（原创）移植ads7846驱动到tiny6410（tiny6410）（ads7846）（移植）（触摸屏）（抖动）
摘要：
目前，市面上很多6410开发板都存在触摸屏抖动的问题，tiny6410也不例外，友善的解决方法是采用一线触摸，即在LCD板上，用一个单片机控制ADS7846芯片AD转换，再将数据通过单总线的方式与6410通讯。可是，我这里没有一线触摸板，于是就开始移植ADS7846驱动到tiny6410。
介绍：
可能有人会问，6410的触摸屏为什么会抖动呢，是不是滤波没做好，或者是硬件走线的原因？是不是硬件的原因，我无法验证。我尝试过通过滤波来改善，但效果一般。不说别的，我在单独测试AD的时候，发现在输入不变的情况下，AD采样的跳幅最大达到25（0～1024范围），可见，跳动还是很大的，这样的情况下，即使再滤波也只是浪费时间。
mini6410-ts.c触摸屏驱动见：
（原创）6410触摸屏驱动分析（s3c-ts.c）（Linux）（分析）
先说说我的硬件：
TS_PEN ----- GPN9 EINT9
TS_MISO ---- GPC0 MISO0
TS_MOSI ---- GPC2 MOSI0
TS_SCK ----- GPC1 SCK0
TS_CS ----- GPC3 CS0
这些端子在核心板的CON1上可以找到，我这里是用的IO模拟的SPI。
下面的开始介绍移植的过程，代码，我在下面会全部帖出来，里面注释也很详细，一般都能看明白。
1、复制/opt/FriendlyARM/mini6410/linux-2.6.38/drivers/input/touchscreen/mini6410-ts.c为mini6410-ads7846.c。
修改后，如下：
/* linux/drivers/input/touchscreen/s3c-ts.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* a misc driver for mini6410 touch screen
* by FriendlyARM 2010
*
* Based on following software:
*
** Copyright (c) 2004 Arnaud Patard <arnaud.patard@rtp-net.org>
** iPAQ H1940 touchscreen support
**
** ChangeLog
**
** 2004-09-05: Herbert Potzl <herbert@13thfloor.at>
** - added clock (de-)allocation code
**
** 2005-03-06: Arnaud Patard <arnaud.patard@rtp-net.org>
** - h1940_ -> s3c24xx (this driver is now also used on the n30
** machines :P)
** - Debug messages are now enabled with the config option
** TOUCHSCREEN_S3C_DEBUG
** - Changed the way the value are read
** - Input subsystem should now work
** - Use ioremap and readl/writel
**
** 2005-03-23: Arnaud Patard <arnaud.patard@rtp-net.org>
** - Make use of some undocumented features of the touchscreen
** controller
**
** 2006-09-05: Ryu Euiyoul <ryu.real@gmail.com>
** - added power management suspend and resume code
*
* 2011-6-23: ADS7846触摸屏驱动程序 by liu_xf
* http://www.cnblogs.com/liu_xf
*
* 2011-6-29 改进滤波，并将AD连续转换8次的间隔缩小了
*/
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/init.h>
#include <linux/serio.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <mach/hardware.h>
//#include <mach/irqs.h>
#include <mach/map.h>
#include <mach/regs-clock.h>
#include <mach/regs-gpio.h>
#include <plat/gpio-cfg.h>
#include <mach/gpio-bank-n.h>
#include <mach/gpio-bank-c.h>
#define CONFIG_TOUCHSCREEN_ADS7846_DEBUG
#undef CONFIG_TOUCHSCREEN_ADS7846_DEBUG
#define DEBUG_LVL KERN_DEBUG
/*
* Definitions & global arrays.
