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Input: ads7846 - add possibility to use external vref on ads7846 

Just set vref_mv in your platform config to use external vref. Otherwise
the internal one is used.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Alexander Stein 2011-05-11 16:24:08 -07:00 committed by Dmitry Torokhov
parent e70bdd41bd
commit ebcaaad9d5
2 changed files with 13 additions and 9 deletions
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19
drivers/input/touchscreen/ads7846.c
View File

@ -109,6 +109,7 @@ struct ads7846 {
u16 pressure_max;
bool swap_xy;
bool use_internal;
struct ads7846_packet *packet;
@ -300,7 +301,6 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
struct ads7846 *ts = dev_get_drvdata(dev);
struct ser_req *req;
int status;
int use_internal;
req = kzalloc(sizeof *req, GFP_KERNEL);
if (!req)
@ -308,11 +308,8 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
spi_message_init(&req->msg);
/* FIXME boards with ads7846 might use external vref instead ... */
use_internal = (ts->model == 7846);
/* maybe turn on internal vREF, and let it settle */
if (use_internal) {
if (ts->use_internal) {
req->ref_on = REF_ON;
req->xfer[0].tx_buf = &req->ref_on;
req->xfer[0].len = 1;
@ -324,8 +321,14 @@ static int ads7846_read12_ser(struct device *dev, unsigned command)
/* for 1uF, settle for 800 usec; no cap, 100 usec. */
req->xfer[1].delay_usecs = ts->vref_delay_usecs;
spi_message_add_tail(&req->xfer[1], &req->msg);
/* Enable reference voltage */
command |= ADS_PD10_REF_ON;
}
/* Enable ADC in every case */
command |= ADS_PD10_ADC_ON;
/* take sample */
req->command = (u8) command;
req->xfer[2].tx_buf = &req->command;
@ -409,7 +412,7 @@ name ## _show(struct device *dev, struct device_attribute *attr, char *buf) \
{ \
struct ads7846 *ts = dev_get_drvdata(dev); \
ssize_t v = ads7846_read12_ser(dev, \
READ_12BIT_SER(var) | ADS_PD10_ALL_ON); \
READ_12BIT_SER(var)); \
if (v < 0) \
return v; \
return sprintf(buf, "%u\n", adjust(ts, v)); \
@ -502,6 +505,7 @@ static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
if (!ts->vref_mv) {
dev_dbg(&spi->dev, "assuming 2.5V internal vREF\n");
ts->vref_mv = 2500;
ts->use_internal = true;
}
break;
case 7845:
@ -1333,8 +1337,7 @@ static int __devinit ads7846_probe(struct spi_device *spi)
if (ts->model == 7845)
ads7845_read12_ser(&spi->dev, PWRDOWN);
else
(void) ads7846_read12_ser(&spi->dev,
READ_12BIT_SER(vaux) | ADS_PD10_ALL_ON);
(void) ads7846_read12_ser(&spi->dev, READ_12BIT_SER(vaux));
err = sysfs_create_group(&spi->dev.kobj, &ads784x_attr_group);
if (err)

3
include/linux/spi/ads7846.h
View File

@ -14,7 +14,8 @@ enum ads7846_filter {
struct ads7846_platform_data {
u16 model; /* 7843, 7845, 7846, 7873. */
u16 vref_delay_usecs; /* 0 for external vref; etc */
u16 vref_mv; /* external vref value, milliVolts */
u16 vref_mv; /* external vref value, milliVolts
* ads7846: if 0, use internal vref */
bool keep_vref_on; /* set to keep vref on for differential
* measurements as well */
bool swap_xy; /* swap x and y axes */