diff options
Diffstat (limited to 'drivers/iio/adc/npcm_adc.c')
| -rw-r--r-- | drivers/iio/adc/npcm_adc.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/iio/adc/npcm_adc.c b/drivers/iio/adc/npcm_adc.c index d9d105920001..f7bc0bb7f112 100644 --- a/drivers/iio/adc/npcm_adc.c +++ b/drivers/iio/adc/npcm_adc.c @@ -25,6 +25,15 @@ struct npcm_adc { wait_queue_head_t wq; struct regulator *vref; struct reset_control *reset; + /* + * 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 event 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; }; /* ADC registers */ @@ -135,9 +144,9 @@ static int npcm_adc_read_raw(struct iio_dev *indio_dev, switch (mask) { case IIO_CHAN_INFO_RAW: - mutex_lock(&indio_dev->mlock); + mutex_lock(&info->lock); ret = npcm_adc_read(info, val, chan->channel); - mutex_unlock(&indio_dev->mlock); + mutex_unlock(&info->lock); if (ret) { dev_err(info->dev, "NPCM ADC read failed\n"); return ret; @@ -187,6 +196,8 @@ static int npcm_adc_probe(struct platform_device *pdev) return -ENOMEM; info = iio_priv(indio_dev); + mutex_init(&info->lock); + info->dev = &pdev->dev; info->regs = devm_platform_ioremap_resource(pdev, 0); |