*/
#define DEVICE_NAME "touchscreen"
static DECLARE_WAIT_QUEUE_HEAD(ts_waitq); //定义并初始化一个等待队列
typedef unsigned TS_EVENT;
#define NR_EVENTS 64 //触摸屏fifo大小
static TS_EVENT events[NR_EVENTS];
static int evt_head, evt_tail; //fifo的头的尾
//驱动写fifo时evt_head++，应用读fifo时 evt_tail++
#define ts_evt_pending() ((volatile u8)(evt_head != evt_tail)) //相等就表示满了
#define ts_evt_get() (events + evt_tail)
#define ts_evt_pull() (evt_tail = (evt_tail + 1) & (NR_EVENTS - 1))
#define ts_evt_clear() (evt_head = evt_tail = 0)
#define ADS7846_CNV_NBR 8 //ADC连续转换的次数
struct ads7846_ts_info {
struct input_dev *dev;
unsigned int xp; //x方向位置
unsigned int yp; //y方向位置
unsigned int count; //adc转换次数
unsigned int cnv_nbr;
unsigned int x_buf[ADS7846_CNV_NBR]; //ad转换buf
unsigned int y_buf[ADS7846_CNV_NBR];
};
static struct ads7846_ts_info *ts;
//ADS7846底层操作========================================================================
#define ADS7846_GPIO_MISO 0 //gpc0
#define ADS7846_GPIO_MOSI 2 //gpc2
#define ADS7846_GPIO_CLK 1 //gpc1
#define ADS7846_GPIO_CS 3 //gpc3
// ADS7846 Control Byte bit defines
#define ADS7846_CMD_START 0x0080
#define ADS7846_ADDR_BIT 4
#define ADS7846_ADDR_MASK (0x7<<ADS7846_ADDR_BIT)
#define ADS7846_MEASURE_X (0x5<<ADS7846_ADDR_BIT)
#define ADS7846_MEASURE_Y (0x1<<ADS7846_ADDR_BIT)
#define ADS7846_MEASURE_Z1 (0x3<<ADS7846_ADDR_BIT)
#define ADS7846_MEASURE_Z2 (0x4<<ADS7846_ADDR_BIT)
#define ADS7846_8BITS (1<<3)
#define ADS7846_12BITS 0
#define ADS7846_SER (1<<2)
#define ADS7846_DFR 0
#define ADS7846_PWR_BIT 0
#define ADS7846_PD 0
#define ADS7846_ADC_ON (0x1<<ADS7846_PWR_BIT)
#define ADS7846_REF_ON (0x2<<ADS7846_PWR_BIT)
#define ADS7846_REF_ADC_ON (0x3<<ADS7846_PWR_BIT)
#define MEASURE_8BIT_X\
(unsigned short)(ADS7846_CMD_START | ADS7846_MEASURE_X | ADS7846_8BITS | ADS7846_DFR | ADS7846_PD)
#define MEASURE_8BIT_Y\
(unsigned short)(ADS7846_CMD_START | ADS7846_MEASURE_Y | ADS7846_8BITS | ADS7846_DFR | ADS7846_PD)
#define MEASURE_12BIT_X \
(unsigned short)(ADS7846_CMD_START | ADS7846_MEASURE_X | ADS7846_12BITS | ADS7846_DFR | ADS7846_PD)
#define MEASURE_12BIT_Y \
(unsigned short)(ADS7846_CMD_START | ADS7846_MEASURE_Y | ADS7846_12BITS | ADS7846_DFR | ADS7846_PD)
#define MEASURE_12BIT_Z1 \
(unsigned char)(ADS7846_MEASURE_Z1 | ADS7846_12BITS | ADS7846_DFR | ADS7846_PD)
#define MEASURE_12BIT_Z2 \
(unsigned char)(ADS7846_MEASURE_Z2 | ADS7846_12BITS | ADS7846_DFR | ADS7846_PD)
// Pin access
//
static inline void set_miso_as_up(void)//gpc0
{
unsigned long tmp;
tmp = readl(S3C64XX_GPCPUD);
tmp &= ~(3U <<0);
tmp |= (2U << 0);
writel(tmp, S3C64XX_GPCPUD);
}
static inline void set_miso_as_input(void)//gpc0
{
unsigned long tmp;
