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Input: ads7846 - pluggable filtering logic 

Some LCDs like the LS041Y3 require a customized filtering
logic for reliable readings, so make the filtering function
replacable through platform specific hooks.

Signed-off-by: Imre Deak <imre.deak@solidboot.com>
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Imre Deak 2007-01-18 00:44:41 -05:00 committed by Dmitry Torokhov
parent 78a56aab11
commit da970e69ef
2 changed files with 105 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

135
drivers/input/touchscreen/ads7846.c
View File

@ -63,11 +63,11 @@ struct ts_event {
/* For portability, we can't read 12 bit values using SPI (which
* would make the controller deliver them as native byteorder u16
* with msbs zeroed). Instead, we read them as two 8-bit values,
* which need byteswapping then range adjustment.
* *** WHICH NEED BYTESWAPPING *** and range adjustment.
*/
__be16 x;
__be16 y;
__be16 z1, z2;
u16 x;
u16 y;
u16 z1, z2;
int ignore;
};
@ -106,6 +106,9 @@ struct ads7846 {
unsigned irq_disabled:1; /* P: lock */
unsigned disabled:1;
int (*filter)(void *data, int data_idx, int *val);
void *filter_data;
void (*filter_cleanup)(void *data);
int (*get_pendown_state)(void);
};
@ -379,13 +382,13 @@ static void ads7846_rx(void *ads)
u16 x, y, z1, z2;
unsigned long flags;
/* adjust: on-wire is a must-ignore bit, a BE12 value, then padding;
* built from two 8 bit values written msb-first.
/* ads7846_rx_val() did in-place conversion (including byteswap) from
* on-the-wire format as part of debouncing to get stable readings.
*/
x = (be16_to_cpu(ts->tc.x) >> 3) & 0x0fff;
y = (be16_to_cpu(ts->tc.y) >> 3) & 0x0fff;
z1 = (be16_to_cpu(ts->tc.z1) >> 3) & 0x0fff;
z2 = (be16_to_cpu(ts->tc.z2) >> 3) & 0x0fff;
x = ts->tc.x;
y = ts->tc.y;
z1 = ts->tc.z1;
z2 = ts->tc.z2;
/* range filtering */
if (x == MAX_12BIT)
@ -453,50 +456,85 @@ static void ads7846_rx(void *ads)
spin_unlock_irqrestore(&ts->lock, flags);
}
static void ads7846_debounce(void *ads)
static int ads7846_debounce(void *ads, int data_idx, int *val)
{
struct ads7846 *ts = ads;
struct spi_message *m;
struct spi_transfer *t;
int val;
int status;
m = &ts->msg[ts->msg_idx];
t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
val = (be16_to_cpu(*(__be16 *)t->rx_buf) >> 3) & 0x0fff;
if (!ts->read_cnt || (abs(ts->last_read - val) > ts->debounce_tol)) {
if (!ts->read_cnt || (abs(ts->last_read - *val) > ts->debounce_tol)) {
/* Start over collecting consistent readings. */
ts->read_rep = 0;
/* Repeat it, if this was the first read or the read
* wasn't consistent enough. */
if (ts->read_cnt < ts->debounce_max) {
ts->last_read = val;
ts->last_read = *val;
ts->read_cnt++;
return ADS7846_FILTER_REPEAT;
} else {
/* Maximum number of debouncing reached and still
* not enough number of consistent readings. Abort
* the whole sample, repeat it in the next sampling
* period.
*/
ts->tc.ignore = 1;
ts->read_cnt = 0;
/* Last message will contain ads7846_rx() as the
* completion function.
*/
m = ts->last_msg;
return ADS7846_FILTER_IGNORE;
}
/* Start over collecting consistent readings. */
ts->read_rep = 0;
} else {
if (++ts->read_rep > ts->debounce_rep) {
/* Got a good reading for this coordinate,
* go for the next one. */
ts->tc.ignore = 0;
ts->msg_idx++;
ts->read_cnt = 0;
ts->read_rep = 0;
m++;
} else
return ADS7846_FILTER_OK;
} else {
/* Read more values that are consistent. */
ts->read_cnt++;
return ADS7846_FILTER_REPEAT;
}
}
}
static int ads7846_no_filter(void *ads, int data_idx, int *val)
{
return ADS7846_FILTER_OK;
}
static void ads7846_rx_val(void *ads)
{
struct ads7846 *ts = ads;
struct spi_message *m;
struct spi_transfer *t;
u16 *rx_val;
int val;
int action;
int status;
m = &ts->msg[ts->msg_idx];
t = list_entry(m->transfers.prev, struct spi_transfer, transfer_list);
rx_val = t->rx_buf;
