aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorImre Deak <imre.deak@solidboot.com>2007-01-18 00:45:21 -0500
committerDmitry Torokhov <dtor@insightbb.com>2007-01-18 00:45:21 -0500
commitde2defd96d7d92fe8b5f9cf2bfd385d8d4819923 (patch)
tree191349b9480dca988f6d776db0a0b00ff10bffca
parentda970e69efb9fd0be0c23ace5bde42d4caf17b40 (diff)
Input: ads7846 - optionally leave Vref on during differential measurements
On some LCDs leaving the Vref on provides much better readings. Signed-off-by: Jarkko Oikarinen <jarkko.oikarinen@nokia.com> 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>
-rw-r--r--drivers/input/touchscreen/ads7846.c30
-rw-r--r--include/linux/spi/ads7846.h2
2 files changed, 19 insertions, 13 deletions
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 03e527c16c2..c34e59b720a 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -145,15 +145,16 @@ struct ads7846 {
#define MAX_12BIT ((1<<12)-1)
/* leave ADC powered up (disables penirq) between differential samples */
-#define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \
- | ADS_12_BIT | ADS_DFR)
+#define READ_12BIT_DFR(x, adc, vref) (ADS_START | ADS_A2A1A0_d_ ## x \
+ | ADS_12_BIT | ADS_DFR | \
+ (adc ? ADS_PD10_ADC_ON : 0) | (vref ? ADS_PD10_REF_ON : 0))
-#define READ_Y (READ_12BIT_DFR(y) | ADS_PD10_ADC_ON)
-#define READ_Z1 (READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON)
-#define READ_Z2 (READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON)
+#define READ_Y(vref) (READ_12BIT_DFR(y, 1, vref))
+#define READ_Z1(vref) (READ_12BIT_DFR(z1, 1, vref))
+#define READ_Z2(vref) (READ_12BIT_DFR(z2, 1, vref))
-#define READ_X (READ_12BIT_DFR(x) | ADS_PD10_ADC_ON)
-#define PWRDOWN (READ_12BIT_DFR(y) | ADS_PD10_PDOWN) /* LAST */
+#define READ_X(vref) (READ_12BIT_DFR(x, 1, vref))
+#define PWRDOWN (READ_12BIT_DFR(y, 0, 0)) /* LAST */
/* single-ended samples need to first power up reference voltage;
* we leave both ADC and VREF powered
@@ -161,8 +162,8 @@ struct ads7846 {
#define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \
| ADS_12_BIT | ADS_SER)
-#define REF_ON (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON)
-#define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN)
+#define REF_ON (READ_12BIT_DFR(x, 1, 1))
+#define REF_OFF (READ_12BIT_DFR(y, 0, 0))
/*--------------------------------------------------------------------------*/
@@ -670,6 +671,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
struct ads7846_platform_data *pdata = spi->dev.platform_data;
struct spi_message *m;
struct spi_transfer *x;
+ int vref;
int err;
if (!spi->irq) {
@@ -767,6 +769,8 @@ static int __devinit ads7846_probe(struct spi_device *spi)
input_set_abs_params(input_dev, ABS_PRESSURE,
pdata->pressure_min, pdata->pressure_max, 0, 0);
+ vref = pdata->keep_vref_on;
+
/* set up the transfers to read touchscreen state; this assumes we
* use formula #2 for pressure, not #3.
*/
@@ -776,7 +780,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
spi_message_init(m);
/* y- still on; turn on only y+ (and ADC) */
- ts->read_y = READ_Y;
+ ts->read_y = READ_Y(vref);
x->tx_buf = &ts->read_y;
x->len = 1;
spi_message_add_tail(x, m);
@@ -794,7 +798,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
/* turn y- off, x+ on, then leave in lowpower */
x++;
- ts->read_x = READ_X;
+ ts->read_x = READ_X(vref);
x->tx_buf = &ts->read_x;
x->len = 1;
spi_message_add_tail(x, m);
@@ -813,7 +817,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
spi_message_init(m);
x++;
- ts->read_z1 = READ_Z1;
+ ts->read_z1 = READ_Z1(vref);
x->tx_buf = &ts->read_z1;
x->len = 1;
spi_message_add_tail(x, m);
@@ -830,7 +834,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
spi_message_init(m);
x++;
- ts->read_z2 = READ_Z2;
+ ts->read_z2 = READ_Z2(vref);
x->tx_buf = &ts->read_z2;
x->len = 1;
spi_message_add_tail(x, m);
diff --git a/include/linux/spi/ads7846.h b/include/linux/spi/ads7846.h
index 1663f940ca1..3387e44dfd1 100644
--- a/include/linux/spi/ads7846.h
+++ b/include/linux/spi/ads7846.h
@@ -14,6 +14,8 @@ enum ads7846_filter {
struct ads7846_platform_data {
u16 model; /* 7843, 7845, 7846. */
u16 vref_delay_usecs; /* 0 for external vref; etc */
+ int keep_vref_on:1; /* set to keep vref on for differential
+ * measurements as well */
u16 x_plate_ohms;
u16 y_plate_ohms;