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ARM-Linux驅動-觸摸屏驅動分析

日期：2017/3/1 11:11:40 编辑：Linux編程

1、下面是ADC和觸摸屏接口的模塊圖

當觸摸屏接口使用時，XM或YM接觸摸屏接口的地

當觸摸屏接口不使用時，XM或YM接模擬信號，做普通ADC使用。

2、觸摸屏接口的幾種操作模式

（1）正常轉換模式

通過設置ADCCON（adc控制寄存器）來完成初始化，並對ADCDAT0數據寄存器進行操作。

（2）分離XY坐標模式

X坐標模式寫X坐標轉換數據到ADCDAT0，觸摸屏接口產生中斷到中斷控制寄存器。Y坐標模式寫Y坐標轉換數據到ADCDAT1，觸摸屏接口產生中斷到中斷控制寄存器。兩種模

式可以選擇一種模式工作。

相應的引腳連接：

（3）自動XY坐標模式

觸摸屏控制器連續的轉換X和Y的坐標，在X坐標轉換後的值存入ADCDAT0後，自動將Y坐標轉換後的值存入ADCDAT1，觸摸屏接口產生中斷到中斷控制器。

相應的引腳連接：

（4）等待中斷模式

當光標被按下，觸摸屏控制器產生中斷IRQ_TC，當產生中斷信號時，等待中斷模式必須被清除。

引腳定義如下：

3、下面是s3c2440觸摸屏驅動的分析

//#define CONFIG_TOUCHSCREEN_S3C2410_DEBUG
#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 <mach/regs-gpio.h>
#include <mach/s3c2410_ts.h>
#include <plat/regs-adc.h>
#define TRUE 1 //CoAsia added
#define FALSE 0 //CoAsia added
#define FILTER_LIMIT 25 //CoAsia added
/* For ts.dev.id.version */
#define S3C2410TSVERSION 0x0101
#define TSC_SLEEP (S3C2410_ADCTSC_PULL_UP_DISABLE | S3C2410_ADCTSC_XY_PST(0))
#define WAIT4INT(x) (((x)<<8) | \
S3C2410_ADCTSC_YM_SEN | S3C2410_ADCTSC_YP_SEN | S3C2410_ADCTSC_XP_SEN | \
S3C2410_ADCTSC_XY_PST(3))
#define AUTOPST (S3C2410_ADCTSC_YM_SEN | S3C2410_ADCTSC_YP_SEN | S3C2410_ADCTSC_XP_SEN | \
S3C2410_ADCTSC_AUTO_PST | S3C2410_ADCTSC_XY_PST(0))
#define DEBUG_LVL "<3>" //KERN_DEBUG
static char *s3c2440ts_name = "s3c2440 TouchScreen";
/*
* Per-touchscreen data.
*/
//定義s3c2440觸摸屏使用的數據結構體
struct s3c2440ts {
struct input_dev *dev;
long xp;
long yp;
int count;
int shift;
};
static struct s3c2440ts ts;
static struct clk *adc_clock;
//__iomem聲明地址空間是設備地址映射空間
static void __iomem *base_addr;
//函數聲明
static void touch_timer_fire(unsigned long data);
static irqreturn_t tc_irq(int irq, void *dev_id);
static irqreturn_t adc_irq(int irq, void *dev_id);
static int __init s3c2440ts_probe(struct platform_device *pdev);
static int s3c2440ts_remove(struct platform_device *pdev);
static int s3c2440ts_resume(struct platform_device *pdev);
//定義定時器
static struct timer_list touch_timer =
TIMER_INITIALIZER(touch_timer_fire, 0, 0);
//IRQ_TC中斷處理函數
static irqreturn_t tc_irq(int irq, void *dev_id)
{
//data0,data1用於存放讀取的ADCDAT數據寄存器的值
unsigned long data0;
unsigned long data1;
int updown;//用於存放光標的按下或提起的狀態
//讀取ADCDAT0、ADCDAT1數據寄存器的值
data0 = readl(base_addr+S3C2410_ADCDAT0);
data1 = readl(base_addr+S3C2410_ADCDAT1);
//查看數據寄存器的第15位的值
updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT0_UPDOWN));
/* TODO we should never get an interrupt with updown set while
* the timer is running, but maybe we ought to verify that the
* timer isn't running anyways. */
//如果data0和data1的第15位都是0，則updown為1，則通過函數touch_timer_fire()函數來啟動ADC轉換
if (updown)
touch_timer_fire(0);
return IRQ_HANDLED;
}
