linux触摸屏驱动分析，touchscreen, struct input_dev,基于TSC2007
【详细说明】linux触摸屏驱动分析，touchscreen, struct input_dev,基于TSC2007代码从2.6.32拷贝：
/*
* 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., 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)
struct ts_event {
u16 x;
u16 y;
u16 z1, z2;
};
struct tsc2007 {
struct input_dev *input;
char phys;
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 Comm S Addr Rd A NA P
* Where DataLow has , DataHigh has .
*/
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);
/* 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");
input_report_key(input, BTN_TOUCH, 0);
input_report_abs(input, ABS_PRESSURE, 0);
input_sync(input);
}
//中断后跑到这里来
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); //计算压力
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 (!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 Touchscreen";
input_dev->phys = ts->phys;
input_dev->id.bustype = BUS_I2C;
input_dev->evbit = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
input_dev->keybit = BIT_MASK(BTN_TOUCH);
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");
看一遍后就大概知道流程了。
当按下触摸板后产生中断，中断里面调用延时函数进入底半部程序。
在调度函数里面，先读取坐标，计算压力，然后根据压力大小上报坐标。
若触摸板一直按下，那么就重新调用，并通过压力值来看触摸板是否释放。
简单吧？
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