tmp = readl(S3C64XX_GPCCON);
tmp &= ~(0xf << 0);
writel(tmp, S3C64XX_GPCCON);
}
static inline void set_cs_mosi_clk_as_output(void)//gpc1 2 3
{
unsigned long tmp;
tmp = readl(S3C64XX_GPCCON);
tmp = (tmp & ~0xfff0) | (0x1110);
writel(tmp, S3C64XX_GPCCON);
}
static inline void set_cs_mosi_clk_as_up(void)//gpc1 2 3
{
unsigned long tmp;
tmp = readl(S3C64XX_GPCPUD);
tmp &= ~((3U <<2)|(3U <<4)|(3U <<6));
tmp |= (2U << 2) | (2U << 4) | (2U << 6);
writel(tmp, S3C64XX_GPCPUD);
}
static inline void set_gpcx_value(int pinx ,int v)
{
unsigned long tmp;
tmp = readl(S3C64XX_GPCDAT);
if (v) {
tmp |= (1 << pinx);
} else {
tmp &= ~(1<<pinx);
}
writel(tmp, S3C64XX_GPCDAT);
}
static inline int get_gpcx_value(int pinx)
{
int v;
unsigned long tmp;
tmp = readl(S3C64XX_GPCDAT);
v = !!(tmp & (1<<pinx));
return v;
}
//读12bit
static unsigned int ads7846_Read_Data(void)
{
unsigned int i,temp=0x00;
for(i=0;i<12;i++)
{
temp <<=1;
set_gpcx_value(ADS7846_GPIO_CLK, 1); udelay(10);
set_gpcx_value(ADS7846_GPIO_CLK, 0); udelay(10);
if(get_gpcx_value(ADS7846_GPIO_MISO) != 0)temp++;
}
return (temp);
}
//写8bit
static void ads7846_Write_Data(unsigned int n)
{
unsigned char i;
set_gpcx_value(ADS7846_GPIO_CLK, 0);
for(i=0;i<8;i++)
{
if((n&0x80)==0x80)
set_gpcx_value(ADS7846_GPIO_MOSI, 1);
else
set_gpcx_value(ADS7846_GPIO_MOSI, 0);
n <<= 1;
set_gpcx_value(ADS7846_GPIO_CLK, 1); udelay(10);
set_gpcx_value(ADS7846_GPIO_CLK, 0); udelay(10);
}
}
//ADS7846转换==
//保存在ts->buf 当中
static void ads7846_conver_start(void)
{
int i;
unsigned int cmd[2];
unsigned int data[2];
set_gpcx_value(ADS7846_GPIO_CS, 0);
//开读
cmd[0] = MEASURE_12BIT_X;
cmd[1] = MEASURE_12BIT_Y;
/* CS# Low */
set_gpcx_value(ADS7846_GPIO_CS, 0);
//连续转换
for(ts->count=0; ts->count<ts->cnv_nbr;)
{
//分别读出x y坐标＝＝
for(i=0; i<2; i++){
ads7846_Write_Data(cmd[i]);
udelay(40);
data[i] = ads7846_Read_Data();
}
//保存转换结果
ts->x_buf[ts->count]= data[0];
ts->y_buf[ts->count]= data[1];
ts->count++;
}
/* CS# High */
set_gpcx_value(ADS7846_GPIO_CS, 1);
#ifdef CONFIG_TOUCHSCREEN_ADS7846_DEBUG
//printk("ts read pos: x = %d, y = %d\n", data[0], data[1]);
#endif
}
//-----------------------------------------------------------------------------
//触摸屏数据滤波算法
//触摸屏AD连续转换N次后，按升序排列，再取中间几位值求平均
#define TS_AD_NBR_PJ 4 //取中间4位求平均值
#define TS_AD_NBR_MAX_CZ 10 //最大与最小的差值
static inline bool touch_ad_data_filter(unsigned int *buf0, unsigned int *buf1)
{
unsigned int i,j,k,temp,temp1,nbr=(ADS7846_CNV_NBR);
//将转换结果升序排列
//buf0
for (j= 0; j< nbr; j++)
for (i = 0; i < nbr; i++)
{
if(buf0[i]>buf0[i+1])//升序排列
{
temp=buf0[i+1];
buf0[i+1]=buf0[i];
buf0[i]=temp;
}
}
//buf1
for (j= 0; j< nbr; j++)
for (i = 0; i < nbr; i++)
{
if(buf1[i]>buf1[i+1])//升序排列
