diff options
| author | Sergiu Cuciurean <sergiu.cuciurean@analog.com> | 2020-09-16 12:29:28 +0300 |
|---|---|---|
| committer | Jonathan Cameron <Jonathan.Cameron@huawei.com> | 2020-09-21 20:41:35 +0300 |
| commit | 8a0f412fca6e55765ad04c67037eb3907f0ad076 (patch) | |
| tree | ab53fd143e9b984061e4013163c94d58c2be0988 /drivers/iio | |
| parent | 3cef2e31b54b5975f45dfd7f88204bb78b03d535 (diff) | |
| download | linux-8a0f412fca6e55765ad04c67037eb3907f0ad076.tar.xz | |
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>
Diffstat (limited to 'drivers/iio')
| -rw-r--r-- | drivers/iio/adc/fsl-imx25-gcq.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c index 8cb51cf7a816..ab5139e911c3 100644 --- a/drivers/iio/adc/fsl-imx25-gcq.c +++ b/drivers/iio/adc/fsl-imx25-gcq.c @@ -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); |