[PATCH 02/16] iio: adc: at91-sama5d2_adc: lock around oversampling and sample freq
From: Claudiu Beznea <hidden>
Date: 2022-06-09 08:30:06
Also in:
linux-devicetree, linux-iio, lkml
Subsystem:
iio subsystem and drivers, microchip sama5d2-compatible adc driver, the rest · Maintainers:
Jonathan Cameron, Eugen Hristev, Linus Torvalds
.read_raw()/.write_raw() could be called asynchronously from user space
or other in kernel drivers. Without locking on st->lock these could be
called asynchronously while there is a conversion in progress. Read will
be harmless but changing registers while conversion is in progress may
lead to inconsistent results. Thus, to avoid this lock st->lock.
Fixes: 27e177190891 ("iio:adc:at91_adc8xx: introduce new atmel adc driver")
Fixes: 6794e23fa3fe ("iio: adc: at91-sama5d2_adc: add support for oversampling resolution")
Signed-off-by: Claudiu Beznea <redacted>
---
drivers/iio/adc/at91-sama5d2_adc.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 32b6f157b803..a672a520cdc0 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c@@ -1542,10 +1542,11 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev, ret = at91_adc_read_position(st, chan->channel, &tmp_val); *val = tmp_val; + ret = at91_adc_adjust_val_osr(st, val); mutex_unlock(&st->lock); iio_device_release_direct_mode(indio_dev); - return at91_adc_adjust_val_osr(st, val); + return ret; } if (chan->type == IIO_PRESSURE) { ret = iio_device_claim_direct_mode(indio_dev);
@@ -1556,10 +1557,11 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev, ret = at91_adc_read_pressure(st, chan->channel, &tmp_val); *val = tmp_val; + ret = at91_adc_adjust_val_osr(st, val); mutex_unlock(&st->lock); iio_device_release_direct_mode(indio_dev); - return at91_adc_adjust_val_osr(st, val); + return ret; } /* in this case we have a voltage channel */
@@ -1620,11 +1622,15 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev, return IIO_VAL_FRACTIONAL_LOG2; case IIO_CHAN_INFO_SAMP_FREQ: + mutex_lock(&st->lock); *val = at91_adc_get_sample_freq(st); + mutex_unlock(&st->lock); return IIO_VAL_INT; case IIO_CHAN_INFO_OVERSAMPLING_RATIO: + mutex_lock(&st->lock); *val = st->oversampling_ratio; + mutex_unlock(&st->lock); return IIO_VAL_INT; default:
@@ -1644,18 +1650,23 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev, (val != AT91_OSR_16SAMPLES)) return -EINVAL; /* if no change, optimize out */ + mutex_lock(&st->lock); if (val == st->oversampling_ratio) - return 0; + goto unlock; st->oversampling_ratio = val; /* update ratio */ at91_adc_config_emr(st); +unlock: + mutex_unlock(&st->lock); return 0; case IIO_CHAN_INFO_SAMP_FREQ: if (val < st->soc_info.min_sample_rate || val > st->soc_info.max_sample_rate) return -EINVAL; + mutex_lock(&st->lock); at91_adc_setup_samp_freq(indio_dev, val); + mutex_unlock(&st->lock); return 0; default: return -EINVAL;
--
2.34.1
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