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linux/drivers/input/touchscreen/ad7879.c
Michael Hennerich b584efc9ea Input: ad7879 - prevent invalid finger data reports 
Considering following scenario - the touch is present on the screen
at the beginning of the last conversion sequence, but by the time
the last sequence is finished, the finger is lift off. The AD7879 data
available interrupt signals (DAV) completion, however some X,Y values
are not valid because the screen inputs were floating during the
acquisition.

The AD7877 acts differently here, since it only asserts DAV if the
touch is still present when the conversion sequence finished.

Based on the fact that this can only happen in the last sample of the
repeated conversion sequence, we simply skip the last (short glitches
are filtered by the AD7879 internal median and average filters).
This doesn't cause noticeable side effects, since the minimum conversion
interval is 9.44ms. We receive ~100 waypoint samples per second, so we
simply delay the result by 9.44ms.

We also reject samples where pressure is greater than pressure_max.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2010-10-28 22:32:50 -07:00

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/*
* AD7879/AD7889 based touchscreen and GPIO driver
*
* Copyright (C) 2008-2010 Michael Hennerich, Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*
* History:
* Copyright (c) 2005 David Brownell
* Copyright (c) 2006 Nokia Corporation
* Various changes: Imre Deak <imre.deak@nokia.com>
*
* Using code from:
* - 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
* - ad7877.c
* Copyright (C) 2006-2008 Analog Devices Inc.
*/
#include <linux/device.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/slab.h>
#include <linux/spi/spi.h>
#include <linux/i2c.h>
#include <linux/gpio.h>
#include <linux/spi/ad7879.h>
#include "ad7879.h"
#define AD7879_REG_ZEROS 0
#define AD7879_REG_CTRL1 1
#define AD7879_REG_CTRL2 2
#define AD7879_REG_CTRL3 3
#define AD7879_REG_AUX1HIGH 4
#define AD7879_REG_AUX1LOW 5
#define AD7879_REG_TEMP1HIGH 6
#define AD7879_REG_TEMP1LOW 7
#define AD7879_REG_XPLUS 8
#define AD7879_REG_YPLUS 9
#define AD7879_REG_Z1 10
#define AD7879_REG_Z2 11
#define AD7879_REG_AUXVBAT 12
#define AD7879_REG_TEMP 13
#define AD7879_REG_REVID 14
/* Control REG 1 */
#define AD7879_TMR(x) ((x & 0xFF) << 0)
#define AD7879_ACQ(x) ((x & 0x3) << 8)
#define AD7879_MODE_NOC (0 << 10) /* Do not convert */
#define AD7879_MODE_SCC (1 << 10) /* Single channel conversion */
#define AD7879_MODE_SEQ0 (2 << 10) /* Sequence 0 in Slave Mode */
#define AD7879_MODE_SEQ1 (3 << 10) /* Sequence 1 in Master Mode */
#define AD7879_MODE_INT (1 << 15) /* PENIRQ disabled INT enabled */
/* Control REG 2 */
#define AD7879_FCD(x) ((x & 0x3) << 0)
#define AD7879_RESET (1 << 4)
#define AD7879_MFS(x) ((x & 0x3) << 5)
#define AD7879_AVG(x) ((x & 0x3) << 7)
#define AD7879_SER (1 << 9) /* non-differential */
#define AD7879_DFR (0 << 9) /* differential */
#define AD7879_GPIOPOL (1 << 10)
#define AD7879_GPIODIR (1 << 11)
#define AD7879_GPIO_DATA (1 << 12)
#define AD7879_GPIO_EN (1 << 13)
