基于S3c6410触摸屏驱动分析（一）

首先说明一下，本文使用的环境是S3C6410（Tiny6410），Linux-2.6.38（友善之臂提供），触摸屏驱动位于drivers/input/touchscreen/目录下。

好吧，就让我们开始我们的触摸屏之旅。。。

一．硬件简介

       S3C6410触摸屏接口与ADC接口集成在一起，触摸屏X、Y坐标所产生的模拟信号通过通道7、5输入如下图示，6410提供触摸屏接口有4种处理模式：普通转换模式、分离的X/Y轴坐标转换模式、自动(连续)X/Y轴坐标转换模式、等待中断模式。具体参考6410芯片手册。

二、触摸屏工作流程：

1、选择模式

2、设置触摸屏接口到等待接口状态

3、如果中断发生，激活转换模式

4、获取坐标后，返回等待中断状态

（INT_TC中断用于按下或弹起触摸屏）

（INT_ADC用于坐标转换完成）

三、触摸屏驱动源码分析

/* 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 <[e-mail]>
 ** iPAQ H1940 touchscreen support
 **
 ** ChangeLog
 **
 ** 2004-09-05: Herbert Potzl <[e-mail]>
 ** - added clock (de-)allocation code
 **
 ** 2005-03-06: Arnaud Patard <[e-mail]>
 **      - 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 <[e-mail]>
 **      - Make use of some undocumented features of the touchscreen
 **        controller
 **
 ** 2006-09-05: Ryu Euiyoul <[e-mail]>
 **      - added power management suspend and resume code
 *
 */
#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 <plat/regs-adc.h>
#include <mach/irqs.h>
#include <mach/map.h>
#include <mach/regs-clock.h>
#include <mach/regs-gpio.h>
#include <mach/gpio-bank-a.h>
#include <mach/ts.h>

#define CONFIG_TOUCHSCREEN_S3C_DEBUG
#undef CONFIG_TOUCHSCREEN_S3C_DEBUG
#define DEBUG_LVL KERN_DEBUG


#ifdef CONFIG_MINI6410_ADC
DEFINE_SEMAPHORE(ADC_LOCK);

/* Indicate who is using the ADC controller */
#define LOCK_FREE 0
#define LOCK_TS 1
#define LOCK_ADC 2
static int adc_lock_id = LOCK_FREE;


#define ADC_free()(adc_lock_id == LOCK_FREE)
#define ADC_locked4TS() (adc_lock_id == LOCK_TS)


static inline int s3c_ts_adc_lock(int id) {
int ret;


ret = down_trylock(&ADC_LOCK);
if (!ret) {
adc_lock_id = id;
}


return ret;
}


static inline void s3c_ts_adc_unlock(void) {
adc_lock_id = 0;
up(&ADC_LOCK);
}
#endif




/* Touchscreen default configuration */
struct s3c_ts_mach_info s3c_ts_default_cfg __initdata = {
.delay = 10000,
.presc = 49,
.oversampling_shift = 2,
.resol_bit = 10
};


/*
 * Definitions & global arrays.
 */
#define DEVICE_NAME "touchscreen"
static DECLARE_WAIT_QUEUE_HEAD(ts_waitq);


typedef unsigned TS_EVENT;
#define NR_EVENTS 64


static TS_EVENT events[NR_EVENTS];
static int evt_head, evt_tail;


#define ts_evt_pending() ((volatile u8)(evt_head != evt_tail))
#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)


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);


if (next_head != evt_tail) {
events[evt_head] = ts_event;
evt_head = next_head;
//printk("====>Add ... [ %4d,  %4d ]%s\n", x, y, down ? "":" ~~~");


