设备中比较常用的触摸屏类型。这里我们以Exynos4412为Android bsp平台，移植一款gslx680电容触摸屏。
关于电容触摸屏的原理，这里不进行讲解，不明白的，可以参照一下博客：http://blog.csdn.net/xubin341719/article/details/7820492
这里只从实际工程出发，讲解移植过程。谢谢~~
###一、具体操作配置
####1.添加GSLX68X到内核的Kconfig配置
路径：xxx/kernel/drivers/input/touchscreen/Kconfig

####2.编写Makefile文件
路径：xxx/kernel/drivers/input/touchscreen/Makefile

####3.在触摸屏驱动目录xxx/kernel/drivers/input/touchscreen/文件夹下，添加一下文件：
gslx680.c
gslx680.h
gsl_point_id
查看附件

注意：gsl_point_id是一个Linux库文件
####4.因为TP采用的是I2C总线驱动，还要在linux/arch/arm/mach-exynos/mach-smdk4x12.c文件中添加

这里的IIC地址一定要与程序上面一致，并且和设备的吻合

###二、程序分析
####1.定义地址和参数

#define GSLX680_I2C_NAME "gslX680"        //IIC的设备名
#define GSLX680_I2C_ADDR 0x40             //IIC 设备的地址
#define IRQ_PORT	    IRQ_EINT(7)     //TP的中断引脚
#define GSL_DATA_REG	0x80            //IIC 设备具体功能寄存器的地址 这个是数据寄存器
#define GSL_STATUS_REG	0xe0            //状态寄存器
#define GSL_PAGE_REG	0xf0
#define PRESS_MAX 255            //手指按下的最大值
#define MAX_FINGERS 10             //支持的最大手指数
#define MAX_CONTACTS 10             //支持的最大关联
#define DMA_TRANS_LEN	0x20           //DMA传输的最大长度

####2.设备的驱动初始化函数
首先，在加载驱动后，Linux系统通过module_init(gsl_ts_init);进行设备的初始化

static int __init gsl_ts_init(void)
{
	int ret;
	if(strcasecmp(tp_name, "gslx680") == 0)
	{
		printk("Initial gslx680 Touch Driver\n");
	}
	else
	{
		return 0;
	}
	print_info("==gsl_ts_init==\n");
	ret = i2c_add_driver(&gsl_ts_driver);
	print_info("ret=%d\n",ret);
	return ret;
}

主要是通过i2c_add_driver(&gsl_ts_driver)将

static struct i2c_driver gsl_ts_driver = {
	.driver = {
	.name = GSLX680_I2C_NAME,
	.owner = THIS_MODULE,
},
#ifndef CONFIG_HAS_EARLYSUSPEND
	.suspend	= gsl_ts_suspend,
	.resume	= gsl_ts_resume,
#endif
	.probe	= gsl_ts_probe,
	.remove	= __devexit_p(gsl_ts_remove),
	.id_table	= gsl_ts_id,
};

挂载到IIC总线
####3.设备的探针函数
设备的探测函数，退出函数、设备的ID等等都注册上去。
在设备工作时，首先是探测函数

static int __devinit gsl_ts_probe(struct i2c_client *client,
                                  const struct i2c_device_id *id)
{
	struct gsl_ts *ts;
	int rc;
	print_info("GSLX680 Enter %s\n", __func__);
	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
		dev_err(&client->dev, "I2C functionality not supported\n");
		return -ENODEV;
	}
	ts = kzalloc(sizeof(*ts), GFP_KERNEL);
	if (!ts)
		return -ENOMEM;
	print_info("==kzalloc success=\n");
	ts->client = client;
	i2c_set_clientdata(client, ts);
	ts->device_id = id->driver_data;
	rc = gslX680_ts_init(client, ts); //初始化gls1680
	if (rc < 0) {
		dev_err(&client->dev, "GSLX680 init failed\n");
		goto error_mutex_destroy;
	}
	gsl_client = client;
	gslX680_init();
	/初始化gls1680相关的IO端口
	init_chip(ts->client);
	check_mem_data(ts->client);
	rc= request_irq(client->irq, gsl_ts_irq, IRQF_TRIGGER_RISING, client->name, ts); //中断请求 ，注册终端，上升沿触发 gsl_ts_irq 回调函数
	if (rc < 0) {
		print_info( "gsl_probe: request irq failed\n");
		goto error_req_irq_fail;
	}
	/* create debug attribute */
	//rc = device_create_file(&ts->input->dev, &dev_attr_debug_enable);
#ifdef CONFIG_HAS_EARLYSUSPEND
	ts->early_suspend.level = EARLY_SUSPEND_LEVEL_BLANK_SCREEN + 1;
	//ts->early_suspend.level = EARLY_SUSPEND_LEVEL_DISABLE_FB + 1;
	ts->early_suspend.suspend = gsl_ts_early_suspend;
	ts->early_suspend.resume = gsl_ts_late_resume;
	register_early_suspend(&ts->early_suspend);
#endif
#ifdef GSL_MONITOR
	print_info( "gsl_ts_probe () : queue gsl_monitor_workqueue\n");
	INIT_DELAYED_WORK(&gsl_monitor_work, gsl_monitor_worker);
	gsl_monitor_workqueue = create_singlethread_workqueue("gsl_monitor_workqueue");
	queue_delayed_work(gsl_monitor_workqueue, &gsl_monitor_work, 1000);
#endif
	print_info("[GSLX680] End %s\n", __func__);
	return 0;
	//exit_set_irq_mode:
error_req_irq_fail:
	free_irq(ts->irq, ts);
error_mutex_destroy:
	input_free_device(ts->input);
	kfree(ts);
	return rc;
}