#define AD7879_PM(x) ((x & 0x3) << 14)
#define AD7879_PM_SHUTDOWN (0)
#define AD7879_PM_DYN (1)
#define AD7879_PM_FULLON (2)
/* Control REG 3 */
#define AD7879_TEMPMASK_BIT (1<<15)
#define AD7879_AUXVBATMASK_BIT (1<<14)
#define AD7879_INTMODE_BIT (1<<13)
#define AD7879_GPIOALERTMASK_BIT (1<<12)
#define AD7879_AUXLOW_BIT (1<<11)
#define AD7879_AUXHIGH_BIT (1<<10)
#define AD7879_TEMPLOW_BIT (1<<9)
#define AD7879_TEMPHIGH_BIT (1<<8)
#define AD7879_YPLUS_BIT (1<<7)
#define AD7879_XPLUS_BIT (1<<6)
#define AD7879_Z1_BIT (1<<5)
#define AD7879_Z2_BIT (1<<4)
#define AD7879_AUX_BIT (1<<3)
#define AD7879_VBAT_BIT (1<<2)
#define AD7879_TEMP_BIT (1<<1)
enum {
AD7879_SEQ_XPOS = 0,
AD7879_SEQ_YPOS = 1,
AD7879_SEQ_Z1 = 2,
AD7879_SEQ_Z2 = 3,
AD7879_NR_SENSE = 4,
};
#define MAX_12BIT ((1<<12)-1)
#define TS_PEN_UP_TIMEOUT msecs_to_jiffies(50)
struct ad7879 {
const struct ad7879_bus_ops *bops;
struct device *dev;
struct input_dev *input;
struct timer_list timer;
#ifdef CONFIG_GPIOLIB
struct gpio_chip gc;
struct mutex mutex;
#endif
unsigned int irq;
bool disabled; /* P: input->mutex */
bool suspended; /* P: input->mutex */
u16 conversion_data[AD7879_NR_SENSE];
char phys[32];
u8 first_conversion_delay;
u8 acquisition_time;
u8 averaging;
u8 pen_down_acc_interval;
u8 median;
u16 x_plate_ohms;
u16 pressure_max;
u16 cmd_crtl1;
u16 cmd_crtl2;
u16 cmd_crtl3;
int x;
int y;
int Rt;
};
static int ad7879_read(struct ad7879 *ts, u8 reg)
{
return ts->bops->read(ts->dev, reg);
}
static int ad7879_multi_read(struct ad7879 *ts, u8 first_reg, u8 count, u16 *buf)
{
return ts->bops->multi_read(ts->dev, first_reg, count, buf);
}
static int ad7879_write(struct ad7879 *ts, u8 reg, u16 val)
{
return ts->bops->write(ts->dev, reg, val);
}
static int ad7879_report(struct ad7879 *ts)
{
struct input_dev *input_dev = ts->input;
unsigned Rt;
u16 x, y, z1, z2;
x = ts->conversion_data[AD7879_SEQ_XPOS] & MAX_12BIT;
y = ts->conversion_data[AD7879_SEQ_YPOS] & MAX_12BIT;
z1 = ts->conversion_data[AD7879_SEQ_Z1] & MAX_12BIT;
z2 = ts->conversion_data[AD7879_SEQ_Z2] & MAX_12BIT;
/*
* The samples processed here are already preprocessed by the AD7879.
* The preprocessing function consists of a median and an averaging
* filter. The combination of these two techniques provides a robust
* solution, discarding the spurious noise in the signal and keeping
* only the data of interest. The size of both filters is
* programmable. (dev.platform_data, see linux/spi/ad7879.h) Other
* user-programmable conversion controls include variable acquisition
* time, and first conversion delay. Up to 16 averages can be taken
* per conversion.
*/
if (likely(x && z1)) {
/* compute touch pressure resistance using equation #1 */
Rt = (z2 - z1) * x * ts->x_plate_ohms;
Rt /= z1;
Rt = (Rt + 2047) >> 12;
/*
* Sample found inconsistent, pressure is beyond
* the maximum. Don't report it to user space.
*/
if (Rt > ts->pressure_max)
return -EINVAL;
/*
* Note that we delay reporting events by one sample.
* This is done to avoid reporting last sample of the
* touch sequence, which may be incomplete if finger
* leaves the surface before last reading is taken.