static void touch_timer_fire(unsigned long data)
{
//用於存儲數據寄存器ADCDAT0、ADCDAT1的值
unsigned long data0;
unsigned long data1;
//用於存放光標是否被按下
int updown;
data0 = readl(base_addr+S3C2410_ADCDAT0);
data1 = readl(base_addr+S3C2410_ADCDAT1);
updown = (!(data0 & S3C2410_ADCDAT0_UPDOWN)) && (!(data1 & S3C2410_ADCDAT0_UPDOWN));
//printk("The number of 'updown' is %d\n ",updown);
//如果光標被按下，執行
if (updown)
{
//ts.count!=0表示ADC已經轉換過，下面就報告事件和光標位置數據
if (ts.count != 0)
{
ts.xp >>= ts.shift;//這裡shift為2，這裡實際上是求均值，四次的和/4，這樣定位更加准確
ts.yp >>= ts.shift;
#ifdef CONFIG_TOUCHSCREEN_S3C2410_DEBUG
{
struct timeval tv;
do_gettimeofday(&tv);
printk(DEBUG_LVL "T: %06d, X: %03ld, Y: %03ld\n", (int)tv.tv_usec, ts.xp, ts.yp);
}
#endif
/*
下面的函數位於/include/linux/input.h，作用是報告事件
static inline void input_report_abs(struct input_dev *dev, unsigned int code, int value)
{
input_event(dev, EV_ABS, code, value);
}
*/
//報告X，Y的絕對坐標
input_report_abs(ts.dev, ABS_X, ts.xp);
input_report_abs(ts.dev, ABS_Y, ts.yp);
//報告事件，1代表光標被按下
input_report_key(ts.dev, BTN_TOUCH, 1);
//報告觸摸屏狀態，1代表觸摸屏被按下
input_report_abs(ts.dev, ABS_PRESSURE, 1);
//等待接收方的確認，用於事件的同步
input_sync(ts.dev);
}
//現在光標被按下，並且ADC轉換沒有啟動
ts.xp = 0;
ts.yp = 0;
ts.count = 0;
//設置觸摸屏控制寄存器的值為 0xdc B:1101 1100，設置控制寄存器上拉無效，自動轉換X，Y坐標
//printk("S3C2410_ADCTSC: 0x%x\n",S3C2410_ADCTSC_PULL_UP_DISABLE | AUTOPST);
writel(S3C2410_ADCTSC_PULL_UP_DISABLE | AUTOPST, base_addr+S3C2410_ADCTSC);
//啟動ADC轉換
writel(readl(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);
}
else//光標沒有被按下
{
ts.count = 0;
//報告事件及光標的位置狀態
input_report_key(ts.dev, BTN_TOUCH, 0);
input_report_abs(ts.dev, ABS_PRESSURE, 0);
//等待接收方的應答，用於同步
input_sync(ts.dev);
//設置觸摸屏控制寄存器為等待中斷模式
writel(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
}
}
static irqreturn_t adc_irq(int irq, void *dev_id)
{
//用於存放數據寄存器的數據
unsigned long data0;
unsigned long data1;
//讀取數據，這次主要讀取的是位置數據
data0 = readl(base_addr+S3C2410_ADCDAT0);
data1 = readl(base_addr+S3C2410_ADCDAT1);
ts.xp += data0 & S3C2410_ADCDAT0_XPDATA_MASK;//累加四次准換結果的X坐標和
ts.yp += data1 & S3C2410_ADCDAT1_YPDATA_MASK;//累加四次准換結果的Y坐標和
ts.count++;//轉換次數加一
//如果轉換次數小於4
if (ts.count < (1<<ts.shift))
{
//再次設置觸摸屏控制寄存器上拉不使能、自動X、Y轉換模式
writel(S3C2410_ADCTSC_PULL_UP_DISABLE | AUTOPST, base_addr+S3C2410_ADCTSC);
//再次啟動ADC轉換
writel(readl(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_ENABLE_START, base_addr+S3C2410_ADCCON);
}
else//這時，ADC轉換四次完成，延遲一個系統滴答，執行touch_timer_fire()函數
{
mod_timer(&touch_timer, jiffies+1);
writel(WAIT4INT(1), base_addr+S3C2410_ADCTSC);
}
return IRQ_HANDLED;
}
/*
* The functions for inserting/removing us as a module.
*/
/*
該結構體定義在/include/linux/platform_device.h
struct platform_device {
const char * name;
int id;
struct device dev;
u32 num_resources;