/* wake up any read call */
if (waitqueue_active(&ts_waitq)) {
wake_up_interruptible(&ts_waitq);
}
} else {
/* drop the event and try to wakeup readers */
printk(KERN_WARNING "mini6410-ts: touch event buffer full");
wake_up_interruptible(&ts_waitq);
}
}


static unsigned int s3c_ts_poll( struct file *file, struct poll_table_struct *wait)
{
unsigned int mask = 0;


poll_wait(file, &ts_waitq, wait);
if (ts_evt_pending())
mask |= POLLIN | POLLRDNORM;


return mask;
}


static int s3c_ts_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
DECLARE_WAITQUEUE(wait, current);
char *ptr = buff;
int err = 0;


add_wait_queue(&ts_waitq, &wait);
while (count >= sizeof(TS_EVENT)) {
err = -ERESTARTSYS;
if (signal_pending(current))
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);
err = -EAGAIN;
if (filp->f_flags & O_NONBLOCK)
break;
schedule();
}
current->state = TASK_RUNNING;
remove_wait_queue(&ts_waitq, &wait);


return ptr == buff ? err : ptr - buff;
}


static int s3c_ts_open(struct inode *inode, struct file *filp) {
/* flush event queue */
ts_evt_clear();


return 0;
}


static struct file_operations dev_fops = {
.owner = THIS_MODULE,
.read = s3c_ts_read,
.poll = s3c_ts_poll,
.open = s3c_ts_open,
};


static struct miscdevice misc = {
.minor = 180,
.name = DEVICE_NAME,
.fops = &dev_fops,
};


#define WAIT4INT(x) (((x) << 8) | \
S3C_ADCTSC_YM_SEN | S3C_ADCTSC_YP_SEN | S3C_ADCTSC_XP_SEN | \
S3C_ADCTSC_XY_PST(3))


#define AUTOPST (S3C_ADCTSC_YM_SEN | S3C_ADCTSC_YP_SEN | S3C_ADCTSC_XP_SEN | \
S3C_ADCTSC_AUTO_PST | S3C_ADCTSC_XY_PST(0))


static void __iomem *ts_base;
static struct resource *ts_mem;
static struct resource *ts_irq;
static struct clk *ts_clock;
static struct s3c_ts_info *ts;


/**
 * get_down - return the down state of the pen
 * @data0: The data read from ADCDAT0 register.
 * @data1: The data read from ADCDAT1 register.
 *
 * Return non-zero if both readings show that the pen is down.
 */
static inline bool get_down(unsigned long data0, unsigned long data1)
{
/* returns true if both data values show stylus down */
return (!(data0 & S3C_ADCDAT0_UPDOWN) && !(data1 & S3C_ADCDAT1_UPDOWN));
}


static void touch_timer_fire(unsigned long data) {
unsigned long data0;
unsigned long data1;
int pendown;


#ifdef CONFIG_MINI6410_ADC
if (!ADC_locked4TS()) {
/* Note: pen UP interrupt detected and handled, the lock is released,
* so do nothing in the timer which started by ADC ISR. */
return;
}
#endif


data0 = readl(ts_base + S3C_ADCDAT0);
data1 = readl(ts_base + S3C_ADCDAT1);


pendown = get_down(data0, data1);


if (pendown) {
if (ts->count == (1 << ts->shift)) {
#ifdef CONFIG_TOUCHSCREEN_S3C_DEBUG
{
struct timeval tv;
do_gettimeofday(&tv);
printk(KERN_INFO "T: %06d, X: %03ld, Y: %03ld\n",
(int)tv.tv_usec, ts->xp, ts->yp);
}
#endif


ts_evt_add((ts->xp >> ts->shift), (ts->yp >> ts->shift), 1);


ts->xp = 0;
ts->yp = 0;
ts->count = 0;
}


/* start automatic sequencing A/D conversion */
writel(S3C_ADCTSC_PULL_UP_DISABLE | AUTOPST, ts_base + S3C_ADCTSC);
writel(readl(ts_base + S3C_ADCCON) | S3C_ADCCON_ENABLE_START,
ts_base + S3C_ADCCON);
} else {
ts->xp = 0;
ts->yp = 0;
ts->count = 0;


ts_evt_add(0, 0, 0);


/* PEN is UP, Let's wait the PEN DOWN interrupt */
writel(WAIT4INT(0), ts_base + S3C_ADCTSC);