*/
if (timer_pending(&ts->timer)) {
/* Touch continues */
input_report_key(input_dev, BTN_TOUCH, 1);
input_report_abs(input_dev, ABS_X, ts->x);
input_report_abs(input_dev, ABS_Y, ts->y);
input_report_abs(input_dev, ABS_PRESSURE, ts->Rt);
input_sync(input_dev);
}
ts->x = x;
ts->y = y;
ts->Rt = Rt;
return 0;
}
return -EINVAL;
}
static void ad7879_ts_event_release(struct ad7879 *ts)
{
struct input_dev *input_dev = ts->input;
input_report_abs(input_dev, ABS_PRESSURE, 0);
input_report_key(input_dev, BTN_TOUCH, 0);
input_sync(input_dev);
}
static void ad7879_timer(unsigned long handle)
{
struct ad7879 *ts = (void *)handle;
ad7879_ts_event_release(ts);
}
static irqreturn_t ad7879_irq(int irq, void *handle)
{
struct ad7879 *ts = handle;
ad7879_multi_read(ts, AD7879_REG_XPLUS, AD7879_NR_SENSE, ts->conversion_data);
if (!ad7879_report(ts))
mod_timer(&ts->timer, jiffies + TS_PEN_UP_TIMEOUT);
return IRQ_HANDLED;
}
static void __ad7879_enable(struct ad7879 *ts)
{
ad7879_write(ts, AD7879_REG_CTRL2, ts->cmd_crtl2);
ad7879_write(ts, AD7879_REG_CTRL3, ts->cmd_crtl3);
ad7879_write(ts, AD7879_REG_CTRL1, ts->cmd_crtl1);
enable_irq(ts->irq);
}
static void __ad7879_disable(struct ad7879 *ts)
{
disable_irq(ts->irq);
if (del_timer_sync(&ts->timer))
ad7879_ts_event_release(ts);
ad7879_write(ts, AD7879_REG_CTRL2, AD7879_PM(AD7879_PM_SHUTDOWN));
}
static int ad7879_open(struct input_dev *input)
{
struct ad7879 *ts = input_get_drvdata(input);
/* protected by input->mutex */
if (!ts->disabled && !ts->suspended)
__ad7879_enable(ts);
return 0;
}
static void ad7879_close(struct input_dev* input)
{
struct ad7879 *ts = input_get_drvdata(input);
/* protected by input->mutex */
if (!ts->disabled && !ts->suspended)
__ad7879_disable(ts);
}
void ad7879_suspend(struct ad7879 *ts)
{
mutex_lock(&ts->input->mutex);
if (!ts->suspended && !ts->disabled && ts->input->users)
__ad7879_disable(ts);
ts->suspended = true;
mutex_unlock(&ts->input->mutex);
}
EXPORT_SYMBOL(ad7879_suspend);
void ad7879_resume(struct ad7879 *ts)
{
mutex_lock(&ts->input->mutex);
if (ts->suspended && !ts->disabled && ts->input->users)
__ad7879_enable(ts);
ts->suspended = false;
mutex_unlock(&ts->input->mutex);
}
EXPORT_SYMBOL(ad7879_resume);
static void ad7879_toggle(struct ad7879 *ts, bool disable)
{
mutex_lock(&ts->input->mutex);
if (!ts->suspended && ts->input->users != 0) {
if (disable) {
if (ts->disabled)
__ad7879_enable(ts);
} else {
if (!ts->disabled)
__ad7879_disable(ts);
}
}
ts->disabled = disable;
mutex_unlock(&ts->input->mutex);
}
static ssize_t ad7879_disable_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct ad7879 *ts = dev_get_drvdata(dev);
return sprintf(buf, "%u\n", ts->disabled);
}
static ssize_t ad7879_disable_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct ad7879 *ts = dev_get_drvdata(dev);
unsigned long val;
int error;
error = strict_strtoul(buf, 10, &val);
if (error)
return error;
ad7879_toggle(ts, val);
return count;
}
static DEVICE_ATTR(disable, 0664, ad7879_disable_show, ad7879_disable_store);
static struct attribute *ad7879_attributes[] = {
&dev_attr_disable.attr,
NULL
};
static const struct attribute_group ad7879_attr_group = {
