diff options
Diffstat (limited to 'drivers/iio/adc/hx711.c')
| -rw-r--r-- | drivers/iio/adc/hx711.c | 32 |
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; |