触摸屏驱动分析之S3C2440_ts.c

arm linux设备驱 2010-04-10
16:03:45 阅读331 评论2 字号：大中小 订阅

//短短两百余行程序颇具玄机，在光标抬起后的处理中尤其值得推敲。

#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 <asm/io.h>

#include <asm/irq.h>

#include
<plat/regs-adc.h>

#include
<mach/regs-gpio.h>

#define S3C2410TSVERSION 0x0101

//x为0时为等待按下中断，x为1是为等待抬起中断

#define WAIT4INT(x)
(((x)<<8) | \

S3C2410_ADCTSC_YM_SEN | S3C2410_ADCTSC_YP_SEN |
S3C2410_ADCTSC_XP_SEN | \

S3C2410_ADCTSC_XY_PST(3))

//自动连续测量X坐标和Y坐标

#define
AUTOPST
(S3C2410_ADCTSC_YM_SEN | S3C2410_ADCTSC_YP_SEN |
S3C2410_ADCTSC_XP_SEN | \

S3C2410_ADCTSC_AUTO_PST | S3C2410_ADCTSC_XY_PST(0))

//设备名

static char *tq2440ts_name = "TQ2440 TouchScreen";

static struct
input_dev *dev;//

static long xp;

static long yp;

static int count;

extern struct
semaphore ADC_LOCK;//申明一信号量该信号量在其他文件中定义

//该标志在按下中断处理函数中置1，抬起处理函数中置0，在AD转换结束中断处理函数中判断，

//如果为1则读取AD转换的数字，如果为0则什么也不做。

static int OwnADC = 0;

//寄存器基地址

static void __iomem *base_addr;

//管脚配置

static inline void tq2440_ts_connect(void)

{

s3c2410_gpio_cfgpin(S3C2410_GPG12,
S3C2410_GPG12_XMON);

s3c2410_gpio_cfgpin(S3C2410_GPG13,
S3C2410_GPG13_nXPON);

s3c2410_gpio_cfgpin(S3C2410_GPG14,
S3C2410_GPG14_YMON);

s3c2410_gpio_cfgpin(S3C2410_GPG15,
S3C2410_GPG15_nYPON);

}

//定时器定时时间到处理函数，该函数在按下抬起中断处理函数中直接调用，

//在AD转换结束中断处理函数中触发定时器经延时后被调用

static void touch_timer_fire(unsigned long data)

{

unsigned long data0;

unsigned long data1;

int updown;

data0 =
ioread32(base_addr+S3C2410_ADCDAT0);

data1 =
ioread32(base_addr+S3C2410_ADCDAT1);

//updown为1则被按下，为0

则为抬起

updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN))
&& (!(data1 &
S3C2410_ADCDAT0_UPDOWN));

if
(updown) {//按下中断执行以下语句

if (count !=
0)

{

long
tmp;

tmp =
xp;

xp =
yp;

yp =
tmp;

xp >>= 2;//四次AD转换求平均值

yp >>= 2;

input_report_abs(dev,
ABS_X, xp);

input_report_abs(dev,
ABS_Y, yp);//将x，y的值发向用户空间

input_report_key(dev,
BTN_TOUCH, 1);//报告光标按下事件

input_report_abs(dev,
ABS_PRESSURE, 1);

input_sync(dev);//表示报告结束

}

xp = 0;

yp = 0;

count =
0;

//每次按下有四次AD转换，以下为在按下中断中触发的第一次AD转换，其余三次在AD转换中断处理函数中触发

iowrite32(S3C2410_ADCTSC_PULL_UP_DISABLE
| AUTOPST, base_addr+S3C2410_ADCTSC);

iowrite32(ioread32(base_addr+S3C2410_ADCCON)
| S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);

}

else

{

count =
0;

input_report_key(dev,
BTN_TOUCH, 0);//向用户空间报告光标抬起事件

input_report_abs(dev,
ABS_PRESSURE, 0);

input_sync(dev);//报告结束

iowrite32(WAIT4INT(0),
base_addr+S3C2410_ADCTSC);//置于按下中断等待状态

if
(OwnADC)//如果抬起中断函数执行则此处不执行

{

OwnADC =
0;

up(&ADC_LOCK);

}

}

}

static struct
timer_list touch_timer =//定义一内核定时器

TIMER_INITIALIZER(touch_timer_fire,
0, 0);//初始化定时器赋予处理函数touch_timer_fire

//光标按下抬起抬起中断处理函数

static irqreturn_t stylus_updown(int irq, void *dev_id)

{

unsigned long data0;

unsigned long data1;

int updown;

if
(down_trylock(&ADC_LOCK) == 0)//获取信号量，在抬起处理函数中释放

{

OwnADC =
1;//该标志置1表示处于光标按下状态中，在光标抬起处理函数中清零

data0 =
ioread32(base_addr+S3C2410_ADCDAT0);

data1 =
ioread32(base_addr+S3C2410_ADCDAT1);

updown
= (!(data0 &
S3C2410_ADCDAT0_UPDOWN)) &&
(!(data1 &
S3C2410_ADCDAT0_UPDOWN));

if
(updown)