{
temp=buf1[i+1];
buf1[i+1]=buf1[i];
buf1[i]=temp;
}
}
//串口调试查看结果
//for (j= 0; j< nbr; j++)
// printk("buf0[%2d]=%4d, buf1[%2d]=%4d,\r\n",j,buf0[j],j,buf1[j]);
//取中间值求平均==
k=((nbr-TS_AD_NBR_PJ)>>1);
temp = 0;temp1 = 0;
//检查值是否有效==
if((buf0[k+TS_AD_NBR_PJ-1]-buf0[k]>TS_AD_NBR_MAX_CZ)||(buf1[k+TS_AD_NBR_PJ-1]-buf1[k]>TS_AD_NBR_MAX_CZ)) //无效值
{
return 0;
}
//--
//将中间指定位数累加
for(i=0;i<TS_AD_NBR_PJ;i++)
{
temp += buf0[k+i];
temp1 += buf1[k+i];
}
//求平均值,将结果保存在最低位
buf0[0]=temp/TS_AD_NBR_PJ;
buf1[0] = temp1/TS_AD_NBR_PJ;
//--
return 1;
}
//将AD转换的值放入FIFO
//这里是一个先进先出的fifo
//只要有数据被添加进来，就会唤醒ts_waitq进程
static void ts_evt_add(unsigned x, unsigned y, unsigned down) {
unsigned ts_event;
int next_head;
ts_event = ((x << 16) | (y)) | (down << 31);
next_head = (evt_head + 1) & (NR_EVENTS - 1);
//没满就装入
if (next_head != evt_tail) {
events[evt_head] = ts_event;
evt_head = next_head;
#ifdef CONFIG_TOUCHSCREEN_ADS7846_DEBUG
printk("====>Add ... [ %4d, %4d ]%s\n", x, y, down ? "":" ~~~");
#endif
/* wake up any read call */
if (waitqueue_active(&ts_waitq)) { //判斷等待隊列是否有進程睡眠
wake_up_interruptible(&ts_waitq); //唤醒ts_waitq等待队列中所有interruptible类型的进程
}
} else {
/* drop the event and try to wakeup readers */
printk(KERN_WARNING "mini6410-ads7846: touch event buffer full");
wake_up_interruptible(&ts_waitq);
}
}
static unsigned int ads7846_ts_poll( struct file *file, struct poll_table_struct *wait)
{
unsigned int mask = 0;
//将ts_waitq等待队列添加到poll_table里去
poll_wait(file, &ts_waitq, wait);
//返回掩码
if (ts_evt_pending())
mask |= POLLIN | POLLRDNORM; //返回设备可读
return mask;
}
//读 系统调用==
static int ads7846_ts_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
DECLARE_WAITQUEUE(wait, current); //把当前进程加到定义的等待队列头wait中
char *ptr = buff;
int err = 0;
add_wait_queue(&ts_waitq, &wait); //把wait入到等待队列头中。该队列会在进程等待的条件满足时唤醒它。
//我们必须在其他地方写相关代码，在事件发生时，对等的队列执行wake_up()操作。
//这里是在ts_evt_add里wake_up
while (count >= sizeof(TS_EVENT)) {
err = -ERESTARTSYS;
if (signal_pending(current)) //如果是信号唤醒 参考http://www.360doc.com/content/10/1009/17/1317564_59632874.shtml
break;
if (ts_evt_pending()) {
TS_EVENT *evt = ts_evt_get();
err = copy_to_user(ptr, evt, sizeof(TS_EVENT));
ts_evt_pull();
if (err)
break;
ptr += sizeof(TS_EVENT);
count -= sizeof(TS_EVENT);
continue;
}
set_current_state(TASK_INTERRUPTIBLE); //改变进程状态为可中断的睡眠
err = -EAGAIN;
if (filp->f_flags & O_NONBLOCK) //如果上层调用是非阻塞方式，则不阻塞该进程，直接返回EAGAIN
break;
schedule(); //本进程在此处交出CPU控制权，等待被唤醒
//进程调度的意思侧重于把当前任务从CPU拿掉，再从就绪队列中按照调度算法取一就绪进程占用CPU
}
current->state = TASK_RUNNING;
remove_wait_queue(&ts_waitq, &wait);
return ptr == buff ? err : ptr - buff;
}
//--
static int ads7846_ts_open(struct inode *inode, struct file *filp) {
