linux 串口触摸屏调试记录

这几天在调试串口触摸屏，网上找了下似乎说的都不大清楚，这里记录下.

实现方法网上说有好几种，这里是将串口作为一个serio总线设备，利用linux内核提供serio总线驱动，通过设置对应的串口，调用serport提供的函数将串口当做serio总线设备，在驱动里面需要按照serio总线设备驱动的框架来实现，在内核源码drivers/input/touchscreen下提供了两个例子,touchright.c和touchit123.c，可以参考这两个例子编写驱动.我的驱动是在网上抄的，源码如下

/*
 *Egalax serial touchscreen driver
 *
 * Copyright (c) 2004-2016
 *
 * Based on Touchright driver (drivers/input/touchscreen/touchit213.c)
 *
 * Zolt??n B??sz??rm??nyi <zboszor@xxxxx>
 */
/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/init.h>

#define DRIVER_DESC	"EETI Egalax serial touchscreen driver"

MODULE_AUTHOR("Zolt??n B??sz??rm??nyi <zboszor@xxxxx>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */
#define SERIO_EGALAX	0x3f
#define EGALAX_FORMAT_MAX_LENGTH 6
#define EGALAX_RESPONSE_BEGIN_BYTE 0x80
#define EGALAX_FORMAT_PRESSURE_BIT 0x40
#define EGALAX_FORMAT_TOUCH_BIT 0x01
#define EGALAX_FORMAT_RESOLUTION 0x06

#define EGALAX_MIN_XC 0
#define EGALAX_MAX_XC 0x4000
#define EGALAX_MIN_YC 0
#define EGALAX_MAX_YC 0x4000

#define EGALAX_GET_XC(data, resbits, shift) ((((data[1] & (resbits)) << 7) | (data[2] & 0x7f)) << shift)
#define EGALAX_GET_YC(data, resbits, shift) ((((data[3] & (resbits)) << 7) | (data[4] & 0x7f)) << shift)
#define EGALAX_GET_TOUCHED(data) (EGALAX_FORMAT_TOUCH_BIT & data[0])

/*
 * Per-touchscreen data.
 */

struct egalax {
	struct input_dev *dev;
	struct serio *serio;
	int idx;
	int bytes;
	int resbits;
	int shift;
	unsigned char data[EGALAX_FORMAT_MAX_LENGTH];
	char phys[32];
};

static void egalax_process_data(struct egalax *pegalax)
{
	struct input_dev *dev = pegalax->dev;
	
	if (++pegalax->idx == pegalax->bytes) {
		input_report_abs(dev, ABS_X, EGALAX_GET_XC(pegalax->data, pegalax->resbits, pegalax->shift));
		input_report_abs(dev, ABS_Y, EGALAX_GET_YC(pegalax->data, pegalax->resbits, pegalax->shift));
		//input_report_key(dev, BTN_TOUCH, EGALAX_GET_TOUCHED(pegalax->data));
		input_report_abs(dev, ABS_PRESSURE, EGALAX_GET_TOUCHED(pegalax->data));
		input_sync(dev);
		pegalax->idx = 0;
	}
}

static irqreturn_t egalax_interrupt(struct serio *serio,
		unsigned char data, unsigned int flags)
{
	struct egalax *pegalax = serio_get_drvdata(serio);

	pegalax->data[pegalax->idx] = data;
	if (EGALAX_RESPONSE_BEGIN_BYTE & pegalax->data[0]) {
		pegalax->bytes = (EGALAX_FORMAT_PRESSURE_BIT & pegalax->data[0] ? 6 : 5);
		switch ((EGALAX_FORMAT_RESOLUTION & pegalax->data[0]) >> 1) {
		case 0:
			pegalax->resbits = 0x0f;
			pegalax->shift = 3;
			break;
		case 1:
			pegalax->resbits = 0x1f;
			pegalax->shift = 2;
			break;
		case 2:
			pegalax->resbits = 0x3f;
			pegalax->shift = 1;
			break;
		default:
			pegalax->resbits = 0x7f;
			pegalax->shift = 0;
			break;
		}
		egalax_process_data(pegalax);
	}
	else
		dev_dbg(&serio->dev, "unknown/unsynchronized data: %x\n",
			pegalax->data[0]);

	return IRQ_HANDLED;
}

static void egalax_disconnect(struct serio *serio)
{
	struct egalax *pegalax = serio_get_drvdata(serio);
	input_get_device(pegalax->dev);
	input_unregister_device(pegalax->dev);
	serio_close(serio);
	serio_set_drvdata(serio, NULL);
	input_put_device(pegalax->dev);
	kfree(pegalax);
}

