1.硬件分析

我所使用的触摸屏分辨率是1158*768，可视区域大小是1024*768（这也是LCD屏的大小），在触摸屏两侧总有5个按键。

 

2.触摸屏按键驱动的修改

既然可视区域在触摸屏中间部位，因此需要在触摸屏驱动中修改input_set_abs_params()函数中的参数

#ifdef VIRTUAL_KEYS
static ssize_t virtual_keys_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
if (1) {
return sprintf(buf,
__stringify(EV_KEY) ":" __stringify(KEY_VOLUMEUP) ":1030:370:30:30"
":" __stringify(EV_KEY) ":" __stringify(KEY_VOLUMEDOWN) ":1030:470:30:30"
":" __stringify(EV_KEY) ":" __stringify(KEY_BACK) ":1030:18:30:30"
":" __stringify(EV_KEY) ":" __stringify(KEY_HOME) ":1030:136:30:30"
":" __stringify(EV_KEY) ":" __stringify(KEY_MENU) ":1030:236:30:30"
"\n");
} else {
}
}
static struct kobj_attribute virtual_keys_attr = {
.attr = {
.name = "virtualkeys.xxxx",
.mode = S_IRUGO,
},
.show = &virtual_keys_show,
};
static struct attribute *properties_attrs[] = {
&virtual_keys_attr.attr,
NULL
};
static struct attribute_group properties_attr_group = {
.attrs = properties_attrs,
};
static void virtual_keys_init(void)
{
int ret;
struct kobject *properties_kobj;
properties_kobj = kobject_create_and_add("board_properties", NULL);
if (properties_kobj)
ret = sysfs_create_group(properties_kobj,
&properties_attr_group);
if (!properties_kobj || ret)
pr_err("failed to create board_properties\n");
}
#endif

1. 具体的可以去HTC网站(http://htcdev.com/devcenter/downloads)上下载HTC手机的linux源码，HTC很多款手机的BACK,MENU,HOME,SEARCH电容屏虚拟按键都是采用这种方式实现的。

1. （三）但是我用的是四线电阻触摸屏，用上面的方式好像没有任何反应，所以我采用最直接的方式用input_event发送按键消息，就是在触摸屏处理芯片TSC2007驱动中当读到一定范围内的触摸事件就发送按键消息：这种方式只要修改TSC2007驱动的几个地方：

1. 1.定义全局局部变量用于记录是否有虚拟按键按下

   static int backkeydown=0;
   static int homekeydown=0;
   static int menukeydown=0;

   2..在prope函数中添加

    set_bit(EV_SYN, input_dev->evbit);
   set_bit(KEY_HOME, input_dev->keybit);
   //set_bit(KEY_SEARCH, input_dev->keybit);
   set_bit(KEY_BACK, input_dev->keybit);
   set_bit(KEY_MENU, input_dev->keybit);

   3.在中断处理work里面添加按键按下消息

           if((tc.y>=81)&&(tc.y<=181))
   {
   if((tc.x>=2711)&&(tc.x<=2832))
   {
   if(backkeydown==0)
   {
   input_event(input, EV_KEY,KEY_BACK, 1);
   backkeydown=1;
   //printk("back key down\n");
   }
   }
   else if((tc.x>=1891)&&(tc.x<=1933))
   {
   if(homekeydown==0)
   {
   input_event(input, EV_KEY,KEY_HOME, 1);
   homekeydown=1;
   //printk("home key down\n");
   }
   }
   else if((tc.x>=1088)&&(tc.x<=1143))
   {
   if(menukeydown==0)
   {
   input_event(input, EV_KEY,KEY_MENU, 1);
   menukeydown=1;
   //printk("menu key down\n");
   }
   }
   }

