摘要:
分析内核s3c-ts.c源码,看它是如何采集坐标信息及防抖动处理的。
介绍:
直接上源码吧,完全注释:
/* 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
*
*/
#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);
//定义并初始化了一个信号量
//37内核就没有DECLARE_MUTEX了吧,功能应该是一样的
/* Indicate who is using the ADC controller */
//ADC的状态,防止触摸屏转换时,ADC正在被使用
#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);
//获取自旋锁
if
(!ret) {
adc_lock_id = id;
}
return
ret;
//返回状态 1:失败 0:成功
}
//--
static
inline
void
s3c_ts_adc_unlock(
void
) {
adc_lock_id = 0;
up(&ADC_LOCK);
//释放自旋锁
}
#endif
/* Touchscreen default configuration */
struct
s3c_ts_mach_info s3c_ts_default_cfg __initdata = {
.delay = 10000,
//转换延时
.presc = 49,
//转换时钟分频
.oversampling_shift = 2,
//转换次数 4次
.resol_bit = 12,
//转换精度
.s3c_adc_con = ADC_TYPE_2
//6410是type2
};
/*
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);
//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)
//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;
//printk("====>Add ... [ %4d, %4d ]%s\n", x, y, down ? "":" ~~~");
/* 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-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;
//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
s3c_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
s3c_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 = s3c_ts_read,
.poll = s3c_ts_poll,
//select系统调用
.open = s3c_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,
};
//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) | \
S3C_ADCTSC_YM_SEN | S3C_ADCTSC_YP_SEN | S3C_ADCTSC_XP_SEN | \
S3C_ADCTSC_XY_PST(3))
//自动连续测量X坐标和Y坐标
#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));
//判断data0,data1最高位是否仍为"0",为“0”表示触摸笔状态保持为down
}
/*===========================================================================================
touch_timer_fire这个函数主要实现以下功能:
1、 触摸笔开始点击的时候, 在中断函数stylus_updown里面被调用,
此时缓存区没有数据,ts.count为0, 并且开启AD转换,而后进入 AD 中断
2、 ADC中断函数stylus_action把缓冲区填满的时候,作为中断后半段函数稍后被调用(由内核定时器触发中断),
此时ts.count为4,算出其平均值后,交给事件处理层(Event Handler)处理,
主要是填写缓冲,然后唤醒等待输入数据的进程。
3、 stylus抬起,等到缓冲区填满后(可能会包含一些无用的数据)被调用,
这时候判断出stylus up,报告stylus up事件,重新等待stylus down。
============================================================================================*/
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);
//读取AD转换数据的值
pendown = get_down(data0, data1);
if
(pendown) {
if
(ts->count == (1 << ts->shift)) {
//定时器触发touch_timer_fire中断时执行这个括号里
#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);
//求平均,并写入fifo
ts->xp = 0;
ts->yp = 0;
ts->count = 0;
}
/* start automatic sequencing A/D conversion */
//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
//AUTOPST表示自动连续测量 以得到X位置,Y位置
writel(S3C_ADCTSC_PULL_UP_DISABLE | AUTOPST, ts_base + S3C_ADCTSC);
// 启动D转换,转换后会产生中断IRQ_ADC
writel(readl(ts_base + S3C_ADCCON) | S3C_ADCCON_ENABLE_START,
ts_base + S3C_ADCCON);
}
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);
/* PEN is UP, Let's wait the PEN DOWN interrupt */
writel(WAIT4INT(0), ts_base + S3C_ADCTSC);
// 设置INT 位,等待 DOWN 中断
#ifdef CONFIG_MINI6410_ADC
if
(ADC_locked4TS()) {
s3c_ts_adc_unlock();
}
#endif
}
}
static
DEFINE_TIMER(touch_timer, touch_timer_fire, 0, 0);
//触摸屏按下松开中断服务==
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
//执行如下语句否则不断产生中断从而把系统卡死
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;
}
//ad转换结束中断服务程序==
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
}
// 转换结果累加
ts->count++;
if
(ts->count < (1 << ts->shift)) {
// 采样未完成,继续下一次采样 ,通过 ENABLE_START 启动 AD 转换,一次一个数据
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
{
// 采样完毕,激活下半部处理程序touch_timer_fire,处理接收数据
mod_timer(&touch_timer, jiffies + 1);
//设置定时器超时的时间,目的是为了延时触发 touch_timer_fire 中断,如果在这段时间有抬起中断发生,则表示是抖动
//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
writel(WAIT4INT(1), ts_base + S3C_ADCTSC);
//设置为等待抬起中断
}
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;
//其它模块要用ADC时,需要调用这个函数,来确定ADC是否可用,如果可用,则将它锁住,不让别的驱动用
int
mini6410_adc_acquire_io(
void
) {
int
ret;
ret = s3c_ts_adc_lock(LOCK_ADC);
//锁住ADC,不让其它模块使用
if
(!ret) {
//如果ADC没有被使用,则保存ADC寄存器的值
_adccon = readl(ts_base + S3C_ADCCON);
_adctsc = readl(ts_base + S3C_ADCTSC);
_adcdly = readl(ts_base + S3C_ADCDLY);
}
return
ret;
// 0:操作成功 1:操作失败
}
EXPORT_SYMBOL(mini6410_adc_acquire_io);
//声明为外部可用
//其它模块不要用ADC了,需要调用这个函数,来解锁ADC让别的驱动用
void
mini6410_adc_release_io(
void
) {
//还原ADC寄存器的设置
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();
//释放ADC,其它模块可以使用
}
EXPORT_SYMBOL(mini6410_adc_release_io);
#endif
//获得触摸屏的配置信息==
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;
//优先使用 arch/arm/mach-s3c64xx中的定义
return
&s3c_ts_default_cfg;
//如果前面没定义,则使用本函数的default定义
}
//--
/*
* 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);
//获取配置参数
//设置ADC分频
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 */
//设置转换延时
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);
//注册这混杂字符设备
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
static
struct
platform_driver s3c_ts_driver = {
.probe = s3c_ts_probe,
.
