[PATCH AUTOSEL 4.19 061/177] iio: dac: ad7303: replace mlock with own lock

Sasha Levin
2019-12-10T21:43:34Z

From: Alexandru Ardelean <alexandru.ardelean@analog.com>

[ Upstream commit c991bf9b650f39481cf3c1137092d4754a2c75de ]

This change replaces indio_dev's mlock with the driver's own lock. The lock
is mostly needed to protect state when changing the `dac_cache` info.
The lock has been extended to `ad7303_read_raw()`, to make sure that the
cache is updated if an SPI-write is already in progress.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iio/dac/ad7303.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/dac/ad7303.c b/drivers/iio/dac/ad7303.c
index 8f3bd19b6dc35..dc1aea5b579e4 100644
--- a/drivers/iio/dac/ad7303.c
+++ b/drivers/iio/dac/ad7303.c
@@ -42,6 +42,7 @@ struct ad7303_state {
struct regulator *vdd_reg;
struct regulator *vref_reg;

+ struct mutex lock;
/*
* DMA (thus cache coherency maintenance) requires the
* transfer buffers to live in their own cache lines.
@@ -80,7 +81,7 @@ static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
if (ret)
return ret;

- mutex_lock(&indio_dev->mlock);
+ mutex_lock(&st->lock);

if (pwr_down)
st->config |= AD7303_CFG_POWER_DOWN(chan->channel);
@@ -91,7 +92,7 @@ static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
* mode, so just write one of the DAC channels again */
ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);

- mutex_unlock(&indio_dev->mlock);
+ mutex_unlock(&st->lock);
return len;
}

@@ -117,7 +118,9 @@ static int ad7303_read_raw(struct iio_dev *indio_dev,

switch (info) {
case IIO_CHAN_INFO_RAW:
+ mutex_lock(&st->lock);
*val = st->dac_cache[chan->channel];
+ mutex_unlock(&st->lock);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
vref_uv = ad7303_get_vref(st, chan);
@@ -145,11 +148,11 @@ static int ad7303_write_raw(struct iio_dev *indio_dev,
if (val >= (1 << chan->scan_type.realbits) || val < 0)
return -EINVAL;

- mutex_lock(&indio_dev->mlock);
+ mutex_lock(&st->lock);
ret = ad7303_write(st, chan->address, val);
if (ret == 0)
st->dac_cache[chan->channel] = val;
- mutex_unlock(&indio_dev->mlock);
+ mutex_unlock(&st->lock);
break;
default:
ret = -EINVAL;
@@ -212,6 +215,8 @@ static int ad7303_probe(struct spi_device *spi)

st->spi = spi;

+ mutex_init(&st->lock);
+
st->vdd_reg = devm_regulator_get(&spi->dev, "Vdd");
if (IS_ERR(st->vdd_reg))
return PTR_ERR(st->vdd_reg);
--
2.20.1