{

touch_timer_fire(0);//若为光标按下中断则调用该函数

}

else//光标抬起时执行的语句

{

OwnADC =
0;//清零

up(&ADC_LOCK);//释放信号量

}

}

return
IRQ_HANDLED;//////

}

///AD转换结束中断处理函数

static irqreturn_t stylus_action(int irq, void *dev_id)

{

unsigned long data0;

unsigned long data1;

if
(OwnADC)//OwnADC为1表示现在处于光标按下中断中

{

data0 =
ioread32(base_addr+S3C2410_ADCDAT0);

data1 =
ioread32(base_addr+S3C2410_ADCDAT1);

xp
+= data0 &
S3C2410_ADCDAT0_XPDATA_MASK;

yp += data1 &
S3C2410_ADCDAT1_YPDATA_MASK;

count++;

if
(count <
(1<<2))//四次AD转换，将四次转换值相加求平均值

{//触发AD转换

iowrite32(S3C2410_ADCTSC_PULL_UP_DISABLE
| AUTOPST, base_addr+S3C2410_ADCTSC);

iowrite32(ioread32(base_addr+S3C2410_ADCCON)
| S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);

}

else

{

mod_timer(&touch_timer,
jiffies+1);//触发内核定时器

iowrite32(WAIT4INT(1),
base_addr+S3C2410_ADCTSC);//将设备置于等待抬起中断状态

}

}

return
IRQ_HANDLED;

}

static struct
clk *adc_clock;

static int
__init tq2440ts_init(void)

{

struct input_dev *input_dev;

adc_clock
= clk_get(NULL, "adc");//获取时钟"adc"

if (!adc_clock)

{

printk(KERN_ERR "failed to get
adc clock source\n");

return -ENOENT;

}

clk_enable(adc_clock);//使能时钟

//以S3C2410_PA_ADC为起点映射一段IO内存

base_addr=ioremap(S3C2410_PA_ADC,0x20);

if (base_addr == NULL)

{

printk(KERN_ERR "Failed to
remap register block\n");

return -ENOMEM;

}

tq2440_ts_connect();//配置管脚

iowrite32(S3C2410_ADCCON_PRSCEN
| S3C2410_ADCCON_PRSCVL(0xFF),base_addr+S3C2410_ADCCON);

iowrite32(0xffff,
base_addr+S3C2410_ADCDLY);

iowrite32(WAIT4INT(0),
base_addr+S3C2410_ADCTSC);//将设备置于等待按下中断状态

input_dev =
input_allocate_device();//为输入设备的结构体input_dev分配内存并做相应初始化

if
(!input_dev)

{

printk(KERN_ERR "Unable to
allocate the input device !!\n");

return -ENOMEM;

}

dev
= input_dev;

dev->evbit[0] = BIT(EV_SYN) |
BIT(EV_KEY) | BIT(EV_ABS);//设置其支持的事件

dev->keybit[BITS_TO_LONGS(BTN_TOUCH)]
= BIT(BTN_TOUCH);//设置支持的keybit

input_set_abs_params(dev, ABS_X, 0, 0x3FF, 0,
0);//设置其最大最小值

input_set_abs_params(dev, ABS_Y, 0, 0x3FF, 0,
0);

input_set_abs_params(dev, ABS_PRESSURE, 0, 1, 0,
0);

dev->name
= tq2440ts_name;

dev->id.bustype = BUS_RS232;

dev->id.vendor = 0xDEAD;

dev->id.product = 0xBEEF;

dev->id.version =
S3C2410TSVERSION;

//申请AD转换结束中断

if (request_irq(IRQ_ADC, stylus_action, IRQF_SHARED|IRQF_SAMPLE_RANDOM,
tq2440ts_name, dev))

{

printk(KERN_ERR "tq2440_ts.c:
Could not allocate ts IRQ_ADC !\n");

iounmap(base_addr);

return -EIO;

}//申请按下抬起中断

if (request_irq(IRQ_TC, stylus_updown,
IRQF_SAMPLE_RANDOM, tq2440ts_name, dev))

{

printk(KERN_ERR "tq2440_ts.c:
Could not allocate ts IRQ_ADC !\n");

iounmap(base_addr);

return -EIO;

}

printk(KERN_INFO
"%s successfully loaded\n", tq2440ts_name);

//注册输入设备，在/dev下会产生一个eventn(n为0,1,2。。。。)的设备结点

input_register_device(dev);

return
0;

}

static void
__exit tq2440ts_exit(void)

{

disable_irq(IRQ_ADC);

disable_irq(IRQ_TC);

free_irq(IRQ_TC,dev);//先禁能中断再释放

free_irq(IRQ_ADC,dev);

if
(adc_clock)

{

clk_disable(adc_clock);

clk_put(adc_clock);//先禁能时钟再释放

adc_clock = NULL;

}

input_unregister_device(dev);

iounmap(base_addr);

}

module_init(tq2440ts_init);

module_exit(tq2440ts_exit);