/* flush event queue */
ts_evt_clear();
return 0;
}
//当应用程序操作设备文件时调用的open read等函数，最终会调用这个结构体中对应的函数
static struct file_operations dev_fops = {
.owner = THIS_MODULE,
.read = ads7846_ts_read,
.poll = ads7846_ts_poll, //select系统调用
.open = ads7846_ts_open,
};
//设备号，设备名，注册的时候用到这个数组
//混杂设备主设备号为10
static struct miscdevice misc = {
.minor = MISC_DYNAMIC_MINOR, //自动分配次设置号
//.minor = 180,
.name = DEVICE_NAME,
.fops = &dev_fops,
};
/**
* get_down - return the down state of the pen
* 获取pen引脚状态，为0表示down
* GPN9 EINT9 TS_PEN
*/
static inline bool get_down(void)
{
int tmp,down;
tmp = readl(S3C64XX_GPNDAT);
down = !(tmp & (1<<9));
return (down);
}
/*===========================================================================================
touch_timer_get_value这个函数的调用：
1、 触摸笔开始点击的时候， 在中断函数touch_down里面被调用，不是直接调用，而是设置定时器超时后调用
这样是为了去抖动
2、 touch_timer_get_value被调用一次后，如果pendown信号有效，则touch_timer_get_value会被持续调用
也是通过定时器实现的
touch_timer_get_value这个函数的功能：
启动7846转换，直到连续转换8次后，再滤波处理，获得有效值，并向上报告触摸屏事件
============================================================================================*/
static void touch_timer_get_value(unsigned long data);
static DEFINE_TIMER(touch_timer, touch_timer_get_value, 0, 0);
static void touch_timer_get_value(unsigned long data) {
int pendown;
pendown = get_down();
#ifdef CONFIG_TOUCHSCREEN_ADS7846_DEBUG
// if(pendown)
// {
// printk("touch is down!\n");
// }
// else
// printk("touch is up!\n");
#endif
if (pendown) {
//关中断===
disable_irq(IRQ_EINT(9));
//--
//启动ADS7846转换==
ads7846_conver_start();
//开中断==
enable_irq(IRQ_EINT(9));
//--
//如果转换了8次，就写入FIFO保存
//if (ts->count == ( ts->cnv_nbr)) {
if(touch_ad_data_filter(ts->x_buf,ts->y_buf)) //滤波处理
{
ts->xp = ts->x_buf[0];
ts->yp = ts->y_buf[0];
ts_evt_add(ts->xp, ts->yp, 1); //向上报告触摸屏事件
}
ts->xp = 0;
ts->yp = 0;
ts->count = 0;
//}
//--
mod_timer(&touch_timer, jiffies + 2); //重新设置系统定时器，超时后，又会调用touch_timer_get_value
//jiffies变量记录了系统启动以来，系统定时器已经触发的次数。内核每秒钟将jiffies变量增加HZ次。
//因此，对于HZ值为100的系统，1个jiffy等于10ms，而对于HZ为1000的系统，1个jiffy仅为1ms
//这里系统配置提HZ是100
} else { //如果是松开，报告其触摸笔状态
ts->xp = 0;
ts->yp = 0;
ts->count = 0;
ts_evt_add(0, 0, 0);
}
}
//触摸屏按下中断服务==
//双边沿中断
static irqreturn_t touch_down(int irqno, void *param)
{
/* Clear interrupt */
//__raw_writel(0x0, ts_base + S3C_ADCCLRWK);
//__raw_writel(0x0, ts_base + S3C_ADCCLRINT);
//稍后调用touch_timer_get_value，去抖动
mod_timer(&touch_timer, jiffies + 2); //等ADS7846转换完成了再读
//同时还可以防抖动，如果定时器没有超时的这段时间里，发生了抬起和按下中断，则定时器的值会被重设，不会超时
//内核配置时HZ值设为100，即1个jiffy等于10ms，
//touch_timer_get_value(1); //直接调用会有抖动
return IRQ_RETVAL(IRQ_HANDLED);
}
//-------------------------------------------
/*
* The functions for inserting/removing us as a module.