.attrs = ad7879_attributes,
};
#ifdef CONFIG_GPIOLIB
static int ad7879_gpio_direction_input(struct gpio_chip *chip,
unsigned gpio)
{
struct ad7879 *ts = container_of(chip, struct ad7879, gc);
int err;
mutex_lock(&ts->mutex);
ts->cmd_crtl2 |= AD7879_GPIO_EN | AD7879_GPIODIR | AD7879_GPIOPOL;
err = ad7879_write(ts, AD7879_REG_CTRL2, ts->cmd_crtl2);
mutex_unlock(&ts->mutex);
return err;
}
static int ad7879_gpio_direction_output(struct gpio_chip *chip,
unsigned gpio, int level)
{
struct ad7879 *ts = container_of(chip, struct ad7879, gc);
int err;
mutex_lock(&ts->mutex);
ts->cmd_crtl2 &= ~AD7879_GPIODIR;
ts->cmd_crtl2 |= AD7879_GPIO_EN | AD7879_GPIOPOL;
if (level)
ts->cmd_crtl2 |= AD7879_GPIO_DATA;
else
ts->cmd_crtl2 &= ~AD7879_GPIO_DATA;
err = ad7879_write(ts, AD7879_REG_CTRL2, ts->cmd_crtl2);
mutex_unlock(&ts->mutex);
return err;
}
static int ad7879_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
{
struct ad7879 *ts = container_of(chip, struct ad7879, gc);
u16 val;
mutex_lock(&ts->mutex);
val = ad7879_read(ts, AD7879_REG_CTRL2);
mutex_unlock(&ts->mutex);
return !!(val & AD7879_GPIO_DATA);
}
static void ad7879_gpio_set_value(struct gpio_chip *chip,
unsigned gpio, int value)
{
struct ad7879 *ts = container_of(chip, struct ad7879, gc);
mutex_lock(&ts->mutex);
if (value)
ts->cmd_crtl2 |= AD7879_GPIO_DATA;
else
ts->cmd_crtl2 &= ~AD7879_GPIO_DATA;
ad7879_write(ts, AD7879_REG_CTRL2, ts->cmd_crtl2);
mutex_unlock(&ts->mutex);
}
static int ad7879_gpio_add(struct ad7879 *ts,
const struct ad7879_platform_data *pdata)
{
int ret = 0;
mutex_init(&ts->mutex);
if (pdata->gpio_export) {
ts->gc.direction_input = ad7879_gpio_direction_input;
ts->gc.direction_output = ad7879_gpio_direction_output;
ts->gc.get = ad7879_gpio_get_value;
ts->gc.set = ad7879_gpio_set_value;
ts->gc.can_sleep = 1;
ts->gc.base = pdata->gpio_base;
ts->gc.ngpio = 1;
ts->gc.label = "AD7879-GPIO";
ts->gc.owner = THIS_MODULE;
ts->gc.dev = ts->dev;
ret = gpiochip_add(&ts->gc);
if (ret)
dev_err(ts->dev, "failed to register gpio %d\n",
ts->gc.base);
}
return ret;
}
static void ad7879_gpio_remove(struct ad7879 *ts)
{
const struct ad7879_platform_data *pdata = ts->dev->platform_data;
int ret;
if (pdata->gpio_export) {
ret = gpiochip_remove(&ts->gc);
if (ret)
dev_err(ts->dev, "failed to remove gpio %d\n",
ts->gc.base);
}
}
#else
static inline int ad7879_gpio_add(struct ad7879 *ts,
const struct ad7879_platform_data *pdata)
{
return 0;
}
static inline void ad7879_gpio_remove(struct ad7879 *ts)
{
}
#endif
struct ad7879 *ad7879_probe(struct device *dev, u8 devid, unsigned int irq,
const struct ad7879_bus_ops *bops)
{
struct ad7879_platform_data *pdata = dev->platform_data;
struct ad7879 *ts;
struct input_dev *input_dev;
int err;
u16 revid;
if (!irq) {
dev_err(dev, "no IRQ?\n");
err = -EINVAL;
goto err_out;
}
if (!pdata) {
dev_err(dev, "no platform data?\n");
err = -EINVAL;
goto err_out;
}
ts = kzalloc(sizeof(*ts), GFP_KERNEL);
input_dev = input_allocate_device();
if (!ts || !input_dev) {
err = -ENOMEM;
goto err_free_mem;
}
ts->bops = bops;
ts->dev = dev;
ts->input = input_dev;
ts->irq = irq;