4.在tsc2007_send_up_event函数中添加按键释放消息

   if(backkeydown==1)
{
backkeydown=0;
input_event(input, EV_KEY, KEY_BACK, 0);
//printk("back key up\n");
}
if(homekeydown==1)
{
homekeydown=0;
input_event(input, EV_KEY, KEY_HOME, 0);
//printk("home key up\n");
}
if(menukeydown==1)
{
menukeydown=0;
input_event(input, EV_KEY, KEY_MENU, 0);
//printk("menu key up\n");
}

整个修改后的TSC2007驱动如下：

/*
* drivers/input/touchscreen/tsc2007.c
*
* Copyright (c) 2008 MtekVision Co., Ltd.
*   Kwangwoo Lee <kwlee@mtekvision.com>
*
* Using code from:
*  - ads7846.c
*   Copyright (c) 2005 David Brownell
*   Copyright (c) 2006 Nokia Corporation
*  - corgi_ts.c
*   Copyright (C) 2004-2005 Richard Purdie
*  - omap_ts.[hc], ads7846.h, ts_osk.c
*   Copyright (C) 2002 MontaVista Software
*   Copyright (C) 2004 Texas Instruments
*   Copyright (C) 2005 Dirk Behme
*
*  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/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/i2c/tsc2007.h>
#define TS_POLL_DELAY           1 /* ms delay between samples */
#define TS_POLL_PERIOD          1 /* ms delay between samples */
#define TSC2007_MEASURE_TEMP0       (0x0 << 4)
#define TSC2007_MEASURE_AUX     (0x2 << 4)
#define TSC2007_MEASURE_TEMP1       (0x4 << 4)
#define TSC2007_ACTIVATE_XN     (0x8 << 4)
#define TSC2007_ACTIVATE_YN     (0x9 << 4)
#define TSC2007_ACTIVATE_YP_XN      (0xa << 4)
#define TSC2007_SETUP           (0xb << 4)
#define TSC2007_MEASURE_X       (0xc << 4)
#define TSC2007_MEASURE_Y       (0xd << 4)
#define TSC2007_MEASURE_Z1      (0xe << 4)
#define TSC2007_MEASURE_Z2      (0xf << 4)
#define TSC2007_POWER_OFF_IRQ_EN    (0x0 << 2)
#define TSC2007_ADC_ON_IRQ_DIS0     (0x1 << 2)
#define TSC2007_ADC_OFF_IRQ_EN      (0x2 << 2)
#define TSC2007_ADC_ON_IRQ_DIS1     (0x3 << 2)
#define TSC2007_12BIT           (0x0 << 1)
#define TSC2007_8BIT            (0x1 << 1)
#define MAX_12BIT           ((1 << 12) - 1)
#define ADC_ON_12BIT    (TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0)
#define READ_Y      (ADC_ON_12BIT | TSC2007_MEASURE_Y)
#define READ_Z1     (ADC_ON_12BIT | TSC2007_MEASURE_Z1)
#define READ_Z2     (ADC_ON_12BIT | TSC2007_MEASURE_Z2)
#define READ_X      (ADC_ON_12BIT | TSC2007_MEASURE_X)
#define PWRDOWN     (TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)
static int backkeydown=0;
static int homekeydown=0;
static int menukeydown=0;
struct ts_event {
u16 x;
u16 y;
u16 z1, z2;
};
struct tsc2007 {
struct input_dev    *input;
char            phys[32];
struct delayed_work work;
struct i2c_client   *client;
u16         model;
u16         x_plate_ohms;
bool            pendown;
int         irq;
int         (*get_pendown_state)(void);
void            (*clear_penirq)(void);
};
static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
{
s32 data;
u16 val;
data = i2c_smbus_read_word_data(tsc->client, cmd);
if (data < 0) {
dev_err(&tsc->client->dev, "i2c io error: %d\n", data);
return data;
}
/* The protocol and raw data format from i2c interface:
* S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
* Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit].
*/
val = swab16(data) >> 4;
dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x\n", data, val);
return val;
}
static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
{
/* y- still on; turn on only y+ (and ADC) */
tc->y = tsc2007_xfer(tsc, READ_Y);
/* turn y- off, x+ on, then leave in lowpower */
tc->x = tsc2007_xfer(tsc, READ_X);
/* turn y+ off, x- on; we'll use formula #1 */
tc->z1 = tsc2007_xfer(tsc, READ_Z1);
tc->z2 = tsc2007_xfer(tsc, READ_Z2);
