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path: root/drivers/iio/adc/hx711.c
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Diffstat (limited to 'drivers/iio/adc/hx711.c')
-rw-r--r--drivers/iio/adc/hx711.c32
1 files changed, 10 insertions, 22 deletions
diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index 88c7fe15003b..c8686558429b 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -23,6 +23,7 @@
/* gain to pulse and scale conversion */
#define HX711_GAIN_MAX 3
+#define HX711_RESET_GAIN 128
struct hx711_gain_to_scale {
int gain;
@@ -100,14 +101,14 @@ struct hx711_data {
static int hx711_cycle(struct hx711_data *hx711_data)
{
- int val;
+ unsigned long flags;
/*
* if preempted for more then 60us while PD_SCK is high:
* hx711 is going in reset
* ==> measuring is false
*/
- preempt_disable();
+ local_irq_save(flags);
gpiod_set_value(hx711_data->gpiod_pd_sck, 1);
/*
@@ -117,7 +118,6 @@ static int hx711_cycle(struct hx711_data *hx711_data)
*/
ndelay(hx711_data->data_ready_delay_ns);
- val = gpiod_get_value(hx711_data->gpiod_dout);
/*
* here we are not waiting for 0.2 us as suggested by the datasheet,
* because the oscilloscope showed in a test scenario
@@ -125,7 +125,7 @@ static int hx711_cycle(struct hx711_data *hx711_data)
* and 0.56 us for PD_SCK low on TI Sitara with 800 MHz
*/
gpiod_set_value(hx711_data->gpiod_pd_sck, 0);
- preempt_enable();
+ local_irq_restore(flags);
/*
* make it a square wave for addressing cases with capacitance on
@@ -133,7 +133,8 @@ static int hx711_cycle(struct hx711_data *hx711_data)
*/
ndelay(hx711_data->data_ready_delay_ns);
- return val;
+ /* sample as late as possible */
+ return gpiod_get_value(hx711_data->gpiod_dout);
}
static int hx711_read(struct hx711_data *hx711_data)
@@ -185,8 +186,7 @@ static int hx711_wait_for_ready(struct hx711_data *hx711_data)
static int hx711_reset(struct hx711_data *hx711_data)
{
- int ret;
- int val = gpiod_get_value(hx711_data->gpiod_dout);
+ int val = hx711_wait_for_ready(hx711_data);
if (val) {
/*
@@ -202,22 +202,10 @@ static int hx711_reset(struct hx711_data *hx711_data)
msleep(10);
gpiod_set_value(hx711_data->gpiod_pd_sck, 0);
- ret = hx711_wait_for_ready(hx711_data);
- if (ret)
- return ret;
- /*
- * after a reset the gain is 128 so we do a dummy read
- * to set the gain for the next read
- */
- ret = hx711_read(hx711_data);
- if (ret < 0)
- return ret;
-
- /*
- * after a dummy read we need to wait vor readiness
- * for not mixing gain pulses with the clock
- */
val = hx711_wait_for_ready(hx711_data);
+
+ /* after a reset the gain is 128 */
+ hx711_data->gain_set = HX711_RESET_GAIN;
}
return val;