struct resource * resource;
};
*/
static int __init s3c2440ts_probe(struct platform_device *pdev)
{
int rc;
/*
下面結構體定義在/include/mach/s3c2410_ts.h
struct s3c2410_ts_mach_info {
int delay;
int presc;
int oversampling_shift;
};
*/
struct s3c2410_ts_mach_info *info;
struct input_dev *input_dev;
/*
void *platform_data;//Platform specific data, device core doesn't touch it
*/
info = ( struct s3c2440_ts_mach_info *)pdev->dev.platform_data;
if (!info)
{
printk(KERN_ERR "Hm... too bad : no platform data for ts\n");
return -EINVAL;
}
#ifdef CONFIG_TOUCHSCREEN_S3C2410_DEBUG
printk(DEBUG_LVL "Entering s3c2440ts_init\n");
#endif
//由於ADC轉換需要時鐘，這裡獲取時鐘
adc_clock = clk_get(NULL, "adc");
if (!adc_clock) {
printk(KERN_ERR "failed to get adc clock source\n");
return -ENOENT;
}
clk_enable(adc_clock);//使能時鐘
#ifdef CONFIG_TOUCHSCREEN_S3C2410_DEBUG
printk(DEBUG_LVL "got and enabled clock\n");
#endif
//通過ioremap實現物理地址到虛擬地址的轉換
base_addr = ioremap(S3C2410_PA_ADC,0x20);
if (base_addr == NULL) {
printk(KERN_ERR "Failed to remap register block\n");
return -ENOMEM;
}
//設置ADCCON控制寄存器為0x4c40,設置預分頻有效，預分頻值為B：110001 D：49
//printk("ADCCON is 0x%x\n",S3C2410_ADCCON_PRSCEN | S3C2410_ADCCON_PRSCVL(info->presc&0xFF));
if ((info->presc&0xff) > 0)
writel(S3C2410_ADCCON_PRSCEN | S3C2410_ADCCON_PRSCVL(info->presc&0xFF),\
base_addr+S3C2410_ADCCON);
else
writel(0,base_addr+S3C2410_ADCCON);
/* Initialise registers */
/*
設置ADC開始延時寄存器ADCDLY: 0x4e20
*/
//printk("ADCDLY: 0x%x\n",info->delay & 0xffff);
if ((info->delay&0xffff) > 0)
writel(info->delay & 0xffff, base_addr+S3C2410_ADCDLY);
/*
設置ADC觸摸屏控制寄存器ADC_TSC: 0xd3 B:1101 0011
[8]檢測光標按下中斷信號
[7]YM輸出驅動有效（GND）
[6]YP輸出驅動無效（AIN5）
[5]XM輸出驅動無效（Hi-z）
[4]XP輸出驅動無效（AIN7）
[3]XP上拉有效
[2]普通ADC轉換
[0:1]等待中斷模式測量X和Y的坐標
*/
//printk("ADC_TSC: 0x%x\n",WAIT4INT(0));
writel(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
/* Initialise input stuff */
memset(&ts, 0, sizeof(struct s3c2440ts));
/*
下面的函數
為新的輸入設備分配內存。
使用free_device()釋放沒有被注冊的函數，使用input_unregister_device()解除已經注冊的設備
定義在/drivers/input/input.c
struct input_dev *input_allocate_device(void)
{
struct input_dev *dev;
dev = kzalloc(sizeof(struct input_dev), GFP_KERNEL);
if (dev) {
dev->dev.type = &input_dev_type;
dev->dev.class = &input_class;
device_initialize(&dev->dev);
mutex_init(&dev->mutex);
spin_lock_init(&dev->event_lock);
INIT_LIST_HEAD(&dev->h_list);
INIT_LIST_HEAD(&dev->node);
__module_get(THIS_MODULE);
}
return dev;
}
*/
input_dev = input_allocate_device();
if (!input_dev) {
printk(KERN_ERR "Unable to allocate the input device !!\n");
return -ENOMEM;
}
//下面初始化輸入設備信息
ts.dev = input_dev;
ts.dev->evbit[0] = BIT_MASK(EV_SYN) | BIT_MASK(EV_KEY) |
BIT_MASK(EV_ABS);
ts.dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
