Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 246af421 authored by Claudiu Beznea's avatar Claudiu Beznea Committed by Greg Kroah-Hartman
Browse files

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



[ Upstream commit 9780a23ed5a0a0a63683e078f576719a98d4fb70 ]

.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: 27e17719 ("iio:adc:at91_adc8xx: introduce new atmel adc driver")
Fixes: 6794e23f ("iio: adc: at91-sama5d2_adc: add support for oversampling resolution")
Signed-off-by: default avatarClaudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220803102855.2191070-4-claudiu.beznea@microchip.com


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 46778752

drivers/iio/adc/at91-sama5d2_adc.c

+8 −4
Original line number Diff line number Diff line
@@ -1321,10 +1321,10 @@ 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;

	}
@@ -1337,10 +1337,10 @@ 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;

	}
@@ -1433,16 +1433,20 @@ 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;