*/
static int __init ads7846_ts_probe(struct platform_device *pdev)
{
struct device *dev;
int ret = 0;
dev = &pdev->dev;
#ifdef CONFIG_TOUCHSCREEN_ADS7846_DEBUG
printk("ads7846_ts_probe start!\n");
#endif
//给ads7846_ts_info指针分配内存==
ts = kzalloc(sizeof(struct ads7846_ts_info), GFP_KERNEL);
ts->cnv_nbr = ADS7846_CNV_NBR;
ts->xp = 0;
ts->yp = 0;
ts->count = 0;
//申请中断==
//TS_PEN双边沿触发 EINT9 GPN9
ret = request_irq(IRQ_EINT(9), touch_down,IRQ_TYPE_EDGE_BOTH,
"ads7864_touch", ts);
if (ret != 0) {
dev_err(dev,"ads7846_ts.c: Could not allocate ts IRQ_EINT !\n");
ret = -EIO;
goto fail;
}
ret = misc_register(&misc); //注册这混杂字符设备
if (ret) {
dev_err(dev, "ads7846_ts.c: Could not register device(mini6410 touchscreen)!\n");
ret = -EIO;
goto fail;
}
//初始化GPIO==
set_miso_as_up();
set_miso_as_input();
set_cs_mosi_clk_as_up();
set_cs_mosi_clk_as_output();
set_gpcx_value(ADS7846_GPIO_MOSI ,1);
set_gpcx_value(ADS7846_GPIO_CS ,1);
set_gpcx_value(ADS7846_GPIO_CLK ,1);
//--
#ifdef CONFIG_TOUCHSCREEN_ADS7846_DEBUG
printk("ads7846_ts_probe end!\n");
#endif
return 0;
fail:
disable_irq(IRQ_EINT(9));
free_irq(IRQ_EINT(9), ts);
return ret;
}
static int ads7846_ts_remove(struct platform_device *dev)
{
printk(KERN_INFO "ads7846_ts_remove() of TS called !\n");
disable_irq(IRQ_EINT(9));
free_irq(IRQ_EINT(9), ts);
return 0;
}
#ifdef CONFIG_PM
static unsigned int adccon, adctsc, adcdly;
static int ads7846_ts_suspend(struct platform_device *dev, pm_message_t state)
{
return 0;
}
static int ads7846_ts_resume(struct platform_device *pdev)
{
return 0;
}
#else
#define ads7846_ts_suspend NULL
#define ads7846_ts_resume NULL
#endif
static struct platform_driver ads7846_ts_driver = {
.probe = ads7846_ts_probe,
.remove = ads7846_ts_remove,
.suspend = ads7846_ts_suspend,
.resume = ads7846_ts_resume,
.driver = {
.owner = THIS_MODULE,
.name = "ads7846-ts",
},
};
static char banner[] __initdata = KERN_INFO "mini6410 ads7846 Touchscreen driver,by liu_xf 20110622,\n";
static int __init ads7846_ts_init(void)
{
printk(banner);
return platform_driver_register(&ads7846_ts_driver);
}
static void __exit ads7846_ts_exit(void)
{
platform_driver_unregister(&ads7846_ts_driver);
}
module_init(ads7846_ts_init);
module_exit(ads7846_ts_exit);
MODULE_AUTHOR("Hunan Create Inc.");
MODULE_LICENSE("GPL");
2、修改当前目录下的Kconfig和makefile，让它在menuconfig里可见，并能被编译。
在 Kconfig里添加：
config TOUCHSCREEN_MINI6410_ADS7846 tristate "ADS7846 touchscreen driver for Mini6410" depends on MACH_MINI6410 default y help Say Y here to enable the driver for the ADS7846 touchscreen on the FriendlyARM Mini6410 development board. If unsure, say N. To compile this driver as a module, choose M here: the module will be called mini6410-ads7846.