####4.设备初始化

static int gslX680_ts_init(struct i2c_client *client, struct gsl_ts *ts)
{
	struct input_dev *input_device;
	int i, rc = 0;
	printk("[GSLX680] Enter %s\n", __func__);
	ts->dd = &devices[ts->device_id];
	if (ts->device_id == 0) {
		ts->dd->data_size = MAX_FINGERS * ts->dd->touch_bytes + ts->dd->touch_meta_data;
		ts->dd->touch_index = 0;
	}
	printk("ts->dd->data_size is %d\n", ts->dd->data_size);
	ts->touch_data = kzalloc(ts->dd->data_size, GFP_KERNEL);
	if (!ts->touch_data) {
		pr_err("%s: Unable to allocate memory\n", __func__);
		return -ENOMEM;
	}
	input_device = input_allocate_device(); //申请输入子系统设备
	if (!input_device) {
		rc = -ENOMEM;
		goto error_alloc_dev;
	}
	ts->input = input_device;
	input_device->name = GSLX680_I2C_NAME;
	input_device->id.bustype = BUS_I2C;
	input_device->dev.parent = &client->dev;
	input_set_drvdata(input_device, ts);
	/*set_bit()告诉input输入子系统支持哪些事件，哪些按键
	*/
	set_bit(ABS_MT_POSITION_X, input_device->absbit);//设置接触面的中心点X坐标
	set_bit(ABS_MT_POSITION_Y, input_device->absbit);//设置接触面的中心点Y坐标
	set_bit(ABS_MT_TOUCH_MAJOR, input_device->absbit);//设置触摸方向
	set_bit(ABS_MT_WIDTH_MAJOR, input_device->absbit);//设置手指触摸接触面积大小
	set_bit(ABS_PRESSURE, input_device->absbit);//设置压力
	set_bit(BTN_TOUCH, input_device->keybit);//按键触摸
	set_bit(EV_ABS, input_device->evbit);//绝对位移
	set_bit(EV_KEY, input_device->evbit);//按键类型
	set_bit(EV_SYN,input_device->evbit);//同步
	__set_bit(INPUT_PROP_DIRECT, input_device->propbit);
	input_mt_init_slots(input_device, (MAX_CONTACTS + 1));
//设置子系统的参数上报
	input_set_abs_params(input_device,ABS_MT_POSITION_X, 0, SCREEN_MAX_X, 0, 0);
	input_set_abs_params(input_device,ABS_MT_POSITION_Y, 0, SCREEN_MAX_Y, 0, 0);
	input_set_abs_params(input_device,ABS_MT_TOUCH_MAJOR, 0, PRESS_MAX, 0, 0);
	input_set_abs_params(input_device,ABS_MT_WIDTH_MAJOR, 0, 200, 0, 0);
	input_set_abs_params(input_device, ABS_MT_TRACKING_ID, 0, 5, 0, 0);
	input_set_abs_params(input_device,ABS_PRESSURE, 0, PRESS_MAX, 0 , 0);
	input_set_abs_params(input_device, ABS_MT_PRESSURE, 0, PRESS_MAX, 0, 0);
#ifdef HAVE_TOUCH_KEY
	input_device->evbit[0] = BIT_MASK(EV_KEY);
//input_device->evbit[0] = BIT_MASK(EV_SYN) | BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
	for (i = 0; i < MAX_KEY_NUM; i++)
		set_bit(key_array[i], input_device->keybit);
#endif
//中断设置
	client->irq = IRQ_PORT;
	ts->irq = client->irq;
//创建单线程的工作队列
	ts->wq = create_singlethread_workqueue("kworkqueue_ts");
	if (!ts->wq) {
		dev_err(&client->dev, "Could not create workqueue\n");
		goto error_wq_create;
	}
//工作队列的挂起
	flush_workqueue(ts->wq);
//初始化工作队列，对应的处理函数为gslX680_ts_worker
	INIT_WORK(&ts->work, gslX680_ts_worker);
//注册输入设备子系统
	rc = input_register_device(input_device);
	if (rc)
		goto error_unreg_device;
	return 0;
error_unreg_device:
	destroy_workqueue(ts->wq);
error_wq_create:
	input_free_device(input_device);
error_alloc_dev:
	kfree(ts->touch_data);
	return rc;
}