input_set_abs_params(ts.dev, ABS_X, 0, 0x3FF, 0, 0);
input_set_abs_params(ts.dev, ABS_Y, 0, 0x3FF, 0, 0);
input_set_abs_params(ts.dev, ABS_PRESSURE, 0, 1, 0, 0);
//ts.dev->private = &ts;
ts.dev->name = s3c2440ts_name;
ts.dev->id.bustype = BUS_RS232;
ts.dev->id.vendor = 0xDEAD;
ts.dev->id.product = 0xBEEF;
ts.dev->id.version = S3C2410TSVERSION;
ts.shift = info->oversampling_shift;
//printk("shift: %d\n",ts.shift);
/* Get irqs */
//申請ADC中斷，注意，中斷類型為IRQF_SAMPLE_RANDOM | IRQF_SHARED，這樣在使用觸摸屏的時候
//可以調試自己的ADC轉換驅動，中斷處理函數為adc_irq
if (request_irq(IRQ_ADC, adc_irq, IRQF_SAMPLE_RANDOM | IRQF_SHARED,
"s3c2440_action", ts.dev)) {
printk(KERN_ERR "s3c2440_ts.c: Could not allocate ts IRQ_ADC !\n");
iounmap(base_addr);
return -EIO;
}
//申請TC中斷，中斷處理函數為tc_irq
if (request_irq(IRQ_TC, tc_irq, IRQF_SAMPLE_RANDOM,
"s3c2440_action", ts.dev)) {
printk(KERN_ERR "s3c2440_ts.c: Could not allocate ts IRQ_TC !\n");
free_irq(IRQ_ADC, ts.dev);
iounmap(base_addr);
return -EIO;
}
printk(KERN_INFO "%s successfully loaded\n", s3c2440ts_name);
/* All went ok, so register to the input system */
/*這裡注冊設備
函數功能：
* This function registers device with input core. The device must be
* allocated with input_allocate_device() and all it's capabilities
* set up before registering.
* If function fails the device must be freed with input_free_device().
* Once device has been successfully registered it can be unregistered
* with input_unregister_device(); input_free_device() should not be
* called in this case.
函數原型如下：
int input_register_device(struct input_dev *dev)
{
static atomic_t input_no = ATOMIC_INIT(0);
struct input_handler *handler;
const char *path;
int error;
__set_bit(EV_SYN, dev->evbit);
init_timer(&dev->timer);
if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {
dev->timer.data = (long) dev;
dev->timer.function = input_repeat_key;
dev->rep[REP_DELAY] = 250;
dev->rep[REP_PERIOD] = 33;
}
if (!dev->getkeycode)
dev->getkeycode = input_default_getkeycode;
if (!dev->setkeycode)
dev->setkeycode = input_default_setkeycode;
snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
"input%ld", (unsigned long) atomic_inc_return(&input_no) - 1);
error = device_add(&dev->dev);
if (error)
return error;
path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
printk(KERN_INFO "input: %s as %s\n",
dev->name ? dev->name : "Unspecified device", path ? path : "N/A");
kfree(path);
error = mutex_lock_interruptible(&input_mutex);
if (error) {
device_del(&dev->dev);
return error;
}
list_add_tail(&dev->node, &input_dev_list);
list_for_each_entry(handler, &input_handler_list, node)
input_attach_handler(dev, handler);
input_wakeup_procfs_readers();
mutex_unlock(&input_mutex);
return 0;
}
*/
