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>
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index c6164b6..03e527c 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -63,11 +63,11 @@
/* 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
/* 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");