diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/input/touchscreen/ads7846.c | 68 |
1 files changed, 44 insertions, 24 deletions
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c index 72cf0a26d67..8c12a974b41 100644 --- a/drivers/input/touchscreen/ads7846.c +++ b/drivers/input/touchscreen/ads7846.c @@ -48,10 +48,13 @@ #define TS_POLL_PERIOD msecs_to_jiffies(10) +/* this driver doesn't aim at the peak continuous sample rate */ +#define SAMPLE_BITS (8 /*cmd*/ + 16 /*sample*/ + 2 /* before, after */) + 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-byte values, + * with msbs zeroed). Instead, we read them as two 8-bit values, * which need byteswapping then range adjustment. */ __be16 x; @@ -68,6 +71,7 @@ struct ads7846 { u16 vref_delay_usecs; u16 x_plate_ohms; + u8 read_x, read_y, read_z1, read_z2; struct ts_event tc; struct spi_transfer xfer[8]; @@ -117,10 +121,10 @@ struct ads7846 { #define READ_12BIT_DFR(x) (ADS_START | ADS_A2A1A0_d_ ## x \ | ADS_12_BIT | ADS_DFR) -static const u8 read_y = READ_12BIT_DFR(y) | ADS_PD10_ADC_ON; -static const u8 read_z1 = READ_12BIT_DFR(z1) | ADS_PD10_ADC_ON; -static const u8 read_z2 = READ_12BIT_DFR(z2) | ADS_PD10_ADC_ON; -static const u8 read_x = READ_12BIT_DFR(x) | ADS_PD10_PDOWN; /* LAST */ +#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_X (READ_12BIT_DFR(x) | ADS_PD10_PDOWN) /* LAST */ /* single-ended samples need to first power up reference voltage; * we leave both ADC and VREF powered @@ -128,8 +132,8 @@ static const u8 read_x = READ_12BIT_DFR(x) | ADS_PD10_PDOWN; /* LAST */ #define READ_12BIT_SER(x) (ADS_START | ADS_A2A1A0_ ## x \ | ADS_12_BIT | ADS_SER) -static const u8 ref_on = READ_12BIT_DFR(x) | ADS_PD10_ALL_ON; -static const u8 ref_off = READ_12BIT_DFR(y) | ADS_PD10_PDOWN; +#define REF_ON (READ_12BIT_DFR(x) | ADS_PD10_ALL_ON) +#define REF_OFF (READ_12BIT_DFR(y) | ADS_PD10_PDOWN) /*--------------------------------------------------------------------------*/ @@ -138,7 +142,9 @@ static const u8 ref_off = READ_12BIT_DFR(y) | ADS_PD10_PDOWN; */ struct ser_req { + u8 ref_on; u8 command; + u8 ref_off; u16 scratch; __be16 sample; struct spi_message msg; @@ -160,7 +166,8 @@ static int ads7846_read12_ser(struct device *dev, unsigned command) INIT_LIST_HEAD(&req->msg.transfers); /* activate reference, so it has time to settle; */ - req->xfer[0].tx_buf = &ref_on; + req->ref_on = REF_ON; + req->xfer[0].tx_buf = &req->ref_on; req->xfer[0].len = 1; req->xfer[1].rx_buf = &req->scratch; req->xfer[1].len = 2; @@ -182,7 +189,8 @@ static int ads7846_read12_ser(struct device *dev, unsigned command) /* REVISIT: take a few more samples, and compare ... */ /* turn off reference */ - req->xfer[4].tx_buf = &ref_off; + req->ref_off = REF_OFF; + req->xfer[4].tx_buf = &req->ref_off; req->xfer[4].len = 1; req->xfer[5].rx_buf = &req->scratch; req->xfer[5].len = 2; @@ -400,7 +408,6 @@ static int __devinit ads7846_probe(struct spi_device *spi) struct input_dev *input_dev; struct ads7846_platform_data *pdata = spi->dev.platform_data; struct spi_transfer *x; - int i; int err; if (!spi->irq) { @@ -414,9 +421,9 @@ static int __devinit ads7846_probe(struct spi_device *spi) } /* don't exceed max specified sample rate */ - if (spi->max_speed_hz > (125000 * 16)) { + if (spi->max_speed_hz > (125000 * SAMPLE_BITS)) { dev_dbg(&spi->dev, "f(sample) %d KHz?\n", - (spi->max_speed_hz/16)/1000); + (spi->max_speed_hz/SAMPLE_BITS)/1000); return -EINVAL; } @@ -469,45 +476,58 @@ static int __devinit ads7846_probe(struct spi_device *spi) /* set up the transfers to read touchscreen state; this assumes we * use formula #2 for pressure, not #3. */ + INIT_LIST_HEAD(&ts->msg.transfers); x = ts->xfer; /* y- still on; turn on only y+ (and ADC) */ - x->tx_buf = &read_y; + ts->read_y = READ_Y; + x->tx_buf = &ts->read_y; x->len = 1; + spi_message_add_tail(x, &ts->msg); + x++; x->rx_buf = &ts->tc.y; x->len = 2; - x++; + spi_message_add_tail(x, &ts->msg); /* turn y+ off, x- on; we'll use formula #2 */ if (ts->model == 7846) { - x->tx_buf = &read_z1; + x++; + ts->read_z1 = READ_Z1; + x->tx_buf = &ts->read_z1; x->len = 1; + spi_message_add_tail(x, &ts->msg); + x++; x->rx_buf = &ts->tc.z1; x->len = 2; - x++; + spi_message_add_tail(x, &ts->msg); - x->tx_buf = &read_z2; + x++; + ts->read_z2 = READ_Z2; + x->tx_buf = &ts->read_z2; x->len = 1; + spi_message_add_tail(x, &ts->msg); + x++; x->rx_buf = &ts->tc.z2; x->len = 2; - x++; + spi_message_add_tail(x, &ts->msg); } /* turn y- off, x+ on, then leave in lowpower */ - x->tx_buf = &read_x; + x++; + ts->read_x = READ_X; + x->tx_buf = &ts->read_x; x->len = 1; + spi_message_add_tail(x, &ts->msg); + x++; x->rx_buf = &ts->tc.x; x->len = 2; - x++; - - CS_CHANGE(x[-1]); + CS_CHANGE(*x); + spi_message_add_tail(x, &ts->msg); - for (i = 0; i < x - ts->xfer; i++) - spi_message_add_tail(&ts->xfer[i], &ts->msg); ts->msg.complete = ads7846_rx; ts->msg.context = ts; |