####5.IO的初始化

static int gslX680_init(void)
{
	/* shutdown pin */
	gpio_request_one(EXYNOS4_GPX0(6), GPIOF_OUT_INIT_HIGH, "GPX0");
	s3c_gpio_setpull(EXYNOS4_GPX0(6),S3C_GPIO_PULL_UP);
	s3c_gpio_cfgpin(EXYNOS4_GPX0(6), S3C_GPIO_OUTPUT);
	gpio_set_value(EXYNOS4_GPX0(6), 1);
	mdelay(50);
	gpio_set_value(EXYNOS4_GPX0(6), 0);
	/* config interrupt pin */
	s5p_register_gpio_interrupt(EXYNOS4_GPX0(7));//
	s3c_gpio_cfgpin(EXYNOS4_GPX0(7), S3C_GPIO_SFN(0xf));//引脚配置，输入
	s3c_gpio_setpull(EXYNOS4_GPX0(7), S3C_GPIO_PULL_UP);//上拉
	irq_set_irq_type(EXYNOS4_GPX0(7), IRQ_TYPE_EDGE_RISING);//上升沿触发终端
	return 0;
}

####6.触摸屏终端回调函数
看看中断回调函数,中断回调函数相当于中断的上半部，主要是做一些简单工作，复制事情交给中断下半部实现，也就是开启的工作队列线程。

static irqreturn_t gsl_ts_irq(int irq, void *dev_id)
{
	struct gsl_ts *ts = dev_id;
	print_info("========gslX680 Interrupt=========\n");
	disable_irq_nosync(ts->irq);//关闭中断
	if (!work_pending(&ts->work)) {
		queue_work(ts->wq, &ts->work);//将工作线程再次加入工作队列
	}
	return IRQ_HANDLED;
}

