iio: ti_am335x_adc: Fix wrong samples received on 1st read
Previously we tried to read data form ADC even before ADC sequencer
finished sampling. This led to wrong samples.
We now wait on ADC status register idle bit to be set.
Signed-off-by: Patil, Rachna <rachna@ti.com>
Signed-off-by: Zubair Lutfullah <zubair.lutfullah@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index 0ad208a..3ceac3e 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -60,7 +60,6 @@
{
unsigned int stepconfig;
int i, steps;
- u32 step_en;
/*
* There are 16 configurable steps and 8 analog input
@@ -86,8 +85,7 @@
adc_dev->channel_step[i] = steps;
steps++;
}
- step_en = get_adc_step_mask(adc_dev);
- am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
+
}
static const char * const chan_name_ain[] = {
@@ -142,10 +140,22 @@
int *val, int *val2, long mask)
{
struct tiadc_device *adc_dev = iio_priv(indio_dev);
- int i;
- unsigned int fifo1count, read;
+ int i, map_val;
+ unsigned int fifo1count, read, stepid;
u32 step = UINT_MAX;
bool found = false;
+ u32 step_en;
+ unsigned long timeout = jiffies + usecs_to_jiffies
+ (IDLE_TIMEOUT * adc_dev->channels);
+ step_en = get_adc_step_mask(adc_dev);
+ am335x_tsc_se_set(adc_dev->mfd_tscadc, step_en);
+
+ /* Wait for ADC sequencer to complete sampling */
+ while (tiadc_readl(adc_dev, REG_ADCFSM) & SEQ_STATUS) {
+ if (time_after(jiffies, timeout))
+ return -EAGAIN;
+ }
+ map_val = chan->channel + TOTAL_CHANNELS;
/*
* When the sub-system is first enabled,
@@ -170,12 +180,16 @@
fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
for (i = 0; i < fifo1count; i++) {
read = tiadc_readl(adc_dev, REG_FIFO1);
- if (read >> 16 == step) {
- *val = read & 0xfff;
+ stepid = read & FIFOREAD_CHNLID_MASK;
+ stepid = stepid >> 0x10;
+
+ if (stepid == map_val) {
+ read = read & FIFOREAD_DATA_MASK;
found = true;
+ *val = read;
}
}
- am335x_tsc_se_update(adc_dev->mfd_tscadc);
+
if (found == false)
return -EBUSY;
return IIO_VAL_INT;