diff options
| -rw-r--r-- | drivers/staging/iio/resolver/ad2s1210.c | 30 |
1 files changed, 22 insertions, 8 deletions
diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c index e0bea3c68664..59c273a4b6a9 100644 --- a/drivers/staging/iio/resolver/ad2s1210.c +++ b/drivers/staging/iio/resolver/ad2s1210.c @@ -287,6 +287,26 @@ static int ad2s1210_regmap_reg_read(void *context, unsigned int reg, } /* + * Toggles the SAMPLE line on the AD2S1210 to latch in the current position, + * velocity, and faults. + * + * Must be called with lock held. + */ +static void ad2s1210_toggle_sample_line(struct ad2s1210_state *st) +{ + /* + * Datasheet specifies minimum hold time t16 = 2 * tck + 20 ns. So the + * longest time needed is when CLKIN is 6.144 MHz, in which case t16 + * ~= 350 ns. The same delay is also needed before re-asserting the + * SAMPLE line. + */ + gpiod_set_value(st->sample_gpio, 1); + ndelay(350); + gpiod_set_value(st->sample_gpio, 0); + ndelay(350); +} + +/* * Sets the excitation frequency and performs software reset. * * Must be called with lock held. @@ -405,10 +425,8 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev, int ret; mutex_lock(&st->lock); - gpiod_set_value(st->sample_gpio, 1); + ad2s1210_toggle_sample_line(st); timestamp = iio_get_time_ns(indio_dev); - /* delay (6 * tck + 20) nano seconds */ - udelay(1); switch (chan->type) { case IIO_ANGL: @@ -444,9 +462,6 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev, ad2s1210_push_events(indio_dev, st->sample.fault, timestamp); error_ret: - gpiod_set_value(st->sample_gpio, 0); - /* delay (2 * tck + 20) nano seconds */ - udelay(1); mutex_unlock(&st->lock); return ret; } @@ -1268,7 +1283,7 @@ static irqreturn_t ad2s1210_trigger_handler(int irq, void *p) mutex_lock(&st->lock); memset(&st->scan, 0, sizeof(st->scan)); - gpiod_set_value(st->sample_gpio, 1); + ad2s1210_toggle_sample_line(st); if (test_bit(0, indio_dev->active_scan_mask)) { ret = ad2s1210_set_mode(st, MOD_POS); @@ -1298,7 +1313,6 @@ static irqreturn_t ad2s1210_trigger_handler(int irq, void *p) iio_push_to_buffers_with_timestamp(indio_dev, &st->scan, pf->timestamp); error_ret: - gpiod_set_value(st->sample_gpio, 0); mutex_unlock(&st->lock); iio_trigger_notify_done(indio_dev->trig); |