#ifdef CONFIG_MINI6410_ADC
if (ADC_locked4TS()) {
s3c_ts_adc_unlock();
}
#endif
}
}


static DEFINE_TIMER(touch_timer, touch_timer_fire, 0, 0);


static irqreturn_t stylus_updown(int irqno, void *param)
{
#ifdef CONFIG_TOUCHSCREEN_S3C_DEBUG
unsigned long data0;
unsigned long data1;
int is_waiting_up;
int pendown;
#endif


#ifdef CONFIG_MINI6410_ADC
if (!ADC_locked4TS()) {
if (s3c_ts_adc_lock(LOCK_TS)) {
/* Locking ADC controller failed */
printk("Lock ADC failed, %d\n", adc_lock_id);
return IRQ_HANDLED;
}
}
#endif


#ifdef CONFIG_TOUCHSCREEN_S3C_DEBUG
data0 = readl(ts_base + S3C_ADCDAT0);
data1 = readl(ts_base + S3C_ADCDAT1);


is_waiting_up = readl(ts_base + S3C_ADCTSC) & (1 << 8);
pendown = get_down(data0, data1);


printk("P: %d <--> %c\n", pendown, is_waiting_up ? 'u':'d');
#endif


if (ts->s3c_adc_con == ADC_TYPE_2) {
/* Clear ADC and PEN Down/UP interrupt */
__raw_writel(0x0, ts_base + S3C_ADCCLRWK);
__raw_writel(0x0, ts_base + S3C_ADCCLRINT);
}


/* TODO we should never get an interrupt with pendown set while
* the timer is running, but maybe we ought to verify that the
* timer isn't running anyways. */


touch_timer_fire(1);


return IRQ_HANDLED;
}


static irqreturn_t stylus_action(int irqno, void *param)
{
unsigned long data0;
unsigned long data1;


#ifdef CONFIG_MINI6410_ADC
if (!ADC_locked4TS()) {
if (ADC_free()) {
printk("Unexpected\n");


/* Clear ADC interrupt */
__raw_writel(0x0, ts_base + S3C_ADCCLRINT);
}


return IRQ_HANDLED;
}
#endif


data0 = readl(ts_base + S3C_ADCDAT0);
data1 = readl(ts_base + S3C_ADCDAT1);


if (ts->resol_bit == 12) {
#if defined(CONFIG_TOUCHSCREEN_NEW)
ts->yp += S3C_ADCDAT0_XPDATA_MASK_12BIT - (data0 & S3C_ADCDAT0_XPDATA_MASK_12BIT);
ts->xp += S3C_ADCDAT1_YPDATA_MASK_12BIT - (data1 & S3C_ADCDAT1_YPDATA_MASK_12BIT);
#else 
ts->xp += data0 & S3C_ADCDAT0_XPDATA_MASK_12BIT;
ts->yp += data1 & S3C_ADCDAT1_YPDATA_MASK_12BIT;
#endif
} else {
#if defined(CONFIG_TOUCHSCREEN_NEW)
ts->yp += S3C_ADCDAT0_XPDATA_MASK - (data0 & S3C_ADCDAT0_XPDATA_MASK);
ts->xp += S3C_ADCDAT1_YPDATA_MASK - (data1 & S3C_ADCDAT1_YPDATA_MASK);
#else
ts->xp += data0 & S3C_ADCDAT0_XPDATA_MASK;
ts->yp += data1 & S3C_ADCDAT1_YPDATA_MASK;
#endif
}


ts->count++;


if (ts->count < (1 << ts->shift)) {
writel(S3C_ADCTSC_PULL_UP_DISABLE | AUTOPST, ts_base + S3C_ADCTSC);
writel(readl(ts_base + S3C_ADCCON) | S3C_ADCCON_ENABLE_START, ts_base + S3C_ADCCON);
} else {
mod_timer(&touch_timer, jiffies + 1);
writel(WAIT4INT(1), ts_base + S3C_ADCTSC);
}


if (ts->s3c_adc_con == ADC_TYPE_2) {
/* Clear ADC and PEN Down/UP interrupt */
__raw_writel(0x0, ts_base + S3C_ADCCLRWK);
__raw_writel(0x0, ts_base + S3C_ADCCLRINT);
}


