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iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock

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As part of the general cleanup of indio_dev->mlock, this change replaces
it with a local lock, to protect against any other accesses during the
reading of sample. Reading a sample requires multiple consecutive regmap
operations and a completion callback, so this requires that no other
read occurs until it completes.

This is part of a bigger cleanup.
Link: https://lore.kernel.org/linux-iio/CA+U=Dsoo6YABe5ODLp+eFNPGFDjk5ZeQEceGkqjxXcVEhLWubw@mail.gmail.com/

Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20200916092928.78026-1-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Sergiu Cuciurean 2020-09-16 12:29:28 +03:00 committed by Jonathan Cameron
parent 3cef2e31b5
commit 8a0f412fca
1 changed files with 13 additions and 2 deletions
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15
drivers/iio/adc/fsl-imx25-gcq.c
View file

@ -40,6 +40,15 @@ struct mx25_gcq_priv {
int irq;
struct regulator *vref[4];
u32 channel_vref_mv[MX25_NUM_CFGS];
/*
* Lock to protect the device state during a potential concurrent
* read access from userspace. Reading a raw value requires a sequence
* of register writes, then a wait for a completion callback,
* and finally a register read, during which userspace could issue
* another read request. This lock protects a read access from
* ocurring before another one has finished.
*/
struct mutex lock;
};
#define MX25_CQG_CHAN(chan, id) {\
@ -137,9 +146,9 @@ static int mx25_gcq_read_raw(struct iio_dev *indio_dev,
switch (mask) {
case IIO_CHAN_INFO_RAW:
mutex_lock(&indio_dev->mlock);
mutex_lock(&priv->lock);
ret = mx25_gcq_get_raw_value(&indio_dev->dev, chan, priv, val);
mutex_unlock(&indio_dev->mlock);
mutex_unlock(&priv->lock);
return ret;
case IIO_CHAN_INFO_SCALE:
@ -314,6 +323,8 @@ static int mx25_gcq_probe(struct platform_device *pdev)
return PTR_ERR(priv->regs);
}
mutex_init(&priv->lock);
init_completion(&priv->completed);
ret = mx25_gcq_setup_cfgs(pdev, priv);