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iio: adc: at91-sama5d2_adc: lock around oversampling and sample freq

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[ Upstream commit 9780a23ed5 ]

.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: 27e1771908 ("iio:adc:at91_adc8xx: introduce new atmel adc driver")
Fixes: 6794e23fa3 ("iio: adc: at91-sama5d2_adc: add support for oversampling resolution")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220803102855.2191070-4-claudiu.beznea@microchip.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Claudiu Beznea 2022-08-03 13:28:39 +03:00 committed by Greg Kroah-Hartman
parent c5c63736d2
commit 5db9b840ac
1 changed files with 8 additions and 4 deletions
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12
drivers/iio/adc/at91-sama5d2_adc.c
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@ -1329,10 +1329,10 @@ 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;
mutex_unlock(&st->lock);
iio_device_release_direct_mode(indio_dev);
if (ret > 0)
ret = at91_adc_adjust_val_osr(st, val);
mutex_unlock(&st->lock);
iio_device_release_direct_mode(indio_dev);
return ret;
}
@ -1345,10 +1345,10 @@ 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;
mutex_unlock(&st->lock);
iio_device_release_direct_mode(indio_dev);
if (ret > 0)
ret = at91_adc_adjust_val_osr(st, val);
mutex_unlock(&st->lock);
iio_device_release_direct_mode(indio_dev);
return ret;
}
@ -1441,16 +1441,20 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
/* if no change, optimize out */
if (val == st->oversampling_ratio)
return 0;
mutex_lock(&st->lock);
st->oversampling_ratio = val;
/* update ratio */
at91_adc_config_emr(st);
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;