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