return IRQ_HANDLED;
}




#ifdef CONFIG_MINI6410_ADC
static unsigned int _adccon, _adctsc, _adcdly;


int mini6410_adc_acquire_io(void) {
int ret;


ret = s3c_ts_adc_lock(LOCK_ADC);
if (!ret) {
_adccon = readl(ts_base + S3C_ADCCON);
_adctsc = readl(ts_base + S3C_ADCTSC);
_adcdly = readl(ts_base + S3C_ADCDLY);
}


return ret;
}
EXPORT_SYMBOL(mini6410_adc_acquire_io);


void mini6410_adc_release_io(void) {
writel(_adccon, ts_base + S3C_ADCCON);
writel(_adctsc, ts_base + S3C_ADCTSC);
writel(_adcdly, ts_base + S3C_ADCDLY);
writel(WAIT4INT(0), ts_base + S3C_ADCTSC);


s3c_ts_adc_unlock();
}


EXPORT_SYMBOL(mini6410_adc_release_io);
#endif




static struct s3c_ts_mach_info *s3c_ts_get_platdata(struct device *dev)
{
if (dev->platform_data != NULL)
return (struct s3c_ts_mach_info *)dev->platform_data;


return &s3c_ts_default_cfg;
}


/*
 * The functions for inserting/removing us as a module.
 */
static int __init s3c_ts_probe(struct platform_device *pdev)
{
struct resource *res;
struct device *dev;
struct s3c_ts_mach_info * s3c_ts_cfg;
int ret, size;

dev = &pdev->dev;

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (res == NULL) {
dev_err(dev,"no memory resource specified\n");
return -ENOENT;
}


size = (res->end - res->start) + 1;
ts_mem = request_mem_region(res->start, size, pdev->name);
if (ts_mem == NULL) {
dev_err(dev, "failed to get memory region\n");
ret = -ENOENT;
goto err_req;
}


ts_base = ioremap(res->start, size);
if (ts_base == NULL) {
dev_err(dev, "failed to ioremap() region\n");
ret = -EINVAL;
goto err_map;
}


ts_clock = clk_get(&pdev->dev, "adc");
if (IS_ERR(ts_clock)) {
dev_err(dev, "failed to find watchdog clock source\n");
ret = PTR_ERR(ts_clock);
goto err_clk;
}


clk_enable(ts_clock);


s3c_ts_cfg = s3c_ts_get_platdata(&pdev->dev);


if ((s3c_ts_cfg->presc & 0xff) > 0)
writel(S3C_ADCCON_PRSCEN | S3C_ADCCON_PRSCVL(s3c_ts_cfg->presc & 0xff),
ts_base + S3C_ADCCON);
else
writel(0, ts_base + S3C_ADCCON);


/* Initialise registers */
if ((s3c_ts_cfg->delay & 0xffff) > 0)
writel(s3c_ts_cfg->delay & 0xffff, ts_base + S3C_ADCDLY);


if (s3c_ts_cfg->resol_bit == 12) {
switch(s3c_ts_cfg->s3c_adc_con) {
case ADC_TYPE_2:
writel(readl(ts_base + S3C_ADCCON) | S3C_ADCCON_RESSEL_12BIT,
ts_base + S3C_ADCCON);
break;


case ADC_TYPE_1:
writel(readl(ts_base + S3C_ADCCON) | S3C_ADCCON_RESSEL_12BIT_1,
ts_base + S3C_ADCCON);
break;


default:
dev_err(dev, "Touchscreen over this type of AP isn't supported !\n");
break;
}
}


writel(WAIT4INT(0), ts_base + S3C_ADCTSC);


ts = kzalloc(sizeof(struct s3c_ts_info), GFP_KERNEL);


ts->shift = s3c_ts_cfg->oversampling_shift;
ts->resol_bit = s3c_ts_cfg->resol_bit;
ts->s3c_adc_con = s3c_ts_cfg->s3c_adc_con;