//printk("x=%d,y=%d\n",tc->x,tc->y);
/* Prepare for next touch reading - power down ADC, enable PENIRQ */
tsc2007_xfer(tsc, PWRDOWN);
}
static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc)
{
u32 rt = 0;
/* range filtering */
if (tc->x == MAX_12BIT)
tc->x = 0;
if (likely(tc->x && tc->z1)) {
/* compute touch pressure resistance using equation #1 */
rt = tc->z2 - tc->z1;
rt *= tc->x;
rt *= tsc->x_plate_ohms;
rt /= tc->z1;
rt = (rt + 2047) >> 12;
}
return rt;
}
static void tsc2007_send_up_event(struct tsc2007 *tsc)
{
struct input_dev *input = tsc->input;
dev_dbg(&tsc->client->dev, "UP\n");
if(backkeydown==1)
{
backkeydown=0;
input_event(input, EV_KEY, KEY_BACK, 0);
//printk("back key up\n");
}
if(homekeydown==1)
{
homekeydown=0;
input_event(input, EV_KEY, KEY_HOME, 0);
//printk("home key up\n");
}
if(menukeydown==1)
{
menukeydown=0;
input_event(input, EV_KEY, KEY_MENU, 0);
//printk("menu key up\n");
}
input_report_key(input, BTN_TOUCH, 0);
input_report_abs(input, ABS_PRESSURE, 0);
input_sync(input);
}
static void tsc2007_work(struct work_struct *work)
{
struct tsc2007 *ts =
container_of(to_delayed_work(work), struct tsc2007, work);
struct ts_event tc;
u32 rt;
/*
* NOTE: We can't rely on the pressure to determine the pen down
* state, even though this controller has a pressure sensor.
* The pressure value can fluctuate for quite a while after
* lifting the pen and in some cases may not even settle at the
* expected value.
*
* The only safe way to check for the pen up condition is in the
* work function by reading the pen signal state (it's a GPIO
* and IRQ). Unfortunately such callback is not always available,
* in that case we have rely on the pressure anyway.
*/
if (ts->get_pendown_state) {
if (unlikely(!ts->get_pendown_state())) {
tsc2007_send_up_event(ts);
ts->pendown = false;
goto out;
}
dev_dbg(&ts->client->dev, "pen is still down\n");
}
tsc2007_read_values(ts, &tc);
rt = tsc2007_calculate_pressure(ts, &tc);
if (rt > MAX_12BIT) {
/*
* Sample found inconsistent by debouncing or pressure is
* beyond the maximum. Don't report it to user space,
* repeat at least once more the measurement.
*/
dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
goto out;
}
if (rt) {
struct input_dev *input = ts->input;
if((tc.y>=81)&&(tc.y<=181))
{
if((tc.x>=2711)&&(tc.x<=2832))
{
if(backkeydown==0)
{
input_event(input, EV_KEY,KEY_BACK, 1);
backkeydown=1;
//printk("back key down\n");
}
}
else if((tc.x>=1891)&&(tc.x<=1933))
{
if(homekeydown==0)
{
input_event(input, EV_KEY,KEY_HOME, 1);
homekeydown=1;
//printk("home key down\n");
}
}
else if((tc.x>=1088)&&(tc.x<=1143))
{
if(menukeydown==0)
{
input_event(input, EV_KEY,KEY_MENU, 1);
menukeydown=1;
//printk("menu key down\n");
}
}
}
if (!ts->pendown) {
dev_dbg(&ts->client->dev, "DOWN\n");
input_report_key(input, BTN_TOUCH, 1);
ts->pendown = true;
}
input_report_abs(input, ABS_X, tc.x);
input_report_abs(input, ABS_Y, tc.y);
input_report_abs(input, ABS_PRESSURE, rt);
input_sync(input);
dev_dbg(&ts->client->dev, "point(%4d,%4d), pressure (%4u)\n",
tc.x, tc.y, rt);
} else if (!ts->get_pendown_state && ts->pendown) {
/*
* We don't have callback to check pendown state, so we
* have to assume that since pressure reported is 0 the
* pen was lifted up.
*/
tsc2007_send_up_event(ts);
ts->pendown = false;
}
out:
if (ts->pendown)
schedule_delayed_work(&ts->work,
msecs_to_jiffies(TS_POLL_PERIOD));
else
enable_irq(ts->irq);
}
static irqreturn_t tsc2007_irq(int irq, void *handle)
{
struct tsc2007 *ts = handle;
