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iio: adc: npcm_adc: 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 on the device's state structure.

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: Mircea Caprioru <mircea.caprioru@analog.com>
Link: https://lore.kernel.org/r/20200928131333.36646-3-mircea.caprioru@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Sergiu Cuciurean 2020-09-28 16:13:31 +03:00 committed by Jonathan Cameron
parent 3a27d11fbf
commit 08dfc6f8aa
1 changed files with 13 additions and 2 deletions
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15
drivers/iio/adc/npcm_adc.c
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@ -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);