makefile里添加
obj-$(CONFIG_TOUCHSCREEN_MINI6410_ADS7846) += mini6410-ads7846.o
3、 ads7846_device_ts设备定义
复制 /opt/FriendlyARM/mini6410/linux-2.6.38/arch/arm/mach-s3c64xx/dev-ts-mini6410.c为dev-ads7846-mini6410.c，更改代码为
/* linux/arch/arm/mach-s3c64xx/dev-ts-mini6410.c
*
* Copyright (c) 2008 Simtec Electronics
* Ben Dooks <ben@simtec.co.uk>
* http://armlinux.simtec.co.uk/
*
* S3C series device definition for touchscreen devices
*
* 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/kernel.h>
#include <linux/platform_device.h>
#include <mach/map.h>
#include <mach/irqs.h>
#include <plat/devs.h>
#include <plat/cpu.h>
#include <mach/ts.h>
/* Touch srcreen */
//resource没有用，先留在这，不管它
static struct resource ads7846_ts_resource[] = {
[0] = {
.start = SAMSUNG_PA_ADC,
.end = SAMSUNG_PA_ADC + SZ_256 - 1,
.flags = IORESOURCE_MEM,
},
[1] = {
.start = IRQ_PENDN,
.end = IRQ_PENDN,
.flags = IORESOURCE_IRQ,
},
[2] = {
.start = IRQ_ADC,
.end = IRQ_ADC,
.flags = IORESOURCE_IRQ,
}
};
struct platform_device ads7846_device_ts = {
.name = "ads7846-ts",
.id = -1,
.num_resources = ARRAY_SIZE(ads7846_ts_resource),
.resource = ads7846_ts_resource,
};
/*
void __init ads7846_ts_set_platdata(struct s3c_ts_mach_info *pd)
{
printk(KERN_ERR "%s: no platform data\n", __func__);
}
*/
4、在/opt/FriendlyARM/mini6410/linux-2.6.38/arch/arm/mach-s3c64xx/mach-mini6410.c的platform_device添加ads7846_device_ts设备（s3c_device_ts附近），注册设备时要用到它
#ifdef CONFIG_TOUCHSCREEN_MINI6410_ADS7846 &ads7846_device_ts, #endif
5、添加设备声明
mach-mini6410里注册ads7846_device_ts设备，但在哪里mach-mini6410并不知道，需要在devs.h里声明，打开当前目录下的devs.h，添加如下代码：
extern struct platform_device ads7846_device_ts;
6、然后再make，放到SD卡里运行
make menuconfig，在device drives－> input device support -> touch screens选择ADS7846 touchscreen driver for Mini6410 ,然后再make zImage。
完成后，再放到SD卡里运行，怎么样，一点也不抖动了吧！
结语：
这个驱动是由mini6410-ts.c修改而来的，那些系统调用的函数都没有改，只是将获取触摸屏数据的方式变了，可以直接用原来的tslib。经测试，效果良好。但是在移植的过程中，有一个问题还是没搞明白，之前，我是将TS_PEN接在EINT6上在的，但一接上去，就一直中断，把系统都弄死了，要按下触摸屏才能停止中断，不知道是什么原因，可能是EINT6被其它地方设置了，还是怎么回事，后来换成EINT9就好了，正好两个端子相邻。知道的大侠还请告诉我一声。