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) 2010 FriendlyARM,\n"
;
static
int
__init s3c_ts_init(
void
)
{
printk(banner);
return
platform_driver_register(&s3c_ts_driver);
}
static
void
__exit s3c_ts_exit(
void
)
{
platform_driver_unregister(&s3c_ts_driver);
}
module_init(s3c_ts_init);
module_exit(s3c_ts_exit);
MODULE_AUTHOR(
"FriendlyARM Inc."
);
MODULE_LICENSE(
"GPL"
);
/*
* 驱动分析
* 1、内核是如何加载驱动的?
* 首先要提到两个结构体:设备用Platform_device表示,驱动用Platform_driver进行注册
* Platform机制开发发底层驱动的大致流程为: 定义 platform_device 注册 platform_device 定义 platform_driver 注册 platform_driver
* 首先要确认的就是设备的资源信息platform_device,例如设备的地址,中断号等 该结构体定义在kernel\include\linux\platform_device.h
* 该结构一个重要的元素是resource,该元素存入了最为重要的设备资源信息,定义在kernel\include\linux\ioport.h中
* 下面我们以本例来进行说明:
* arch/arm/mach-s3c64xx中dev-ts-mini6410.c中定义了platform_device s3c_device_ts
* 定义好了platform_device结构体后就可以调用函数platform_add_devices向系统中添加该设备了,之后可以调用platform_driver_register()进行设备注册。
* 要注意的是,这里的platform_device设备的注册过程必须在相应设备驱动加载之前被调用,即执行platform_driver_register之前,原因是因为驱动注册时需要
* 匹配内核中所以已注册的设备名。
* platform_devicerr的注册是在arch/arm/mach-s3c64xx中mach-mini6410.c中的mini6410_machine_init函数实现的。
* mini6410_machine_init是在启动后调用,它是在module_init之前;更具体的见MACHINE_START
* MACHINE_START(MINI6410, "MINI6410")
*
* .boot_params = S3C64XX_PA_SDRAM + 0x100, //.boot_params是bootloader向内核传递的参数的位置,这要和bootloader中参数的定义要一致。
*
* .init_irq = s3c6410_init_irq, //.init_irq在start_kernel() --> init_IRQ() --> init_arch_irq()中被调用
* .map_io = mini6410_map_io, //.map_io 在 setup_arch() --> paging_init() --> devicemaps_init()中被调用
* .init_machine = mini6410_machine_init, //init_machine 在 arch/arm/kernel/setup.c 中被 customize_machine 调用,
* //放在 arch_initcall() 段里面,会自动按顺序被调用。
* .timer = &s3c24xx_timer, //.timer是定义系统时钟,定义TIMER4为系统时钟,在arch/arm/plat-s3c/time.c中体现。
* //在start_kernel() --> time_init()中被调用。
* MACHINE_END
* 再来看看platform_driver,这个定义在本文中,
* 在驱动初始化函数中调用函数platform_driver_register()注册platform_driver,需要注意的是s3c_device_ts结构中name元素和s3c_ts_driver结构中driver.name
* 必须是相同的,这样在platform_driver_register()注册时会对所有已注册的所有platform_device中的name和当前注册的platform_driver的driver.name进行比较,
* 只有找到相同的名称的platfomr_device才能注册成功,当注册成功时会调用platform_driver结构元素probe函数指针,这里就是s3c_ts_probe
*
* 2、timer在这里的作用
* timer是用来防抖的,我们知道,触摸屏处理分为两个时间段,一个是由按下中断触发的四次AD转换的时间A,一个是4次AD转换完成后将AD数据存入FIFO的时间B,在时间A,没有打开抬起中断,
* 也就是说如果在这段时间有抬起事件,也不会触发中断,不会影响AD的转换。在时间B,打开抬起中断,打开定时器延时触发touch_timer_fire,如果在延时这段时间,有抬起事件发生
* 则touch_timer_fire不会将前面的数据存入到FIFO中,否则写入FIFO,表示值有效。
*
*
*/
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