if (!ts->get_pendown_state || likely(ts->get_pendown_state())) {
disable_irq_nosync(ts->irq);
schedule_delayed_work(&ts->work,
msecs_to_jiffies(TS_POLL_DELAY));
}
if (ts->clear_penirq)
ts->clear_penirq();
return IRQ_HANDLED;
}
static void tsc2007_free_irq(struct tsc2007 *ts)
{
free_irq(ts->irq, ts);
if (cancel_delayed_work_sync(&ts->work)) {
/*
* Work was pending, therefore we need to enable
* IRQ here to balance the disable_irq() done in the
* interrupt handler.
*/
enable_irq(ts->irq);
}
}
static int __devinit tsc2007_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct tsc2007 *ts;
struct tsc2007_platform_data *pdata = pdata = client->dev.platform_data;
struct input_dev *input_dev;
int err;
if (!pdata) {
dev_err(&client->dev, "platform data is required!\n");
return -EINVAL;
}
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_READ_WORD_DATA))
return -EIO;
ts = kzalloc(sizeof(struct tsc2007), GFP_KERNEL);
input_dev = input_allocate_device();
if (!ts || !input_dev) {
err = -ENOMEM;
goto err_free_mem;
}
ts->client = client;
ts->irq = client->irq;
ts->input = input_dev;
INIT_DELAYED_WORK(&ts->work, tsc2007_work);
ts->model             = pdata->model;
ts->x_plate_ohms      = pdata->x_plate_ohms;
ts->get_pendown_state = pdata->get_pendown_state;
ts->clear_penirq      = pdata->clear_penirq;
snprintf(ts->phys, sizeof(ts->phys),
"%s/input0", dev_name(&client->dev));
input_dev->name = "TSC2007";
input_dev->phys = ts->phys;
input_dev->id.vendor = 0x0001;
input_dev->id.product = 0x0001;
input_dev->id.version = 0x0100;
input_dev->id.bustype = BUS_I2C;
input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
set_bit(EV_SYN, input_dev->evbit);
set_bit(KEY_HOME, input_dev->keybit);
//set_bit(KEY_SEARCH, input_dev->keybit);
set_bit(KEY_BACK, input_dev->keybit);
set_bit(KEY_MENU, input_dev->keybit);
input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, 0, 0);
input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);
if (pdata->init_platform_hw)
pdata->init_platform_hw();
err = request_irq(ts->irq, tsc2007_irq, 0,
client->dev.driver->name, ts);
if (err < 0) {
dev_err(&client->dev, "irq %d busy?\n", ts->irq);
goto err_free_mem;
}
/* Prepare for touch readings - power down ADC and enable PENIRQ */
err = tsc2007_xfer(ts, PWRDOWN);
if (err < 0)
goto err_free_irq;
err = input_register_device(input_dev);
if (err)
goto err_free_irq;
i2c_set_clientdata(client, ts);
return 0;
err_free_irq:
tsc2007_free_irq(ts);
if (pdata->exit_platform_hw)
pdata->exit_platform_hw();
err_free_mem:
input_free_device(input_dev);
kfree(ts);
return err;
}
static int __devexit tsc2007_remove(struct i2c_client *client)
{
struct tsc2007  *ts = i2c_get_clientdata(client);
struct tsc2007_platform_data *pdata = client->dev.platform_data;
tsc2007_free_irq(ts);
if (pdata->exit_platform_hw)
pdata->exit_platform_hw();
input_unregister_device(ts->input);
kfree(ts);
return 0;
}
static struct i2c_device_id tsc2007_idtable[] = {
{ "tsc2007", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);
static struct i2c_driver tsc2007_driver = {
.driver = {
.owner  = THIS_MODULE,
.name   = "tsc2007"
},
.id_table   = tsc2007_idtable,
.probe      = tsc2007_probe,
.remove     = __devexit_p(tsc2007_remove),
};
static int __init tsc2007_init(void)
{
return i2c_add_driver(&tsc2007_driver);
}
static void __exit tsc2007_exit(void)
{
i2c_del_driver(&tsc2007_driver);
}
module_init(tsc2007_init);
module_exit(tsc2007_exit);
MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>");
MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
MODULE_LICENSE("GPL");

