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iio: adc: fsl-imx25-gcq: Replace indio_dev->mlock with own device lock
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>
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1 changed files with 13 additions and 2 deletions
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@ -40,6 +40,15 @@ struct mx25_gcq_priv {
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int irq;
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struct regulator *vref[4];
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u32 channel_vref_mv[MX25_NUM_CFGS];
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/*
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* Lock to protect the device state during a potential concurrent
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* read access from userspace. Reading a raw value requires a sequence
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* of register writes, then a wait for a completion callback,
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* and finally a register read, during which userspace could issue
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* another read request. This lock protects a read access from
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* ocurring before another one has finished.
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*/
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struct mutex lock;
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};
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#define MX25_CQG_CHAN(chan, id) {\
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@ -137,9 +146,9 @@ static int mx25_gcq_read_raw(struct iio_dev *indio_dev,
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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mutex_lock(&indio_dev->mlock);
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mutex_lock(&priv->lock);
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ret = mx25_gcq_get_raw_value(&indio_dev->dev, chan, priv, val);
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mutex_unlock(&indio_dev->mlock);
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mutex_unlock(&priv->lock);
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return ret;
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case IIO_CHAN_INFO_SCALE:
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@ -314,6 +323,8 @@ static int mx25_gcq_probe(struct platform_device *pdev)
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return PTR_ERR(priv->regs);
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}
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mutex_init(&priv->lock);
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init_completion(&priv->completed);
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ret = mx25_gcq_setup_cfgs(pdev, priv);
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