/*
 * egalax_connect() is the routine that is called when someone adds a
 * new serio device that supports egalax protocol and registers it as
 * an input device. This is usually accomplished using inputattach.
 */

static int egalax_connect(struct serio *serio, struct serio_driver *drv)
{
	struct egalax *pegalax;
	struct input_dev *input_dev;
	int err;
	pegalax = kzalloc(sizeof(struct egalax), GFP_KERNEL);
	input_dev = input_allocate_device();
	if (!pegalax || !input_dev) {
		err = -ENOMEM;
		goto fail1;
	}

	pegalax->serio = serio;
	pegalax->dev = input_dev;
	snprintf(pegalax->phys, sizeof(pegalax->phys),
		 "%s/input1", serio->phys);

	input_dev->name = "EETI eGalaxTouch Serial TouchScreen";
	input_dev->phys = pegalax->phys;
	input_dev->id.bustype = BUS_RS232;
	input_dev->id.vendor = SERIO_EGALAX;
	input_dev->id.product = 0;
	input_dev->id.version = 0x0001;
	input_dev->dev.parent = &serio->dev;
	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
	//input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
	input_set_abs_params(pegalax->dev, ABS_X,
			     EGALAX_MIN_XC, EGALAX_MAX_XC, 0, 0);
	input_set_abs_params(pegalax->dev, ABS_Y,
			     EGALAX_MIN_YC, EGALAX_MAX_YC, 0, 0);
	input_set_abs_params(pegalax->dev, ABS_PRESSURE, 0, 1, 0, 0);
	serio_set_drvdata(serio, pegalax);

	err = serio_open(serio, drv);
	if (err)
		goto fail2;

	err = input_register_device(pegalax->dev);
	if (err)
		goto fail3;

	return 0;

fail3:	serio_close(serio);
fail2:	serio_set_drvdata(serio, NULL);
fail1:	input_free_device(input_dev);
	kfree(pegalax);
	return err;
}

/*
 * The serio driver structure.
 */

static struct serio_device_id egalax_serio_ids[] = {
	{
		.type	= SERIO_RS232,
		.proto	= SERIO_EGALAX,
		.id	= SERIO_ANY,
		.extra	= SERIO_ANY,
	},
	{ 0 }
};

MODULE_DEVICE_TABLE(serio, egalax_serio_ids);

static struct serio_driver egalax_drv = {
	.driver		= {
		.name	= "egalax",
	},
	.description	= DRIVER_DESC,
	.id_table	= egalax_serio_ids,
	.interrupt	= egalax_interrupt,
	.connect	= egalax_connect,
	.disconnect	= egalax_disconnect,
};

/*
 * The functions for inserting/removing us as a module.
 */

static int __init egalax_init(void)
{
	return serio_register_driver(&egalax_drv);
}

static void __exit egalax_exit(void)
{
	serio_unregister_driver(&egalax_drv);
}

module_init(egalax_init);
module_exit(egalax_exit);

只是修改了最后一点,其中egalax_serio_ids中的几个参数在应用程序中需要用到，加上驱动编译内核更新后，此时这个驱动是没有起作用的，需要通过应用程序将串口与之绑定，后才能正常工作.

应用程序如下,这个代码网上也有

/*************************************

NAME:seriotouch.c

*************************************/

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <errno.h>
#include <string.h>
#include <linux/fb.h>
#include <malloc.h>
#include <sys/mman.h>
#include <termio.h>
#include <linux/serio.h>

#define SERIO_ANY	0xff
#define SERIO_EGALAX	0x3f

int main(int argc, char* argv[])
{
	int dev,ret;
	char comdev[20];
	int ldisc;
	unsigned long type;
	struct termios option;
	int fd = -1;
	if(argc != 2)
	{
		printf("-----------------------------------------\n");
		printf("\nUsage: %s [serial device(1-5)]\n", argv[0]);
		printf("Example: %s 5 n", argv[0]);
		printf("-----------------------------------------\n");
		return 0;
	}

	dev = strtol(argv[1],NULL,10);
	sprintf(comdev,"/dev/ttyAMA%d",dev);
	fd = open(comdev,O_RDWR|O_NONBLOCK|O_NOCTTY);
	if (fd < 0) {
		perror(comdev);
		exit(1);
	}
	
	tcgetattr(fd, &option);
    option.c_iflag = IGNPAR | IGNBRK;
	option.c_cflag = HUPCL | CS8 | CREAD | CLOCAL | B9600;
	option.c_cc[VMIN] = 1;
	option.c_cc[VTIME] = 0;
	
	cfsetispeed(&option,B9600);
	cfsetospeed(&option,B9600);

	ret = tcsetattr(fd, TCSANOW, &option);
	if(ret < 0) {
		perror("TCSANOW");
		exit(1);
	}

	ldisc = N_MOUSE;
	ret = ioctl(fd,TIOCSETD,&ldisc);
	if(ret) {
		perror("TIOCSETD");
	}
	type = SERIO_EGALAX | (SERIO_ANY << 8) | (SERIO_ANY << 16);
	ret = ioctl(fd,SPIOCSTYPE, &type);
	if(ret) {
		perror("SPIOCSTYPE");
	}
	read(fd,NULL,0);
	//close(fd);
	return 0;
}

需要注意的是，应用程序最后这个read一定要执行，不然驱动里不会进行连接.

编译生成可执行文件seriotouch

应用程序配制完串口后需要与之前的驱动连接，看设置spiocstype的设置，需要保证这里的几个参数与驱动进行对应。

系统启动后执行seriotouch 5 &

后面这个５对应的是串口号,执行这个后会看到驱动里的connect执行了，同时会生成一个input节点，如下图

此时将tslib里的tsdevice修改为这个，进行校准后，就可以正常使用了