rc = input_register_device(ts.dev);
if (rc) {
free_irq(IRQ_TC, ts.dev);
free_irq(IRQ_ADC, ts.dev);
clk_disable(adc_clock);
iounmap(base_addr);
return -EIO;
}
return 0;
}
static int s3c2440ts_remove(struct platform_device *pdev)
{
disable_irq(IRQ_ADC);
disable_irq(IRQ_TC);
free_irq(IRQ_TC,ts.dev);
free_irq(IRQ_ADC,ts.dev);
if (adc_clock) {
clk_disable(adc_clock);
clk_put(adc_clock);
adc_clock = NULL;
}
input_unregister_device(ts.dev);
iounmap(base_addr);
return 0;
}
#ifdef CONFIG_PM
static int s3c2440ts_suspend(struct platform_device *pdev, pm_message_t state)
{
writel(TSC_SLEEP, base_addr+S3C2410_ADCTSC);
writel(readl(base_addr+S3C2410_ADCCON) | S3C2410_ADCCON_STDBM,
base_addr+S3C2410_ADCCON);
disable_irq(IRQ_ADC);
disable_irq(IRQ_TC);
clk_disable(adc_clock);
return 0;
}
static int s3c2440ts_resume(struct platform_device *pdev)
{
struct s3c2440_ts_mach_info *info =
( struct s3c2440_ts_mach_info *)pdev->dev.platform_data;
clk_enable(adc_clock);
msleep(1);
enable_irq(IRQ_ADC);
enable_irq(IRQ_TC);
if ((info->presc&0xff) > 0)
writel(S3C2410_ADCCON_PRSCEN | S3C2410_ADCCON_PRSCVL(info->presc&0xFF),\
base_addr+S3C2410_ADCCON);
else
writel(0,base_addr+S3C2410_ADCCON);
/* Initialise registers */
if ((info->delay&0xffff) > 0)
writel(info->delay & 0xffff, base_addr+S3C2410_ADCDLY);
writel(WAIT4INT(0), base_addr+S3C2410_ADCTSC);
return 0;
}
#else
#define s3c2440ts_suspend NULL
#define s3c2440ts_resume NULL
#endif
/*
下面是/linux/platform_device.h定義的platform_driver結構體
struct platform_driver {
int (*probe)(struct platform_device *);//設備的檢測，所以需要先前的設備注冊
int (*remove)(struct platform_device *);//刪除該設備
void (*shutdown)(struct platform_device *); //關閉該設備
int (*suspend)(struct platform_device *, pm_message_t state);
int (*suspend_late)(struct platform_device *, pm_message_t state);
int (*resume_early)(struct platform_device *);
int (*resume)(struct platform_device *);
struct pm_ext_ops *pm;
struct device_driver driver;//設備驅動，定義在include/linux/device.h中
};
內核提供的platform_driver結構體的注冊函數為platform_driver_register(),該函數定義在driver/base/platform.c中
*/
static struct platform_driver s3c2440ts_driver = {
.driver = {
.name = "s3c2440-ts",
.owner = THIS_MODULE,
},
.probe = s3c2440ts_probe,
.remove = s3c2440ts_remove,
.suspend = s3c2440ts_suspend,
.resume = s3c2440ts_resume,
};
static int __init s3c2440ts_init(void)
{
int rc;
rc = platform_driver_register(&s3c2440ts_driver);
if (rc < 0)
printk(KERN_ERR "platform_driver_register error!\n");
return rc;
}
static void __exit s3c2440ts_exit(void)
{
platform_driver_unregister(&s3c2440ts_driver);
}
module_init(s3c2440ts_init);
module_exit(s3c2440ts_exit);
MODULE_AUTHOR("YANMING");
MODULE_DESCRIPTION("My s3c2440 touchscreen driver");
MODULE_LICENSE("GPL");