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iio: addac: stx104: Fix race condition when converting analog-to-digital

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[ Upstream commit 4f9b80aefb ]

The ADC conversion procedure requires several device I/O operations
performed in a particular sequence. If stx104_read_raw() is called
concurrently, the ADC conversion procedure could be clobbered. Prevent
such a race condition by utilizing a mutex.

Fixes: 4075a283ae ("iio: stx104: Add IIO support for the ADC channels")
Signed-off-by: William Breathitt Gray <william.gray@linaro.org>
Link: https://lore.kernel.org/r/2ae5e40eed5006ca735e4c12181a9ff5ced65547.1680790580.git.william.gray@linaro.org
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
William Breathitt Gray 2023-04-06 10:40:11 -04:00 • committed by Justin Hammond
parent 20e8e99d64
commit 6e6ede7e2b
1 changed files with 4 additions and 0 deletions
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4
drivers/iio/addac/stx104.c
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@ -117,6 +117,8 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
return IIO_VAL_INT;
}
mutex_lock(&priv->lock);
/* select ADC channel */
iowrite8(chan->channel | (chan->channel << 4), &reg->achan);
@ -127,6 +129,8 @@ static int stx104_read_raw(struct iio_dev *indio_dev,
while (ioread8(&reg->cir_asr) & BIT(7));
*val = ioread16(&reg->ssr_ad);
mutex_unlock(&priv->lock);
return IIO_VAL_INT;
case IIO_CHAN_INFO_OFFSET:
/* get ADC bipolar/unipolar configuration */