/* adjust: on-wire is a must-ignore bit, a BE12 value, then padding;
* built from two 8 bit values written msb-first.
*/
val = be16_to_cpu(*rx_val) >> 3;
action = ts->filter(ts->filter_data, ts->msg_idx, &val);
switch (action) {
case ADS7846_FILTER_REPEAT:
break;
case ADS7846_FILTER_IGNORE:
ts->tc.ignore = 1;
/* Last message will contain ads7846_rx() as the
* completion function.
*/
m = ts->last_msg;
break;
case ADS7846_FILTER_OK:
*rx_val = val;
ts->tc.ignore = 0;
m = &ts->msg[++ts->msg_idx];
break;
default:
BUG();
}
status = spi_async(ts->spi, m);
if (status)
@ -689,14 +727,25 @@ static int __devinit ads7846_probe(struct spi_device *spi)
ts->vref_delay_usecs = pdata->vref_delay_usecs ? : 100;
ts->x_plate_ohms = pdata->x_plate_ohms ? : 400;
ts->pressure_max = pdata->pressure_max ? : ~0;
if (pdata->debounce_max) {
if (pdata->filter != NULL) {
if (pdata->filter_init != NULL) {
err = pdata->filter_init(pdata, &ts->filter_data);
if (err < 0)
goto err_free_mem;
}
ts->filter = pdata->filter;
ts->filter_cleanup = pdata->filter_cleanup;
} else if (pdata->debounce_max) {
ts->debounce_max = pdata->debounce_max;
if (ts->debounce_max < 2)
ts->debounce_max = 2;
ts->debounce_tol = pdata->debounce_tol;
ts->debounce_rep = pdata->debounce_rep;
if (ts->debounce_rep > ts->debounce_max + 1)
ts->debounce_rep = ts->debounce_max - 1;
ts->filter = ads7846_debounce;
ts->filter_data = ts;
} else
ts->debounce_tol = ~0;
ts->filter = ads7846_no_filter;
ts->get_pendown_state = pdata->get_pendown_state;
snprintf(ts->phys, sizeof(ts->phys), "%s/input0", spi->dev.bus_id);
@ -737,7 +786,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
x->len = 2;
spi_message_add_tail(x, m);
m->complete = ads7846_debounce;
m->complete = ads7846_rx_val;
m->context = ts;
m++;
@ -755,7 +804,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
x->len = 2;
spi_message_add_tail(x, m);
m->complete = ads7846_debounce;
m->complete = ads7846_rx_val;
m->context = ts;
/* turn y+ off, x- on; we'll use formula #2 */
@ -774,7 +823,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
x->len = 2;
spi_message_add_tail(x, m);
m->complete = ads7846_debounce;
m->complete = ads7846_rx_val;
m->context = ts;
m++;
@ -791,7 +840,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
x->len = 2;
spi_message_add_tail(x, m);
m->complete = ads7846_debounce;
m->complete = ads7846_rx_val;
m->context = ts;
}
@ -820,7 +869,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
spi->dev.driver->name, ts)) {
dev_dbg(&spi->dev, "irq %d busy?\n", spi->irq);
err = -EBUSY;
goto err_free_mem;
goto err_cleanup_filter;
}
dev_info(&spi->dev, "touchscreen, irq %d\n", spi->irq);
@ -856,6 +905,9 @@ static int __devinit ads7846_probe(struct spi_device *spi)
sysfs_remove_group(&spi->dev.kobj, ts->attr_group);
err_free_irq:
free_irq(spi->irq, ts);
err_cleanup_filter:
if (ts->filter_cleanup)
ts->filter_cleanup(ts->filter_data);
err_free_mem:
input_free_device(input_dev);
kfree(ts);
@ -876,6 +928,9 @@ static int __devexit ads7846_remove(struct spi_device *spi)
/* suspend left the IRQ disabled */
enable_irq(ts->spi->irq);
if (ts->filter_cleanup)
ts->filter_cleanup(ts->filter_data);
kfree(ts);
dev_dbg(&spi->dev, "unregistered touchscreen\n");

10
include/linux/spi/ads7846.h
View File

@ -5,6 +5,12 @@
*
* It's OK if the min/max values are zero.
*/
enum ads7846_filter {
ADS7846_FILTER_OK,
ADS7846_FILTER_REPEAT,
ADS7846_FILTER_IGNORE,
};
struct ads7846_platform_data {
u16 model; /* 7843, 7845, 7846. */
u16 vref_delay_usecs; /* 0 for external vref; etc */
@ -21,5 +27,9 @@ struct ads7846_platform_data {
u16 debounce_rep; /* additional consecutive good readings
* required after the first two */
int (*get_pendown_state)(void);
int (*filter_init) (struct ads7846_platform_data *pdata,
void **filter_data);
int (*filter) (void *filter_data, int data_idx, int *val);
void (*filter_cleanup)(void *filter_data);
};