setup_timer(&ts->timer, ad7879_timer, (unsigned long) ts);
ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
ts->pressure_max = pdata->pressure_max ? : ~0;
ts->first_conversion_delay = pdata->first_conversion_delay;
ts->acquisition_time = pdata->acquisition_time;
ts->averaging = pdata->averaging;
ts->pen_down_acc_interval = pdata->pen_down_acc_interval;
ts->median = pdata->median;
snprintf(ts->phys, sizeof(ts->phys), "%s/input0", dev_name(dev));
input_dev->name = "AD7879 Touchscreen";
input_dev->phys = ts->phys;
input_dev->dev.parent = dev;
input_dev->id.bustype = bops->bustype;
input_dev->open = ad7879_open;
input_dev->close = ad7879_close;
input_set_drvdata(input_dev, ts);
__set_bit(EV_ABS, input_dev->evbit);
__set_bit(ABS_X, input_dev->absbit);
__set_bit(ABS_Y, input_dev->absbit);
__set_bit(ABS_PRESSURE, input_dev->absbit);
__set_bit(EV_KEY, input_dev->evbit);
__set_bit(BTN_TOUCH, input_dev->keybit);
input_set_abs_params(input_dev, ABS_X,
pdata->x_min ? : 0,
pdata->x_max ? : MAX_12BIT,
0, 0);
input_set_abs_params(input_dev, ABS_Y,
pdata->y_min ? : 0,
pdata->y_max ? : MAX_12BIT,
0, 0);
input_set_abs_params(input_dev, ABS_PRESSURE,
pdata->pressure_min, pdata->pressure_max, 0, 0);
err = ad7879_write(ts, AD7879_REG_CTRL2, AD7879_RESET);
if (err < 0) {
dev_err(dev, "Failed to write %s\n", input_dev->name);
goto err_free_mem;
}
revid = ad7879_read(ts, AD7879_REG_REVID);
input_dev->id.product = (revid & 0xff);
input_dev->id.version = revid >> 8;
if (input_dev->id.product != devid) {
dev_err(dev, "Failed to probe %s (%x vs %x)\n",
input_dev->name, devid, revid);
err = -ENODEV;
goto err_free_mem;
}
ts->cmd_crtl3 = AD7879_YPLUS_BIT |
AD7879_XPLUS_BIT |
AD7879_Z2_BIT |
AD7879_Z1_BIT |
AD7879_TEMPMASK_BIT |
AD7879_AUXVBATMASK_BIT |
AD7879_GPIOALERTMASK_BIT;
ts->cmd_crtl2 = AD7879_PM(AD7879_PM_DYN) | AD7879_DFR |
AD7879_AVG(ts->averaging) |
AD7879_MFS(ts->median) |
AD7879_FCD(ts->first_conversion_delay);
ts->cmd_crtl1 = AD7879_MODE_INT | AD7879_MODE_SEQ1 |
AD7879_ACQ(ts->acquisition_time) |
AD7879_TMR(ts->pen_down_acc_interval);
err = request_threaded_irq(ts->irq, NULL, ad7879_irq,
IRQF_TRIGGER_FALLING,
dev_name(dev), ts);
if (err) {
dev_err(dev, "irq %d busy?\n", ts->irq);
goto err_free_mem;
}
__ad7879_disable(ts);
err = sysfs_create_group(&dev->kobj, &ad7879_attr_group);
if (err)
goto err_free_irq;
err = ad7879_gpio_add(ts, pdata);
if (err)
goto err_remove_attr;
err = input_register_device(input_dev);
if (err)
goto err_remove_gpio;
return ts;
err_remove_gpio:
ad7879_gpio_remove(ts);
err_remove_attr:
sysfs_remove_group(&dev->kobj, &ad7879_attr_group);
err_free_irq:
free_irq(ts->irq, ts);
err_free_mem:
input_free_device(input_dev);
kfree(ts);
err_out:
return ERR_PTR(err);
}
EXPORT_SYMBOL(ad7879_probe);
void ad7879_remove(struct ad7879 *ts)
{
ad7879_gpio_remove(ts);
sysfs_remove_group(&ts->dev->kobj, &ad7879_attr_group);
free_irq(ts->irq, ts);
input_unregister_device(ts->input);
kfree(ts);
}
EXPORT_SYMBOL(ad7879_remove);
MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
MODULE_DESCRIPTION("AD7879(-1) touchscreen Driver");
MODULE_LICENSE("GPL");
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