这里我们看看中断下半部核心处理部分，包括数据采集与上报子系统等等

static void gslX680_ts_worker(struct work_struct *work)
{
	int rc, i,j;
	u8 id, touches, read_buf[4] = {0};
	u16 x, y;
	struct gsl_ts *ts = container_of(work, struct gsl_ts,work);
	print_info("=====gslX680_ts_worker=====\n");
#ifdef GSL_MONITOR
	if(i2c_lock_flag != 0)
		goto i2c_lock_schedule;
	else
		i2c_lock_flag = 1;
#endif
#ifdef GSL_NOID_VERSION
	u32 tmp1;
	u8 buf[4] = {0};
	struct gsl_touch_info cinfo = {0};
#endif
	rc = gsl_ts_read(ts->client, 0x80, ts->touch_data, ts->dd->data_size);//读取触摸屏的信息
	if (rc < 0) {
		dev_err(&ts->client->dev, "read failed\n");
		goto schedule;
	}
	touches = ts->touch_data[ts->dd->touch_index];//触点数
	print_info("-----touches: %d -----\n", touches);
#ifdef GSL_NOID_VERSION
	cinfo.finger_num = touches;
	print_info("tp-gsl finger_num = %d\n",cinfo.finger_num);
	for(i = 0; i < (touches < MAX_CONTACTS ? touches : MAX_CONTACTS); i ++) {
		cinfo.x[i] = join_bytes( ( ts->touch_data[ts->dd->x_index + 4 * i + 1] & 0xf),
		                         ts->touch_data[ts->dd->x_index + 4 * i]);
		cinfo.y[i] = join_bytes(ts->touch_data[ts->dd->y_index + 4 * i + 1],
		                        ts->touch_data[ts->dd->y_index + 4 * i ]);
		cinfo.id[i] = ((ts->touch_data[ts->dd->x_index + 4 * i + 1] & 0xf0)>>4);
		print_info("tp-gsl before: x[%d] = %d, y[%d] = %d, id[%d] = %d \n",i,cinfo.x[i],i,cinfo.y[i],i,cinfo.id[i]);
	}
	cinfo.finger_num=(ts->touch_data[3]<<24)|(ts->touch_data[2]<<16)
	                 |(ts->touch_data[1]<<8)|(ts->touch_data[0]);
	gsl_alg_id_main(&cinfo);
	tmp1=gsl_mask_tiaoping();
	print_info("[tp-gsl] tmp1=%x\n",tmp1);
	if(tmp1>0&&tmp1<0xffffffff) {
		buf[0]=0xa;
		buf[1]=0;
		buf[2]=0;
		buf[3]=0;
		gsl_ts_write(ts->client,0xf0,buf,4);
		buf[0]=(u8)(tmp1 & 0xff);
		buf[1]=(u8)((tmp1>>8) & 0xff);
		buf[2]=(u8)((tmp1>>16) & 0xff);
		buf[3]=(u8)((tmp1>>24) & 0xff);
		print_info("tmp1=%08x,buf[0]=%02x,buf[1]=%02x,buf[2]=%02x,buf[3]=%02x\n",
		           tmp1,buf[0],buf[1],buf[2],buf[3]);
		gsl_ts_write(ts->client,0x8,buf,4);
	}
	touches = cinfo.finger_num;
#endif
	for(i = 1; i <= MAX_CONTACTS; i ++) {
		if(touches == 0)
			id_sign[i] = 0;
		id_state_flag[i] = 0;
	}
	for(i= 0; i < (touches > MAX_FINGERS ? MAX_FINGERS : touches); i ++) {
#ifdef GSL_NOID_VERSION
		id = cinfo.id[i];
		x = cinfo.x[i];
		y = cinfo.y[i];
#else
		x = join_bytes( ( ts->touch_data[ts->dd->x_index + 4 * i + 1] & 0xf),
		                ts->touch_data[ts->dd->x_index + 4 * i]);
		y = join_bytes(ts->touch_data[ts->dd->y_index + 4 * i + 1],
		               ts->touch_data[ts->dd->y_index + 4 * i ]);
//id = ts->touch_data[ts->dd->id_index + 4 * i] >> 4;
		id = ts->touch_data[ts->dd->id_index + 4 * i] >> 4;
#endif
		print_info("-->x = %d, y = %d,id = %d, max = %d,ts->dd->x_index = %d\n",x,y,id,MAX_CONTACTS,ts->dd->id_index);
//id = touches;
		if(1 <=id && id <= MAX_CONTACTS) {
#ifdef FILTER_POINT
			filter_point(x, y ,id);//滤波
#else
			record_point(x, y , id);//记录处理
#endif
			print_info("-->x_new = %d, y_new = %d\n",x_new,y_new);
			report_data(ts, x_new, y_new, 10, id);	//上报数据
			id_state_flag[id] = 1;
		}
	}
	for(i = 1; i <= MAX_CONTACTS; i ++) {
		if( (0 == touches) || ((0 != id_state_old_flag[i]) && (0 == id_state_flag[i])) ) {
#ifdef REPORT_DATA_ANDROID_4_0
			input_mt_slot(ts->input, i);
			input_report_abs(ts->input, ABS_MT_TRACKING_ID, -1);
			input_mt_report_slot_state(ts->input, MT_TOOL_FINGER, false);
#endif
			id_sign[i]=0;
		}
		id_state_old_flag[i] = id_state_flag[i];
	}
	if(0 == touches) {
#ifndef REPORT_DATA_ANDROID_4_0
		input_mt_sync(ts->input);
#endif
#ifdef HAVE_TOUCH_KEY
		if(key_state_flag) {
			input_report_key(ts->input, key, 0);
			input_sync(ts->input);
			key_state_flag = 0;
		}
#endif
	}
	input_sync(ts->input);//同步更新
schedule:
#ifdef GSL_MONITOR
	i2c_lock_flag = 0;
i2c_lock_schedule:
#endif
	enable_irq(ts->irq);//再次开启中断
}

####7. 上报输入子系统

static void report_data(struct gsl_ts *ts, u16 x, u16 y, u8 pressure, u8 id)
{
	swap(x, y);
//	print_info("#####id=%d,x=%d,y=%d######\n",id,x,y);
	print_info("#####id=%d,x=%d,y=%d######\n",id,x,y);
	if(x > SCREEN_MAX_X || y > SCREEN_MAX_Y) {
#ifdef HAVE_TOUCH_KEY
		report_key(ts,x,y);
#endif
		return;
	}
	input_mt_slot(ts->input, id);
	input_report_abs(ts->input, ABS_MT_TRACKING_ID, id);
	input_report_abs(ts->input, ABS_MT_POSITION_X, x);
	input_report_abs(ts->input, ABS_MT_POSITION_Y, y);
	input_report_abs(ts->input, ABS_MT_PRESSURE, pressure);
	input_report_key(ts->input, BTN_TOUCH, 1);
}

至此，glax680电容触摸屏的驱动移植与分析完毕，希望能给大家带来一点点的帮助…有任何问题可以发邮件给我
参考资料下载地址：http://download.csdn.net/detail/zgkxzx/9763694