From de2defd96d7d92fe8b5f9cf2bfd385d8d4819923 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Thu, 18 Jan 2007 00:45:21 -0500 Subject: 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 Signed-off-by: Imre Deak Signed-off-by: Juha Yrjola Signed-off-by: David Brownell Signed-off-by: Dmitry Torokhov --- drivers/input/touchscreen/ads7846.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) (limited to 'drivers/input/touchscreen') 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); -- cgit v1.2.3-70-g09d2