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@xxxxxxxxxxxxxxxxxxxxx>
---
Changes since v1:
* Actually change the SPI commands to select internal or external reference.
drivers/input/touchscreen/ads7846.c | 19 +++++++++++--------
include/linux/spi/ads7846.h | 3 ++-
2 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
index 1de1c19..c25049c 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -109,6 +109,7 @@ struct ads7846 {
u16 pressure_max;
bool swap_xy;
+ bool use_internal;
struct ads7846_packet *packet;
@@ -307,7 +308,6 @@ 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)
@@ -315,11 +315,8 @@ 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;
@@ -331,8 +328,14 @@ 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;
@@ -416,7 +419,7 @@ 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)); \
@@ -509,6 +512,7 @@ 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:
@@ -1340,8 +1344,7 @@ 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)
diff --git a/include/linux/spi/ads7846.h b/include/linux/spi/ads7846.h
index 92bd083..c64de9d 100644
--- a/include/linux/spi/ads7846.h
+++ b/include/linux/spi/ads7846.h
@@ -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 */
--
1.7.3.4
--
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