实践证明上述方式完全可行，这里我没有指定TSC2007的kl和kcm文件，android系统会自动选择默认的\android\sdk\emulator\keymaps\目录下的qwerty.kl和qwerty.kcm文件,如果你的系统不能正常收到按键消息，你首先可以用android的getevent看看驱动是否能正常发送按键消息给上层，如果能正常收到触摸屏驱动发送的按键消息，上层android系统不能收到的原因就是kl和kcm文件不对。

5.另外附上加载TSC2007驱动的代码

/* TouchScreen */
#define IRQ1 1
unsigned int tsc2007_int;
unsigned int tsc2007_irq_no;
static int ts_get_pendown_state(void)
{
int result=!(imapx_gpio_getpin(tsc2007_int, IG_NORMAL));
//printk("%d\n",result);
return result;
}
static int ts_init(void)
{
//printk("====ts_init===\n");
tsc2007_int  = __imapx_name_to_gpio(CONFIG_TP_TSC2007_INT);
if(tsc2007_int == IMAPX_GPIO_ERROR) {
printk(KERN_ERR "failed to get tsc2007_int pin.\n");
return -1;
}
tsc2007_irq_no = imapx_gpio_to_irq(tsc2007_int);
imapx_gpio_setcfg(tsc2007_int, IG_INPUT, IG_NORMAL);
imapx_gpio_setirq(tsc2007_int, FILTER_MAX, IG_FALL, 1);
return 0;
}
struct tsc2007_platform_data tsc2007_info = {
.model          = 2007,
.x_plate_ohms       = 180,
.get_pendown_state  = ts_get_pendown_state,
.init_platform_hw   = ts_init,
};
static struct i2c_board_info ts_i2c_clients = {
I2C_BOARD_INFO("tsc2007", 0x48),
.type       = "tsc2007",
.platform_data  = &tsc2007_info,
.irq        = IRQ1,
};
static int __init imap_arch_init(void)
{
int ret;
// do the correct init for cpu
if (cpu == NULL)
panic("imap_arch_init: NULL cpu\n");
ret = (cpu->init)();
if (ret != 0)
return ret;
ret = platform_add_devices(imap_uart_devs, nr_uarts);
if (ret != 0)
return ret;
/*瑙︽懜灞?/
i2c_register_board_info(1, &ts_i2c_clients, 1);
/*瑙︽懜灞忚櫄鎷熸寜閿?/
//virtual_keys_init();
printk(KERN_INFO "leaving imap_arch_init\n");
return ret;
}

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