/* For IRQ_PENDUP */
ts_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
if (ts_irq == NULL) {
dev_err(dev, "no irq resource specified\n");
ret = -ENOENT;
goto err_irq;
}


ret = request_irq(ts_irq->start, stylus_updown, IRQF_SAMPLE_RANDOM, "s3c_updown", ts);
if (ret != 0) {
dev_err(dev,"s3c_ts.c: Could not allocate ts IRQ_PENDN !\n");
ret = -EIO;
goto err_irq;
}


/* For IRQ_ADC */
ts_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 1);
if (ts_irq == NULL) {
dev_err(dev, "no irq resource specified\n");
ret = -ENOENT;
goto err_irq;
}


ret = request_irq(ts_irq->start, stylus_action, IRQF_SAMPLE_RANDOM | IRQF_SHARED,
"s3c_action", ts);
if (ret != 0) {
dev_err(dev, "s3c_ts.c: Could not allocate ts IRQ_ADC !\n");
ret = -EIO;
goto err_irq;
}


printk(KERN_INFO "%s got loaded successfully : %d bits\n", DEVICE_NAME, s3c_ts_cfg->resol_bit);


ret = misc_register(&misc);
if (ret) {
dev_err(dev, "s3c_ts.c: Could not register device(mini6410 touchscreen)!\n");
ret = -EIO;
goto fail;
}


return 0;


fail:
free_irq(ts_irq->start, ts->dev);
free_irq(ts_irq->end, ts->dev);


err_irq:
kfree(ts);


clk_disable(ts_clock);
clk_put(ts_clock);


err_clk:
iounmap(ts_base);


err_map:
release_resource(ts_mem);
kfree(ts_mem);


err_req:
return ret;
}


static int s3c_ts_remove(struct platform_device *dev)
{
printk(KERN_INFO "s3c_ts_remove() of TS called !\n");


disable_irq(IRQ_ADC);
disable_irq(IRQ_PENDN);


free_irq(IRQ_PENDN, ts->dev);
free_irq(IRQ_ADC, ts->dev);


if (ts_clock) {
clk_disable(ts_clock);
clk_put(ts_clock);
ts_clock = NULL;
}


misc_deregister(&misc);
iounmap(ts_base);


return 0;
}


#ifdef CONFIG_PM
static unsigned int adccon, adctsc, adcdly;


static int s3c_ts_suspend(struct platform_device *dev, pm_message_t state)
{
adccon = readl(ts_base + S3C_ADCCON);
adctsc = readl(ts_base + S3C_ADCTSC);
adcdly = readl(ts_base + S3C_ADCDLY);


disable_irq(IRQ_ADC);
disable_irq(IRQ_PENDN);


clk_disable(ts_clock);


return 0;
}


static int s3c_ts_resume(struct platform_device *pdev)
{
clk_enable(ts_clock);


writel(adccon, ts_base + S3C_ADCCON);
writel(adctsc, ts_base + S3C_ADCTSC);
writel(adcdly, ts_base + S3C_ADCDLY);
writel(WAIT4INT(0), ts_base + S3C_ADCTSC);


enable_irq(IRQ_ADC);
enable_irq(IRQ_PENDN);
return 0;
}
#else
#define s3c_ts_suspend NULL
#define s3c_ts_resume NULL
#endif

//触摸屏驱动的定义
static struct platform_driver s3c_ts_driver = {
.probe = s3c_ts_probe,//探测函数
.remove = s3c_ts_remove,
.suspend = s3c_ts_suspend,
.resume = s3c_ts_resume,
.driver = {
.owner = THIS_MODULE,
.name = "s3c-ts",
},
};

static char banner[] __initdata = KERN_INFO "S3C Touchscreen driver, (c) 2011 lwaltlee\n";

static int __init s3c_ts_init(void)
{
printk(banner);
return platform_driver_register(&s3c_ts_driver);//这里把触摸屏当做平台设备处理，该函数是把触摸屏驱动作为平台设备注册到内核中
}

static void __exit s3c_ts_exit(void)
{
platform_driver_unregister(&s3c_ts_driver);//注销驱动
}

module_init(s3c_ts_init);
module_exit(s3c_ts_exit);

MODULE_AUTHOR("FriendlyARM Inc.");
MODULE_LICENSE("GPL");